Upgraded heads recommendation for my 87?

[chris989]

Originally Posted by Skunksmash

Well I've pretty much got my answer. The 350 really isn't what I'm looking for. Another question for you:

Did you ever get the burb in the link dyno'd? I'd be curious to know what its final power numbers were. Also, what kind of mileage does it get around town, and on the highway. Also, have you verified that by doing the math at the gas pump.

Honestly even now, when not towing, I've got nearly no problem with the power the truck has. While of course its not "fast", it will get out of its own way. Its usable on the highway. I can pass other vehicles no problem, and use the fast lane without everyone trying to get around me and without drinking gas. I think that I actually like the gears that it has, pretty well. While I'm not going to win many races, it fulfills its function ok.

But I did say "nearly" no problem, cause we've all been to that place where we'd like that bump up to the next level in power.

I have not dyno'd the truck. I was waiting for one of those dyno days so it did not cost me so much $.

My butt dyno says 250/380 give or take. It tows every bit as nice as my 454 (290/410) but if i posted those numbers people would call BS.

I think nick has the right idea with the 342 gears. It is cheap, easy and easily reversible if you do not like it. it would be my first mod.

If you are going to swap heads, you may as well swap cams. From there it is easy to keep gong because in your head you say, "well i am down this far I may as well xyz". It starts to add up.

[Gregski]

Originally Posted by Skunksmash

My old truck just needs more power. Its not gutless, but its pretty far from great too. So I've got a few questions regarding upgrading the cylinder heads on my 1987 Silverado 5.7L. It has the stock engine. I'm looking to just bolt on a new upgraded set of heads (and maybe a few other necessary parts) and leave the stock bottom end. Not looking to pull the engine out or anything like that.


1. What are the best possible bang for the buck heads that will fit my 87 350, that are cast iron? Please be very specific because I'm not real familiar with this topic.

GM Chevrolet Performance Vortec cylinder heads ($50 bucks each used pulled from 1999 Chevrolet Suburbans at the junk yard)

Originally Posted by Skunksmash

2. What are the best bang for the buck heads, that are aluminum?

Blue Print by far best bang for the buck

H8002K - Heads - 195cc SB Chevy Head

Originally Posted by Skunksmash

3. Is there any reason I should buy aluminum instead of iron?

better cooling properties, pros / cons (lighter on your hands / heavier on your wallet, lol)

Originally Posted by Skunksmash

4. What kind of power increases can be expected from both sets? I assume that by now, that should be pretty well known by the 350 community.

as they say how much do you want to pay, you can spend crazy amounts of money to pay a machine shop that knows what they are doing to put bigger valves in pretty much any decent iron heads and port and polish them and make them 400 HP heads, it takes many many other components to deliver a total package, cam, rockers, pistons, carb, exhaust, etc.

visit the Chevrolet Performance website and select Small Block engines, you can sort them by horse power, torque or size and start clicking on them one by one then look at their output and read their specs, they list every part that goes into building that engine, even if you don't buy GM, you can see what the cylinder head specs were, or the cam specs, etc.

here's a chart for an engine called the 350 HO TURN-KEY with Vortec iron; 64-cc chambers Cylinder Heads (P/N 12558060):
Camshaft Type (P/N 24502476):Hydraulic flat tappet
Camshaft Lift (in.):.435 intake / .460 exhaust
Camshaft Duration (@.050 in.):212° intake / 222° exhaust

Originally Posted by Skunksmash

5. What other parts should also be bought at the same time, to maximize the potential of the new heads? Don't want my old stock parts to be choking them out and hindering their power somehow.

Cam ie Camshaft anything with 1/2 inch or less is a good cam for a street daily driver (1/2 inch in cam specs is .500 or less valve lift), after that your vacuum will be too low and your truck won't idle smoothly or good

this is street car recommendation not weekend warrior at the drag strip

Originally Posted by Skunksmash

6. Is there anything else that you think I should know, regarding such an upgrade? Please keep in mind that I just haven't dealt much with these old 350's. Aside from standard maintenance and just replacing consumable parts like spark plugs and distributor caps and oil pressure sending units and the like. Most of my work in daily life, is all done on modern engines, usually 4 cylinders like hondas and toyotas and such.

Watch out for the domino effect, sometimes when you change heads you will need new valve covers as there are two kinds, center bolt and outside bolt

also some heads (like the Vortec ones) have a different intake manifold angle and therefor require a special Vortec style intake manifold

and as always where do you stop, ok so you bought heads and a cam, might as well get new lifters, or do you? might as well get new push rods, or do you?, might as well get new rockers, or do you? hewk got a new cam so might as well replace the timing set (chain and sprockets) or do you? well since we took the water pump off to get the cam out no sense in bolting the old still working water pump back on might as well get a new one, or do you? etc. etc. etc.

put a plan down on paper with a budget, six months later when you are done, see how you've done

[LT7A]

Skunk, based on how you evaluated your truck's current performance, I'll summarize, "mostly happy with it", I think you can have some fun tweaking your small block since you don't need a lot more power. I have a 93 TBI motor (non-Vortec) that is pretty fun to drive and makes all the right noises. I ran a Flowmaster cat-back exhaust and felt the difference. I went to an open element air cleaner and that was a good change. I went to a high flow catalytic converter, and that helped. Next are mods to the TBI. I did the "salad bowl" under the air cleaner and that helped air flow. Google ultimate TBI mods. From there, the projects on the tbichips.com website actually give you a ton of good info, commentary, and recipes (for power, not grandma's sawdust and horse-hide biscuits).

You can progressively do the mods I have listed. None of them require a change in the ECU chip. Once you change the cam, you may need to get a custom chip. My understanding is that the Vortec heads are worth about 40-50 hp out of the box, if the intake and exhaust will flow enough to utilize them. You could do those heads down the road with the GMPP TBI manifold. Then add headers if you want. Regardless, if you have an accordion Y-pipe in the exhaust, you can replace it with a mandrel bent one or go to dual exhaust (spendy if you have to run cats). They stock Y-pipes are known to be a major restriction in the 88-98 trucks. If your system has a cat I would keep running a cat. It makes captain planet happy and keeps your computer seeing more of what it expects.

Bear in mind that low end torque is what you want if you are pushing tall gears, so use moderate exhaust diameter and moderate cam specs. If you do any driving in town, the shorter gears may save you gas there to balance the higher RPMs on the highway. The 3.42s may be a great compromise. I don't think we know how big/heavy your truck is (or isn't). I went with 3.73s instead of the standard 3.50s when I ordered my truck since it is an extended cab 4x4 and relatively heavy. My RPMs are about 1800 at 70 mph with a 4L60E.

Let us know what you decide to do and how it works out. Even if it's one thing at a time, I'll enjoy following along.

Thanks, LT7A