i have an engine out of a 86 c30 dually, it is standard deck. open chamber. oval port. running a th350 trans. Cast iron heads looking around online it says these choked down motors put out about an average of 230 horses (with original exhaust carb etc) and tons more of torque, i have a few questions first of all what compression ratio is the motor likely running at 9:1? and how can i tell? what kind of horsepower gain will i get out of an aluminum intake? (using weiand street warrior) what kind of horsepower gain will i get if i chopped down the exhaust pipes to 4 feet then installed gl*** packs? (exhaust manifolds sadly for now) last of all what kind of extra ponies will i get out of bolting on a 700 holley compared to a 600?? if that was a bit confusing here is a recap summary what kind of horsepower do you think i would get out of this setup (guestimations welcome) motor out of a c30 p/u ,454 oval port,open chamber cast iron cylinder heads, weiand street warrior intake, cherry bombs, 700 holley, th350, unsure on diff gears,12 bolt diff. going to install cam,lifters,springs,headers, as soon as i can round up the bucks. any suggestions here are also welcome. Thanks.
Not sure exactly but my mild BBC with a Comp cams 282, Edelbrock Performer RPM, 830Dp Holley Oval port heads with a bit of a clean up put out 480ish HP and 530lb ft on the dyno. CR was around 8.5-1. Managed to push my 56 to a 12.3 1/4 at 112mph using a DNE 5 speed and a 3.25 rear end with 29" tyres with a **** 60' time plus it still pulls down over 20mpg on a run. Does that help?? P.
change out the heads for the best bang for the buck upgrade or get some older rectangle port heads (not cheap). $1600 a pair http://www.carcraft.com/techarticles/ccrp_0803_big_block_cylinder_heads/index.html
Don't get rectangular port heads for a basically stock BBC. They're designed for racing or high performance, and will not work well with a 8.5 CR engine like you have. You should change the heads out, as those are the "peanut" heads and wont make much HP regardless of what else you do. Go to an older pair of oval port heads with the small combustion chamber, then put your intake, carb, cam and a set of headers with 2.5" dual exhaust behind it. You can easily pull over 400 HP and be very streetable.
I pulled the heads they are oval's not peanut, i dont know if they were switched i have the cast numbers though. i have another set laying around that need machining they are closed chamber (cast iron)
2 bolt, Plain Jane engine. Not sure on the head numbers but they are just nicely cleaned up with a little bit of work, nothing too fancy. It just works and it was quite cost effective to put together. P.
engine casting number 1401544 = 1975-87 454 truck and i had the head casting numbers i must have lost the paper, i will pull the valve cover and get back with you guys on that.
If they're not closed chamber, they're peanut heads. Put that pair of closed chamber heads on it. Only difference between the two is the chamber, but that makes an easy .5 point of CR. You want the larger 2.19/1.88" valaves that the earlier oval ports had.
im sure you know your stuff, but peanut ports are shaped like a peanut.or kidney bean. and the ports are damn close compared to the other set i have, and i continue to have power after the 4 grand range. also i ordered the oval port intake and its an exact fit,
There are small ovals and large ovals though, as i found by searching here is a picture of the large vs small ovals, ill see if i can find a peanut pic
what he said..for mild street you want oval port (intake runners) and closed combustion chamber similar to a bathtub not a peanut..you want velocity not volume for your application..600 carb is a little small..hope this helps
you might be right but why would the cast numbers come back as ovals? here is a mock up of peanuts with a rec gasket
The 91 TBI 454 I had in my work truck was 7.9 to 1. It had great off idle torque but fell on its face after 3 grand, not a performance motor by any means. They run forever if you change the oil...I had 350k on mine when I sold it and it still ran perfect. It still used only a half quart between changes, just like it did when I bought it at 60k Big parts, low compression,= no stress on the motor, they run forever.. But ya if you could come up with a set of heads that would bump compression. that would make a big difference, before you do cam lifters springs etc. Or maybe a set of cast flat tops and new rings...... Greg
Im going to dyno it later this week or maybe early next at school. i will post a link for a video, im thinking atleast 260-300 if she isnt too worn out. The max hp and torque at a certain rpm will prove for sure if they are peanuts. I doubt they are because when i did the intake they didnt look like midget ports as in the picture comparison above.
Your stock compression is probably about 8:1 and the cam is tiiiiiiny. That motor probably has flattop pistons with a small dish in the center. It only will make around 250hp in this configuration. It really needs some cam and compression to wake it up. The peanut port heads are actually ok up to about 400hp and 5000rpm. What I would try to do is find a set of early oval ports off of a 396 - they will have chambers that are 98 or 101cc's and bump you up a full point in compression. Don't worry about trying to find a set with 2.19 intake valves - no oval ports came with them stock, only retangle ports did. They do make a good upgrade however. Throw in a mild cam like the Comp XE268, and a decent intake like an Edelbrock Performer RPM or similar, and headers. BBC's really like headers. and you will be right around 400hp.
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