Head Swap Options For 5.7L 350 TBI Engine

[Sean Buick 76]

Personally having had some 700R-4 and 4L60E trans in my trucks over the years I never once let off or babied them. If the trans needs a rebuild it will tell you. But hey that’s just me I wouldn’t take my advice of driving them like they are stolen but it’s sure been fun and I’m not gonna stop!

 

[Sean Buick 76]

The trans I’ve been happy with is the 6 speed! Behind a cammed, headered 6.0 L-96 it’s been flawless for 10 years and I’m never easy on it.

 

[Majoraslayer]

So I guess I have a bigger question now, did GM ever make a good head for the 350, or are they all junk? I'm out $300 on Vortec heads at this point because 90% of the existing ones are already cracked or doomed to do so. They may have flowed great at one time, but at the price of being an engineering failure (or success, if you believe in planned obsolescence). Aftermarket heads cost as much as a complete LS engine. The consensus everywhere but this thread seems to be that TBI/TPI heads flow like trash, and every other head I've looked into seems to be considered only slightly less crack-prone than the Vortecs. The only exception is the 882 head, but sentiment around them seems to have shifted in recent years to calling them outdated and overrated. That only leaves aftermarket solutions that cost half the value of the entire truck. I've always thought the 350 was a good value for building because it had 50 years worth of parts availability, but I'm learning the hard way that most of those parts were made of paper and broken dreams.

 

[Schurkey]

apparently they're rated to withstand around 350 horsepower but are generally known to actually start blowing up around the 300 horsepower mark.

The (original?) trans in my '88 K1500 5.7L popped at ~230K; planetaries shredded, clutches cooked. Dead-stock TBI engine, nowhere close to 300 horsepower.

20 years later, (but only about 80K miles) the planetaries and the 2--4 band had had enough.

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When I was in the dealership in '84, emissions-choked V-6s and carb'ed V8s were tearing-up 700s as fast as we could rebuild 'em. There were incremental improvements over time, and a big upgrade in--I think--mid-year '87.

OTOH, my '03 Trailblazer has a ~275 hp DOHC six-popper, the 4L60E trans is original with a few fluid/filter changes, and still going strong at 280K miles and 21 years. The thing is old enough to vote and buy cigarettes. It does have an issue finding reverse when the temperature drops below freezing, first thing in the morning. Been doing that for about a decade, now.

did GM ever make a good head for the 350, or are they all junk?

Define "junk".

Nothing is perfect, especially in high-volume, cost-cut production vehicles.

I'm out $300 on Vortec heads at this point because 90% of the existing ones are already cracked or doomed to do so.

Did I miss that yours were tested and they found cracks? If they haven't been tested, it might be a good idea to do so before giving-up on them.

I've HEARD from everyone and his brother that Vortec heads crack like cheap drinking glasses...my favorite automotive machinist says he's never seen a cracked Vortec head. He has said that the Vortec heads that come on GM vehicles have head-gasket surfaces that are machined better than the Vortec heads that get sold over-the-counter at the GM Dealership. He says "I don't know how I would set-up my surface grinder to produce that bad of a surface." But that's his major complaint--improper machining, not cracks.

Aftermarket heads [NEW] cost as much as a complete [USED] LS engine.

FIFY. And hope that the LS you get doesn't have the heads made by Castech. GM has a bulletin on them...

Cracked Head Bulletin

www.gmfullsize.com

#06-06-01-019B: Information on Gradual Coolant Loss Over Time with No Evidence of Leak Found - (Jun 12, 2007)

every other head I've looked into seems to be considered only slightly less crack-prone than the Vortecs.

I think you're getting bad advice.

most of those parts were made of paper and broken dreams.

That's the nature of mass-produced items where cost is a concern. Nothing new there.

 

[Majoraslayer]

Did I miss that yours were tested and they found cracks? If they haven't been tested, it might be a good idea to do so before giving-up on them.

I've HEARD from everyone and his brother that Vortec heads crack like cheap drinking glasses...my favorite automotive machinist says he's never seen a cracked Vortec head. He has said that the Vortec heads that come on GM vehicles have head-gasket surfaces that are machined better than the Vortec heads that get sold over-the-counter at the GM Dealership. He says "I don't know how I would set-up my surface grinder to produce that bad of a surface." But that's his major complaint--improper machining, not cracks.

On three of them, I found cracks after getting them home and cleaning off rust myself. Another 3 I sent to the machine shop, where I received word today that magnaflux found cracks I couldn't see in two of them. I have one good head, and can't justify buying six more heads to gamble on one of them not being trash.

I get that it's my own fault for being stupid enough to try to learn any of this, but holy hell I can't catch a break.

 

[PlayingWithTBI]

I have a pair of "low mileage" 193 TBI heads you're welcome to. Just come and get them

 

[98 Nitro]

Sbc heads starting around 74 were thinner than those early muscle car heads. I have a set of 492's like 70 Vettes and Camaros had, with 2.02/1.6 valves that have been ported, definitely a heavier head than say Vortec/Tbi heads. But having said that both my 94 and 98 trucks have 200K miles on the original engines/heads so idk that they are really that prone to cracking. Junk yard heads are just that junk, buy stock rebuilt heads or new Mexican Vortecs or new aftermarket Vortecs.

 

[Erik the Awful]

Aftermarket heads cost as much as a complete LS engine.

You can get a pair of fully assembled AFR Enforcers for $1250. If that's too steep for you, DNA Motoring will sell you a cheap set of bare Chinese castings for under $500. Alternatively, you can probably beat the bushes and find a friend who has an uncracked pair of stock heads they'll throw at you for a case of beer.

But it sounds like you're looking for an excuse to jump at an LS swap. If you feel froggy, then jump.

my favorite automotive machinist says he's never seen a cracked Vortec head.

I'm no machinist, and about 2/3 of the Vortec heads I've seen had cracks. Two of those came out of my own Suburban. It's bad.

 

[Majoraslayer]

You can get a pair of fully assembled AFR Enforcers for $1250. If that's too steep for you, DNA Motoring will sell you a cheap set of bare Chinese castings for under $500. Alternatively, you can probably beat the bushes and find a friend who has an uncracked pair of stock heads they'll throw at you for a case of beer.

But it sounds like you're looking for an excuse to jump at an LS swap. If you feel froggy, then jump.

I'm definitely not interested in doing an LS swap, it's just a cost comparison.

I did find a seller on eBay that is a lot cheaper than the ~$1300 option from sites like JEGS or Summit. They're probably selling a cheap Chinese casting like you mentioned, which was my main concern when someone recommended them. However, I've had several people say their experience dealing with them worked out great, and unlike most Chineseum eBay dealers they also offer custom machining options for your order (.520 spring upgrades or anything else you need for an upcharge). They're based in North Carolina and offer the heads at $345 plus tax per head. As for getting anything local, I drove an hour away twice over the weekend just to end up with a garage full of cracked heads. I'm done gambling on them, and I'd never recommend anyone else do it either. The machine shop I took them to said that in all the used Vortec heads he checks, maybe one in every 7 will be any good without cracks.

 

[L31MaxExpress]

I'm definitely not interested in doing an LS swap, it's just a cost comparison.

I did find a seller on eBay that is a lot cheaper than the ~$1300 option from sites like JEGS or Summit. They're probably selling a cheap Chinese casting like you mentioned, which was my main concern when someone recommended them. However, I've had several people say their experience dealing with them worked out great, and unlike most Chineseum eBay dealers they also offer custom machining options for your order (.520 spring upgrades or anything else you need for an upcharge). They're based in North Carolina and offer the heads at $345 plus shipping per head. As for getting anything local, I drove an hour away twice over the weekend just to end up with a garage full of cracked heads. I'm done gambling on them, and I'd never recommend anyone else do it either. The machine shop I took them to said that in all the used Vortec heads he checks, maybe one in every 7 will be any good without cracks.

That is why the latest L31 I built has thickly cast Chinese Vortec clones. They were on my 99 Tahoe when I bought it and I kept them. I put a good used set of OE valves in them from a cracked pair, LS6 springs and Comp 787 retainers. Then smoothed up some casting imperfections in the ports and chambers.

For the money Dart Iron eagles are a heck of a head as well. They made or may even still make a Vortec replacement head as well.