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Old 10-13-2005, 11:58 AM   #1
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Default Increasing compression - Need scan help, please view!

I forgot to ask about valve clearances last time I had a topic about heads.... If I take .060" off a set of heads, will the pistons contact the valves? If you figure this in with a higher-lift cam profile, will I be in trouble? What kinds of clearances are we talking about in a Series 2?
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Old 10-13-2005, 12:30 PM   #2
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I know that you can take 0.040" off the heads (using stock size gaskets) with the most agressive GT cam and be ok.
Are you planning ok running headers? Your going to need flooow to battle KR.
I'm assuming you read this?:
http://www.zzperformance.com/latest_news1.php?id=48
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Old 10-13-2005, 02:45 PM   #3
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Yeah, I remember reading that some time ago. I didn't know if there were any special parts used to prevent piston-valve contact. The plan is to take .060" off and send the stock cam to CompCams for a regrind. Hopefully between those two things we can still use the stock pushrods and rockers to produce a bunch more power. It'll be a while before this project actually happens, but I'm trying to do my research now so it'll go as smoothly as possible. The plan is to get before-and-after dyno pulls to document the gains.

Speaking of the regrind: has anybody tried it with a stock Series 2 cam?
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Old 10-13-2005, 07:01 PM   #4
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I honestly can't imagine why it would be an issue. With a regrind, you should just have to time it right. You probably won't see over .530" lift at the seat. Additionally, when you send it in, get duration! about .5" of lift at the seat should be enough. If you want more later(and can handle it), get 1.9 rockers. So figure if you shave .060" off with a .5" lift at the seat, that'd be the same likelyhood of PTV with a cam that had .560" of lift at the seat. So the question is. The heads should handle .5" lift. I believe that it'll fit.

Heck, we got that block. We can bolt the heads on it first and put the cam in and give it a couple rotations to make sure.
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Old 10-13-2005, 07:58 PM   #5
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I would really talk to comp about the regrind. Sometimes you don't have to even change the pushrod size. It all depends on how much of the base circle needs to be cut down. Our lifters can adjust up to 0.015".
For the cam specs, I would stick to the proven GT cam series specs. They seem to have the best power curve. (not so peaky)
And you shouldn't have to time the cam. There are dots on the cam & crank gears to line up.
I'm thinking that you will need to custom mill the LIM to match up with the heads correctly if you go past 0.040".
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Old 10-13-2005, 08:23 PM   #6
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Quote:
Originally Posted by 95naSTA
I would really talk to comp about the regrind. Sometimes you don't have to even change the pushrod size. It all depends on how much of the base circle needs to be cut down. Our lifters can adjust up to 0.015".
For the cam specs, I would stick to the proven GT cam series specs. They seem to have the best power curve. (not so peaky)
And you shouldn't have to time the cam. There are dots on the cam & crank gears to line up.
I'm thinking that you will need to custom mill the LIM to match up with the heads correctly if you go past 0.040".
Well... Lining up dots is still timing in my books.... and it can be screwed up ! Good point on the LIM deal as well. Will let you know. Milling shouldn't be more than $20.00 on the LIM. Once the heads are milled we can put it together and see how it looks on the spare shortblock... address potential issues, etc.
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Old 10-13-2005, 08:57 PM   #7
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Ohh I ***-umed that you ment degree it. My fault.
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Old 10-13-2005, 09:13 PM   #8
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If you have a stock cam reground, you'll then need to have it rehardened. Truthfully, it'* just not worth the effort when there are plenty of proven N/A cam grinds out there that use new cores at fair prices.
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Old 10-14-2005, 02:06 AM   #9
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I know there are some great aftermarket cams out there Ed (or Scott, whichever one you are ), but from the research we've done I can get a regrind for about half the price of an INTENSE or ZZP cam. I'm pretty sure the process includes rehardening when CompCams does it. We'll have to double check, or maybe you know already?

This project is basically devoted to getting the most bang for your buck out of an L36. Doug has done a great job hand-porting the spare heads and LIM, so the plan is to mill the heads for increased compression and throw 'em on there to see what kind of numbers we come out with. As I said before, we'll do a stock baseline dyno, then get all the parts on there and do another pull to see what the gains are. If the regrind only costs $120 (which is what Comp quoted over the phone) we'll go that route just to save money. Ideally I'd like to send a stock cam to Comp and see what they can do with it so we know how much longer the pushrods need to be. Then we'll remove the corresponding amount from the heads in the hopes that we can have higher compression and a more aggressive cam while maintaining the stock valvetrain geometry.

Bottom line: we should be able to use stock pushrods and rockers, which will save lots of money. Remember, our goal here is not necessarily maximum N/A power; we're seeing how much power we can get for the lowest possible cost. Then, we'll pass the results on to the rest of the club, and hopefully there will be many members who benefit from our 'research.' Even if it'* not cost effective, at least we can say we tried to do it. It'* all a learning experience.

Let'* hear some feedback or comments on this strategy. I'd love to know if there are weak spots in my plan.
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Old 10-14-2005, 02:37 AM   #10
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Sounds like a good cost effective plan to me.
Hopefully comp dosen't have to take much off the cam though. I don't think the stock exhaust manifolds ported or not could flow enough to keep a high 10.x:1 compression ratio happy. (I figured your not going to want to buy headers)
Are you going to port the LIM, TB, and exhaust manifolds too?
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