Re: Can OEM TBI Feed a 400???
OK, little late, but here goes. I should just save this stuff so I can copy and paste. /forums/images/graemlins/smile.gif
Vortecs have pressed in studs. Not a real big deal, but aftermarket/high performance stuff is screw in. If I had a choice, screw in for sure. Used I'd be more concerned with this issue.
Vortecs have 1.94/1.5 valves, period. You can have them reworked, but you are already adding cost at that point.
Require rail rockers as shipped. With my roller cam, I spent a fair amount of time grinding the pushrod holes in the heads to clear. I like rail rockers, but using non-rail rockers isn't an option, at least not without additonal $$ on the heads.
Vortec springs are good to about .450" lift, if you believe you need some valve spring retainer clearance at max lift.
Vortec valve springs are weak, so better springs might be necessary depending on cam, etc. The cam manufacturer will let you know.
Vortecs use special valve springs...either you machine the heads or buy special springs, of which there isn't much variety.
Vortec's don't have provisions for EGR. (no crossover passage) If emissions is a concern, or you just want EGR (like me) you've got to plumb it externally. More $$
Vortecs are thin castings. Not a concern for most people, but it IS something to think about. Don't 400's tend to run a little warm?
Vortec injection intakes are about $3-400, and almost no selection.
I don't think I've missed anything. If you can get by with completely bone stock Vortecs, and just add a TBI intake, you'll be looking at what, around $900? ($500 heads, $300 intake, $100 for shipping?) Not a bad price I guess, but again, potential extra expense you don't have to pay necessarily.
BUT, if you do some research, and find another head that doesn't have the problems I've listed above, you can probably have a BETTER head, for the same overall money.
It still requires research, there are a lot of variables, and I don't know ALL of them. The Vortec is a good design, but the combustion chamber itself is one of the main benefits, and most aftermarket heads have adopted that innnovation. Vortecs have great ports compared to earlier heads, but again, a set of aftermarkets should be just as "clean".
I really liked the price I saw for the Pro-toplines on a post here on CK5, something like $500 complete. I only use those because thats a LOT cheaper than the $900-1000 the other aftermarket heads seem to run. BUT, you've got to make sure they have the '87+ intake bolt pattern, exhaust crossover, and so on.
I guess my main advice is to spend a LOT of time researching...if you don't, what seems to be a good value early on, won't be, once you actually put money on it. /forums/images/graemlins/smile.gif
