L98 into K1500--> HEADS?

[Vettepilot]

Hey guys. 1994 GMC K1500 w/5.7 I'm fixing up. Use will be everyday. Sometimes spirited driving, some weekend offroad, but nothing very intense. Just "hold my beer" fun.

So I am going to replace the tired old 350 with a 1987 Corvette engine. I will freshen up the Vette engine first, though it runs good and uses no oil. It'll get a small, computer ok cam. Rpm 5000 to 5500. Will likely lose the TPI, maybe. (Yeah, I know it's only good to 4500. Man, do I know!)

The question is do I rebuild the aluminum Corvette heads, or just buy decent aftermarket?? The Corvette heads might have a small crack somewhere's, (which could be welded up), and definitely need guides and springs. I'm guessing 500$ to rebuild those.

Or, just go aftermarket? Whose for torque, and why??

Thanks!!
Vettepilot

 

[rebelyell]

I know those L98 (aka ZZ4 aka x113) heads somewhat. They're ancient tech; only redeeming qualities are they're alum, they fit Gen 1 sbc, and they have a tiny 58cc chamber that'll serve to raise compression on a dish-piston motor. As stock, they don't flow so much. Also, even when ported, their potential is rather limited; especially compared to what's available new & cheap today. Those heads have Loong been discontinued by GM; obsolete. Suggest not worth spending $500 to improve their limited potential. Suggest sell them as is. If ya want little chambers, TFS has a good USA head: DHC 175.

 

[Schurkey]

Look at what GM did with those heads on the ZZ-series of crate engines. Granted, the ZZ-series used upgraded components compared to the Corvette engine--but he'd be changing all of that anyway.

They're a fine ENTRY-LEVEL head.

If they're cracked...my advice might be very different.

 

[Vettepilot]

The Vette. It got run up to 280+ once. Then I bought it, fixed the radiator and have put a few thousand miles on it. While it passes a pressure test and runs cool now, it has always used some water. I figure there's a small crack somewhere. But being aluminum, if that's true it could be welded. It smoked like hell on startup until I put new valve seals on it, so I'm sure they need guides too.

How do the L98 aluminum Vette heads compare to Vortecs? (Just curious.)

Vettepilot

 

[Schurkey]

Vortecs are hard to beat as a budget-friendly head.

I would have thought that the Vortec head was "better" than the aluminum Corvette head, but GM went with the aluminum head on the ZZZ--ZZ4 engines. I can't remember what comes on the ZZ5.

It may be that GM went with the aluminum head simply because it bolted to the existing manifold, and "aluminum" justifies additional asking-price.

 

[Vettepilot]

If the L98 head was rather equal to the vaunted Vortecs, I would probably fix them and run them.

I'm not looking for high rpm horsepower on this one. Got other stuff for that...

Vettepilot

 

[rebelyell]

If the L98 head was rather equal to the vaunted Vortecs, I would probably fix them and run them.

I'm not looking for high rpm horsepower on this one. Got other stuff for that...

Vettepilot

But they're not. And it's fortunate that you already recognize that.
Neither their chambers are "fast burn" or are their intake ports anything like a Vortec casting.
The first version did not have a D-shape exhaust port; that came later.

It's my understanding the first priority of design criteria for what became the "fast burn" was efficiency.
Also consider an entirely new engine design (LS) was in the works during same period.

Performance ZZ-series that're Post-ZZ4 have a very good alum "fast burn" heads. Those are current, were never production heads but they're rather pricey. Compared to x113 aka ZZ4; apples & oranges.
Assembled head PN 19417591. First versions did not have "beehive springs" (as they currently do).
Like it or not, they have a so-called dual-pattern intake bolt pattern.

*EDIT GM's line of Circle Track race crates DID include a once popular "603" which was essentially a ZZ4 motor with a circletrack left turn pan and breathers. Also long obsolete and discontinued. I became rather familiar w/ 603 motors. It was supplanted by 604 with its aforementioned 19417591 heads.

 

[L31MaxExpress]

But they're not. And it's fortunate that you already recognize that.
Neither their chambers are "fast burn" or are their intake ports anything like a Vortec casting.
The first version did not have a D-shape exhaust port; that came later.

It's my understanding the first priority of design criteria for what became the "fast burn" was efficiency.
Also consider an entirely new engine design (LS) was in the works during same period.

Performance ZZ-series that're Post-ZZ4 have a very good alum "fast burn" heads. Those are current, were never production heads but they're rather pricey. Compared to x113 aka ZZ4; apples & oranges.
Assembled head PN 19417591. First versions did not have "beehive springs" (as they currently do).
Like it or not, they have a so-called dual-pattern intake bolt pattern.

*EDIT GM's line of Circle Track race crates DID include a once popular "603" which was essentially a ZZ4 motor with a circletrack left turn pan and breathers. Also long obsolete and discontinued. I became rather familiar w/ 603 motors. It was supplanted by 604 with its aforementioned 19417591 heads.

The aluminum 113 head is a better head than the crack prong garbage vortecs. It is worth putting a little money in a 113 head, would not put a penny into an OE Vortec. The 113s start out with a small 163cc port and still flow a bit over 200 cfm. A competent porter has no problem getting 260-270 cfm or more out of them. Fast burn is more than just a combustion chamber shape. Lingenfelter, SLP, and TPIS had some potent engine setups using 113s.

 

[Komet]

If you had good 113s or vortec heads, they would both be pretty good. I wouldn't put money into rebuilding them though, AFR Enforcers are going to outflow them both and having people weld and mill your 113s will likely cost the same.

You should keep the TPI, it's perfect for trucks.

 

[rebelyell]

The aluminum 113 head is a better head than the crack prong garbage vortecs. It is worth putting a little money in a 113 head, would not put a penny into an OE Vortec. The 113s start out with a small 163cc port and still flow a bit over 200 cfm. A competent porter has no problem getting 260-270 cfm or more out of them. Fast burn is more than just a combustion chamber shape. Lingenfelter, SLP, and TPIS had some potent engine setups using 113s.

Had ... until better heads came along from aftermarket / GM ... that's been a while.
If I had to guess, and even further back, land speed records were realized with flathead Fords ... until Navarro & Offenhauser came along.

Perhaps we'll agree to disagree; I'm a fan of OE Vortecs ... warts & all. Nothing's perfect. Anyone spending time in CT racing knows Vortecs are everywhere; de rigueur. Vast majority of grassroots V8 CT classes are dominated by Vortec motors; if they were so awful, that wouldn't be the case. Hence huge popularity of "602" CT racing in both Canada & USA.

Port Flow ain't necessarily the be all-end all; see Port Velocity. Neither is a 46* seat angle always best.

Sadly, AFAIK EngineQuest brand iron Vortecs are no longer available; they were a heavier casting.

Perhaps OP should First have his x113 / L98 heads professionally tested for cracks and/or leaks ... IF they have none ... and $500 will return them to a like-new condition And will suit his minimal needs ... then fix em.
Otherwise, move on to other heads.