Thread: 4.3 v-6 buildup

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Is there a block or head modification required to use the late model heads on the earlier block?

The 2114 Edelbrock manifold ( 4 bolt intake per head) is for the 1996 and up vortec heads, 2111 Edelbrock manifold is 1995 and under. The later 1996 and up vortec heads flow better. The 1992 to 94 eye brow heads flow the best of the six bolt intake heads non-vortec (2111 intake manifold). The 600 cfm 4bbl is about as large as you can go on a street engine.
Comp Cams has some nice cams for both pre 1992 engines and also balance shaft engines. Do not worry about balance shaft for the street can use either engines but remember to use the the roller lifter hold downs from a 1994 engine (p/n 12551431 from a GM dealer to clear the Edelbrock intake) instead of the metal tunnel cover type roller lifter hold downs on an early balance shaft engine. The balance shaft engine cannot use a sbc double roller cam chain kit but the earlier ones can.
You will need a HEI big cap even fire 4.3L V6 distributor with vacuum advance which can be found at different places. Procomp has them.

Hope this helps.

Originally Posted by keotie

Is there a block or head modification required to use the late model heads on the earlier block?

No you can bolt the vortec heads on the early block but you must use the correct intake for them (2114). Also use the correct rockers for the heads you are using. Check your rocker angle for the correct pushrod length. If you use a more exotic roller rocker then talk to a machine shop about what must be modified.