Shaun41178 they have changed their web site since I told them about the typo. My deck height on my 3.4 block varied from .007-. 025” so I just rounded off the number to come up with .016”. The deck height from engine to engine can vary quit a bit. They can be off as much as .150” on small block Chevy’s according to Ron from Aeric High Performance. For anyone to get the exact compression ratio for their engine they would have to do what I did and have the their heads cc’ed and they would have to measure their own deck height to calculate the compression ratio. The compression ratios I have given would be right on with my engine but they are only a rough estimate for all you guys with your sixty-degree engines. They are probably within two tenths of a point though from what you guys actually have. The ratios I have given are better than figures form a book or just guessing.

The basic equation goes like this, Compression Ratio = Swept Cylinder Volume + Combustion Volume/ Combustion Space Vol. I could break it down from there but I think you get the picture. The program does all the math for me so all I have to do is type in the values like head chamber volume, head gasket bore, head gasket thickness, deck height, bore, stroke, and volume above piston. The dish on the Silvolite 1486 piston is 12 cc not 8. If I changed the piston volume to 8cc and the deck height to 0 than the compression ratio would be 8.9-1 on a 3.1-liter engine with a .020 over bore. The head gasket volume is 7.28cc. I put a micrometer on my used (crushed) 3.4-liter head gasket and it measured .042”. Head gaskets can vary in thickness from one manufacturer to another so like I said before measuring the part you have in your engine is much more accurate than relying on what someone else told you. Your head gaskets for your 2.8-liter engine probably do measure .035”, I don’t know. The difference between a .042” and .035” thick head gasket is .1 or one tenth of a point in compression on your 3.1-liter engine.

N_Man you would have to get custom pushrods to correct the valve train geometry and yes you would have to mill the intake manifold. That to me is Havoc. If it were me I would also make sure there was enough meat on the deck surface so that the head gasket would seal reliably.

Eric you could get the GM 12363220 camshaft since you already have the right lifters, springs, and retainers for that camshaft and just swap the camshafts. The camshaft as you know is the brains of the whole operation and it is what dictates the kind of power your engine makes. Maybe this would change your mind. Here is a dyno of a 3.4-liter engine with a .030 over bore, Federal Mogul H684CP DOHC pistons that have a 9.63 compression ratio with a 0 deck height, ported heads, GM 12363220 cam, and FOCOA headers.

RPM Horsepower Torque
2000 86 224
2500 109 229
3000 133 233
3500 158 236
4000 181 237
4500 196 229
5000 207 217
5500 208 199
6000 200 175
6500 184 148

Here is the same engine with the GM12364059 camshaft
RPM Horsepower Torque
2000 87 228
2500 111 234
3000 136 238
3500 161 242
4000 183 240
4500 198 231
5000 202 213
5500 197 188
6000 179 156
6500 154 124

With the GM 12363220 camshaft in that 3.4-liter engine your 5-speed fiero would go 0-60 mph in 5.66 seconds and run the quarter mile in 13.91 seconds @ 98.3 mph. Your 60-foot time would be 2.17 seconds With the GM 12364056 camshaft the same fiero would go 0-60 mph in 5.78 seconds and run the quarter mile in 14.01 seconds @ 97.2 mph. Your 60-foot time would be 2.16 seconds.

If you add a fifty-shot of nitrous to that 3.4-liter engine with the GM12363220 cam your 0-60 mph time would be 4.72 seconds and you would run the quarter mile in 12.9 seconds @ 106.5 mph. You would have to launch off the line @ 1200 rpm though because you would just spin your tires with that much torque. Your 60-foot time would be a traction limited 2.016.

This is why I chose the build up a 3.4-liter engine.

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[This message has been edited by 88formula (edited 02-08-2001).]

I hate to say it, but there is a mistake being made about cams. The 12363220 and the 12364059 are the same cam. The big difference is 3220 is cam by itself, and the 4059 is cam with lifters. I know that the GM hi-pro catalog give different lobe separation (107* vs.112*). This is a misprint in the catalog. I know this because of where I work. I am a contract employee for GM. I work in the catalog department, and I help write the catalogs. I had never noticed this misprint untill some people were giving dyno results on the forum, so I went to the service engineer, he just laught, and show me that the cam you get in the kit 12364059 is the 12363220, and that crane even boxes it up for us. So if anyone wanted to know, the correct lobe sep. is 112* for both. Just one is with lifter, and one without.

[This message has been edited by Steven (edited 02-09-2001).]

Thanks for the heads up there Steve. So maybe we are back to either compression ratio or tuning. I think it is tuning as compression ratio doesn't give that much of a performance increase going from 8.5:1 to 9.5:1

We may never know for sure though I guess. Eric i would get that exhaust fixed, get it tuned on a dyno and see what kind of power you can make then.

Hey this is pretty crazy. I guess we're back where we started from. I'll get this thing on a dyno soon and then we'll have some more numbers to throw around at eachother. I checked out that guys website, Shaun. I didn't realize the chips would be that expensive, so I'm probably going to put that money into a new exhaust and a few dyno pulls before I make a decision on the bigger injectors and a chip. I wouldn't mind putting a 70 shot or so through the engine either, once I'm comfortable with it. So eventually I'll call your guy and have him pound out something.

I'm kind of suprised no one else who has a rebuilt 3.2 has joined in on our conversation. I'm sure there's a few more people out there with my setup who could share the insight.

Well if that is true than GM is losing money on the GM12364059 camshaft compared to the GM12363220 camshaft and ripping off the guys who are buying the GM12363220 camshaft that have to buy the lifters separately. GM could end up with a lawsuit for this if its true.

But again we are only going by what some unknown guy said and I don’t believe it. Someone with this camshaft should degree the GM12364059 camshaft to find out if this is really true. I will not believe that they are the same camshafts until I see the evidence that proves it. I will also bring this up with Ron from Aeric High performance. Guessing at this stuff is like gambling, sometimes you win but most of the time you lose.

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You know what, I try and pass on some info and I get a crap from someone saying that I am wrong. If you degree a cam. Make sure that it is the 12363220 cam, because that is the one that I (the unknown wrong guy) is stating is listed incorrectly in the GM Hi/Pro Catalog as having a 107* lobe separation. Hell if you like I will be here at work till 6:30 pm est tonight and back here Mon-Fri 9-6:30 pm (lunch is from 12:30-1 so I will be away from my desk) call me with a fax number, and I will send you the info. My number is 1-810-606-4234.

Why don't you post that information here for everyone to see not just me? Maybe some pictures of those numbers on the end of the camshafts would be good. This isn’t some childish flame war were egos are what matter and the way to get your opinion across is to curse me because I wanted to see the facts. I started this post to answer some ongoing questions about compression ratios and have an intelligent argument if it arose, not a childish cursing quarrel like you see on those F-body forums. This question has been going on here since this forum started and the last thing I want to do is have some guy come on here and start cursing me because he is annoyed when I ask him to prove his claim. I'm not "giving you crap" I'm asking you for some proof of your claim and not just for me but for everyone here that may believe you when you could be wrong. What if you are wrong and some people go on here believing that those camshafts are the same when they may not bet? I won’t let that happen.

You have already proven what kind of guy you are from your last post. There’s one thing you got right and that is I like to always be right but I don’t argue with facts. The gambling statement was an analogy not a bet against you.

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I do not have a scanner to put them on computer If anyone has one, I put my work number here. Call me on Monday, and I will fax it to them, and maybe they will post it. As to where to find the number on a cam go to www.cranecams.com it show where on the cam you can find the part number, and what some of the other numbers mean. I beleave that it is Cam Spec. Cards. You can enter the Crane Cam No. there, but just below that you will find a place to click asking something like "need help to id you cam" click on that and It tell where the number are and what they mean. Sorry about the ego, I have a hard time dealing with people when the just assume that I am wrong, because it goes against what they think. I would have acted differently if you had just asked to see my proof instead of stating you didn't beleave the word of some unknown guy. Sorry.

When I said “unknown guy” I meant your service engineer not you. You’re right I should have worded it differently and for that I apologize.

Instead of arguing with each other about this lets try to come up with an answer and prove that these two camshafts are either the same or not. I have the GM12363220 camshaft but it is at the machine shop so I cannot check the numbers on the camshaft until probably Tuesday or Wednesday. I should also have the block back by then so I can also degree the cam to confirm the numbers. I hope this camshaft doesn’t turn out to have a 112-lobe center instead of a 107-lobe center. That would really set me back.

I don’t have a scanner so I cannot post those pictures for you.

[This message has been edited by 88formula (edited 02-09-2001).]

Sounds like we both could have done thing differently. Hey If you want, I don't know what you do for a living, buy if you have a fax machine at your work, I would still fax it to you, and you could take a look at it and see if interpret it the same way. And who knows some one here on the forum must have a scanner, and I could fax it to them to post here for everyone to look at.

253901, that's the number that is on the camshaft and the installation manual. Steven, you're right about my cam at least. I gave the guy at the Chevy dealership a hard time about the part numbers not matching up with the performance parts book. 88, check your camshaft to see if the numbers match.

I had Ron form Aeric high performance check the number on the end of my GM 12363220 camshaft and the number on the end was not 253901 it was 256697. He said he could barely make out the number though because it was stamped on top of another number. When I pick up the motor this weekend I will confirm this for sure.

Also Ron says he knows the original owner of Crane Cams. He said that Camshaft Machine INC makes their camshafts along with 90% of all other camshafts.

I will also include pictures to back this up. Right now my camshaft is not the same as the GM 12364059 camshaft.

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Called Cranes Cam Tech support and talked to a Dave. He told me that the number 256697 is a core number. In other word it is the number of the cam before it is ground. Their ph# is (904) 258-6174.

88formula, You have e-mail from p_car_guy@yahoo.com. That is me. I sent you the info that I wanted to fax you. Hopefully you will have better luck putting it on the forum than I did.