To Stroke or not to Stroke?

[Joe50]

Well I blew another motor. Its junked. Water was slowly been getting into the oil. No telling how long its been like this. Its had a miss for a while but I just thought it needed a tune up. Well I did the tune up and pulled the number 8 plug and found the gap on it to be bent shut, so I decided to i pull the heads off. Part of number 8 piston broke off was bouncing around in the chamber and now the block is cracked.

So the question arrises what to do now. I know I want to keep the same heads for now (GT-40p's from central coast). I know they arent that great, but they will have to do for now. I was looking on www.speedomotive.com and found a 347 kit for just under $1300, a 317 kit for just under $1200, or a longrod 302 kit for $860. Im kinda afraid to use my old crank, that is why im thinking stroker kit. Water just doesnt lubricate that well.

I want this engine to last at least 75000 miles. Has anyone had any experience with speedomotive? Are there any other kits you would suggest? Can you get 75000 miles out of a 347? Am I pissin in the wind with a 347 and these heads? Should I just put another 306 in it?

Thanks everyone,
Joe50
'93 GT N.A.
12.74 @108

P heads, Cobra Intake, B cam, longtubes, x-pipe, 70mm accufab
t-body, 76mm C&L MAF, 3.73's and tremec 3550.

[Smokedawg]

I was recently running a 347 with p heads and couldnt wait to get them off of there. I wouldnt recommend going with the 347 wanting 75,000 miles. Not saying that it wont get there, but I just wouldnt suggest it. I would either go with a 306 or 331. I currently have Dart Sr. heads for my 347 and topping it off will be a holley systemax intake port matching them..
Good Luck

[PKRWUD]

The 347 was never designed to be a high mileage engine. While I have seen claims of 100k miles, these are the exception, not the rule. If you expect 75k+ miles, I would go with the 306. Maybe the 331.

Take care,
-Chris

[Moxie]

As long as you have to replace the crank and rods, I vote for the 331. Unlike a 347:

The block doesn't need to be machined for clearance. It can be assembled just like a 302.

The piston pin doesn't intersect the oil ring.

Better rod ratio, so less lateral load on the piston.

IMO, you'll get better durability out a 331 than a 347, and almost the same power. You may want to consider porting the P heads.