4.3l non vortec to vortec upgrade?

[Bergerson]

I have a 1990 Chaparral 19' 4.3l 2bbl alpha one, I just aquired all parts to do a vortec upgrade, I got vortec heads intake and 4bbl carb off of a 99 4.3l merc. had the heads redone and i need to know how to adjust the valves and what do i torque the rockers to? these are flat hydraulic lifters correct? any help would be appreciated. thanks

 

[Rat Capri]

Re: 4.3l non vortec to vortec upgrade?

should be a roller motor, 3/4 turn past 0 lash

 

[Bergerson]

Re: 4.3l non vortec to vortec upgrade?

should be a roller motor, 3/4 turn past 0 lash

Should be? I have no idea? I have read everything from just torque them down to 22ft/lbs to .003" then 1/4 turn to 1/4 turn past 0 lash to uhhh I don't know.. where could i find this info? thanks in adavance

 

[Rat Capri]

Re: 4.3l non vortec to vortec upgrade?

either way, if they're adjustable (rocker on threaded stud) adjust to 3/4 turn past 0 lash, if they're not adjustable (rocker on stands or shaft system) torque to 22 ft-lbs...

 

[ryendube]

Re: 4.3l non vortec to vortec upgrade?

vortec is a roller lifter/cam setup, though if you just bought heads and intake are you using the old lifter setup? ive always practiced adjusting lifters with engine running.


just to add they are going to be hydraulic lifters weither roller or not, no need to measure clearance etc., thats for old school solid lifters.

 

[chick92064]

Re: 4.3l non vortec to vortec upgrade?

Hopefully I'm not threadjacking by jumping in on this with a question of my own in a similar vein.

I recently was the lucky recipient of a brand new Mercruiser 4.3L Vortec Long Block. I had some repairs done on my 1989 Mach 1 Challenger (MV1900CC) last fall and the people doing the work stored the boat for the winter as part of the deal. Evidently everyone thought "the other guy" winterized the engine. Long story short, the exhaust manifolds, risers and even the engine block itself had serious cracks. So to make good on it all of the above was replaced with genuine Mercury Marine parts. My question is relative to the fact that I went from a non Vortec to a Vortec and a lot of peripheral pieces were taken of the non Vortec - - - including the 2bbl carburetor. The new engine is not yet broken in, but runs basically very well with a few exceptions - - all of which point to the carb when I read the troubleshooting section of the service manual on the engine. Can anyone tell me if I need to replace the 1989 2bbl with a more update version or can I have my existing carb rebuilt ? Or, as the orginal post in this thread seems to suggest, do I need to replace the intake manifold and go with a 4bbl to make this engine run to it's potential ?

 

[ryendube]

Re: 4.3l non vortec to vortec upgrade?

only difference between reg 4.3 and a vortec is head design (small combustin chamber better spark plug position, better flow) and not 100% on the boat versions but they use roller lifter/cam set up. its still a 4.3L. you have to match size of carb (cfm) to size of motor. its not as simple as 2 types of carbs 2 and 4.

 

[Bergerson]

Re: 4.3l non vortec to vortec upgrade?

yes the rockers are on a threaded stud, so, I am guessing 3/4 turn past 0, in 1/4 turn incerments. Thanks guys

 

[MikDee]

Re: 4.3l non vortec to vortec upgrade?

You might need longer, or shorter pushrods to keep the rocker geometry intact? with the Vortec heads. I usually set 1/2 of the valves to zero lash with the engine on Cyl. #1 at TDC, then the rest at Cyl. #4 at TDC, pre-startup, there is a special procedure describing which ones to adjust, and when,,, in the Mercruiser manual, Then I set them one, by one, once it's warmed up, & running, at 1/2 a turn down from zero lash.