Not sure what displacement engine I have

[Skutt]

I recently bought my sisters 1988 GMC S15 4WD pick-up. About four years ago I swapped the worn out 2.8L V6 for her. We ordered a 2.8 long block from the local NAPA deaer. I did the engine swap and all was well until the fuel pump failed after about 5000 miles. Nobody would put in a new one for her and I had moved 3000 miles away so I was not able to do it. The truck sat until I moved back recently and she sold it to me for $500. I replaced almost everything under the hood with new parts when I installed the engine so I knew it was in good condition and ready to go except for needing a new fuel pump. I installed the new pump and it runs and drives better than it ever did with the old engine. In fact it has so much more power now (still a small v6 of course) that I am of the opinion that the long block we received is not a 2.8L. The old engine was not even close to the one that is in there now as far as power goes. When I did the swap I used all the parts off the old engine so no upgrades have been done to increase power output. I suspect that it may in fact be a Camaro or Firebird 3.4L but I am only guessing from how it drives. With the old engine, it ran great, you had to take off from a standing stop on level pavement in first gear. It has a 5 speed manual transmission. I had tried 2nd on occasion and had to slip the clutch too much with the old 2.8L and it just was too sluggish. Now I have no problem doing that in 2nd gear without slipping the clutch and it just takes off.

My question is how can I identify the engine? I am sure there must be numbers stamped on the block to the right of the distributor but I am unable to find a list of what codes could be there and what they mean. I am really enjoying driving this old truck and want to keep it as it was babied by my sister and doesn't have a single hard mile on it. It is still a pleasure to drive so I figure it is worth fixing up a little.

[60dgrzbelow0]

Welcome Mr. Skutt ...and congratulations for having such a strong machine. Its remarkable torque and power reflect an an engine that is probably such a surprise because it is so fresh and new when compared to the old one. But for a great look at the long history and transitions for all 60* brethren, this is probably the best place to get a rundown on all flavors of our V6 power houses:

http://en.wikipedia.org/wiki/GM_60-Degree_V6_engine

The break point to look for has to do with the carburetor fed engines, as the "early bird" Sixty* 2.8L (3.1L I'm not certain about) featured an obvious distributor in the back of the block that also served to drive the oil pump and sports a very distinctive feature in the upper left angled side of the engines where there is a casting feature for a bolt-on fuel pump, powered by a stout push rod mated to an eccentric cam driven mechanism to develop fuel pressure. This feature is not in evidence on the 93-95 (Camaro-Firebird) 3.4L VIN "S" engine.

So just compare what you have with what is mentioned on that list for all the engines, right up to the time frame when the 3.1L engines were bored out to make the 3.4L motors. After that, the inception of electronic computer controlled fuel injection came into being because of EPA driven federal fuel efficiency and smog control standards and laws (California) and when it comes to highly efficient street performance, GM has never looked back. Hopefully there will be some input from some others on the forum with better scoop on any other engines that used carburetors and mechanically powered fuel pumps.

Bob

[Skutt]

This engine does have the distributor in the usual Chevy location (back center of engine) and yes it does drive the oil pump, I remember that from doing the installation. I looked for that casting for the manual fuel pump where it would be on an older small block v8, I am not sure as there is little room in front of the driver side motor mount but there seems to be an unused tapped bolt hole in that spot. This engine does have TB injection rather than a carburetor. I drove this truck on occasion when the old engine was still reasonably fresh and there is a big difference between that old one back then and what is under the hood now. Whatever it is I sure like it and I think I am getting right at 20 mpg also. Not bad for 4WD.

[95Grand-Am]

If it is a 3.4L cammaro engine there should be a F on the side of the block about 2" tall.

[Skutt]

Where would the F be located, I mean what side, front, back? I want to know for certain so I can plan any upgrades in the future. I really like this little old truck and would love to fix it up somewhat.

[60dgrzbelow0]

Where would the F be located, I mean what side, front, back? I want to know for certain so I can plan any upgrades in the future. I really like this little old truck and would love to fix it up somewhat.

Look at above image in my second post...it shows the "F" mentioned by 95Grand-Am (circled in RED) on the Driver's Side of the engine block ...just above and slightly behind the Oil Filter Adapter/Interface...