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Final configuration of rebuilding my 502

Old 03-18-2018, 11:54 AM
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Default Final configuration of rebuilding my 502

It looks like finding a good ring pack for the stock 4.46 bore is a pita, so may as well punch it out to 4.5 bore, and my biggest question is upping my CR a good idea for 91 pump gas? Iím switching out the ZZ502 cam for the 168731 can which should bleed off a little more pressure, and SRP makes a -10cc piston that was made for the Edelbrock heads. It looks even if I deck the block .010 I should be at 10.25:1 at most, and thatís not including the bore notching and the fact that the Edelbrock heads tend to measure out closer 113cc according to the internet. Thoughts?

stock GM 4bolt 9.8 block
edelbrock Rpm Performer oval heads (advertised 110cc chambers)
Victor Jr intake
QF850m carb
Crane 731 cam
SRP pistons w/moly too ring
https://www.summitracing.com/parts/srp-212161-8
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Old 03-18-2018, 11:55 AM
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Old 03-18-2018, 12:06 PM
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Bore notch is about 1 cc give or take. I'm on way out the door but shouldn't you have not used -neg for piston volume. Just put in 10?
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Old 03-18-2018, 12:12 PM
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If you can find the cam card valve (timing events) for the zz cam post it. Also I may have mis read your first post with your piston being dome or dish. I can ck comp calculator also when I get back.
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Old 03-18-2018, 12:55 PM
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It should be +10 cc for a dish. That would give you 8.85

With a 3 cc dish, you'd be about 9.3 and adding 1 cc for bore notching would be 9.23

With flat tops you'd be at 9.5 and 9.43

Last edited by Griff; 03-18-2018 at 12:57 PM.
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Old 03-18-2018, 01:27 PM
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The Summit calc considers the area displaced by the dome, so a dish would be a + number. The stock piston a 1cc done and the replacements that I’m looking at are 10cc domes.
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Old 03-18-2018, 04:59 PM
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You could use a thicker MLS gasket .051, drop it down a little.
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Old 03-18-2018, 05:48 PM
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Originally Posted by GPM View Post
You could use a thicker MLS gasket .051, drop it down a little.
Adding a cc for the bore notch and the .051 brings it down to a fair enough level. What is a general rule of thumb for the highest CR that youíd be comfortable with on a N/A engine w/Al heads?

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Old 03-18-2018, 07:05 PM
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I'm not an engine builder, I would run it on 93 pump gas, I would run more cam though. Here's another calculator Compression Ratio Calculator | Tools | Diamond Racing Pistons
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Old 03-18-2018, 07:06 PM
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Looking through the old threads of the same question it looks to be prudent to keep it 9.8:1 and 34* max timing.
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