big block questions

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dustinmoran91

dustinmoran91

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How thick is the stock steel shim headgasket on a 77-78 motor home 440? Im trying to squeeze the compression up a bit and was looking for thinner gaskets to go along with shaving the heads. And does anyone know the stock compression ratio, i come up with about 8:1 but want to double check that. And what was the factory horsepower rating? What i found says about 225 brake horsepower so thats about 250 crank right?
 
To my knowledge, BHP is read off the flywheel. I don't know for sure, but I was under the impression all the steel shim gaskets were .020" thickness; that being said, if you want to bump up compression, it's time to shave the heads or use different pistons.

What all are you looking to do? What's your HP goal? Ideas? Limitations?

Define your end goal first, and the setup of the engine will be more easily defined.
 
I dont want to tear into it because its still so fresh. It still has crosshatching and bearings are like new. I think ill just have the heads shaved down something like .030-.050 im not sure yet. Also i need to find the formula for how much to cut the intake when milling the heads that far. Id like to see 400 hp at the crank but i dont think that will happen without a turbo lol just to save the time, labor and money i might run it as is with headstuds and a turbo. Any idea what the torque numbers would be for a 440 with 250 bhp? Id think somewhere near 300 atleast?
 
...........measure how far down the pistons are...i've seem them down .150, thats maybe 7.5 to 1....u could get some 516 closed chamber heads.........kim.......
 
Kimmer is on to something there. Even with 8:1 CR, a good intake, well-tuned carb (about 700cfm or so), split pattern cam with around 220-225 @ 050, and some free flowing exhaust would work wonders.
 
Their about .150 in the hole. And i have 452's right now that were on it. Thats what i was thinking. I just build a magnum headed 318 with 9:1 compression, air gap intake, healthy cam and magnum manifolds. It should be around 300ish horsepower so i think an 8:1 440 witg an intake, cam, carb, headers and light port work should have atleast 350 horsepower and i hope aolt more torque.
 
Low compression 440's have been kicking *** in A bodies for decades. Traction is where to spend your time and effort.
 
I have a 76 440 that's been bored .030 over. The pistons are flat and are about .17 in the hole. I do have a fresh set of 915 closed chamber heads with HP sized exhaust valves. The cam is a Comp Xtreme 274 and so far my Duster has gone 12.69 @ 105 in the quarter. I feel that's pretty good for an 8.1 to 1 motor.
 
SlimPikins said:
I have a 76 440 that's been bored .030 over. The pistons are flat and are about .17 in the hole. I do have a fresh set of 915 closed chamber heads with HP sized exhaust valves. The cam is a Comp Xtreme 274 and so far my Duster has gone 12.69 @ 105 in the quarter. I feel that's pretty good for an 8.1 to 1 motor.
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Wow! Is it your blue duster? Mine is a 70 with full frame connectors, ford 8.8 with 3.73's a limited slip, 27/10.5/15 slicks and is gutted like a hog! Lol all .040 aluminum sheet floor front to rear and no interior. Should come in around 28-2900 pounds loaded with me in it and the 318 for now.
 
The low compression 440 should do very well in that car if you select the right cam, and get the heads breathing good. My car is full weight and I'm about 300 lbs.
 
I looked at 440source.com and read about some of the truck/rv blocks and they said some of them had extra material cast into the main web area and my block has the extra material there. It should be a pretty stout set up even with cast internals.
 
Abodybomber said:
Sounds like fun,wish I could find a $75.00 big block.
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I coudnt believe it! I saw it and thought it was gonna be another 318 but i looked anyway and it was a 440. I was so excited i pulled my phone out and called the office to see what it would cost. I almost crapped myself when i had enough money to buy it lol
 
dustinmoran91 said:
I dont want to tear into it because its still so fresh. It still has crosshatching and bearings are like new. I think ill just have the heads shaved down something like .030-.050 im not sure yet. Also i need to find the formula for how much to cut the intake when milling the heads that far. Id like to see 400 hp at the crank but i dont think that will happen without a turbo lol just to save the time, labor and money i might run it as is with headstuds and a turbo. Any idea what the torque numbers would be for a 440 with 250 bhp? Id think somewhere near 300 atleast?
Click to expand...

For every .010 cut off the deck surface you cut .0123 off the intake surface ,also be warned that the valley end rails would need to be cut that same .0123 , most don't do it and just force the valley gasket into place.
 
JohnRR said:
For every .010 cut off the deck surface you cut .0123 off the intake surface ,also be warned that the valley end rails would need to be cut that same .0123 , most don't do it and just force the valley gasket into place.
Click to expand...

Thanks! Im thinking i might just bolt it all back together with a bigger cam, better valve springs, new intake and carb. And add a turbo with 8pounds of boost max. I wont use this motor till a little down the road when im tired of my magnum headed 318 lol
 
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