Head Swap Options For 5.7L 350 TBI Engine

[L31MaxExpress]

You can buy the castings I have bare, but it is cheaper to get the Assault or DNA castings. I only used them because I had them and got them off the blown up 350 that came in the Tahoe.

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[Erik the Awful]

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.

Pay real close attention to "bare" versus "assembled". That's at least a $400 difference that makes the AFRs much more competitive.

DNA heads - $250 each - $500 for both, plus $400 worth of valves, springs, seals, rockers, retainers, and keepers puts you at $900 total, and you have to make sure your parts match the application.

AFR heads - $625 each - $1250 for both, plonk them on and go.

 

[98 Nitro]

An option if you are worried about cash upfront is to buy the Edelbrock Performer Centerbolt heads with the Affirm app. Or
both Jegs and Summit have the pay in four with PayPal. Dart and Trick Flow have 87-95 style available but mostly not in stock until Apr/May but Summit does show both 1 bare and 1 assembled TF 87-95 head. Also Jegs brand Vortecs are on sale if you prefer that route.

 

[Majoraslayer]

Pay real close attention to "bare" versus "assembled". That's at least a $400 difference that makes the AFRs much more competitive.

DNA heads - $250 each - $500 for both, plus $400 worth of valves, springs, seals, rockers, retainers, and keepers puts you at $900 total, and you have to make sure your parts match the application.

AFR heads - $625 each - $1250 for both, plonk them on and go.

The ones I'm looking at are fully assembled with valves and springs, "ready to bolt on".

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[Erik the Awful]

Yup, "fully assembled", which means "not fully assembled". They're $345 a piece and you'll still need rockers, which puts you at $800 if you go for self-aligning long-slots.

 

[Majoraslayer]

Yup, "fully assembled", which means "not fully assembled". They're $345 a piece and you'll still need rockers, which puts you at $800 if you go for self-aligning long-slots.

Is there any reason I can't just use the rockers I already have? Rockers go on after the head, lifters and rods are installed. I'm not sure what you mean by them being "not fully assembled". With springs and valves already on them, I don't know what else you would attach to them before they're on the engine. Are rockers something that's usually included otherwise?

 

[Schurkey]

Is there any reason I can't just use the rockers I already have?

Are they worn-out? Pretty likely, especially at the valve-tip end.

Are rockers something that's usually included otherwise?

No.

 

[Majoraslayer]

Are they worn-out? Pretty likely, especially at the valve-tip end.

You are indeed correct. I pulled the heads today, and noticed before taking everything apart that pretty much all of the rocker arms were sitting completely at an angle instead of centered on the valve. They didn't really have any excessive play in them, but they were very cockeyed. When I took them off, I found that not only had they been riding off-center but they had worn large divots off-center and were kinda stuck riding that way. I think they may have even worn in a bit on the rod side, as the rods kept trying to pull out with them.

I did find a good deal on a set of new OEM rocker arms for $40 without pivot balls, and Summit seems to sell those for around $30. The replacement rocker arms also seem to have a recessed spot to ride centered on the valve, instead of being designed completely flat on the bottom like the old ones.

 

[Erik the Awful]

'm not sure what you mean by them being "not fully assembled". With springs and valves already on them, I don't know what else you would attach to them before they're on the engine. Are rockers something that's usually included otherwise?

Doh! You're right. For some reason I thought the AFRs included rockers.

You can reuse the stock rockers if they're in good shape, but the stuff I've read says they flex under high loads and only give a 1.48:1 ratio. I'd reuse them on a mild build, but for anything with significant lift you'll need long slot rockers to avoid binding on the rocker stud.

 

[Schurkey]

The replacement rocker arms also seem to have a recessed spot to ride centered on the valve, instead of being designed completely flat on the bottom like the old ones.

WAITAMINUTE.

What cylinder heads do you have? I would expect that your engine requires "self-aligning" rocker arms--the ones with the recess in the valve tip end--and not the "completely flat on the bottom" kind.

The TBI and Vortec heads I've seen do not have pushrod guideplates, and they do not have pushrod holes in the heads that are oval--tight front-to-rear on the head, longer-slotted side-to-side on the head. The holes are round, and "large". Therefore, nothing guides the pushrod, and so the rockers have to be self-guiding.

If your heads have guideplates or oval holes, you CANNOT use self-guiding rockers. If you don't have guideplates or oval holes, you MUST use self-guiding rockers. You'll need to know how the heads you buy are set up, before you can buy rockers.