4.3 V6 heads and valves

[mikeasis]

can larger valves be installed in these heads? 2.02 intake and whatever the heck exhaust size would be? i can get eh machine work done cheaply and figured that a a home port job would help it breath. i have 86 castings at this time.

also any links to sites showing how to port heads and any tips appreciated.

[Caddyman]

Re: 4.3 V6 heads and valves

Their loosely based on 350 castings (3.8 chev v-6 was based on a 305, with smaller chambers/bore).

If its like a lot of castings back then, the chamber walls get too close to the intake valve to do much when going over a 1.94.
I've seen a lot of unshrouding done, but its sorta hit-miss if doing it by hand. Its better to use "old school" grinding stones, and make all the chamber unshrouding even. I would think a 2.02/2.05 might get awfully close to the chamber, and sorta screw up the gains at certain lift levels.

From what I've heard, the exhaust is more of a problem on all the 80's heads (sbc, v-6's) anyway.

If available, I'd put at a 1.94 intake valve (if not already in them), and a 1.60 or maybe a 1.65 exhaust, using a split pattern cam.

Let the larger exhaust valves make the cam "bigger" on the exhaust side, while maintaining good tract speed on the intake side (balance is the key here). I've never messed with them too much, but I'd treat it like an 80's sbc.

More about exhaust than intake, and good headers.

[mikeasis]

Re: 4.3 V6 heads and valves

ive got a pretty free flowing exhuast...the stock manifolds on this 6 look like a header and from there its 2 1/2 inch pipe to the dynomax high flow cat and single 2 1/2 to the dynomax muffler with dual 2 inch pipes coming out back.

i think the stock heads have 1.94 intakes not sureon the exhaust.
i was told i could put 2.02 intakes and 1.64 exhaust valves. i figure this and some home port work should free them up a bit. anything aftermarker for the 4.3 is aluminum and big dollar. im not sure if i see the cost to witch not vortec 4.3 heads after paying for them to be rebuilt and then buying a vortec intake manifold.

[AFFORDILLAC]

Re: 4.3 V6 heads and valves

http://www.hotrod.com/techarticles/engine/113_0208_chevy_43l_262ci_v6_engine_build/index.html

[mikeasis]

Re: 4.3 V6 heads and valves

SWEET! thanks man, ive read that article and saved it to my hard drive but for some reason didnt think to even reread it.
atleast now i nkow i can stuff in some bigger valves and do some prot work!

imagine if they used the stroker kit on this thing! then later they added a vortech supercharger for 500hp......the engine is capable but few people or companies do it.

[Mr4Speed]

Re: 4.3 V6 heads and valves

The Vortec heads are waaaaay better-just like on the V8's. There is a cast iron Q-jet intake for Vortec heads that came on the marine engines and they can be found cheap on ebay. You can use a stock 454 tbi adapter with it, but if you need egr you will have to rig up an external one like on tpi Corvettes.

[mikeasis]

Re: 4.3 V6 heads and valves

is it just combustion chamber wise they are better or do they actually breath/flow better also....

ive wondered if upgrading to vortec heads would be worth it just for the combustion chamber and the way todays fuels are. i.e to help with pinging issues and such.

where the hell is DF on this anyway....i have yet to see a pair of perimeter bolt valve cover heads for a 4.3.....they must have found the only set when they did that article as i have yet to see them. last year i went and looked at an 85 monte for parts that had a 4.3, supposedly all orignal, and it ahd center bolt valve covers....but i could have been a late 85 or a replacement motor under warrenty.

[SpiderGearsMan]

Re: 4.3 V6 heads and valves

4.3 always had centerbolts
you could get some 229 heads , ugh
the price of gas is low - big blocks for all !!!!

[mikeasis]

Re: 4.3 V6 heads and valves

anyojne know where to get some flow numbers for the vortec 4.3 heads? any opionions if the combustion chamber alone would be a big benifit?




spidey man you been hitting the bottle hard latley????