4.3 Vortech mods/build q's [Archive]

XJOSHX

04-29-2005, 05:16 PM

I am rebuilding my 4.3 and I want some more power out of it. it's a TBI vortech motor from an older blazer. I am not to sure if I am going to keep using the TBI or not.

Going .030 over with forged pistons 9.25:1 compression
all new bearings
all felpro gaskets
edelbrock performer intake

now here are where my questions come in. Can I use regular SBC rocker arms?

Whats a good cam for low end TQ

Should I Mill the heads for more compression (worried about piston to valve clearance)

Will porting the heads give me better low end tq at all?

How big of a carb can I stick on this?

Thanks in advance for the help :)

no excuses

04-30-2005, 03:38 PM

I just built my 4.3 getting readu to fire it up today :flipoff2: , I am keeping mine TBI ,

Was going to go carg and was looking at a 2barrel Qjet but just as cheap to reprogramTBI and buy a harness as buy new carb. can reprogram for only 100$. I have to run 305 injectors on mine.

DO not need to go with a big carb, it will just kill ur bottom end power.

I have a 214I 214E @ .050 with a lsa of 110 and .500 lift, biggest cam I could get an still run TBI. I am still running stock rockers, will see how they like it. Cam is a reground stock cam.

A buddy is putting a 4.3 together and using stock roller rockers, 235I 245E @ .050 with a 112 lsa and with 1.6 rockers .630 lift :eek: and no piston to valve problems, and no dogbone to lifter problems.

Yes port ur heads and intake, it needs all the help it can get. I took out the devider between the 4-6 and 3-5 ports on the intake. Gasket match intake and exhaust ports also. WHen porting ur heads do not do much on the exhaust side because they almost flow as much as the intake already. Do not take a lot of material off the floor of the itake either.

Do not forget a set of headers.

I would not worry about milling the heads much , about all u will gain if u pick up one compression point os about 10-15 hp and tq, but u will have to run better $gas.

On my motor it should be around 275-300hp and 325-350 tq w/flat tops (9.5-1) fully ported heads and intake, TBI W/305 injectors and AFI chip, 214/214 @ .050 w/ .500 liftand 110 lsa

Good luck and enjoy :grinpimp:


Pirate4x4.Com > Brand Specific Tech > Chevy > 4.3 Vortech mods/build q's PDA : 4.3 Vortech mods/build q's XJOSHX 04-29-2005, 05:16 PM I am rebuilding my 4.3 and I want some more power out of it. it's a TBI vortech motor from an older blazer. I am not to sure if I am going to keep using the TBI or not. Going .030 over with forged pistons 9.25:1 compression all new bearings all felpro gaskets edelbrock performer intake now here are where my questions come in. Can I use regular SBC rocker arms? Whats a good cam for low end TQ Should I Mill the heads for more compression (worried about piston to valve clearance) Will porting the heads give me better low end tq at all? How big of a carb can I stick on this? Thanks in advance for the help :) no excuses 04-30-2005, 03:38 PM I just built my 4.3 getting readu to fire it up today :flipoff2: , I am keeping mine TBI , Was going to go carg and was looking at a 2barrel Qjet but just as cheap to reprogramTBI and buy a harness as buy new carb. can reprogram for only 100$. I have to run 305 injectors on mine. DO not need to go with a big carb, it will just kill ur bottom end power. I have a 214I 214E @ .050 with a lsa of 110 and .500 lift, biggest cam I could get an still run TBI. I am still running stock rockers, will see how they like it. Cam is a reground stock cam. A buddy is putting a 4.3 together and using stock roller rockers, 235I 245E @ .050 with a 112 lsa and with 1.6 rockers .630 lift :eek: and no piston to valve problems, and no dogbone to lifter problems. Yes port ur heads and intake, it needs all the help it can get. I took out the devider between the 4-6 and 3-5 ports on the intake. Gasket match intake and exhaust ports also. WHen porting ur heads do not do much on the exhaust side because they almost flow as much as the intake already. Do not take a lot of material off the floor of the itake either. Do not forget a set of headers. I would not worry about milling the heads much , about all u will gain if u pick up one compression point os about 10-15 hp and tq, but u will have to run better $gas. On my motor it should be around 275-300hp and 325-350 tq w/flat tops (9.5-1) fully ported heads and intake, TBI W/305 injectors and AFI chip, 214/214 @ .050 w/ .500 liftand 110 lsa Good luck and enjoy :grinpimp: