Thread: 657 swap into 657x setup
08-18-2014, 07:45 AM #1
657 swap into 657x setup
I've built a standard 657 up a few years ago but never dropped it into my SPX where it belongs. I just found a clean '95 GTX with a blown 657x engine for $200....so if I swap the entire base 657 engine/pipe/carb assembly into the GTX, am I going to have issues without changing the MPEM, impeller, readouts, ect....?
I'd rather have a 3 seater, and I already know the physical differences between the 657 and the 657x.
08-19-2014, 09:10 AM #2
Don't swap the base. It's an exact fit in the gtx base. The gtx base will have a better chance of keeping proper pump alignment. Keep all the parts you can from the GTX, carbs, rotary valve cover, stator, flywheel, exhaust etc and everything will work just fine.
02-29-2016, 12:45 PM #3
In a great turn of irony, I bought a 1994 GTX, rebuilt the 'normal' 657 motor that I had bought in a million pieces, and now I find out that case was a 657x case with the carb pulse fitting on the wrong side. Arrgggg...
03-01-2016, 08:40 AM #4
Carb pulse fitting isn't anything to get all tore up about... lol. Buy a Longer piece of hose to connect it... problem solved.
03-01-2016, 10:17 PM #5
When swapping around 587/657/717 just remember 5 wire stator with 5 wire MPEM.........4 wire stator with 4 wire MPEM. Simple as that. keep complete motor carbs and exhaust with each setup or trade up to better parts. I put a GTS together last year with a ported 587 a ported single carb intake and late acc pump style single carb, and a 717 pipe. With a solas 14/19 I got 46mph on GPS out of it. Not bad for spare parts. Mix and match away!
03-07-2016, 03:14 PM #6
Cool, thanks. I'll post it up when I get it running
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