Engine swap 88 into an 85 (350/5.7)

[chengny]

Need a new motor for my stock 1986 GMC Sierra- cracked block. Have two options:

1. A real pretty one out of a 1986 Chevy 3/4 ton. Looks well taken care of. Painted with high-temp red (no peeling or holidays), Edelbrock intake. big Holley carb, etc. The kid is unsure of the history but it appears as if its been torn down (probably bored) and rebuilt with care. He claims it runs "sick" - I can only hope that means really good. Mileage unknown.

2. A fairly new (8K miles) crate engine that was part of a restore project that went sour. The truck it is coming out of is a 1988 GMC. It is of the TBI type. Will this present any problems in a 1985 heavy duty K-2500. I do have an ECM on the firewall but as far as I can determine it does nothing.

Both are going for $300.

I am not asking anyone to recommend which engine is better mechanically. I am only seeking advice/input as to whether there would be problems setting the later model engine with the TBI into my truck. Plans are to only use the block and heads whichever one I pick. My exhaust manifolds are original welded stainless tube type (with dual air injection pumps and SS tubes feeding the exhaust ports). Also, I would prefer to use my OEM intake just due to the fact that everything bolts up to it so well.

My truck has absolutely no emissions control components other than those two air pumps, the PCV valve and the EGR valve (and as I mentioned it is stock - somehow it came that way). The reason I say that the ECM does nothing is because there are no inputs at all. There are only five wires connected to the engine - coolant temp sender ( only operates the dash gauge), oil pressure sender (again for the dash gauge), another oil pressure sender that controls the choke heater, the choke heater supply wire and an inlet air temp sensor that mounts through the air cleaner.
Thats it. There are no catylitic converters, no O2 sensors, no knock sensors, no vacuum sensing system and no wires to the carb (other than the choke heater). The exhaust system has never had anything replaced - other than hangers. It is dual - SS welded from the maniflod flange to the end of the tail pipes. Even the mufflers are original. I firmly believe that the AIR injection system has allowed this to happen. And don't get the wrong impression, I drive this truck every day and treat it like a truck - it's unbelievable.

So anyway let me get down off my soapbox; Does anyone see any conflict with buying the low mileage 1988 (with TBI)? I have no doubt that the dressed up Chevy motor will drop right in but I really like the idea of getting a crate engine with only 8 thousand miles on it.

I would greatly appreciate anyone's thoughts or advice.

[jimbo543]

buy an aftermarket intake for the tbi engine and use it (86 intake won't fit), you might have to put an inline electric fuel pump if boss isn't machined for use

[scavanger]

I agree , go for the crate motor with the tpi. One thing you might want to be carefull about is if the engine is externally balance you need the right flywheel with the weights in it.

Scav.

[leolkfrm]

gm balanced by adding weight to the harmonic blancer or punching holes in the flywheel,however with the newer motors its not an issue

[scavanger]

Originally Posted by leolkfrm

gm balanced by adding weight to the harmonic blancer or punching holes in the flywheel,however with the newer motors its not an issue

So your saying that the newer crate motor doesn't need the balance holes in the flywheel ?
My 90 Vette has them.

Scav.

[chengny]

Moot question after all - the guy selling the 1988 (the crate with only 8K) went under a rock all of a suddden. No idea why - the thing had been up since early Sept.

So now I have the 85 with all the shiny stuff. Doesn't look so cool now that I own it and can take a few minutes to really check it out. And, I bought it on faith - couldn't even do a comp check. We'll see what I got stuck with. My only consolation is that given the price of short blocks these days (around $2500 for a no-frills unit) I can get 7 losers at $300 and still be ahead of the game.

Thanks for your input, all of you. I was headed towards the 88 TBI just like you suggested, ****!

[FaselZ71]

Well let us know about the motor that you did buy! If you have any questions you know where to find the answers! You closer, faster, friendly, TAD Forums!!!