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Old 01-28-2013, 10:20 PM
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SBC Cylinder Head Suggestions

I currently have a 4-Bolt Main (grey caps) 350 chevy bored .040" over. Cast steel crank and a set of "powder" rods. The crank and rods were given to me by a friend and I had the necessary machine work done on them. I would like to replace the tired and worn out 305 in my 85' Chevy 4x4.

I'm at the point of considering cylinder heads, likely cast iron but possibly aluminum and cam selection, possibly even a roller.

Truck ways about 4000 lbs according to factory tag.

I would love to build a fairly high hp engine with some streetability. I was thinking around 400-450 hp would be doable, but being a 4x4 I don't want it to be a dog on the bottem rpm.

Any thoughts or suggestions would be appreciated.

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Old 01-28-2013, 11:05 PM
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build a longer stroke engine if you want torque.bigger engine makes it easier to get the horse power figures you are asking for. A 454 big block would be a really good choice,and a 502 would be excellent
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Old 01-28-2013, 11:34 PM
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Quote:
Originally Posted by vinniekq2 View Post
build a longer stroke engine if you want torque.bigger engine makes it easier to get the horse power figures you are asking for. A 454 big block would be a really good choice,and a 502 would be excellent
You have to appreciate the logic here. A bone-stock 454 would be the best option in my opinion. You'd likely spend less money too, finding a good-running BBC and selling your parts.
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Old 01-29-2013, 03:00 AM
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Quote:
Originally Posted by Mouser View Post
I currently have a 4-Bolt Main (grey caps) 350 chevy bored .040" over. Cast steel crank and a set of "powder" rods. The crank and rods were given to me by a friend and I had the necessary machine work done on them. I would like to replace the tired and worn out 305 in my 85' Chevy 4x4.

I'm at the point of considering cylinder heads, likely cast iron but possibly aluminum and cam selection, possibly even a roller.

Truck ways about 4000 lbs according to factory tag.

I would love to build a fairly high hp engine with some streetability. I was thinking around 400-450 hp would be doable, but being a 4x4 I don't want it to be a dog on the bottem rpm.

Any thoughts or suggestions would be appreciated.
A BBC is a natural for a truck. A BBC can make a LOT of torque- sometimes more than the rest of the driveline can deal with. Depending on what you're set up with now, this could mean some changes are needed for reliability.

If you want to stay w/a SBC, you'll want to build it as large as practical. So if you're starting out w/a 350, the next step upward is to use a 3-3/4" stroke crank to make a 383 stroker.

There are a bazillion 383 builds here and elsewhere, so no real point in going into it too much more until you've made a decision on what direction you'll take.

A few things that help boost the bottom end regardless of the engine size:
high velocity ports, which usually means a smaller port volume (170cc-180cc for a 350 SBC, 190cc-200cc for a 383; if using a 454 BBC even peanut port heads and a mild cam can easily make 450 hp/550 tq). For a sbc, aftermarket heads are preferred but Vortec production heads can be used if the compression ratio is kept in check. I don't personally care for swirl port sbc heads, but they can make decent torque
dual plane intake
Q-jet carb, or a carb sized on the smaller side
ignition timing curve set up correctly for the application
an earlier intake closing point
tighter lobe separation angle
compression adds torque, but too much compression can cause detonation so do not get carried away- match the CR to the gasoline you want to use and then spec the cam around that CR and vehicle needs.
long tube headers don't necessarily help the basement power but are a necessity to make good power overall. Keep the primaries at 1-5/8", using a free-flowing exhaust system. I use an H pipe connecting both sides, you can research this for yourself
use enough final drive ratio and converter stall (if AT) to match the cam and overall combo
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Old 01-29-2013, 02:57 PM
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Thanks for the good advice guys.

Food for thought:

I do have a 366 BBC Truck engine. I know they are not performance oriented but they do make lots of torque. Better set of heads and upgraded cam : keep the rpms 5k or less. I have read pros and cons but never anything very definitive. Any thoughts?
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Old 01-29-2013, 03:08 PM
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Useing the smallest CID engien of a engine family is a poor swap choice especially if you want 400-450hp as it will just as much to mod the 366BB to that power level as a 350 SBC.

The stock 366BBC is not even close to that power level and will need extensive changes to achieve that.

In a 4x4 ( that does not need to go fast (MPH) what you really want is raw torque, not horsepower.

If you want raw engine torque from and engine that does not rev high use a very large cubic inch engine.

If you want a lot of torque from a small engine rev it and gear the vehicle accordingly.
Or supercharge it. or both.

Swapping in a BBC has a weight penality that has to be accounted for to get a net benefit.
If you re going to a heavier engiene family you want a large CID version of that engine family.
a 366 Cid BBC is not a great choice. Especialy in stock form.

Find a 472 or a 500 Caddy motor. Raw low rpm torque. Bullet proof.
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Old 01-29-2013, 06:18 PM
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That makes good sense, thanks for the input.
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Old 01-30-2013, 03:20 AM
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Quote:
Originally Posted by Mouser View Post
That makes good sense, thanks for the input.
Any of the GM 455 engines can be a good choice. I've used Olds and Pontiac 455 engines and had good results from them both. The Olds was basically a stock rebuild from a wagon I put into a '76 Cutlass and even w/a car that big it was strong.

I installed a 455 Pontiac into a '78 K5 Blazer 4WD and it was a killer combo. I used an adapter plate and bolted the Pontiac up to the TH350 that was in it. The only compromise I had to make was because the owner didn't want to spring for a floor mounted shifter, so I had to run exhaust manifolds on it instead of headers. It cost a lot of power, but it might have helped the tranny to live.

Last edited by cobalt327; 01-30-2013 at 03:26 AM.
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Old 01-30-2013, 04:00 PM
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Quote:
Originally Posted by cobalt327 View Post
Any of the GM 455 engines can be a good choice. I've used Olds and Pontiac 455 engines and had good results from them both. The Olds was basically a stock rebuild from a wagon I put into a '76 Cutlass and even w/a car that big it was strong.

I installed a 455 Pontiac into a '78 K5 Blazer 4WD and it was a killer combo. I used an adapter plate and bolted the Pontiac up to the TH350 that was in it. The only compromise I had to make was because the owner didn't want to spring for a floor mounted shifter, so I had to run exhaust manifolds on it instead of headers. It cost a lot of power, but it might have helped the tranny to live.
Yup the 455 CID Oldsmobile and Buick and Pontiac V8's are just the ticket for this. Huge torque. !
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Old 01-30-2013, 08:53 PM
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Am I remembering correctly that torque is also directly related to compression?
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Old 01-30-2013, 10:28 PM
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Torque is part of the formula that explains power. Most engines are rated in kilowatts now,but no one cares. We want horse power figures,mostly for bragging rights.
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