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Hey all,

So my engine is due to come out next weekend. I'm going over the build sheet from the guy I got the engine from and trying to figure out my current compression ratio. I'll be honest, I'm not a true through and through engine guy so I'm trying to get this sorted. (I just drive mostly:grin2:)

I have a 454 .060 over. The guy I got it from used Fel Pro gaskets.
-4.310" +10 cc forged Wiseco pistons
-heads are 119cc
-4" stroke

I'm not sure what the deck clearance is actually at. The decks were trued but not sure how much they took off. Playing around with some different clearances I'm showing between an 8.8:1 and 9:1 compression. Talking to my buddy he said there is no way, that he doesn't think the car would get out of its own way if it's compression was that low. With a tune that wasn't dialed in I ran a 12.4 at 109mph. I'm guessing I could dip in to the 11's with this setup. Does this seem right to you all in a full weight 70 Chevelle with TH400 with 3-3500 stall and 12bolt with 3.73's?

If it is that low, how would you all recommend bumping the compression or should I just not worry about it? I'm assuming a new set of pistons would be the only way to really go. I was hoping I was going to be able to pull the heads and have them gone through and a new cam since it came with the big mutha thmpr cam, now it looks like I might possibly have to do a little more.

Here all my goals for this setup. I'd like to hit low 11's or better with this setup NA. I won't make too much fuss if I'm not there. I do street it quite often and more so than the track and always run 93 octane.

-OEM block. Line honed, bored .060 and torque plate honed, decks were trued
-Wiseco Pistons Fully Forged +10cc dome 4.310"
-Genuine Scat Pro-Stock I beam with ARP cap screws 6.135" forged steel
-Genuine Scat cast nodular crankshaft 4.00"
-Aluminum Rectangle Port Heads (no name heads) 2.25in SS valves 1.88 ex 300 runners 119cc
-1.7 Scorpion Roller Rockers
-570/554 lift 243/257 duration cam (Big Mutha Thumper Cam)
-Edelbrock Vic Jr
-870 street avenger Holley

Thank you ahead of time for the help.
 

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Boldly procrastrinating
66 El Camino 57 Chevy pickup 2004 Tahoe
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4.310 4.00 .010 deck 4.4 x .039 gasket 118cc 10cc dome

I get about 8.96:1.

enough, and not so high that it prevents aggressive tuning. higher compression isn't better if limits your options on spark advance and carb jetting.

dump that noise maker and get a real cam. A hyd roller with the right springs.
 
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Tom is correct based on a .010 deck and an .039 gasket your at 9.1 which is fine to run the ets you want your CR is fine no need to change anything maybe .019 head gasket if your deck closer to .020 which typical factory most average rebuilds end up around .010 deck sounds like you had good machining if ring seal good leave it alone

Lots here run that cr and go 11's all about cam matched to the heads and car set up


just get a cam matched to your head flow and CR ........ carb is fine too yes you would be better off with a dual plane intake and some 1 7/8 headers ...... your cam is holding you back the most a roller in the 230/240 range 600 lift 110 lsa is pbly close then its all about getting it to 60'
 

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Boldly procrastrinating
66 El Camino 57 Chevy pickup 2004 Tahoe
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29,330 Posts
What Bill said. Check his sig for his results. 1.4 short time.

That Holley, does it have screw-in air bleeds?

Think seriously about offing that Vic and getting an RPM air gap.
 

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It will ET and MPH better with an RPM intake and 850 double pumper.
..IMHO and experience.
Along with a set of massaged 781's or 049's.


I took the rectangular ports at 12.5-1 along with the single plane off my motor.
Switched them to 781's, ( home ported ) an RPM Air Gap and 850dp and a smaller cam and went faster at 10.8-1comp.
 
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