Thread: Vortec Heads

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Mike: I'm not a Chevy guy normally, although I am using one in the T. It is a marine 350. a 1999. The heads are vortec, does that mean only trucks and marine engines used vortecs? My last boat had a 4.3 in it, and had vortec heads too.

So are these marine heads the vortecs that Chevy guys like? Just curious.


Don

If the heads are "Vortec", they have four manifold bolts on each side and the bolts are vertical (not at an angle like normal Chevy manifold bolts). The bolts are something like 6mm dia and torque to 12 ft lbs as I remember.
The two common Vortec casting numbers are:
10239906 casting has one large single hump.
12558062 casting has 3 small humps.

I forgot about marine engines, they could be Vortec also since the marine stuff is kin to the truck stuff. Yes, Vortec heads did not ship installed in cars. And yes, there are six cyl 4.3 Vortec stuff too.

If you look at the web page that I posted a link to, it compares the flow of the Vortec heads to several aftermarket brands....the "lowly" Vortecs match up really well and actually outperform the Edelbrocks and World Products heads at higher valve lifts. Note that Vortec heads when stock cannot accommodate cam lifts over about 0.450" (at the valve); they can be modified easily to go higher.

For iron heads on the street, they are really good.

mike in tucson

That all makes sense. I know all of Volvo's and Mercruiser engines have been Vortec since '99 in boats, I guess to take advantage of the increased HP. The one I am using is a Volvo 280 HP 5.7, and came out of a boat we repowered for a customer. I think the cam profile will be ok (it's a roller cam engine) and I hope by adding an aluminum intake it will bump up to maybe 300 HP.

Thanks for the good info.


Don