Rusty Shackleford

As it reads....can i use a 80' or 83' 12a in my 85' GS???? I need an engine and somebody in my state happens to have a rebuilt 80' with 15,000 on it or a 83' that was pulled from a running parts car....?? They are going to throw a price out at me but I wasnt sure if the Rebuilt (the better choice im gussing) would work being that there were differences..??.....??.....??.....

Midwest 7's

iTrader: (4)

if your already running a fmoc there should be no problems.

Rusty Shackleford

not yet but i have one sitting in my garage i snagged out of the junk yard that i was going to put on my car before it went out.

trochoid

iTrader: (6)

Strip both engines down to the block, leave the oil pan, install your engine externals on the new one, drop in engine bay.

Midwest 7's

iTrader: (4)

best mod you can do to a 83-85 12a, imo.

Rogue_Wulff

The only other issue to consider with the '80 engine, is the thermal reactor ports.
These are close to the exhaust ports, but not close enough to be able to use a stock 81-85 exhaust manifold without having exhaust leaks. However, if you have a header, no worries.
To use a stock exhaust manifold, you need to make a block-off plate/spacer, or fill the TR ports.

Rusty Shackleford

I checked the RB website to see if my Streetable header from a 85' 12a was listed under the same as the 80' but its not..

But the Engine to Header Flanges are the same listing from 74'-85' so i gusse the difference in the headers is just the placement of mount differences??

Rogue_Wulff

The RB headers all have the same engine flange. On the gasket RB sells for the header to engine, you will see 2 small holes. Those are the TR ports I was reffering to.
Since you have a header, no worries. Your '85 header will bolt up to any 12a, except a factory P port.
The different year headers are desinged to fit the stock exhaust system, they are all the same at the engine.
Hope that helps.

Rogue_Wulff

Oh yeah, almost forgot. You may need to use the starter from the 80.
I recently dropped an 85 engine into a 79. I checked the ring gear diameter, and they were the same (replaced the ring gear on the 85 flywheel) but the 79 starter would not engage. Put the starter off my 86 on it, and it works fine. Only visible difference was the starter drive gear diameter, with the 79 being smaller.
Doesn't make much sense that the starter that had been working on the older engine wouldn't work for the later one, since the ring gear was the same, but that's how it was.

Mazdax605

iTrader: (5)

Also of note is there is no means for an oil pressure gauge on the 79-80 motors,but that is not a big deal.You can get a spacer form RB that allows the use of a pressure gauge,and temp as well if I remember right.

Chris

Rusty Shackleford

Will my 85' tranny mount up to the 80' engine fine??

I got a good deal because he said if I came to pick it up he would take $400..which is really good in my eyes considering its been rebuilt and has 15,000 miles on it.

I have an FMOC and it looks like the only other thing I need is a starter and im good?

All the wiring and hoses should just plug right up??

trochoid

iTrader: (6)

Tranny will bolt up but you need to keep the early flywheel and clutch on the engine. As long as you swap all of your current externals over to the new engine, you should have no problems, other than the mentioned exhaust.

Midwest 7's

iTrader: (4)

your starter may or may not work.
i'd try it before you bought a new one.
i have a good one from my 79 if you end up needing one pm me.

Rusty Shackleford

What do you mean externals?? sorry...

Do you mean intake manifold,carb, dizzy, etc?

trochoid

iTrader: (6)

Start with the new engine with only the flywheel, clutch, pp, water pump and housing and dizzy. Then install your old carb, intake and rats nest. Flywheel and clutch are the only parts that you really need to keep on the old engine.