Not what it looks to be or is it

['86 S-15 Jimmy]

Hello there I have an '86 GMC Jimmy I've had this truck for 6 years now and have not done many things to it and am looking to do some mods to engine.The emblems on it and the valve covers say 2.8 Liter V-6 goodwrench on them and 4.3's didnt come out till '88 on these trucks. I bought it from some old guy and he said the engine was just rebuilt and he didn't know to much about it. The other day me and my Dad were trying to figure out if the timing was ok and we looked in the Haynes work manual for the 2.8L It told us that the Firing order is 1-2-3-4-5-6 and the powerbrake booster hose screws in from behind the intake manifold What I have is the hose for the booster screws in from the front of the intake manifold like for the 4.3L And the firing order is 1-6-5-4-3-2 . I don't know if the old guy had it swapped out for the 4.3 or what but I'm just wanting to know more about what I got under the hood can you tell me how to really make sure its a 4.3L this would make me happy if I have a 4.3 because I was thinking I had a 2.8 and wanted to swap to a 4.3 or bigger I can't believe this can you tell me more.Thanks

[blue2kzr2]

If the valve covers say 2.8 and they're stamped with that, you have a 2.8. I'm pretty sure the covers from a 2.8 won't fit a 4.3.

 

Looking in my Haynes manual for that vintage truck, it looks like the spark plugs go in at angles on the 2.8, they go in straight on the 4.3. Also, if you look at the passenger's side of the engine, you should have 2 plugs behind the middle exhaust port if it's a 2.8, there would be 2 in front of the middle exhaust port on the 4.3.

[Colorado Kid]

Where in Colorado are you?

 

I've owned both a 2.8L and a 4.3 and could tell them apart at 10 paces, but that doesn't mean I can tell you how to tell them apart when you dont' have one or the other to compare too.

 

A 4.3 is quite a bit wider than a 2.8 because the 4.3 has a 90 degree V angle but the 2.8 has a 60 degree V.

 

I work in Denver, near I-25 and Colorado Blvd. I'll send you an e-mail.

[juiced01s10]

2.8 and 4.3 covers are not interchangeable

[PewterC3]

I also has a '86 and they've already said it. Yes, it's most likely the 2.8, doubtfull it's been changed to a 4.3.

 

The 4.3 is basically a 350 with 2 cylinders cut off...a big difference in apperance between it and the 2.8 60 degree V6.

 

And I thought the 4.3 was 1st available in '87?