Another aluminum head question.

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DeCaff2007

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Alright, finally a question directly regarding a GMT400. We all know my junk by now... 89 RCSB 4.3L MT, swapping to a 94 5.7L and keeping the MT.

SO! I'm making the swap to aluminum, NON Vortec heads. Anything has to be better than those junk smogger heads that came with the engine. I've been doing so much research that my head is starting to confuse one set of heads for another. UGH!

AFR seems to be a top choice for budget vs performance and reliability, but here's the catch: I'm sticking with a stock cam, which is hydraulic tappet. Not going roller cam at this time.

I have these heads in mind right now: https://www.summitracing.com/parts/AFR-1006

Any suggestions? I know some of us here have gone this route, so the input is appreciated.
 

Vikingdude

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I looked long and hard at them. At the end of the day, I don't trust chinese metallurgy. Valve job is also done in China. China produces great castings, but struggles with great machining. Valves are installed in USA, but I don't know if they are checking concentricity. I would hope installed height is correct on the springs.
If I had gone with them, at the very least I would take them to a machine shop and have them gone over.

Flow numbers look great, and the price is right. It almost sounds too good to be true! They have sold a ton of them, but finding actual real world reviews is harder than I would have thought. Lots of "haven't installed yet but they look great" type of stuff. Most of them wind up on weekend cruisers, so I haven't seen any high mileage or daily driver reports.

I went with the summit vortec heads for my application. Cast iron, which handles heat a little better when towing, or offroading. They are at the machine shop now, getting springs replaced and a few things cleaned up.
 

Schurkey

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No exhaust crossover, therefore no EGR.

Vortec and "old" 6-bolt intake manifold bolt patterns. The TBI manifold won't fit without (at minimum) rework of the center two bolt holes on each side.

When I looked at my TBI manifold, I couldn't see how the thing could be ground-out enough to work. Going the other direction--from TBI bolt pattern on the heads, to "old 6-bolt" pattern on the manifold, is easy enough if you also have the angled washers.

I'd be asking whether the intake port entrance is Vortec-shaped. If it is, some 6-bolt manifolds won't cover the tops of the ports.

Perimeter bolts for the valve cover. You'll need different valve covers 'cause your original center-bolts won't work.

Angled spark plugs. "Good luck" with headers. I don't know about iron manifolds. May be OK.

Overall, not my first choice.
 

DeCaff2007

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Ok so those heads are pretty much a no go. I won't likely be doing much, if any, towing with this rig. Offroading? Eh, maybe. Revving the balls off the tach and having lots of fun with a 5-speed truck? Yes, definitely.

Fair enough. Any other suggestions?
 

PlayingWithTBI

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Any other suggestions?
These are direct replacement TBI heads kinda like the NLA Summit Racing ones but, more expensive (sold as 1 each instead of by the pair)

www.edelbrock.com/performer-small-block-chevy-cylinder-head-hydraulic-flat-tappet-cam-60859.html

 

Erik the Awful

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If I end up yanking the engine from WCJr for Roscoe, those AFRs are the heads I'm aiming for when I build another motor. Yes, the heads are cast in China, but AFR does the porting and final machine work.

They're set up for lighter 8mm valve stems like the LS uses instead of the older 11/32" valve stems (8.7mm). They use pushrod guides instead of self-aligning rockers. The intake manifold opening needs to be checked against whatever intake you're using, but that's neither an insurmountable nor even expensive problem. Putting a TBI on top of Vortec heads is a simple matter of a Vortec 4-barrel intake manifold and a TBI adapter.

Don't even bother with a flat-tappet hydraulic cam. Seriously. Make the jump now. Even swapping to a Vortec roller cam is an upgrade from the TBI cam.
LO5 cam
.382" / .401" lift
166 / 175 duration @ .050"
109° LSA

L31 cam
.414" / .428" lift
191 / 196 duration @ .050"
111° LSA
 

DeCaff2007

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If I end up yanking the engine from WCJr for Roscoe, those AFRs are the heads I'm aiming for when I build another motor. Yes, the heads are cast in China, but AFR does the porting and final machine work.

They're set up for lighter 8mm valve stems like the LS uses instead of the older 11/32" valve stems (8.7mm). They use pushrod guides instead of self-aligning rockers. The intake manifold opening needs to be checked against whatever intake you're using, but that's neither an insurmountable nor even expensive problem. Putting a TBI on top of Vortec heads is a simple matter of a Vortec 4-barrel intake manifold and a TBI adapter.

Don't even bother with a flat-tappet hydraulic cam. Seriously. Make the jump now. Even swapping to a Vortec roller cam is an upgrade from the TBI cam.
LO5 cam
.382" / .401" lift
166 / 175 duration @ .050"
109° LSA

L31 cam
.414" / .428" lift
191 / 196 duration @ .050"
111° LSA

Well, I already have an OEM Melling hydraulic flat tappet on order. I can return it, but there's a plethora of aftermarket cams out there. One never knows what to choose. Oh and did I mention it's EFFING expensive?

Back on topic, It seems there's just not many streetable options for aluminum heads.

Oh and the other big problem: Tuning the damn ECM. That's another reason I don't want to have a ridiculously lopey cam.

Maybe I should stick with the smogger heads I have now and just throw the stock cam in there. I know it'll be a dog, but there will also be less problems down the road.
 

PlayingWithTBI

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Oh and the other big problem: Tuning the damn ECM. That's another reason I don't want to have a ridiculously lopey cam.
That's why you ordered the EBL, right (get a WBO2 sensor too)? Nobody in their right mind wants a "lopey cam". Even with a 224/[email protected]", .525/.525" roller cam you can get it to idle smooth @~800RPM, plus give you torque and power throughout (maybe with a 2500 stall converter :rolleyes:).

Yes it is expensive (I spent ~$2200 for my roller cam and hardware) but, you'll go back into the engine soon to replace your flat tappet (and cam lobes) setup, then your block will be contaminated with all kinds of pretty metal flakes, just saying ;)
 

DeCaff2007

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That's why you ordered the EBL, right (get a WBO2 sensor too)? Nobody in their right mind wants a "lopey cam". Even with a 224/[email protected]", .525/.525" roller cam you can get it to idle smooth @~800RPM, plus give you torque and power throughout (maybe with a 2500 stall converter :rolleyes:).

Yes it is expensive (I spent ~$2200 for my roller cam and hardware) but, you'll go back into the engine soon to replace your flat tappet (and cam lobes) setup, then your block will be contaminated with all kinds of pretty metal flakes, just saying ;)

EBL? What's that?
 

Schurkey

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That's why you ordered the EBL, right (get a WBO2 sensor too)?
You're thinking of 351FUN.

Nobody in their right mind wants a "lopey cam". ;)
Thanks for that. SO true. Folks end up with a "lopey cam" as a side-effect of high-rpm tuning, or because they can't tune properly, not because lope is desirable in itself.

"Lope" is misfire. Misfire is a loss of power and fuel economy, coupled to an increase of catalyst-killing HC emissions.

EBL? What's that?
Check out 351FUN's thread.

I ordered the ebl this morning so I'm commited to that. It's 1/4 the price I'm used to for tuning and the benefits seem immense.
 
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