Heads, let's talk....

[big_mike]

Ok, so I'm doing lots of parts research on my build and I'm trying to decide what the best route would be.

Port/polish/valve job stock heads
Or
Summit Racing replacement heads

I have had worked over stock heads on my LS motor and they were great while saving me about 1k over aftermarket heads. But with the vortec stock heads I have read there is a little extra machine work if you wanna run the LS springs and to get screw in rocker studs. But I have also heard from more than one engine builder to NEVER install aftermarket heads without checking valve runout and installed spring heights first. Apparently mass cast heads even if advertised with a valve job have outta tolerance valve specs, even brands like AFR. Now that doesn't mean they won't work but it's not optimal. I have never messed with aftermarket castings though, only worked over stock units.

 

[TylerZ281500]

everything mass produced has tolerance, which means everything and anything can be succeptable to this. i assume we are talking sbc. vortec intake? ill straight up say aluminums have gotten cheap enough that id just go with them. on the other hand, you shouldnt pay much for vortecs, they like to crack so sonic checking and magnafluxing will need to be tested. going aftermarket cast iron vortec repalcement may be a decent optionn if thats the route you plan. LS springs however fit right over. and screw in studs arent hard. the real effort is machining and facing off the decked surfaces.

 

[Keepinitoldskool]

Operator error, ignore post

 

[big_mike]

everything mass produced has tolerance, which means everything and anything can be succeptable to this. i assume we are talking sbc. vortec intake? ill straight up say aluminums have gotten cheap enough that id just go with them. on the other hand, you shouldnt pay much for vortecs, they like to crack so sonic checking and magnafluxing will need to be tested. going aftermarket cast iron vortec repalcement may be a decent optionn if thats the route you plan. LS springs however fit right over. and screw in studs arent hard. the real effort is machining and facing off the decked surfaces.

The motor I'm using is out of my 97' Z71 K1500. I'm gonna have the stock lower intake port/polished up some and delete the egr. The heads I was looking at are the Summit (dart) heads. They can be had fully assembled for about $700 with stainless valves. Then possibly a trip to the machine shop depending on the valve seat/guide tolerances. They are marketed as a replacement head not performance but are supposed to be a decent increase over completely stock heads.

I'm just wondering if port/polishing a stock head, tapping it, valve job, and spring set would be worth it. Would the Summit heads still outflow a worked stock set?

I wonder this cause I had a stock set of 5.3 LS heads done for my WS6 and they flowed right with the Patriot Performance Stage 3 which were $1600 at the time and I had $600 in those stock cast heads.

 

[slowburb]

Summit vortec < GM vortec. The architecture is not the same. What makes vortec vortec is the raised intake port. Summit vortec heads do not have this. They are old school sbc heads with more bolt holes. Do not count on them to even perform equal to a pair of 062/906 gm vortec castings. Period.

If you want aftermarket, maybe the edelbrock etec 170s are still around. Maybe the RHS or EQ castings. Either of those I would want a machine shop to check over, but big name aftermarket like edelbrock or AFR, you're fine to bolt them on and go.

I was exactly where you are, and I got a set of gm vortecs, ported them, added a trick spring/retainer setup, a ramjet/marine cam, some scorpion 1.6 rockers and am completely pleased.

I just drive around knowing that frigging intake manifold, although ported, is a UUUGE choke point, holding back the rest of the combination I put together.

 

[big_mike]

Are you talking about these Summit heads? Cause the info on them looks pretty good.

They are Summit part# SUM-151124

Cylinder Head, Vortec, Cast Iron, Assembled, 67cc Chamber, 175cc Intake Runner, Chevy, 5.7L

 

[Hipster]

Are you talking about these Summit heads? Cause the info on them looks pretty good.

They are Summit part# SUM-151124

Cylinder Head, Vortec, Cast Iron, Assembled, 67cc Chamber, 175cc Intake Runner, Chevy, 5.7L

They're not a true vortec head. The intake ports are only raised at the intake mating surface to just inside the runner. The same as the dart 165's drilled for a vortec intake and the port doctored up to match. larger chamber then a stock vortec also.

 

[big_mike]

So what has been linked as the source issue with the stock cast vortec heads cracking? I know part is they are a thinner casting but just being thinner shouldn't cause them to crack unless the material they are cast from doesn't heat cycle well.

And is a GM set the only "true" vortec heads then as far as castings?

 

[Hipster]

This something I have run across. 2 brand new gaskets. You'll notice the extra water hole between 4/6 cylinders in one of the gaskets. Not all blocks have the waterhole nor do all gaskets, and between 4/6 or 3/5 where I've seen vortecs commonly crack. The block can be drilled and the gasket with the extra hole can be used. The lower gasket is a Fel-pro marine Stainless and the upper came in an Enginetech kit supposedly also SS/graphite. The extra hole supposedly provide better circulation.

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[Hipster]

So what has been linked as the source issue with the stock cast vortec heads cracking? I know part is they are a thinner casting but just being thinner shouldn't cause them to crack unless the material they are cast from doesn't heat cycle well.

And is a GM set the only "true" vortec heads then as far as castings?

Never used a set, but the Enginquest heads get pretty good reviews for a cast iron head(Think they're 185cc), and there are quite a few shops selling them assembled with a 3 angle VJ and a throat cut. At that point though $$ you're close to aluminum. Personally I'd rather the iron heads on a daily driver that I planned on putting thousands of miles on towing etc.