Max bore for a "production" 502 block
 

I'm at 4.5" right now but my piston to wall clearance is 6 - 8 thousandths and the bore NEEDS to be cleaned up some...

Has anyone gone to 4.530"


Thanks,


Doug

I have 2 blocks that are .060 over, no issues so far.

I'm there with Gen 5 blocks. A Gen 6 can go 4.560 most times. It helps to sonic check the block first.

That's good to hear.. Mine is a Gen VI block....

I found a place today that can sonic check it for $100.00 :cool-smiley-011:


Thanks,

Doug

I got my sonic test results back..:)
Gen VI block currently bored to 4.5"

cylinder Frnt Out rear Inside
#1 top .278 .303 .357 .312
bottom.301 .286 .351 .465
#2 top .276 .303 .338 .315
bottom.268 .314 .330 .312
#3 top .341 .282 .228 .309
bottom.425 .280 .332 .362
#4 top .340 .278 .362 .331
bottom.355 .279 .345 .368
#5 top .360 .296 .337 .329
bottom.349 .291 .345 .393
#6 top .327 .273 .354 .326
bottom.337 .261 .442 .369
#7 top .360 .310 .281 .326
bottom.484 .342 .281 .362
#8 top .325 .248 .283 .334
bottom.327 .266 .276 .385



....never had a sonic test done before, but it definately looks like it's safe to go to 4.530":evilb:


Doug

Going .030 over is the norm. It will make it a 509ci

It already was at .030 over.....

I'm tryin' to go .060 over.. :D


Doug

Standard bore is 4.466. w/4" stroke =502CI
4.500 w/4" stroke =509CI
4.530 =516CI
4.560=523CI

no problem at 60 over, i would sonic test if 60 over would not clean cylinder

Piston to wall at .006 is perfect .008 is fine too when using a forged piston.
I also read where testing was done with hyper pistons from .003 to around .008 (if I remember right) and there was no issue with them either.
"Cleaning up" means .0005 -.001. .009 will work with good rings.

my.02

That's a good thick block. It's good for another overbore after this one.:cool-smiley-011: And then you put in the 4.25 stroke crank ......

.....AND a blower!!! :drink:



I'm thinkin' this build will be enough for now...

My last build made just shy of 600 hp and got me to 80.5 mph... (I only have 21' of hull;))

This time 'round I'm running a little more compression, AFR heads and a bit bigger "Rmbuilder" cam... Hopefully it'll be close to 650 hp or so..


Oh, I also just installed a Stern Jack.. should be fun!!:evilb::evilb:


Doug

I bore the Gen 6 502's to 4.600. We ran the same engine for 2 straight racing seasons. When I put the torque plates back on and rehone the cylinders they clean right up.

Same here. Can't even begin to remember how many I have bored to 4.600. Have never had the first bit of trouble out of one of them. Eddie

Sorry to ask but, What happened that the engine needs rebuilding after only 2-3 years?

....Well, actually it only ran about an hour this time...

It's a llooong story but I'll try to condense it some..:food-smiley-007:

I had 90 hours on the engine so I decided to check the valve springs and found they were going soft so I bought an "on the engine" valve spring compressor and was using air pressure to hold the valves in place while I changed out the springs.
I did the even side of the the engine and had no problems whatsoever. When I was in the process of changing the springs on the # 3 cylinder I felt air blowing on my leg.. Much to my surprise it was comming out of the # 5 spark plug hole. I then put the air hose on the # 5 cylinder and air came out of the # 7 spark plug hole..

I pulled the head to find that the head gasket was just starting to blow between the cylinders....
Turns out my engine "builder" had used stock head gaskets...:mad:

Well, I'm not one to leave well enough alone and a friend of mine happened to have a set of AFR heads for sale for a good price so I figure I might as well "freshen" the whole engine and change the cam to better compliment the new heads.
I had the block decked and had the crank checked out and everything was good.
I assembled the engine myself THIS time and threw it back in the boat and took it over to
Full Throttle Marine to run on his propshaft dyno.
The first pull we were just taking it easy on it and it made 515 hp at 5000 rpm at the prop. :D
The next pull it was down 50 hp and wouldn't pull over 5000 rpm. We checked EVERYTHING and finally I pulled a valve cover to check valve adjustment and found that the oil was FULL of metal. :eek:


I pulled the engine and found 6 spun rod bearings and metal EVERYWHERE. :(
Still not exactly sure what went wrong but we're still working on figuring that out..
My crank, rods, and pistons are junk and my block needs to be bored...



Doug

Sounds like it's time for a 540 Doug!

What about in a blower aplication?

I think there are differences as to how far you can bore based on Bulldog vs Dart vs regular block.

I wish I could swing it.. I could if I sat out yet another season but that just ain't happenin'

I priced an assembled 540 shortblock from Rehyer Morrison and by the time I got yet another new cam and everything else needed I'd have $7500 in it using my heads and intake...


I have it at the machine shop right now on it's way back together..
I got a crank from Kidnova (THANKS AGAIN BILL :cool-smiley-011:)
It'll have Eagle rods with the l-19 bolts and JE pistons.
I also got a 10 quart pan off Ebay ..

Everything said and done I'll get it back together for around $4200.... should be done and back on the water sometime in January. :evilb:

Doug

Boating in January ............. you chit head :p :D

He!!, the last time I had it out was October in Wisconsin with temps in the 40's....:D

http://www.speedwake.com/upload/atta...&postid=583736


....It was 81 here last Sunday and supposed to be 77 today so far December boating wouldn't have been all too bad..
I'm REALLY glad we finally moved :drink:


Doug