Mark Pietz
Member
Got the pipe back from Jeff's, and now all painted and purdy. Put it in tomorrow.
Limited disassembly of a 1980 IC 196
- Thread starter Mark Pietz
- Start date
Mark Pietz
Member
All hooked up. The routing around the return fitting on the pump is busy but will be cleaned up later on. So I took it for a run. It's 85 degrees now, cooler than the other day when I flogged it, but the results are still worth noting. Instead of the oil running 210 degrees, it runs around 185 degrees, or about 25 degrees difference. I would like to run it over the same course on a 100 degree day for a true comparison. In any case, it now has a lot of capacity to pull heat out of the oil.
Robert Kenney
Super Moderator
Nice work, great results and write up.
Mark Pietz
Member
Robert,
thanks for the kudos. This was a learning experience, to be sure. Now, moving on the greater project. Here are some factoids that need digesting. I think the engine is sound and running well. Compression is within 5 lbs. On all cylinders, around 150 psi.; it's fairly quiet as far as an IH engine goes, getting 15 mpg "around town", possibly 20 mpg on the highway at steady state driving. I just took it down to be weighed with the travel top on it, a full tank, back seat installed, and all other junk removed. It has 31" tires on metal rims. Weight was 4,030 lbs.
My concern...I re-ran the hp using the iphone app, made a few runs, got one or two good ones. Getting clean runs is sketchy as I don't really have a great stretch where I can take my time and get clean launches and I'm watching for chp and other traffic. My previous hp readings need to be taken with the following variables in mind: my best, back in January, showed 89 and 90 wheel hp. The graph (have to use your imagination here since I don't know how to download it yet) of those runs clearly shows I get great acceleration in second gear, you see where 3rd comes in and pulls well. My shift points are very consistent here. On the runs today 3rd gear acceleration curve was much flatter. Best hp was 71 hp, yet I had a 2nd to best ever et (23.7 seconds). Something has changed but I don't know what. Maybe I had a wrong weight in the data. My thought is that I'll take this figure as my baseline until I can find a decent stretch to do more testing. But it really isn't all that bad, considering. We'll see what effect on et the turbo has.
Edit: re-examining the acceleration curves. I think I'm figuring out how this program works. It maps acceleration curves and reads out the highest peak (duh), but you can also clearly see your shift points. It will require a little more analysis but my best 90 hp measurement came after a shift into 4th gear and I still had the capacity to accelerate. I must have found the "magic point" to shift into 4th, but not in subsequent runs. Shifting after this point clearly shows a flattening in the curve (negative acceleration which we call "slowing"). In shifting into 4th after this point, you're so close to the end of the run that you can't recover the lost momentum and get no real acceleration in 4th. I ran my 2003 camry (with big six) through this, and you can see clearly where the automatic shifts into 3rd and you get that slowing down in the shift (like the Scout 727 shift into 3rd) and acceleration flattens out, and then recovers. That little bugger cranks out 124 hp at the wheels!
thanks for the kudos. This was a learning experience, to be sure. Now, moving on the greater project. Here are some factoids that need digesting. I think the engine is sound and running well. Compression is within 5 lbs. On all cylinders, around 150 psi.; it's fairly quiet as far as an IH engine goes, getting 15 mpg "around town", possibly 20 mpg on the highway at steady state driving. I just took it down to be weighed with the travel top on it, a full tank, back seat installed, and all other junk removed. It has 31" tires on metal rims. Weight was 4,030 lbs.
My concern...I re-ran the hp using the iphone app, made a few runs, got one or two good ones. Getting clean runs is sketchy as I don't really have a great stretch where I can take my time and get clean launches and I'm watching for chp and other traffic. My previous hp readings need to be taken with the following variables in mind: my best, back in January, showed 89 and 90 wheel hp. The graph (have to use your imagination here since I don't know how to download it yet) of those runs clearly shows I get great acceleration in second gear, you see where 3rd comes in and pulls well. My shift points are very consistent here. On the runs today 3rd gear acceleration curve was much flatter. Best hp was 71 hp, yet I had a 2nd to best ever et (23.7 seconds). Something has changed but I don't know what. Maybe I had a wrong weight in the data. My thought is that I'll take this figure as my baseline until I can find a decent stretch to do more testing. But it really isn't all that bad, considering. We'll see what effect on et the turbo has.
Edit: re-examining the acceleration curves. I think I'm figuring out how this program works. It maps acceleration curves and reads out the highest peak (duh), but you can also clearly see your shift points. It will require a little more analysis but my best 90 hp measurement came after a shift into 4th gear and I still had the capacity to accelerate. I must have found the "magic point" to shift into 4th, but not in subsequent runs. Shifting after this point clearly shows a flattening in the curve (negative acceleration which we call "slowing"). In shifting into 4th after this point, you're so close to the end of the run that you can't recover the lost momentum and get no real acceleration in 4th. I ran my 2003 camry (with big six) through this, and you can see clearly where the automatic shifts into 3rd and you get that slowing down in the shift (like the Scout 727 shift into 3rd) and acceleration flattens out, and then recovers. That little bugger cranks out 124 hp at the wheels!
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Mark Pietz
Member
Took the day off to begin reinstalling the turbo. Up on stands, removed old exhaust system, carb and linkage, installed 3-bolt manifold and wedge, and then the turbo. Took four hours. There is a sequence to how seemingly simple bolts and bits and pieces go on. These manifolds, etc. Must have been a pain for the IH mechanics to service in the field. Tomorrow bolt on the carb, fuel and oil lines. Hoping to have it running by Monday!
Mark Pietz
Member
I had forgotten how many little bits and pieces and contortions were required to reinstall this stuff. Breathing a sigh of relief that my adaptor-to-the-adaptor seems to line up right and that the carb can be set level and the turbo's outlet goes into the intake elbow fairly straight. Plan is still to fab a new one-piece adaptor for the corvair f-flow compressor housing.
Coming in for a landing, but still to do: bend up a new oil line; hook up the carb linkage and install air cleaner; hook up line for pcv valve and a few other vacuum lines. I was very unsatisfied with the throttle linkage, meaning the cable. Length and lack of flexibility make adaptation marginal. Real tempted this week to go to Jeff's and pick up a lokar cable.
Hope to fire up the beast this coming weekend. One thing I will do right before firing it up is to pull the cut down distributor and spin up the oil pressure like you'd do for an initial start after a rebuild. Although I was told that the turbo's oil feed needed to be from above, not below, and in thinking back on the last start-up, am now convinced that I wiped out the bearing on the initial start up. Marginal feed from below was the final blow after 50 miles. Weather was cold, engine had set a few weeks without running, and somehow I hadn't disabled the ignition while cranking it to build up oil pressure first. It fired off with a vengeance and I believe it didn't get oil in time before damage was done. It has some assembly lube on parts, but the damage was done.
Btw, that's an IH oem turbine housing heat shield. You tuck the ends around and wrap bailing wire around little metal buttons to secure. Simple.
The last two pictures are the beginnings of a modification I plan on adding additional bracing. I always felt that IH should have added some type of additional bracing and heard the stories of broken exhaust manifold parts. My plan is to have a plate of 3/16" plate 11 inches long by 5 inches wide (sort of a trapezoid, actually - see cardboard template) and sandwich one end between the coolant outlet and the t-stat housing. Measurements show a 2 1/4" hole will flow the coolant and I can add two additional bolts to the t-stat housing's unused holes. Today I tapped those for heli-coils for 3/8" bolts. The plate will slant along the t-stat's surface plane and end up right next to the bottom edge of the turbine housing. Fabbing a couple of little brackets to bolt the housing to the plate should provide additional support for peace of mind.
Coming in for a landing, but still to do: bend up a new oil line; hook up the carb linkage and install air cleaner; hook up line for pcv valve and a few other vacuum lines. I was very unsatisfied with the throttle linkage, meaning the cable. Length and lack of flexibility make adaptation marginal. Real tempted this week to go to Jeff's and pick up a lokar cable.
Hope to fire up the beast this coming weekend. One thing I will do right before firing it up is to pull the cut down distributor and spin up the oil pressure like you'd do for an initial start after a rebuild. Although I was told that the turbo's oil feed needed to be from above, not below, and in thinking back on the last start-up, am now convinced that I wiped out the bearing on the initial start up. Marginal feed from below was the final blow after 50 miles. Weather was cold, engine had set a few weeks without running, and somehow I hadn't disabled the ignition while cranking it to build up oil pressure first. It fired off with a vengeance and I believe it didn't get oil in time before damage was done. It has some assembly lube on parts, but the damage was done.
Btw, that's an IH oem turbine housing heat shield. You tuck the ends around and wrap bailing wire around little metal buttons to secure. Simple.
The last two pictures are the beginnings of a modification I plan on adding additional bracing. I always felt that IH should have added some type of additional bracing and heard the stories of broken exhaust manifold parts. My plan is to have a plate of 3/16" plate 11 inches long by 5 inches wide (sort of a trapezoid, actually - see cardboard template) and sandwich one end between the coolant outlet and the t-stat housing. Measurements show a 2 1/4" hole will flow the coolant and I can add two additional bolts to the t-stat housing's unused holes. Today I tapped those for heli-coils for 3/8" bolts. The plate will slant along the t-stat's surface plane and end up right next to the bottom edge of the turbine housing. Fabbing a couple of little brackets to bolt the housing to the plate should provide additional support for peace of mind.
Mark Pietz
Member
Coming in for a landing. The last few steps are like pulling teeth if you want to do things right. I was never happy with the throttle cable adaptation I did for the first iteration, which used the original (and very stiff) throttle cable and welding up a bracket to hold the end of the cable housing. So I went to Jeff's and bought a lokar universal unit. Omg. Why did I not think to do this in the first place. So I ditched the other home made bracket and welded up a simpler one that was so....right. The lokar's flexibility was also key to this. And I discovered a 30" 1/4" brake line is exactly the right length to go from the turbo to the oil gallery pick-off point which is where the oil pressure sending unit normally sits.
Still need to route the gas line and vapor canister line out of the way of the exhaust down-pipe. Melted one of them last time; now need to do a proper fix. Still puzzling that out. Am thinking of routing them inside the frame rail forward of the back of the wheel well.
Edit: this morning went over all nuts and bolts and hoses. I primed the turbo by spinning up the oil pump and oil came out the end of the feed tube within seconds, unlike before. In hooking it up to the turbo, priming again had oil coming out the drain line in maybe four or five seconds so I think that's a real good sign. I routed the nylon gas line through the frame for the time being and the nylon canister line up and over the heater box. "press the lapels" on that later, so those lines are now well away from the exhaust. Tomorrow morning's looking like a great time to fire'r 'er up!
Still need to route the gas line and vapor canister line out of the way of the exhaust down-pipe. Melted one of them last time; now need to do a proper fix. Still puzzling that out. Am thinking of routing them inside the frame rail forward of the back of the wheel well.
Edit: this morning went over all nuts and bolts and hoses. I primed the turbo by spinning up the oil pump and oil came out the end of the feed tube within seconds, unlike before. In hooking it up to the turbo, priming again had oil coming out the drain line in maybe four or five seconds so I think that's a real good sign. I routed the nylon gas line through the frame for the time being and the nylon canister line up and over the heater box. "press the lapels" on that later, so those lines are now well away from the exhaust. Tomorrow morning's looking like a great time to fire'r 'er up!
Attachments
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Mark Pietz
Member
It's ready for the test ride. I've tidied up as many details as I can think of. Fired it up yesterday...no leaks! Nothing fell off! With no smog pump 
, and three-bolt flange connections before and after the turbo, this engine is noticeably quieter. The extra mass of the exhaust manifolding and turbo soak up a lot of normal exhaust sound. I figured out how to clean up the mess of hoses and things that are just different. Last time, I didn't believe there was clearance between the valve cover mounted backfire fitting and bought a oil filler cap w/nipple and ran a long hose from it to the air cleaner. I now realize there was enough room and have added a pipe elbow and run the fitting horizontally, removing a lot of excess hose in the area under the turbo that is quite busy. This helps with running the heat stove hose from the cast iron elbow to the snorkel I grafted onto the corvair spyder air cleaner. I also added the snorkel thermostat and guess what - the hot air choke and snorkel actually work. I also pinched the check valve from the power brake booster of a volvo turbo brick and these are identical to what we use except it will withstand boost pressure going the other direction without blowing out. I'd hate to think what an air/fuel mixture would do to my brake booster. I added a metal bracket to keep the valve in place. In working on this thing I keep bumping the hose and dislodging the valve. Anyway, paying attention to these sorts of details, in my opinion, makes the difference between a fairly decent looking conversion vs. A hack-job where things haven't been thought through. I want everything on this to work and make it have good manners.
Edit: took it for a brief run. It's real hot outside and the corvair yh went into it's "heat soak" mode. It didn't do this with my run over a year ago because it was later winter/early spring and cool. This is a well known problem where the fuel pressure overcomes the float and floods it. The solution is two-fold: add a return line from the fuel filter area back to the tank (GM did this), and get a fuel pressure regulator and dial it down to 2-3 psi. That usually fixes it. But back to the run...this thing runs so smoothly compared to the 1940 Holley, and it gets boost effortlessly, and fairly early. I need a tank of premium before I dare push it further.
, and three-bolt flange connections before and after the turbo, this engine is noticeably quieter. The extra mass of the exhaust manifolding and turbo soak up a lot of normal exhaust sound. I figured out how to clean up the mess of hoses and things that are just different. Last time, I didn't believe there was clearance between the valve cover mounted backfire fitting and bought a oil filler cap w/nipple and ran a long hose from it to the air cleaner. I now realize there was enough room and have added a pipe elbow and run the fitting horizontally, removing a lot of excess hose in the area under the turbo that is quite busy. This helps with running the heat stove hose from the cast iron elbow to the snorkel I grafted onto the corvair spyder air cleaner. I also added the snorkel thermostat and guess what - the hot air choke and snorkel actually work. I also pinched the check valve from the power brake booster of a volvo turbo brick and these are identical to what we use except it will withstand boost pressure going the other direction without blowing out. I'd hate to think what an air/fuel mixture would do to my brake booster. I added a metal bracket to keep the valve in place. In working on this thing I keep bumping the hose and dislodging the valve. Anyway, paying attention to these sorts of details, in my opinion, makes the difference between a fairly decent looking conversion vs. A hack-job where things haven't been thought through. I want everything on this to work and make it have good manners. Edit: took it for a brief run. It's real hot outside and the corvair yh went into it's "heat soak" mode. It didn't do this with my run over a year ago because it was later winter/early spring and cool. This is a well known problem where the fuel pressure overcomes the float and floods it. The solution is two-fold: add a return line from the fuel filter area back to the tank (GM did this), and get a fuel pressure regulator and dial it down to 2-3 psi. That usually fixes it. But back to the run...this thing runs so smoothly compared to the 1940 Holley, and it gets boost effortlessly, and fairly early. I need a tank of premium before I dare push it further.
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Mark Pietz
Member
Update. The issues with the carb took me to the "go to" forum for the yh carb - a corvair site. After screwing around with this thing I believe I have found the cause of the problem of it dying after the choke comes off, plus there was a flat spot that wasn't there 18 months ago when I ran it in its first iteration. Somehow the float level got out of whack, as in set too low. That would explain these symptoms. And for other reasons I pulled the turbo (center section out to the carb as one unit - aren't v-clamps wonderful? That only took 15 minutes!). I discovered the carbon seal was leaking and there was oil inside the compressor housing. I have a spare seal to install (a repop updated seal assembly is $134, so I'll take my chances for now with a hopefully serviceable seasoned Piece), but needed to order a new left-hand nut that secures the compressor wheel to the turbine shaft. These are special, one-use only items. So it's on order, hopefully to arrive Friday or Saturday. I should have this critter up and running by early next week. Stay tuned.
Robert Kenney
Super Moderator
On the edge of my seat. 
Mark Pietz
Member
on the edge of my seat.
As am I, but my confidence was rattled. I thought I was so close, and Sunday was at the point of throwing in the towel and going back to stock until I could make another plan (we'll have to talk about that...which is probably my long term plan...). I was at Jeff's today buying a composite exhaust manifold gasket to put the 2-ear job on. My impression, based on just a couple of miles driving it the other day, was that the trw b flow turbo (with an f flow compressor) was actually sized right for the 196 that IH was bringing on line at the time. The 152, with its asthmatic breathing, low max rpm, and relatively deep 4.27 gearing, and the crappy t90, all conspired to make even the b flow "too large" for it. My rig, with 3.73 gears and the flexibility of a t19n, are ideal. I went back and looked at the map of the gt2554r you mentioned, and yes, that's a good map for what you think this 196 will do. It also is quite similar to the trw/rayjay f map, but of course the modern turbo is more efficient and all that. If I did efi and that gt would bolt to my t4 flange (with an adaptor) and all else clears and fits up, I think I'd have a hell of an engine. In the meantime, I'm cautiously optimistic that my analysis of all this will pan out. I'll be able to data log its performance, too.
Time will tell.
Mark Pietz
Member
Test ride. It's running better than it was, but the carb isn't giving a decent idle. Without smog junk on this you forget how Rich things ran. I think that this thing May run best with a stock needle/jet, but I have a +1 Rich rod in it now just so I don't run lean. I really need to slap an a/f meter on it to see where it is.
In this hilly area, boost comes on quick. Begins to pull in 2nd gear, 3rd is effortless with throttle. I can pull 5 lbs. In a blink. I haven't gone higher although I know it will. I put about 1/3 tank of premium in it (all it would handle) and will wait until I get a full tank of it before I press it more.
I have a spare yh, and it is the smaller one used on the 62-64 spyders. Thinking of cleaning it up and putting it on to act as a restriction before I know how this thing will operate.
Edit: one thing that really bothers me is the tremendous heat that pours off this thing. You have no idea. The Scout II engine compartment is cramped and restrictive and doesn't ventilate well. In a normal setup the exhaust manifold is set down low and is a little above the level of the bottom of the inner fender skirt. Hot air from the radiator comes down around this and exits near the frame. The exhaust manifold now protrudes away from the head a couple of more inches and with the essential oem heat shielding, crowds the space between the manifold and inner fender even more. There is now a lot more iron mass above it (elbow and turbine housing). There is now virtually no space around the heater box for heat to exit, and it's crowded around the much larger exhaust pipe exiting the turbo. I had put that reflective foil backed with that asphalt material used for sound deadening, in the interior on the firewall. It melted. When I opened the hood after my run, that panel with the smog decals was hot enough to burn you.
So I have a situation that is really unacceptable until a solution can be found. One thought is to modify the inner skirt - put a bulge in it about midway along its length - to create space so the heat can escape as before. The bulge would be fashioned so as to not be hit by the tire when it is in either lock position. Another option would be to put one of those louver panels in the hood. Not real crazy about that.
All this makes me curious about how much space there was in this area with the original 152t setup on a model 80. Maybe it sucked as well.
In this hilly area, boost comes on quick. Begins to pull in 2nd gear, 3rd is effortless with throttle. I can pull 5 lbs. In a blink. I haven't gone higher although I know it will. I put about 1/3 tank of premium in it (all it would handle) and will wait until I get a full tank of it before I press it more.
I have a spare yh, and it is the smaller one used on the 62-64 spyders. Thinking of cleaning it up and putting it on to act as a restriction before I know how this thing will operate.
Edit: one thing that really bothers me is the tremendous heat that pours off this thing. You have no idea. The Scout II engine compartment is cramped and restrictive and doesn't ventilate well. In a normal setup the exhaust manifold is set down low and is a little above the level of the bottom of the inner fender skirt. Hot air from the radiator comes down around this and exits near the frame. The exhaust manifold now protrudes away from the head a couple of more inches and with the essential oem heat shielding, crowds the space between the manifold and inner fender even more. There is now a lot more iron mass above it (elbow and turbine housing). There is now virtually no space around the heater box for heat to exit, and it's crowded around the much larger exhaust pipe exiting the turbo. I had put that reflective foil backed with that asphalt material used for sound deadening, in the interior on the firewall. It melted. When I opened the hood after my run, that panel with the smog decals was hot enough to burn you.
So I have a situation that is really unacceptable until a solution can be found. One thought is to modify the inner skirt - put a bulge in it about midway along its length - to create space so the heat can escape as before. The bulge would be fashioned so as to not be hit by the tire when it is in either lock position. Another option would be to put one of those louver panels in the hood. Not real crazy about that.
All this makes me curious about how much space there was in this area with the original 152t setup on a model 80. Maybe it sucked as well.
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Mark Pietz
Member
Update. Drove it again today. Carb is still rough at idle and cuts out when I let off the gas, as in slowing down in going round a corner. Losing steering and brakes is not a good thing.
So what to do. I obviously have some vacuum leaks. Before putting this on, the stock 1-bbl pulled a decent idle and 17.5" hg. Now I'm pulling 13, if that, and it's erratic. Spraying starting fluid (ether) around intake parts tells me I have leaks around at least two of the three studs that mount the carb adaptor to the other adaptor. I'll put o-rings and/or rtv under the nuts that hold things down. I've sent off for a carb kit. I had a fresh on in it 18 months ago but that was 18 months ago. And it idled like a sewing machine back then. Gaskets shrink and this thing has a real thick one, a stack, actually, between the throttle body and main body. Plus the accelerator pump does double duty in moderating the operation of the rod in the jet. They are known to leak or fail and modern fuels are not their friend. So it's time. I also just picked up a Holley 12-804 1-4psi fuel regulator to reduce pressure. I just slapped a pressure gauge on it and the stock mechanical pump is pushing out 5 1/2 pounds. The carter yh does not like pressure that high.
So after doing the diagnostics, I have a path forward for now. Oh, and I did push it a little more. Went to 6 pounds. I was pulling 4th gear and it pulled very smoothly and I was at 60 mph before I knew it, where before I'd be struggling. I'd say under those conditions it was pulling much like a 304. Not the push you back in the seat kind of thing, but more like a small v8.
So what to do. I obviously have some vacuum leaks. Before putting this on, the stock 1-bbl pulled a decent idle and 17.5" hg. Now I'm pulling 13, if that, and it's erratic. Spraying starting fluid (ether) around intake parts tells me I have leaks around at least two of the three studs that mount the carb adaptor to the other adaptor. I'll put o-rings and/or rtv under the nuts that hold things down. I've sent off for a carb kit. I had a fresh on in it 18 months ago but that was 18 months ago. And it idled like a sewing machine back then. Gaskets shrink and this thing has a real thick one, a stack, actually, between the throttle body and main body. Plus the accelerator pump does double duty in moderating the operation of the rod in the jet. They are known to leak or fail and modern fuels are not their friend. So it's time. I also just picked up a Holley 12-804 1-4psi fuel regulator to reduce pressure. I just slapped a pressure gauge on it and the stock mechanical pump is pushing out 5 1/2 pounds. The carter yh does not like pressure that high.
So after doing the diagnostics, I have a path forward for now. Oh, and I did push it a little more. Went to 6 pounds. I was pulling 4th gear and it pulled very smoothly and I was at 60 mph before I knew it, where before I'd be struggling. I'd say under those conditions it was pulling much like a 304. Not the push you back in the seat kind of thing, but more like a small v8.
Mark Pietz
Member
Just got the carb kit and other bits and pieces. Pulled the entire carb/adaptor/turbo assembly (again!) and it takes about 20 minutes - no biggie. There was engine oil in the turbo's outlet, so my next best used carbon seal was also leaking. I'm going to have to bite the big one and order a repop/updated seal ($$$). I am informed that a carbon seal that leaks oil is also a vacuum leak. Duh! This should hopefully put things right in the turbo.
My aem uego a/f meter will arrive tomorrow. I passed on the innovate after reading all the reviews. May not make any difference, they're comparable devices, but what the heck. In the meantime I also installed the Holley pressure regulator. Looks almost factory. It's pre-set at 2.7 psi. Should be an improvement.
My goal is to now get things back together so I can drive this thing to the IHPA meet in Grass Valley in two weeks!
My aem uego a/f meter will arrive tomorrow. I passed on the innovate after reading all the reviews. May not make any difference, they're comparable devices, but what the heck. In the meantime I also installed the Holley pressure regulator. Looks almost factory. It's pre-set at 2.7 psi. Should be an improvement.
My goal is to now get things back together so I can drive this thing to the IHPA meet in Grass Valley in two weeks!
FDChappie
Well-known member
A little late to chime in here, but I use a standard narrow band o2 sensor on my Scout to tune the carb. It outputs 0-1.1 vdc. I just hook a multi-meter up to it to read the mixture when needed. Definitely not as cool as an a/f gauge though, but it only cost $8.
Kudos on your stick-2-it-ive-ness with this project. Looks like you're almost there.
Kudos on your stick-2-it-ive-ness with this project. Looks like you're almost there.
Mark Pietz
Member
I have an old k&n a/f meter that runs off a narrow band sensor. I had hooked it up when I was playing with this about two years ago (it's been that long). But I wanted a setup I could data-log, hence the interest in the innovate lc-2, that interfaces with the megajolt and other systems. Then I discover that innovate sells a gauge with the guts inside that also exports a 0-5v signal as well as an analog signal (their mtx). So does aem. So hey, I could have a 2 1/16" gauge and also export to data log. But the real motivation is that for my purposes a wide band is more accurate, especially when under boost, which is the whole purpose of this in the first place. I want to be between 11:1 to 12:1 under boost so I don't melt pistons and things. Or so I am told. The absolutely wonderful benefit will be to keep an eye on the a/f gauge real-time as I'm blasting (or is that boosting?) with the other eye on the boost gauge. Gee, I'd look like marty feldman. Data logging is gravy on top of that. Robert May chime in here to fine-tune what the need is. I'm starting out Rich and am thinking I May end up with the original yh needle/jet combo, but I dare not take a chance that I am wrong. This morning I ordered the new, updated carbon seal. Hoping it arrives by Saturday and I can get it installed by Sunday, and hopefully have a day to run it before the gv meet.
Edit: took the yh apart. If you are familiar with these critters...I had to file flat the main body (zinc) flange that mates to an iron throttle body, and they put a thick stack of gaskets (around 1/2" thick) between them. It was bowed or warped (around 0.020" or so daylight between them) and I can see where the gaskets hardened and wouldn't seal. Idle passages run right up to the edge of this casting and gasket. No wonder it wouldn't idle, or maybe that was just one of several leaks. I filed the pieces flat enough - now about 0.002" rocking between them. And a little warpage on the top of the float bowl. Now filed down to a just a crack of daylight. I believe the gaskets will now seal up. Sheesh!
Edit: took the yh apart. If you are familiar with these critters...I had to file flat the main body (zinc) flange that mates to an iron throttle body, and they put a thick stack of gaskets (around 1/2" thick) between them. It was bowed or warped (around 0.020" or so daylight between them) and I can see where the gaskets hardened and wouldn't seal. Idle passages run right up to the edge of this casting and gasket. No wonder it wouldn't idle, or maybe that was just one of several leaks. I filed the pieces flat enough - now about 0.002" rocking between them. And a little warpage on the top of the float bowl. Now filed down to a just a crack of daylight. I believe the gaskets will now seal up. Sheesh!
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Robert Kenney
Super Moderator
That is what I liked about flying. The manual mixture adjustment.
50* Rich of peak egt (stoch) and your good to go. An insight engine monitor and you could watch egt and cht on all cylinders + tit (turbine inlet temperature).
So in your case leaner makes more power and boost more easily. You'll need to keep it Rich under boost but could run close to 14.5-1 in cruise to ambient/sea level map.
Does the have an enrichment valve or power valve?
50* Rich of peak egt (stoch) and your good to go. An insight engine monitor and you could watch egt and cht on all cylinders + tit (turbine inlet temperature).
So in your case leaner makes more power and boost more easily. You'll need to keep it Rich under boost but could run close to 14.5-1 in cruise to ambient/sea level map.
Does the have an enrichment valve or power valve?
Mark Pietz
Member
We touched on this quite a while back. No enrichment valve. This carb did well with the corvair because they gave it a needle that went over-Rich when under boost, but it was also over-Rich when not in boost. Indexing the vacuum circuit that positions the needle, upstream of the turbo, is a possibility. But for now it is what it is. I am confident I can get an acceptable compromise, and having an a/f meter is the tool that makes all things possible (or points out where things are impossible). If under hood clearance wasn't so tight, I'd consider an su, which has also been done. I like chappie's zenith-stromberg, too. If I didn't have the option of the yh, I don't know how far I would have gotten. Probably would have had to have jumped right to efi. I think my patron saint must be st. Jude - I seem to be drawn to hopeless mechanical things and old, obsolete technologies.
edit: the carb is now "surfaced". I knew there was a vacuum leak between the interface of the two adaptors and have discovered that one of the three threaded rod studs between them isn't aligned good enough and prevents them mating up flat. I need to hog out one of the holes passing through the original adaptor, unfortunately it's the longest passage. Fabbing a new, one piece adaptor will have to wait until after the gv meet. I'll have two triangular flanges made if I can't find an off-the-shelf flange at the specialty shop I go to for such things, and use heavy wall exhaust tubing in between.
edit: the carb is now "surfaced". I knew there was a vacuum leak between the interface of the two adaptors and have discovered that one of the three threaded rod studs between them isn't aligned good enough and prevents them mating up flat. I need to hog out one of the holes passing through the original adaptor, unfortunately it's the longest passage. Fabbing a new, one piece adaptor will have to wait until after the gv meet. I'll have two triangular flanges made if I can't find an off-the-shelf flange at the specialty shop I go to for such things, and use heavy wall exhaust tubing in between.
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Mark Pietz
Member
Spent the morning reassembling the turbo with a new, modern carbon seal assembly, and bolting everything together. I pre-lubed the turbo until oil came out the drain line and it fired right up. The carb has a goofy fast idle mechanism and it's set a little fast, but once everything warmed up and the choke came off, it settled down to a half-way decent idle. I'm pulling 17-18" hg, which is great. Sprayed starting fluid around the previously troublesome locations without noticeable effect, so hopefully my vacuum leaks have been fixed. Hoping to mount the a/f meter tomorrow, and then take it for a ride.
Getting closer!
Getting closer!