how much do i machine?
 

ide like to get some advice about how much to machine on one of my stock 502's.

ill try and make this short.
head gasket leaked and hydraulic locked the motor.meaning it ran till i shut it off then it wouldnt turn over.my mechanic replaced the stock gasket with fellpro gasket and it seamed to run ok for awhile.6 or so run hours later the knocking started.

obvious damage: number 7 cylinder scored and piston damaged.bearings have water spots.crank appears to be ok.

how much should i machine and replace.mechanic thinks .030 over will fix the cylinder.how risky is it to just bore one cylinder , install 1 new piston and install new bearings?please keep in mind i have a limited budget.

thanks in advance ,
lotoparty

Do it right the first time even if it costs more. If not you'll be spending even more in the near future and paying for more labor and machine costs.

Can't help but to agree with Griff. Once you go through all you have to go through to do one cylinder it doesn't really cost all THAT much more to do it right. Anyhow; I don't know anybody in this boating game whose budget didn't get limited after being into it for awhile. --- Jer

thanks for the advice guys!!

i tend to agree with what you say as far as doing it right the first time.

question is , what constitutes "doing it right".

bore all 8 cylinders , 8 new pistons , new bearings?

is that enough?

Yes, bore all the cylinders. If you don't you will have one piston that will not weigh the same as the other 7. Being out of balance I could see the crankshaft and bearing life shortend.
Just my .02.

Give Bruce a call @ State of Mind Watersports in St. Louis. He will give a straight answer and if he says you can get buy with a one cylinder bore, which I doubt, that would be good enough for me.

His number is (314) 731-3795. He is usually very busy, so leave a message if he is not there.

mike

deck the block and shave the heads just enough so they seal properly this time. it's not expensive. don't forget to account for this when choosing a head gasket as your compression ratio will change. trw forged pistons may be the least expensive ones that are pretty good.

What about sleeving the one cyl and using everything else stock?

Katdrvr ,

i appreciate the referal but i dont want to call and bug someone that im not going to give business to.
im on the other side of the state from st. louis.

thanks again though!!!

Bruce has several KC based customers. Bruce has meet me in KC a couple of times to trade parts, I'm in Omaha.

mike

Bore all 8 and do it right, check the rods if you compressed water the rod might be bent.....

yes dyno , i will have rods checked as well as the crank.

does anyone have any ballpark figures on how much this will cost me.

check crank
check rods
bore (8) cylinders .030 over
(8) new pistons
new bearings
:confused:

Your engine builder is the bottom line on the price no matter what we say. However consider, you can go .060 over for the same price as .030 and get the benefit of the extra cubes. Also makes a C/R change to your benefit. See a good MARINE engine guy in your area. --- Jer

part #L2513F in PAW catalog is, forged TRW pistons .030 for 502 , speed pro rings, rod and main bearings and pins. $688
don't quote me but i'm guessing $150 to dip block, and install new freeze plugs and cam bearings, $8 per cylinder to bore, and the guy i go to doesn't charge me to check rods or crank.

jpclear , forgive my ignorence.what does C/R mean.

do i really want (1) 502 stock and the other .060 over?

i do like the idea of the extra cubes.
:D


excaleagle42 , thanks for the info.

im feeling alot better about the whole thing.
i was expecting to hear cost in the 2000.00 range.

now if i can just get it done before memorial day weekend
at loto.

By C/R I meant compression ratio. Again, your local MARINE engine builder is the guy to give you the final on this. AND I DO MEAN A MARINE ENGINE BUILDER, NOT THE LOCAL STREET ROD BUILDER!!! If you find that guy and he'll get it done so that you can get it installed and running by "M" day I want to know who he is. That 502 should be a "bowtie" so .060 over will still leave you clean-up room for the next time you squeek it. Get it wet asap. --- Jer

I've seen factory rebuilt motors that come with only one cylinder overbored that were installed in customers vehicles and have had no problems. I've also been involved with stock car motors that have 7 cylinders bored .060 over and one cylinder left stock. The stock cylinder is left in the position that has the easiest access from outside the car in case track officials want to "puff test" the engine for rules violation. These cheater engines have logged many trouble free high RPM miles on the race track. The ideal situation would be to have the whole motor done but you said you were on a tight budget and I just wanted to let you know 1 cylinder can be bored with no problems.

Bo

Don't do it ,do all 8 cyl. its hard enough to match compress & piston weight when everybodies the same dimension.I have owned a shop for 23 years now and have built just about every kind of engine out there.I got into marine engines in the mid 80's and about to turn complete shop into nothing but marine repair.Just purchased 2000HP DTS dyno (same as Tyler Crokett).Dyno will be complete in about 6 weeks if anybodies interested.

loto,

If you go the bore route, I have two sets of crank, pistons and rods for sale. The pistons are .060 over 502. All the parts are is good shape.

I am putting in a stroker crank with new rods and pistons.

mike

It just depends on what you want to do. I'm assuming the rest of the compnonents including the cam and lifters are in good shape. If you want to sleeve the one hole and run all standard pistons, this is perfectly acceptable. If you would rather bore the one hole to an oversize, this is also an acceptable repair. To address the balance issue, your machine shop would simply weigh the old piston/pin and match the weight of the oversize piston/pin to it. Both of these options will be much less expensive than a complete bore and rebuild. But if you feel the right thing to do is to completely rebuild the engine, no one is going to argue with that either. It's all in what YOU feel is the right way to do the job. Good luck on the project.

heres an update for anyone interested.

picked engine up tonight and paid bill of $1856.00

bored all (8) .030 over.

new j & e pistons.
new stock gm cam.
new bearings.
new timing chain.
decked the block.
new lifters.

those pistons and cylinders sure look pretty!!!

droped engine off to mechanic at loto where boat is.
he says she will be ready friday!!!!!

have my fingers crossed that new cam will be ok after reading about other guys having problems.

maybe ill see some of you guys at loto.

Lees Summit , Mo. Irish Wake

thanks again for the advice i got from the board.

I was just going to say that if any of you needed a set of Ross 4.50" (turns a 502" into a 509" engine) forged 8.5 cr flat top pistons (8.5 cr based on a 121cc chamber) I have 2 sets that have low hours (without pins) for $150 per set or $250 for both sets. Mark 616-291-7932