2.8 to 3.4

[hadaveha]

i have a 1986 s15 jimmy we r fixing up for my son, looks like the 2.8 is on its last leg, bad main bearings, i can get a replacement 2.8 with a 100000 mile war. for 1200.00 my question is would the expence to up grade to a 3.4 be with the trouble and xtra money, and from what i have read the bell housing is about the only change needing to be made.

[Sparky2263]

That is an excellent (and some consider only) way to go. 3.1's and 3.4's are plentiful. The flywheel needs to be for the motor you are using, not the 2.8 flywheel.

[wrenchead3]

Your "key" comment was"1986".That was just a bad plan that was redesigned ( search the other posts for details).I have a 88 2.8 with 240k on it and I spin her hard all the time.Still smog tests uses no oil.Your options are plenty,read, read then read till your eyes bleed!

[Maximus]

The 3.4 is a better option with more possibilities than the 2.8 can achieve.To me the old saying is still true there is no replacement for displacement.And there are plenty of MPFI 3.4's out there to scavenge from to get good power and good torque.And if you did go with a MPFI setup you gain flexibility with the fuel system that even the 4.3 cannot achieve.A upgradeable fuel system that can only be had on a 4.3 buy building your own that is upgradeable.I say go with the 3.4 you won't be disappointed.

[T Man]

In 86 there were two variations of the 2.8, one had smaller main journals, and of the two is was obviously the weaker. When it comes to converting, all the accy's from your 2.8 will bolt right up. The 3.4 is the same as the 2.8 other than the larger bore and stroke. The only diff like sparky said would be the flywheel. The 3.4 is also a better base for power. Go with the 3.4, it wouldnt be any more work than replacing the 2.8

[Maximus]

Bingo and many varations of the engine make for several ways to approach it.You can go Carb,TBI,and MPFI.The 3.4 was available in several RWD cars.And you can supercharge it on a good platform to.But it's yo money and time.

[hadaveha]

thnku guys im dwn to about 10 pnds of oil pressure, with some slaping from the old 21.8 engine im going to runner until she is done and go with the 3.4 any sugestions on a good dealer of rebuilt 3.4.

[sdime03]

You could go to pull a part in birmingham and pick one up for a lil over 100 and you and your son could rebuild/build it up for a father son bonding thing......what color i might have seen it around...i live between ashland and wadley