tuning 2300

7

78IH

Member
I am rebuilding my 78 345e and decided to have the machinist zero deck the block in addition to boring 0.03 over. For now I will be using the sealed power replacment cam from northern auto parts. I am also using the 2bbl manifold. Its a 78 SLL 345/727/d20 SOA 4.56s and 35s. I also have a petronix flame thrower coil and ignition module with a prestolite distributor. I wondered what it would take to get it in tune. Could I just jump up a couple jet sizes w/ the stock carb? The machinist mentioned he had a used marine Holley 2bbl, off a 302. I am assuming this is the 300 cfm variation of the 2300s. He said we could probably get tuned right on the dyno, but to find out what size air bleeds and jets to start with. I hear alot about the 350 cfm 7448. Could I get this mairine carb to run as good? Or should I start with the 7448? He is gonna cc the heads, so I dont have the exact compression number. Also what plugs, gapped to what? Sorry about the specific tuning questions, I just want to get off to the right start.
 
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0 decked a .030 345 with stock heads and .040 thick composite head gaskets, will be real close to 9-1.
Assuming :)dita:) you are using the stock IH supplied carb and jetting I would leave it alone.

If you could supply some cam specs on the sp cam that would help.
Also what carb are you using? You don't want to over fuel a new engine. So for initial beak-in very easy jetting is perfered.
Nail the timing and break the cam in then put a few 100 miles on it. Then do a few plug checks before really getting in to teh throttle. You can be very lean in cruise porew settings with out hurting anything.
 
That's a good start regarding your engine details.

But I need to to know the detail of the carb you plan to use. Start off by posting the list number off the air horn along with well-focused pics of the same. I will determine the setup on the carb as it came and which variation it is. A true "marine" carb (whether Holley or any other brand) is a completely different animal as compared to a "street legal" or aftermarket performance mixer...very different! Most especially in the venting, choke, and idle circuits.

And if that carb has been sitting unused and open to the atmosphere and shop trash floating in the air, it begs to be reconditioned before attempting to put it into operation.

Only when it's totally disassembled will you know what's inside, and we can then work out a "base" set up for it. This is never a one size fits all kinda deal when you are dealing with performance tuning. The "air bleeds" in either the oem carb or the referred to aftermarket 7448 are not replaceable/tunable unless several aftermarket components have been changed out. The oem carb is a smog mixer and no tuning parts (other than the standard pattern Holley main jet) were ever produced for 'em. They are considered throwaways. The aftermarket tuning componentry for the venerable centerhung 2300 series is aimed at both the drag race and circle track market which are wot applications, not street-driven carbs.

I also need to know the part number of the distributor you have converted so that we'll know the advance curve set up which is critical to a decent dial-in. You can review all the threads in both "carb tech" and "ignition tech" and see that in nearly every new thread, how convoluted and intertwined this stuff is!

Has that distributor been rebuilt and had the mechanical advance snugged up? Has the end play been verified/corrected? The ignition you describe is a simple "upgraded" inductive design, not hardly state-of-the art in performance ignition circles by any stretch of the imagination. Max plug gap I'd ionize on that one is 0.040" using autolite 85 plugs a a basis for dial-in, do not change around heat range as that completely scruus with getting carb and ignition set up correctly, stay with one single plug number throughout this deal for repeatability in determining carb set up.

Nothing here indicates carb set up other than what was oem until it's tested! There is no magic formula, every engine set up will vary...you are not dealing with oem specs so all that can be thrown out.

Yes, having an ability to make multiple dyno runs is certainly a tuning aid for dial-in, but no dyno simulates real world drivability since they don't have gears, and tires, and drag, and frontal area, and wind load, parasitic loads (multiple) and ambient temperature anomalies, and fuel chemistry variations.
 
The Holley carb that came off reads r 7309 a over 465663 c91 over 2797 on the front of the fuel bowl. I was planning on replacing it with a reman carb from rock auto before I decided on zero decking and wondered about tuning. The distributor reads 484778091 over prestolite over idn 4002b 41 7. Its electronc but I havent converted it yet. It has not been rebuilt, snuged, or verified/ corrected. Havent gotten the marine carb numbers yet, or the cam specs. I dont own a camera yet did you want pictures of the #s or the carb? Thanks for all the help I will find out about the cam , carb #s.
 
The list 7309 is an oem "22xx" smogerator, you can see reference to those many times over in this sub-forum.

A true Holley or edelbrock "marine" carb is not an item I'd ever want to try and mount up onna street or street/offroad rig! Many reasons for that...they are "marine" carbs in order to meet coast guard-developed engine regulations, venting systems are different, much more expensive to service, choke won't be suitable,etc., etc. You are just asking for dial-in headaches!

By far the best carb solution if you stick with a 2v manifold is the often-pimped Holley centerhung 2300 performance aftermarket carb, list 7448 along with the installation of an electric choke kit (not available new with an electric choke, they must be converted). We talk about that one here nearly every day! And pics/set up info is outlined in many threads.

Your distributor p/n is 484778c91 and is actually a prestolite electronic p/n idn-4002b. That distributor was oem on m/y 1978 304 and 345 apps inna Scout II. The curve numbers will be fine for your engine if the distributor is in good condition overall, this is prolly the best version to have...performance-wise. There is no reason to do anything with it "conversion-wise", it's electronic trigger is still state of the art for conventional distributors, but it is capable of triggering an msd/mallory/accel/crane "6" series box and low primary resistance ignition coil for much improved ignition performance all around.
 
I definatly like the 7448 idea. And am pleasantly suprized that you sell them ready to go. Although im pondering wheather or not I can afford it now. I read about that side hung 2300 what is it the 2997? And I think I had one of those on 345 68 1200c. I know it was some 2300 variation. It worked great. Could I use one of those. Thank you very much for all the help. I think im gonna forget about the marine carb. But where can I find the cam specs?
 
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For cam/cam timing info see this thread:

http://www.forums.IHPartsAmerica.com/gas-engine-tech/1205-timing-set-indexing-sv-4-cyl-apps.html

I believe Robert has worked out the cam specs for an oem sv engine...if so, we'll get him to post the data in that thread or where he sees fit.

For any aftermarket cam, the specs will be found on the respective manufacturer's web site by looking up the part number for any cam in their lineup which is an IH application.

Any oem-style Holley 2300 as you mentioned would be an excellent choice for your engine also at a much more affordable cost. And we do have several of those cores available and can set one up for ya, or talk ya through the process. This kinda stuff comes and goes through the shop here all the time so when you are ready give Jeff a call and we'll work out the best soultion for ya within your budget.

If ya use an oem 2300 that was originally equipped with a hot air choke, those can be easily converted to full electric actuation. The oem 2300 carbs that were manual choke cannot be converted to electric choke, totally different main body! We currently have a few nice hot air choke cores that are candidates for this, any can be built for your use, and ya get all the tech help ya will ever need to make the carb play nice! Those would be set up and jetted so that very little additional tuning would be required once the motor is fired off.
 
Alright, so I searched the p/n cs 415 on the sealed power/fed mog site and came up w/ no results. I guess now would be a good time to ask why do people use degree wheels, should I bother to degree my stock-ish cam? I have a clevite timing set, dont have the # on hand though. I know this is carb tech but I just want to set it up right. Im glad to hear an oem 2300 can be set up. Ill be placing my order for one of those for sure. Those 6 series ignition systems look like they start around $150, so I cant fit it into my budget immediately. And the pertronix flame thrower 1.5 ohm coil I have isnt within IH specs. I cant remember why not, I lent my manual to the machinist. Will the original ignition system and coil be satisfactory for the time being as long as it is operating correctly?
 
Jesse b. said:
Robert,


clevite #cep2291415 has the following specs:

duration @ .050 lobe lift (intake): 188*
duration @ .050 lobe lift (exhaust): 178*
valve timing @ .050 lobe lift (intake opens): 17* atdc
valve timing @ .050 lobe lift (intake closes): 25* abdc
valve timing @ .050 lobe lift (exhaust opens): 19* bbdc
valve timing @ .050 lobe lift (exhaust closes): 21* btdc

thanks, jess
Click to expand...

The preceding valve event info was posted by Jesse and is from a stock replacement cam sold under the clevite logo. Seems real close to what the engine spec from IH calls out.

As for degreeing your cam. It is possibly the single most important step you cam do to assure the power is where it is supposed to be. If anyone tells you "don't bother it won't make any difference" They don't know how to build an engine. We/I have seen 10 degree discrepancies in cam timing when an engine is simply bolted together by lining up the factory timing marks. That is a 500-600 rpm shift in your torque curve.:icon_eek: that in some cases will make the rig undrivable. Take the time and go through the exercise of verifying the cam timing.
 
Ditto cam "degree" process, without verifying cam timing on a performance engine build yore pissin' in the wind and blowin' on all yore friends.

The pertronix coil which is manufactured/rated at a nominal 1.5 ohms is perfect for any IH (sv application, not I-4) oem/stock ignition system, whether running breaker points, Holley gold box electronic distributor, or the prestolite distributor (either points or electronic). I personally "like" a 1.8 ohm coil as the perfect unit when running breaker points but it's splitting hairs.

Only if incorporating any of the previously-mentioned "6 series" capacitive discharge ignition system boxes, would you use a "low resistance" (under 1.0 ohms primary value) coil, that will allow full advantage of any of those "boxes" in providing a secondary ignition side that will continuously provide a high energy ionization of a wide gap plug (no more than 0.050") on a conventional spark plug like the autolite 85 or champion equivalent. Those plugs are not designed to allow a gap greater than 0.050" without a potential for mechanical failure.

That recently intro'd ignition box under the "summit" label is simply a re-branded/boxed mallory hyfire 6. Who the hell needs a "rev limiter" onna IH motor...even a built one??

http://www.forums.IHPartsAmerica.com/ignition-tech/644-ignition-system-performance-upgrades.html

All the "stuff" I'm posting in that thread revolves around a "progressive" upgrade where ya select which distributor you will run first...then optimize the distributor mechanically...then add peripheral devices as the cash flows (or doesn't).

Any ignition system that will ionize all eight plugs at the proper moment in time will start and run the engine, upgrades can be phased in progressively as the budget allows.
 
I dont know how to build an engine. This is my first build, and originaly I wasn't going to do anything special. I don't remember reading anything about a degree wheel in my manual. I assumed:)dita:) that degree wheels were for people running performance cams, who wanted to set the timing to thier own specs, not the manufacturer's, moderater. But I figured :)dita:) I should find out for sure, and that although, this is carb tech you might be the right people to ask. Thank you again for your insight. Can you beleive I thought there was only one version of an electronic prestolite distributer for sv engines. Ohh how embarassing, but someday we'll be able to look back and laugh.
 
We all start from the same place when scruuin' with this stuff! I just got a major head start on most of the kidz around here and did most of my fuckups about 35 years ago, but it still occurs onna regular basis!

And you are dealing with a product that disappeared from the scene before many of ya were born! So how tha hail would anyone know to get an automotive technical education by going back in time??? I only know this shit 'cause I was teaching it when the shit was new! I can remember that stuff pretty good most days, it's what happened yesterday and an hour ago I have trouble with! That's why a buncha folks around here watch out for me and take care of my back!

After over ten years of playing with the various IH I-net resources out in cyberspace, it's a great feeling to look back and see how so many folks who had not a clue as to which hole to put the gas nozzle in, are now rebuilding engines, trannys, carbs, etc. Like real mechanics (I don't use the word "technician" in relation to this stuff).

Thank you for being honest in stating your position, that makes things much easier, we never wanna "talk" inna condescending manner...but we just never know what an individual's skill level and experiences are unless we start somewhere! Smokeblow has no place here at ihon!!

By the way...we are the right people to ask! And if we do not know the "right" answer to any question, we will find out or refer you to someone who does! Keep in mind, the knowledge base here in this forum grows every day. And I have engine builders from around the country call me onna regular basis asking questions after they figger out these dam tractor motors ain't chryfordrolets! I know that Jeff gets many more calls than I do and he's just a kid but he grew up with this IH legacy and is a quick learn!!!
 
78ih said:
I dont know how to build an engine. This is my first build, and originaly I wasn't going to do anything special. I don't remember reading anything about a degree wheel in my manual. I assumed:)dita:) that degree wheels were for people running performance cams, who wanted to set the timing to thier own specs, not the manufacturer's, moderater. But I figured :)dita:) I should find out for sure, and that although, this is carb tech you might be the right people to ask. Thank you again for your insight.
Click to expand...

Nothing condescending was meant by me. Just answering your inquiry. The fact that you asked was great. Most just bolt the things together and wonder why they don't run right.. I don't want that to happen to you.

Many cam grinders grind the cams straight up ( no advance or retard in the timing marks) but intent them to be put on a specific timing index (usually advanced 4*). You want to make sure that is where you put it. Historically aftermarket timing sets can have a lot of error in them so degreeing the cam is even more important.

I am writing this from my perspective based on my experience. I am not prone to make light of these build steps so don't take my recommendations as pointed in any way. Lets make this build a learning experience for you. We can walk you through all of the needed steps.
 
What would be done to this carb? Will it meet or exceed the quality of other reman carbs? I think I read that each carb is run on an engine to test. Do you test it with it jetted to that engine, then switch the jets for the customer? And how do you get the gas smell out before shipping? I liked the idea of the marine carb for the offroad advantages. But I understand that there are many factors in getting carbs tuned right. Will this carb run the way it should by just adjusting the 2 mixture screws properly, or could it require more? Should it be run lean at first on this new engine, or tuned right? Are these sold by ihon? I didnt see much about carbs advertised.
 
Our carb work is done on a custom basis after an extensive discussion with the customer/end user.

If needed, yes...I run any carb we provide. But most of the time that is not needed, I know how to set 'em up based upon experience with the various IH engines/platforms. We know what works...and what doesn't!

And right now, some of the "specs" I use are changing due to the forced use of e10 fuel supply.

Other than the restoration of the "factory" chromate finish on reconditioned carburetors, they are gonna be better than any other commercial rebuilt due to the fact they will be calibrated for the end user! There are times when we might use a commercial reman core, most especially if it is an oem list number for ihc and carries an IH part number on the air horn or body stamping...but it will be completely calibrated for the end user's application, this is not a "one size for all" kinda deal.

A true "marine" carb has no advantage in an offroad situation...where did that come from??? In fact, those will be far less "adaptable" in most cases...especially regarding the Holley product! Marine engine use and functionality has nothing in common with a street/trail rig in actual use other than they both burn gasoline (or e10 shit).

Any carb we ship (new or reconditioned) will start and run the engine. The fuel levels must be verified once the engine is operating, just like any new Holley carb taken out of the box! The idle mixture screws will be adjusted likewise, but the installer must make all final adjustments, same as installing any other engine part/component.

There is no difference in the carb set up for a fresh engine as compared to one with miles...major urban myth! Gas smell??? I suppose ya mean the "excess co" odor? Obviously ya have experience with carbs/ignition/engines not being tuned properly. 90% of the time regarding this IH stuff, that "co" odor is actually resulting from a idle mixture that is way lean! There is much detailed work involved with that...but I can provide you with a screen shot of a two gas analyzer (analog) with the details of the selected carb running on my highly tuned test mule....and that will also include a shot of actual vacuum reading at curb idle.

A fresh carb will never make up for an engine in a poor state of tune or that has mechanical issues....whether high mileage or "re-built". Example?....not verifying actual camshaft installation!
 
I'd like to throw in my 2 cents here.

There is no way to know for absolute sure how to set up a carb for a specific engine without installation and running on that engine. There's simply too many variables, including the "performance" parts on the engine, the altitude it will be used at, and the varying qualities of gasoline around this country.

Michael and the IHOnly boys do everything they can to provide a carb that will suit your specific needs. This includes tricks to optimize off-road performance. You won't get this quality and level of service anywhere else that I know of. Their experience means that they can usually pick the right jets and power-valve for your application, but it is possible that you'll have to make changes. This is why they offer unparalleled support after the purchase. They will work with you to get things perfect.
 
Ohh I thought I read you test run all the carbs, I meant how do you get the gasoline smell out of the carb before shipping. Robert said to go lean on that new engine, but that answers my question. If I understand, I will need to check/adjust the fuel level then make minor adjustments to the mixture screws? Or are there additional minor adjustments required that im not aware of? And I read about a build long ago where someone posted, reminding him to degree the cam. I knew I should find out about that before I put the thing together. I could have asked the machinist, not clear on the purpose of degreeing I decided to ask some guys with more IH experience. And I got the right answer. Is there anything in the service manuals about degree wheels? Mine are with the machinist. Also, this engine will need to run on premium right, because I read other discussions where people had similar compression and they were saying with the right tune you could run mid grade maybe even the cheap stuff? I should have asked sooner
 
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