cam selection

T

TheDon

New member
I've recently torn into a 304, po says it was bored .040 over. During the teardown, I removed the timing gear in hopes of getting some id on the cam. There was no indication/markings/etchings on the end of the cam, so Joe and I pulled the cam hoping to find some other indication of lift/duration-- no luck. Cam and cam bearings look to be in good physical condition (no scoring, no obvious uneven wear, etc).

The purpose of this sii is to be a daily driver-type. It's got d30/d44, 3.31 gears, stock height, street tires, 727. I've got an aluminum intake, and Mike mayben has got a Holley 4bbl on the way. In theory, a stock cam is probably fine, but I wouldn't mind a little extra "pep in the step" as long as it didn't destroy my fuel economy. A little highway oomf would be nice.

I will never be in the this engine again, so I'm weighing the expense of a new cam and cam bearings just to be on the safe side. I'm leaning towards new gear, just so I know its condition and what's really going on inside my engine.

The question to you more-experienced IH fellas is this:
-should I run the current cam without really knowing its type?

The follow-up question:
-if I go with the current cam/bearings, what precautions should I take before re-installation to help ensure the cam's success?
-if I get a new cam, what grind would you recommend? IH Parts America has a couple that look/sound pretty good, but I have no real experience to base opinions.

And this is a total rookie question, but when you order a new cam, does it come with new cam bearings? Or is that a separate order? If it's a separate order, which bearings would you recommend?
 
Don,
my choice would be to replace the cam and lifters now. Bearings are sold separately unless you buy an extensive kit which I am sure Jeff can do for you..

The stock IH grind was fine for the lower speed driving when your Scout was built but with todays speed demon drivers I would step up a bit.
Since you are putting on a 4 barrel carb you could stand to let your motor make more hp on the top lets say around 4000 but also gain mid and low end torque.. Keep the @ .050 duration in the 202-204 for the intake and 206-210 on the exhaust. This cam that Jeff sells would by good. While you are in the motor bump the compression up 1 point to 9.0-1. There are many ways to go about it. When you are ready post the question and some one will advise as to the best way. Really cam and compression go hand in hand. Bigger cam needs more static compression to maintain good low speed cylinder pressures. This is often over looked ant the performance will suffer

isky performance camshaft for IH v8 engines - IH Parts America Scout

The following suggestions are fore all engines in a basic sense and come from the building of many performance motors used in many different applications which include IH's

if you want to have more hp install it @ 110 intake lobe center line which should be straight up.. This will move your stock cams torque curve up in the rpm range 400-500 and most likely give you 25 - 30 more horsepower over stock

if you place more importance on torque and low end performance I would install the cam @ 108 intake lobe center which is 2 degrees advanced. This will allow the torque curve to mature 100-150 rpm sooner with no real affect on hp..

If you want still more performance the next level up would be this cam that ihon also sell

isky performance camshaft for IH v8 engines - IH Parts America Scout

I would stick this one it @ 105-106 intake lobe cl. Will give you more hp but with a small sacrifice in low end and vacuum. Advancing like I recommend will help counter this. Also recommend 9.5-1 compression especially if put in straight up.

Cam break-in is super important. Use a good high zinc oil (1200 ppm+) along with an adder for zinc (zddp) . Don't use a synthetic or blend during engine or cam break-in. The synthetic oils will inhibit lifter rotation due to the high slipperyness( word usage??).



Robert kenney
 
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Cam bearings are always a separate part don.

See this thread for discussion regarding that:

http://www.forums.IHPartsAmerica.com/basic-tech-questions/986-durabond-cam-bearing-spit-holes.html

Joe has seen the fallout from crapped oem cam bearing when he and joanna spent the week up here with us!

Personally, either the clevite 77 cam bearings aor the durabond bearings are equivalent in performance. But as ya can see, the durabonds May need some up close and personal "fitment" attention! But any cam bearing install needs careful installation, screw one up in the install, then ya have ta buy another set these days. Back in the day, ya could buy individual cam bearings through IH/navistar parts distribution.

Be safe, pull the cam, inspect the bearings. Even if you have to have a machine shop measure 'em for id/"roundness". And any damage is gonna be readily apparent inna visual inspection as you have seen from pics others have posted around here on that subject. When re-installing the cam, treat it just as if the cam bearings were new. Proper pre-lube of an engine build is imperative!

I fully agree with Robert's analysis regarding cam selection. And...ihon has other cam options available also now, both in "brand name" and in any grind ya wanna specify (within reason) from either new cam cores or welded/reground used cores. Those are not yet shown in the online store.

Since the cam gear is off now (I think?), then look on the gear and post the part number found on the cam gear. Particularly the r1, r2, or r3 suffix, that will help us track this kinda stuff. Also record all the details of stuff like that for future reference along with pics!
 
Also don...invest $20 or so inna "degree wheel", that is a tool yawl can share for the future! Learn how to use it (the instructions included with it are real decent!), right now you have the ability to do that easily and in comfort! And ya can get a good idea of what ya have for a cam in the process.

Just a sample reference for what we're talkin' here:

http://www.compcams.com/technical/catalogs/106-07/330-343.pdf
 
Thanks a lot guys! As usual, my education continues.

Sounds like I need to read up on the advice above and hopefully understand more of what's being said. "@ 110 intake lobe centerline" is greek to me. :icon_eek: there's a local engine builder who's got my heads now (to grind down the exhaust humps), so I might get him to install the cam and cam bearings. I'll try to be there to watch and learn, as I'd rather watch it done correctly before I do it myself.

I'll get numbers from the gears next time I'm over at Joe's, unless he sees this thread and wants to check it out. Yes, the cam gear is removed and the cam removed. I've been taking pictures of basically everything for documentation, but I didn't think to take pics of the gear.

I've got shell rotella oil for the engine, which seems to be recommended. Should I also run the additive during break-in, or is the rotella sufficient?

Robert, you mention new lifters... The lifters that I removed from this 304 looked pretty good, and Joe agreed. Worth new ones? Are they all about the same, or is there a preferred brand/design? I didn't see any on IH Parts America's website to reference.

I'll also have to look into options for bumping up compression a little, as well as degree wheel options.
 
thedon said:
thanks a lot guys! As usual, my education continues.





I've got shell rotella oil for the engine, which seems to be recommended. Should I also run the additive during break-in, or is the rotella sufficient?
Click to expand...

The oil dilemma is a touchy one. I like to error on the safe side and use a zddp adder. Jeff May sell one but if not GM sells a product called eos which can be added to your oil for added protection during initial start up. You will hear "you don't need the additive the oil is good enough!!!". Think about it this way, when or if you eat the cam will the nay sayers be there to help you out??? I doubt it..

thedon said:
Robert, you mention new lifters... The lifters that I removed from this 304 looked pretty good, and Joe agreed. Worth new ones? Are they all about the same, or is there a preferred brand/design? I didn't see any on IH Parts America's website to reference. ?.
Click to expand...

A new cam needs new lifters. While you break the cam in the lifters bed in to the surface of the new cam so they match exactly and will have a long life. Any cam manufacturer will tell you the same thing..

Lifters while basically the same are not created equal. Major cam grinders that I have dealt with seem to use only johnson made lifters. Jeff sells only johnson lifters. They are id'd by the swirl polished face not the dark parkerized face. This was covered in a recent post I made. Also got rid of an annoying tick I had on my new engine.

http://www.forums.IHPartsAmerica.com/basic-tech-questions/965-odd-lifter-wear-pattern-152-a.html

Rk
 
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Thanks Robert. I just got off the phone with Jeff, and he's got the lifters and bearings no problem.

We spoke for a few minutes about the cam itself, and we wanted to make sure some more details about the Scout and its intended use were understood before we committed to a particular cam. As I mentioned in the first post of this thread, the Scout is a 100% daily driver-type, with 3.31 gears, no lift, and street tires. The most it would ever see off-road is car camping and gravel roads. It might pull a small uhaul, utility trailer, or something every once in a while, but it'd be so occasional that it's hardly worth mentioning.

With that in mind, Jeff suggests this cam would be a little more pep but still keep economy in mind. What do you guys think?
isky performance camshaft for IH v8 engines - IH Parts America Scout

Though he did agree this cam was good (though a bit peppier and perhaps a little less economical):
isky performance camshaft for IH v8 engines - IH Parts America Scout

He didn't think anything more 'performance' was in-line with the Scout's intended use and set-up. What do you guys think? I'm totally at your recommendation here, as I know precisely bagel about cams.

Jeff has the green light to ship the cam which becomes the consensus opinion here.
 
Another option that I have here are the comp cams. I have yet to personally run one but dave the gearman highly recommends them. The grind that I have here in stock is part# ih260h-10. Specs are 260 duration(212 at .050 lift) with .440 lift and 110 lobe seperation. This cam seems to somewhat compare to the isky 190125/26.
 
Don,
I think you are ok either way. Jeff has more application specific info on real world installs of the cams he sells and I would say the difference is basically very small.

However you are doing some exhaust port modification to the heads so bigger cam will make more use of that. Advancing the bigger cam offsets some of the loss in economy but will give you more pep.

The bigger cam has tighter lobe centers that give you more overlap. This will effect idle vacuum but will give you a bigger torque peak at a higher rpm. There is always a trade off when choosing a cam.

I would go with the smaller cam Jeff recommends and the next time you build a motor you will know better which choice to make.

Robert
 
Robert kenney said:
don,
I think you are ok either way. Jeff has more application specific info on real world installs of the cams he sells and I would say the difference is basically very small.

However you are doing some exhaust port modification to the heads so bigger cam will make more use of that. Advancing the bigger cam offsets some of the loss in economy but will give you more pep.

The bigger cam has tighter lobe centers that give you more overlap. This will effect idle vacuum but will give you a bigger torque peak at a higher rpm. There is always a trade off when choosing a cam.

I would go with the smaller cam Jeff recommends and the next time you build a motor you will know better which choice to make.

Robert
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I'd have to 2nd w/Robert.I have that same cam in a 392-.030 over.w/johnson lifters,from napa.threw away the anti-pump up that came w/cam.28k miles an no issue's yet.has nice lope to it.very good for towing,thats why I went w/it.my next motor will have a 5-spd.,behind it an I'll prolly have charlie make me 1.
 
Cool fellas, thanks.

Jeff-- since you've never run the comp, I'm happy to be a 'test case' to confirm dave's opinion of the comp. His opinion is enough assurance to me that the comp will be fine.

Thanks for the feedback and advise everyone. I'll post some post-installation thoughts, observations, and mpg feedback on the comp.

Don
 
Iirc comp grinds their cams 4 degrees advanced. That is where I would put that one.
Remember the 212 duration @.050 will move your torque curve up another 200 rpm and needs the compression to be up from 8-1 that is stock. I think you will like the power of that cam better. It will make your IH pop.

Maybe Jeff cam post a cam card for us to admire.:gringrin:

Robert
 
Well, I guess now is the time to post the question about raising the compression.... When the cam and related bits come in from Jeff, I'll be installing them and putting the engine back together.

What would you recommend? Besides that I do some reading...... :gringrin: I know that I need to read up some, I'll do that this weekend. I just want to get some pointers on what I should be reading about.

There's a great summary from Tom mandera on bb in this thread, post #30. I'm not sure I'm ready to spend all that much money, as I'm already stretched thin as it is. Your thoughts?
345 build up!??! - binder bulletin forums
 
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Do you have an e 304 with the flat top pistons or the contoured pistons?

If you use the .045 thick composite head gaskets instead of the .022 thick steel only head gaskets you will need to address that also by decking the block .020 as that will lower the compression about 1/2 of a point

Robert
 
Flat type pistons. And the designation stamp on the engine says 304-a, if it matters. I'm pretty sure the head gaskets in my kit were steel, but I'll check.

So you're saying that the thinner, steel head gaskets and a .020 decking of the block would put me in a good place... Can he not deck the heads instead? The reason I ask is because he's already got my heads at his shop, but I'd have to tote that heavy mamma jamma block if he needs to deck it.
 
thedon said:
There's a great summary from Tom mandera on bb in this thread, post #30. I'm not sure I'm ready to spend all that much money, as I'm already stretched thin as it is. Your thoughts?
345 build up!??! - binder bulletin forums
Click to expand...


That is where we May have to go but that assumes a lot of guessing about where your compression will end up. The 0 decking is important for proper squish band/quench turbulance it May also bump your compression to much. You won't know that untill you cc the combustion chambers. May mm can do it on a core head of the same casting # as your heads. Then we can set you up perfectly. No guessing.

Really need a combustion chamber volume before you cut to much from the block. Also you will only need 90 # of seat pressure and 250 max open on the comp cam you chose.

Robert
 
thedon said:
flat type pistons. And the designation stamp on the engine says 304-a, if it matters. I'm pretty sure the head gaskets in my kit were steel, but I'll check.

So you're saying that the thinner, steel head gaskets and a .020 decking of the block would put me in a good place... Can he not deck the heads instead? The reason I ask is because he's already got my heads at his shop, but I'd have to tote that heavy mamma jamma block if he needs to deck it.
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If you got a recent kit from felpro or any of the others the head gaskets are probably composite. The intake and exhaust gaskets will be steel.

Many people have the block decked and the heads kissed to allow for the extra thickness of the composite head gaskets which will put your compression at stock. Additional machining of the mating surfaces is required to actually raise compression. You won't want compression over 9.5:1 if you intend to run pump regular. Mine is somewhere around 9-9.5:1 and has no trouble with pump gas.

The steel head gaskets haven't been made for a long time. I got some from Jeff campbell that I originally used in my engine assembly. With those gaskets I already had heads that were machined, ported, new valves/springs and so forth and I used a brand new 6" silicone carbide flat stone from sears with wd40 to dress the top of the block. It took a long time because of the hi nickle content but I eventually got it dressed flat enough with the stone. At least you won't have to take the block to the machinist but your arms might wish you did.
 
Also, when ya start shaving heads and blocks and playing with head and intake gasket thickness, the angle of the dangle of the intake manifold comes into play, it will also have to be "cut" for a proper match.

Once the long block "combo" is assembled/torqued, the machine shop will have to calc how much and what angle to cut the manifold. From that point forward, that rpt intake manifold will only match that particular motor setup (or another motor that has been dimensioned exactly the same).

So ya gotta lock in onna gasket combo too. The oem-type intake gaskets are steel shim and work just fine. But there are "options" involving composition intake gaskets out there as well as head gaskets. When ya get into this type rebuild (involving changing block/head dimensions), then ya must allow for the gaskets you will be using and have those on hand for verification at the time the machine work is calculated.

And if the valves are gonna be done (assuming the "installed height" is correctly set), then ya might need to look at push rod length.

All this is a "systems" approach that needs to be worked out in full before making any cuts! That insures no surprises at assembly time or after the motor goes back in the rig.

And regarding "compression" be aware of what the fuel limitations May be for this motor as a daily driver. If ya have to run premium fuel to take advantage of all the mods, then that will most definitely impact the budget! What I saw in norcal last week regarding kalifornikate "octane" for regular grade fuel was a real eye opener!

Beware trickledown! Advance planning is everything!
 
I've already gotten the full gasket kit from anything Scout, most of which was felpro. I don't have them in front of me at this moment to say what the head gaskets are made of. I wouldn't mind bumping up the compression a little to help with performance, but I'm not planning on investing a pile of money to get it. As it is, I'll have more in this motor than the rest of the Scout cost me!

I want the effort in this motor to be enjoyed after completion, but I don't want to be so broke after it's complete that I can't enjoy it. I'm trying to keep an eye out for project creep...

And I hesitate cutting the aluminum intake, as that would preclude me using it on another motor (should I want to swap it over later).

Edit: I do have the bbc valve springs, o-ring stem seals, and umbrella seals. But otherwise I had not planned to do any valve work.
 
Don,
if you set this motor up correctly you will need the piston @ tdc to be between .040 and .050 away from the head. The correct heads for the flat top pistons have the small d shaped chambers not the basically round chambers used on the non emissions motors. The chamber overhangs the piston bore. That creates the squish band that produces turbulence which make the air fuel mixture homogeneous. This inhibits detonation and slow burn rates. An engine with 8-1 and improper quench will have a higher octane requirement than an engine with 9-1 and proper quench.

Decking the block to compensate for the thicker head gasket won't change the manifold geometry because the assembled distances won't change. You need to dry assemble your motor and measure how fare the piston is in the hole @ tdc before we can go any further. These steps will ensure everything ends up correct and makes you a happy guy.

Rk
 
If I deck (I.e. Lower) the heads and/or block, the heads will ride lower. Even if I lower each head the same distance, the intake will get 'pinched' as the heads come a fraction closer (nearer the center of the crank means closer together). That would mean that any decking of the heads/block would result in a need to deck the intake manifold. Am I thinking wrong here?

I'll get the heads back next week and will be able to dry fit everything for inspection. I'll take pics of everything so we're not relying on my 'superior' mechanical descriptions... :sosp:
 
Don,
that is correct if you try to 0 deck the block. But if you only compensate for the thicker hg the geometry stays the same. That is why the dry mock assembly is so important. If your piston is in the hole .020 the cut for the hg will "0" deck and you will end up with a perfect quench distance of .040-.045"

the fact of the matter is even an extra .020 from the deck won't be that much if need.

Robert
 
Robert kenney said:
don,
but if you only compensate for the thicker hg the geometry stays the same.
Robert
Click to expand...

"I see," said the blind man. "as I spit into the wind, it all comes back to me..." that makes total sense, duh.

What's a reasonable cost for the decking work? My machinist is well respected, but his price to grind the exhaust humps was very reasonable. I'd like to have a data point before he and I talk turkey on the decking.

Based on the discussion above, the difference in height due to the composite head gasket is ~.023". So that sounds like what needs to go in order to bring it back to 'stock' compression. Then a bit further to up the compression? Obviously the dimensions are all dependant upon what I measure on the dry mock-up, I'm just trying to get the steps straight.
 
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Decking prices are not standard but iirc I payed $45.00 to deck .020 from the last sbc I built. Do it once after mock up measurements. Then maybe the heads will need it also but the block should be first.

Rk
 
I have decided that I'm not going to do any decking, but rather just roll with it. I think the compression will be good enough for now. This is no hot rod, and I'm itching to get the truck back on the road.

Jeff, I haven't heard anything on the order but I think you said the comp cam, lifters, and bearings were in stock... I'm hoping to have the cam, lifters, bearings here by Thursday (maybe Friday) afternoon if possible. Joe and I are trying to do the engine swap this weekend.
 
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