Stroker rebuild

Dave999 · Post by **Dave999** » Wed Apr 30, 14 1:48 pm

lucky you had the issue....

its a blessing in disguise

better to find out now

i'd be checking the torque on the mains and the un disturbed rods as well

do your pistons have offest pins?

4 the wrong way won't have helped.
different rod angle from the other 4 at igntion

Dave

mopar_mark · Post by **mopar_mark** » Wed Apr 30, 14 1:55 pm

Glad to see your still upbeat & making strides in the right direction, the lessons learned from putting your own motor together will be invaluable...

You seem to be taking the right approach of taking your time, checking everything, better to check 2 or 3 times to be 100% confident.

If it was me, I would be completely pulling the motor to bits & re assembling myself. Even more so with the issues you have found so far, I would not trust anything.

I'm sure it has already been mentioned or you are aware, but ensure you have the rocker shafts installed the right way to ensure oil holes are correct.

Remember, when putting it all back together, clean, clean & clean again

Good luck & keep us updated on your progress

Carl · Post by **Carl** » Wed Apr 30, 14 2:06 pm

Yep im going to be stripping the whole lot down cant trust any of it to be honest. All pistons coming out and re rung I will give the bores re hone, crank will be out new big ends and mains, total re-build, while im this far into it, it would be silly to do half a job.

Carl · Post by **Carl** » Wed Apr 30, 14 3:14 pm

Dave999 wrote:lucky you had the issue....

its a blessing in disguise

better to find out now

i'd be checking the torque on the mains and the un disturbed rods as well

do your pistons have offest pins?

4 the wrong way won't have helped.
different rod angle from the other 4 at igntion

Dave

No offset pins Dave so not an issue with rod angle. I have noticed letters on the underside of the pistons a single letter from A to H on each piston I wondered if these are marked for specific cylinder as marking them 1 to 8 would be, if so they are all over the place.

mopar_mark · Post by **mopar_mark** » Wed Apr 30, 14 3:28 pm

No, just ignore the AH Marking. Go by the valve reliefs, assuming they have been machine correctly.

Carl · Post by **Carl** » Wed Apr 30, 14 4:29 pm

mopar_mark wrote:No, just ignore the AH Marking. Go by the valve reliefs, assuming they have been machine correctly.

Thanks Mark that clears that up.

Carl · Post by **Carl** » Wed Apr 30, 14 5:03 pm

Im just wondering if I can get away without swapping the pistons over onto the relevant rods? I have swapped the 4 offending rods and pistons about and have them in the correct positions regards valve reliefs and the rods are still in their correct orientations with the large chamfer facing the crank journal, the only difference is the rods wont be in the same cylinder they came out of.

Goes against what I was originally taught, where we used to stamp numbers on them so they went back in the same cylinder.

Dave999 · Post by **Dave999** » Wed Apr 30, 14 5:54 pm

well in theory your rods would have been weighed and balanced across the set.

and possibly end to end as well

and your pistons/pins should all be within a few grammes of the lightest one. keep the piston with the pin it had

and then your crank will be balanced, possibly with balancer on it cos it only goes on 1 way.

i doubt anyone checked the big end and bigend pin weight of the crank was acurately counter balanced by the counterbalance bob weights on the crank.. if fact you do that, i don't know if thats releveant on a v8 with 2 rods per crank pin tiz on a 4 and a bit on a 6

so swapping a piston onto a different rod should not make a huge amount of difference or swapping a rod /piston/pin combined from 1 spot to the other shouldn't

given that there were a couple of mistakes made in the orginal build i doubt anyone went to the length of boring and honeing each bore to a specific piston either...some do but you can go over the top for a street/weekend engine

so with a hone and new rings you'd be back to square 1

and with new bearings in the rod i can't see a problem

to be honest you could probably just swap the lot about, check the bearing clerance and be done with it, all sorted bar the gaskets...

its unlikley that the car went far between you purchasing it and when the motor was built. 2 years max

i'd be more inclined to get those 4 valves checked or swapped

i have had a droped valve before it it took out the full piston crown

and that was a 1600 CC 700-4000 rpm VW engine

most pistons unless custom have a F near the pin on the side that should face forwards to the FFFFFRont

unless thats just pistons with a slight offset to the pins

Dave

Adrian Worman · Post by **Adrian Worman** » Wed Apr 30, 14 5:58 pm

You may be able to Carl but I would ask the machine shop to measure the piston before honing, it will only remove a couple thou from the bore but you don't want the skirt to bore clearance too loose. With a cast piston you can have the skirt dimpled to take up some slack but not with a forged piston.
If the clean up hone takes away enough material it won't matter which pistons go where, it'll all be a new mating surface

Carl · Post by **Carl** » Wed Apr 30, 14 6:07 pm

Cheers Dave I didn't think it would be much of an issue swapping the complete rod and piston over, if they couldn't get that right in the first place and not check.

Carl · Post by **Carl** » Wed Apr 30, 14 6:15 pm

Adrian Worman wrote:You may be able to Carl but I would ask the machine shop to measure the piston before honing, it will only remove a couple thou from the bore but you don't want the skirt to bore clearance too loose. With a cast piston you can have the skirt dimpled to take up some slack but not with a forged piston.
If the clean up hone takes away enough material it won't matter which pistons go where, it'll all be a new mating surface

I was planning to do the honing myself, well more of a deglaze as the engine shouldn't of done a lot of miles. But on removal of the Pistons something else has come to light. So it will have to be re honed.

Carl · Post by **Carl** » Wed Apr 30, 14 6:26 pm

Looks like there has been a possible over heating of this Engine at some point the way the piston skirt has scored the bore? Scoring of the skirts and bores on all 8 Pistons and cylinders

Mossy68 · Post by **Mossy68** » Wed Apr 30, 14 6:37 pm

Bloody hell mate.
What else you gonna find ???

Great idea to start a thread.
You never know I might even learn something

Dave81 · Post by **Dave81** » Wed Apr 30, 14 9:30 pm

Sorry to see that the engine is constantly showing up new issues.

On the positive side, all the stuff you have found would ony hurt HP......................So when rebuilt and to the right way, you should find your stroker is putting out a load more power!!!!!

Trying to find the positive........

Mossy68 · Post by **Mossy68** » Wed Apr 30, 14 9:34 pm

Dave81 wrote:Sorry to see that the engine is constantly showing up new issues.

On the positive side, all the stuff you have found would ony hurt HP......................So when rebuilt and to the right way, you should find your stroker is putting out a load more power!!!!!

Trying to find the positive........

Sorry Dave but disagree mate.
Breaking engine parts ( especially performance ) hurts the wallet as well !!!