I see reference to Vortec heads for the 350. Can someone share their knowledge of how these compare to the L98 iron heads on an 85/86? What engines did have them etc.?

 

Not compatible with the TPI base unless you redrill the mounting holes.

 

L-31 Vortec heads are far superior to the stock L-98 cast iron heads, the Alum L-98 heads and any prouduction SBC cyl head GM has prouduced in the last 40yrs... except for the new "Bowtie Vortecs".

Here is a comparison to how they stack up against other 23 degree SBC cyl heads. The numbers he has posted here are very close to the numbers we get on our bench (an SF 600).

http://www.purplesagetradingpost.com...fo/heads1.html

Orginally prouduction Vortecs came on 96 and later "Vortec" 5.7L SBC's, full size Chevy/GMC trucks and vans. There is alot to know about these heads and I'm going to try to give it all to you - so forgive me if I miss something. There are 2 different Vortec prouduction castings. The 062 casting and the 906 casting. The 062 came on light duty trucks and vans the 906 came on 1 ton stuff. You can also skip the junk yard scouring and buy them over the counter from GM or many of the oval track engine parts suppliers (PM me and I will be glad to point you in the right direction). Some mis information is out there to stay away from the 906 casting because of bad mid lift flow due to it having hardened exhaust seat inserts. This is a bunch of BS and I have proved it many times on our flow bench, the difference in the 2 castings in stock form is minor almost nill depending on the quality of the factory valve job and condition of the heads. Once you do a nice new 3 angle valve job there is NO difference.

They do have a different intake manifold bolt pattern and require a Vortec specific intake manifold (YES one is availiable for the TPI) OR you can buy the heads from a few oval track engine parts suppliers already drilled and tapped to fit old style SBC intake manifolds. Be aware you have to be careful to not over tourq the intake bolts on these. The Vortec heads flange is a little thinner than the old SBC in this area and stupid people have stripped the threads out. We have used many of the "re drilled" Vortec heads in the past before the proper intakes were availiable and never had a problem.

Stock springs will only go to .480 lift. Also the valve guides should be machines down to go much further than .480 lift.

And I think that is it.
Will

 

I think the ports are shaped differently, too. The Vortecs have taller, narrower intake ports (further developed in the LSx heads) compared to the gen 1. For that reason, you'd also want an intake manifold that matches the port shape in addition to the bolt pattern.

 

I purchased a GM Crate motor 350ci 330hp/380tq with vortec heads then my mechanic took the TPI and placed it on the new engine. I had to purchase a new Edelbrock intake manifold.

Hope this helps

 

You can now buy the vortecs in aluminum. Also they sell a high flow vortec head that accepts a larger lift and the studs are not pressed in. I dont remember the valve sizes but you can find all these in a summit or jegs magazine. You can up the lift on the stock original heads by tapping the wholes so you can put in a screw in rocker stud and beehive valve springs will also help since you can only fit so big of a spring on there.

 

Nice. Now I have an understanding of what folks are talking about. Thanks

 

I run vortec head on my 85. I did before and after dyno runs with the only changes being the vortec heads and the SDPC vortec intake. This was on a stock 85, if I remember correct HP only went up something like 20 but the TQ went up about 50.
Dave