I was wondering, what is the compression ratio of my 454? It has 049 heads (122 cc) and stock, flat top pistons. Thanks for your time!

http://www.rbracing-rsr.com/compstaticcalc.html

Ok, thanks. But I don't know much about 454's What is the bore and stroke of a stock 454? Also, since EVERYTHING is stock on this block, does anyone know what it is from experience? Thanks again!

Use this one at the ROSS RAcing Pistons site.

http://www.rosspistons.com/calculator.php

You are probably down about 7.76 to 1 or so CR. so a CC 260HE to NO bigger than a 268HE hy-cam should do you nicely!!

454;

4.25" bore;
4.00" stroke;
.025" down in the hole piston;
.035" to .045" quench
-5 to -6 cc's valve notch volume(??);
.020" steel shim headgasket;
6.135" long stock rod;

pdq67

PS., and fwiw, an old -206 closed chambered head at 96 to 98 cc's will up you CR to 9.2 to 9.34 to 1 AND that 268HE cam will really go!! Should border on being explosive, imho!!

What makes my compression so low!? I would like to raise it a little bit so i have some versatility with the cam (i want a lopey idle and am going to be putting in a hydroboost braking system so vacuum is not a worry). Can you lower the cc of the heads by shaving them? Is there a fairly cheap way of increasing the ratio to around 9-9.5? Thanks!

You just can't flat plane enough off a head that is 122 cc's to get it down to 96 or so cc that you need to create about 9+ CR up from 7+ CR.!

I can't say if max. angle machining a 122 cc head and then spot-facing the head-bolt holes and re-aligning the header flange and intake flange will even get it down to 96 cc's or so????

This is why I wish W/P's would make a true 290 cc large oval cast-iron el-cheapo head that was 90 cc's and used stock valve train stuff!

IT would be a real winner for us P/U motor guys b/c of our true flat-top pistons TERRIBLE CR!!

pdq67

[QUOTE=pdq67]You are probably down about 7.76 to 1 or so CR. so a CC 260HE to NO bigger than a 268HE hy-cam should do you nicely!!

[QUOTE]


I've run bigger cams than in stock 049 and 781 flat top 454's

the Crane 272H and the 221/230 .510/.515 Lunati Bracketmaster

You'd be suprised what those cams will do to a low compression 454 in regards to performance gains,both seat of the pants and ET
I would not go any bigger than those 2 cams
The Lunati really sounds nice and pulls well in a heavy M20/3.31 geared 70 Monte Carlo
Even stock those motors run well,low compression and all.
I recently put a stock 1973 454 into a 1980 Malibu with a 2800 flash stall and 3.42 gears,had those big Hooker Suoer Comp headers with a 2.24" exhaust,runs well right up to about 4800,although 4500 is more realistic.
Has a Performer and a 3310,and loves 87 octane
Does big silly burnouts too :D
The older closed chamber heads are ticket for some compression as pdq67 mentioned

So, Mr. 4 speed, if i had that lunati cam that you suggested, and 4.11 gears in the rear, about stock weight 71 chevelle, what range stall speed torque converter should i be looking at?Also, would that lunati cam pull enough vacuum to run my power brakes? (may need to put this motor in sooner than expected due to my current one's actions!! LOL, but notice i'm not really kicking and screaming about that!!!)

Right mr 4-speed,

I'm almost positive I canned a good CC 280 Magnum when I bought my '75 454 P/U motor and took it apart to haul home in the back of my '87 Chevy Sprint ER, 3-banger corn-popper!

I say this b/c I think it was the motor that belonged to the guy that worked for me and he put a CC 280 Magnum in his BUT he wouldn't own up to it being his that I bought! BUT he SURE looked funny when I canned the cam..

And, yes, it was a flat-top piston motor with good -781's on it AND hearing it run when he had it after he put the 280 cam in it DIDN'T impless me AT all!! Cam was tooooo BIG, imho b/c I figure the CR was below 8 to 1!!!

pdq67

PS., and fwiw, I bought the motor with a bad crank off an old used truck old man Buddy of his AND he worked for the old man on the weekends... And both of them had a funny look on their faces when I asked them who had owned the motor before the old man got it?

DARN good core motor for $300 so I was happy!!

So, Mr. 4 speed, if i had that lunati cam that you suggested, and 4.11 gears in the rear, about stock weight 71 chevelle, what range stall speed torque converter should i be looking at?Also, would that lunati cam pull enough vacuum to run my power brakes? (may need to put this motor in sooner than expected due to my current one's actions!! LOL, but notice i'm not really kicking and screaming about that!!!)

4.11 gear is too much...these motor makes so much low end torque and don't need to rev
No more than 3.73's are needed,3.55's would be perfect.
At any rate,a 255/60 or 275/60 would be a great tire size to have.
Use a B&M 2400 Holeshot,it will flash to about 2800 with a stock cammed 454,maybe a hair more with a mild cam like the ones I mentioned