3100 SFI Whats so special?

[Ryan from Ohio]

I have a 1997 Buick Century.

Ive been trying to find a motor and its been rather difficult. THe palces that do have one are all $600+

The motor is the 3100 SFI

I have found one in a junkyard 45 minutes away for $300 with 78K on it and it runs good.

Is there something special about the motor in my car thats not interchangeable with other 3100 SFI?

Guy at the JY said something about a heat sensor on the heads. My motor has no sensor on the head, nor did the one in the car that I noticed. It did have a plug in the corner of the rear head and the heads I have hear do not?

I thought they were common engines?

The car its in is a 199X? Grand Prix. Its not the wide body styles, its probably a 94-96?

I guess the big question: WIll this motor install into my car without modification?

[Superdave]

if that's a gen2 3.1 the JY guy is talking about.. yes, they have a temp sensor in the rear head. That engine won't work out very well in your car. lol Some of the older 3100's still had that sensor in the rear head. If it is infact a 3100 then you don't have to hook up that sensor. Just leave it alone and use the same sensor your original 3100 came with under the thermostat housing.



There are 3100's everywhere here, it's the 3400's that are hard to find

[PCGUY112887]

There are 3100's everywhere here, it's the 3400's that are hard to find

Are you being serious about that?

[Ryan from Ohio]

I replaced a 2.8 MPFI in my beretta. The replacement had some sensor in the rear head. Since I didnt have a plug for it on my wiring harness I just left it be.

Neither 3100 SFI's (one thats in my car and the junkyard one) have a sensor on that rear head. Just the one at the JY has a plug. I will assume that wont hurt anything then

So it sounds like Im safe with this 3100 SFI?

[Ryan from Ohio]

There seems to be plenty of 3400's around here, but they are all 700ish area and probably more...

[bszopi]

Leaving the sensor alone won't be an issue.

[Superdave]

Are you being serious about that?

Yes

Most of the 3100's are small port tho... the large port 3100's and 3400's are a little harder to find... I've got 2 lined up incase i need them tho... possibly starting a new project in the fall/winter.

[IsaacHayes]

94-99 3100 small port would bolt right up. There won't be any issues, just swap whatever you need to over if it doesn't match up.

Some 94 gm cars got the 3.1mpfi like j-bodies though.

[Ryan from Ohio]

Well I got the motor home tonight.

Degreasing the engine compartment and a little on the motor. GOing to shoot the block with some black 1200 degree paint quick then isntall it tonight/tomorrow.

I think Im gonna have to take the plenum off to put my fuel rail on as I dont know how to use the connectors on it??? THey just like plug in.

Also the exhaust manifolds are different, styled moreso like my 2.8 MPFI.

[Rhedalert]

yeah you're gonna have to use your old rear manifold, if you want to keep your exhaust/downpipe unmodified.

[Ryan from Ohio]

I figured as much. Actually the rear manifuold is still on the down pipe as its to hard to disconnect/re connect for me.

Bad thing is I broke an exhaust stud so now Im going to have to drill it out and re tap it. Well unless my easy out works, which it rarely seems that it does anymore.

Ahhh the benefit of being a machinist I can drill & tap like a mofo