I have a 90 RS with a 3.1 mpfi 700r4 for a donor car.
My "reciever" car is a '83 2.8 carbed with a t5
tranny. Does anyone know for sure if I can use the
long block from the 3.1 and put it in place of the
2.8. The differences I have noted are: the manifolds
need swapped, the timing chain cover and oil pan need
changed. I will need to add an electric fuel pump. I
will have to insert a pilot bushing to the 3.1. Does
anyone know if the manifolds will swap out (are the
heads the same), will the crank from an automatic take
a standard t5 pilot bushing, and is the pan and timing
cover swap straight forward. I know I need to change
the flywheel and if possible will use the harmonic
balancer from the 3.1 but I.E. is a 1990 3.1 long
block Identical to a 1983 2.8 long block? And 'am I
missing anything else. I have the 3.1 on a stand right
now and 'am about to yank out the 2.8 but before I get
too far and see the roadblock (if there is one) I was
wondereing if anyone could either allay these fears
of the unknown or stop me in my tracks. I'm trying to
get this done before thanksgiving. You ask why would I
do this? The 83 is a work car and cash is tight and
the 90 is t-boned and in my posession now. I'd could
really use some knowledgable help and or assurance.
Thank You

 

is the 90 3.1 long block identical to the 83 2.8 long block.. no..

i attempted something simular that ur doin now (83 w/ 200r4 - 85 w/ 700r4).. i got stopped by a cracked head..

the 83 has a mechanical clutch and the 90 block wont have provisions for it.. gm changed to a hydrolic clutch in 84.. thats the only thing i can think of that u didnt list..

manifold? are you talking about the intake or exhaust? in which case u need to use both from the 83 and they both will bolt on..
ull probably need to use the oil pan from the 90 block
donno bout the timing chain cover
electric fuel pump is a must (no provision for the stock mechanical fuel pump)
i donno much bout the auto-manual stuff, but from what ive read, everything should bolt up..

if u have any specific questions, let me know.. ill do my best to at least stear u in the right direction..


-mike (loomdog)

 

In my reading I found out they went to an internally balanced engine around 87 so that means that my weighted flywheel won't work. I knew the front cover had to be changed as the water pump was different. Which leads to the pan needing to be changed. Turns out the water pump was different because the vbelt runs in the direction of the engine and the serpentine belt runs in reverse. My biggest worry was the heads were different and my intake wouldn't bolt up. I'd have been major bummed to piece that 3.1 together only to find out my flywheel was throwing the whole thing out. But Thanks loads for the info!

 

Swap exhaust amnifold (AIR tubes are needed)
Elec Fuel pump is needed Carter (4-6 lbs pressure) Sells one & I'm installing it. See subject below
Intakes swap perfectly.
T Covers....
match pan to timing chain
Using old 2.8 use old 2.8 oil pan....
Balancing, using 3.1 matching weighted stuff only.
If ya need help I'll show ya pics of the 3.4 SFI before & my S-10 3.4 carb'd after. Send me an email.
Clutch stuff unsure I've only done auto swaps.

 

The 2 things that seem to be stopping me cold are the flywheel (needing zeroed out) and there is a casting issue that in '84 they went to a hydraulic clutch so there is a piece of cast missing for my mechanical linkage. Those heads were worring me the most. I could probably find a local shop to zero out the flywheel but the engine block casting for the clutch linkage post is what seems to be the back breaker. But thanks very much for the reply. You Da Man

 

Jimmy Mac,
It is possable to weld onto a cast engine block. - check with yer local shop.

 

It is quite possible to weld onto the block, but you'd better have someone do it that knows what is going on, else you can crack the block, or the ear you weld on won't hold very well.

My suggestion is to pirate the pedals and clutch master cylinder/slave cylinder from a later model five speed out of a junkyard, and not worry about the linkage bolting up. Those pieces shouldn't be that hard to come by. I am assuming that the car that is donating the 3.1 liter is an automatic. You could swap out the pedals, trans, and console and make it an auto. I understand that you probably want a manual, though, and I don't blame you. If you do go the junkyard route, you might want to get a rebuilt clutch master cylinder and start with that, just so that it won't leak all over your driver's floor. You could make the car a full fuel injected car, but it would be a lot of work swapping over all the components and harnesses.

 

I will have to call around to see if I can get and see what they want for it. I live in the Pittsburgh area and I imagine it is the same all over, that the bone yards vary in price greatly. If I could pick the setup up very reasonably I think that would be the way to go. Thank you for the suggestion. I think Monday I'll call around to see if it is feasable. Yeah I did want the injection. I picked up the donor car with the intention of using the mpfi but when I realized the amount involved I begged off. I have an 87 IROC for a sunday driver so I'm not hard up for the extra juice but really wanted the extra preformance and milage the injection offers for the work car. But the '83 is a tired car and I probably shouldn't have gotten into this to begin with. But I also have to finish what I started. Thank You again!