350 head ?'s

[panhead59]

I've got a 1989 completely rebuilt 350 engine. (Center valve cover bolts). It's .030 0ver. It was rebuilt by PO. I pulled one head just to be sure. Intake valves measure darn near 2" Like 1 15/16. Hey I'm a carpenter not a machinist!!! My book says this is a truck motor that was rated at 210 HP. I know it was fuel injected, but that's gone so I plan on getting an intake since I've already got a good 650 carb. Why so little hp ? Anyway, I've got a chance to buy a set of dbl hump heads that have been maged, decked, new everything. For $500. I know that's a SMOKIN' price!! What are they worth ? 69 cc on comb. chamber. 202 intakes, hardened seats, even has roller rockers. Questions are 1- will they bolt up to my 89 350? 2- Owner says 69 cc would give me high 9's to 10.0 compression ratio, with stock pistons and stock ht. deck. Is that accurate and is that surpassing the 93 octane threshold? I know it's close for cast heads. Casting # 3947041 - my book list that as 69 vette heads or 300 hp Camaro,Nova, Chevelle. How much power/hp would these heads be over my 89 heads? Worth the cost? Thanks for any/all replies.

[Warrens69GMC]

The 210 is "net" horsepower not "gross". If you were to dyno it with a carb you would probably get close to 260-270hp. There are powertrain losses until you get to the rwhp (rear wheel horsepower).

These engines have a swirl in the chamber to promote torque to 4000 rpm while hp suffers.

Hp is a formula
Formula (RPM * T) / 5252=HP, where RPM is the engine speed, T is the torque, and 5,252 is rpms per second

Since most HP happens over 5000 rpm, that is why it is rated so low in these motors. The "swirl" stalls at 4000, not allowing HP to build.

What is your real goal with this motor?

There is no way I personally would by camel hump heads when new vortecs are just a little more.

[panhead59]

Goal is to have a good running sunday only driver on pump gas. Rebuilding/ restoring a 68 swb. Just gonna keep old 3 speed (till I break it!!) tranny for now, then who knows, maybe just a 4 speed muncie on the floor. Of course overdrive would be nice, but that's dreaming. But I am a product of the 50-60's so power is a must. I've got a 66 GTO w/sligthly built 455 ci. but still iron heads, to compare "power". I don't need that 450 HP or so, but I can't settle for 200 either. It's gotta have a little cam/ sound and be able to get out of it's own way!! I know that's vauge but hopefully u get my drift.

[chris mc bride]

IMO and 2 cents it worth. Bypass the old head hop up deal Normally cost more t han worth and borderline cost of new and way improved heads,Heads will make or break power level.

As for cam. I have had great luck with the Edlebrock combo's. Performer Rpm setup has great sound and power.Now if going to tow it might be over edge w/o gearing and OD would be extra nice there.Comp 268 to 274 XE cams would be next choice. Throw on good headers and free flowing exgaust and you should be rocking.

As for compression 10:1 not problem 10.5 tuned real well work great.Any more and pushing luck. For little you gain I would call 10 the high side. 400 to 425 hp Is not real hard with sbc.

[panhead59]

My motor has the stock heads for a 1989 350. Are these any good for what I am looking for? They are totally rebuilt and ready to to. I bought a rebuilt longblock. It was cheap. Also, my sisters boyfriend gave me this- New in box, never installed. Not even opened. Comp Cams Magnum Hyd. cam kit. K12-212-2. Cam,lifters,seals, timing chain, even springs in kit. Specs are- 280/280 advertised duration, 230/230 @ .050. 480/480 lift. lobe sep. 110. Says it fits 67-2002 350. I haven't pulled the cam out of the rebuilt engine yet but I would guess it's a stock equivalent. Not planning on towing with this truck. So here's the bottom line question- so far- If I use my heads and this cam, what kinda power will I get? Or should I bite the bullet with different heads ? I know heads are the key here. Maybe just mill heads to get desired comp. ratio. It's gotta be pretty lame for a 1989 engine. I would think. Again though, I need 0-60 torque for around town performance, not high end HP. No drag strip for this old truck. Just a very good running Sunday driver. Note- Wife will want Vintage A/C in the future I'm sure. What would you do ? NOTE-Pulled one head. I've got .110 between top of flat top piston and block.

[chris mc bride]

Piston is .110 below deck? Sure it was TDC ? .011 maybe?

[panhead59]

You were right to ? my measurement.,sir!!!! I was measureing from center of piston , not outter "ring" of piston, which is the hightest point. Sorry about that. How about .052 or .053? Hard for me to hold everything square and straight with the tools I am using.

[Tom]

Originally Posted by panhead59

Intake valves measure darn near 2" Like 1 15/16.

Factory intakes are 1.94"

Anyway, I've got a chance to buy a set of dbl hump heads that have been maged, decked, new everything. For $500. I know that's a SMOKIN' price!!

Smoking crack perhaps. Thats about the cost of new vortecs, which outflow even 2.02 valved humpers. Your already getting a new intake manifold so that makes the cash outlay the same. Just need self aligning rocker arms, stock on tons of stuff and super cheap.

[GRX]

"How much power/hp would these heads be over my 89 heads?"

Wait a minute and we can get out the crystal ball.
Seriously though. Any numbers would be guessing since you do not even know what you have now, only what a book said about a factory rating. Probably not too much different than what you are running now since the camshaft will be the same.

[Captainfab]

If it were me, I would use that Comp Magnum 280 cam kit and bolt a set of L31 Vortec heads on the short block (change the springs). Buy a Performer RPM intake and set a 600-670 cfm Holley on top of it. That should make a nice running engine with a little lope at idle.

[Ironangel]

Originally Posted by Tom

Factory intakes are 1.94"

Smoking crack perhaps.

Thats kinda rough Tom, the guy dont know thats why he's asking?

Originally Posted by Captainfab

If it were me, I would use that Comp Magnum 280 cam kit and bolt a set of L31 Vortec heads on the short block (change the springs). Buy a Performer RPM intake and set a 600-670 cfm Holley on top of it. That should make a nice running engine with a little lope at idle.

This! The Captain pretty well sums it up right here! Forget the double humps and just buy a set of plain Jane L-31 Vortec heads and have them reworked for the springs and cam in that kit. The kit is good as long as the heads (valve guides) are machined for those springs. A good machine shop will know what to do with that kit and a set of naked (new) Vortec heads. Get the Edelbrock Performer intake for a Vortec heads and top it all off with a good or new 650cfm carb and have a little monster of a small block!

[panhead59]

Thanks guys. Well most of you. Some people get a little cocky when not in person. No harm done. I know how to do a "Bryce Harper move" if necessary. I'll do just what was suggested, even though I wish I didn't have the added expense of new heads. But you play, you pay!!!! Thanks again!!!

[chris mc bride]

First rule of speed .SPEED COST and even more if Barney is around.Laughing my lawyer broke butt off.

[chris mc bride]

Agree skip the old head ,lots of monay and still less flow thing. Dbl humps great in 1965 but 52 years later we have too many way better options.

As for cam.230* at .050 for mild daily driver with some towing. Maybe 250* at .050 for more hot rod and no towing. Then we have the hey dude listen to this bad sounding mother that only makes power above 4500 rpm cams.

[61K10]

from what all that has been done to the old heads, not a bad deal if you don't need bolt holes. I would say they won't crack being a heavy casting. A vortec manifold is pretty $$$ also. have fun with what ever you build.

[DieselSJ]

Originally Posted by panhead59

My motor has the stock heads for a 1989 350. Are these any good for what I am looking for? They are totally rebuilt and ready to to. I bought a rebuilt longblock. It was cheap. Also, my sisters boyfriend gave me this- New in box, never installed. Not even opened. Comp Cams Magnum Hyd. cam kit. K12-212-2. Cam,lifters,seals, timing chain, even springs in kit. Specs are- 280/280 advertised duration, 230/230 @ .050. 480/480 lift. lobe sep. 110. Says it fits 67-2002 350. I haven't pulled the cam out of the rebuilt engine yet but I would guess it's a stock equivalent. Not planning on towing with this truck. So here's the bottom line question- so far- If I use my heads and this cam, what kinda power will I get? Or should I bite the bullet with different heads ? I know heads are the key here. Maybe just mill heads to get desired comp. ratio. It's gotta be pretty lame for a 1989 engine. I would think. Again though, I need 0-60 torque for around town performance, not high end HP. No drag strip for this old truck. Just a very good running Sunday driver. Note- Wife will want Vintage A/C in the future I'm sure. What would you do ? NOTE-Pulled one head. I've got .110 between top of flat top piston and block.

IMHO, 230 @ 050 is too much for stock compression. You want to keep that down under 220. With that motor I'd probably find something around 210-215 @ 050 which would give you much better torque and be much more fun on the street than that big cam. Big cam with stock compression makes them soggy on the bottom end. I had a basically stock 350 in my old CJ5 with an isky cam that was 208/212 @ 050 with a Performer intake. It was out of breath by 5000rpm, but it pulled hard over the entire RPM range and there wasn't much that could keep up through the top of 3rd gear.

[panhead59]

Lots of good info, thanks everyone.

[Warrens69GMC]

Brand new head, would require you to run a shim gasket-

https://www.summitracing.com/parts/sum-152123/overview/