'93 rr 3.9-have motor out-what are some secrets or mods i need to concider? flat top pistons? port heads? light weight pistons? different cam? if so which one is best PN roller lifters ?just want better performance and torque. who's been there and done that.

 

This was never considered to be a performance, just a way tired 50 year old Buick.
Best performane tips, all of which have to be done together would be opening up the heads, cam,lifter and springs, headers and new exhaust. The one other oprtional item would then be larger injectors and a better coil system.

 

I installed a set of Bosch injectors from a 302 Mustang. It smoothed out the idle and gave it a little more response. I also added the K&N air filter (but then again I put one of those on my garage air compressor).

I'm in the same boat as Rambo. I have my 3.9L out of one of my 1990 RRs. I am looking to give it some semblance of power. I've been rebuilding Chevys and Fords for almost 20 years. This old Buick should have power...if we can only find parts.

I am researching installing an MSD box in my RR. I'll let you know how that went.

 

My local automotive machine shop has built a couple of the old buick 215s for a guy who is stuffing them in MGs. They are getting almost 800 hp out of them. The only details I got is that it includes a bore and stroke job. I only mention this because if they can get those kind of ponys out of the 45 year old verson of our engine, with a carb on it no less, there should be some power avalible to us without going crazy. Heck, buick even had a blown version doing 215 hp already in the 60s.

 

The old buicks evolved into a 300ci cast iron engine. Did LR make changes to the crank? Stroker motor??? I was curiuos about this. Disco Mike would this result in too much power for trutrac diffs or other driveline components?

 

A 4.2L cam is a direct replacement (ERR5295 / $189.95). I ordered one from Atlantic British today. I'll post power increase when I'm finished the rebuild. I have noted that parts availability is quite limited. I have yet to find anything in the piston or bearing arena that is larger than .020 over/under respectively. Seems like everything cost $100 too.