Stroker rebuild

Carl · Post by **Carl** » Wed May 14, 14 11:41 pm

Mossy68 wrote: If so why could it be a problem to hone to correct PTW ?
Sorry chaps. Just interested.

Usually it wouldn't be but my block has been bored out to its maximum any further boring or heavy honing will weaken the cylinder to get the correct PTW will mean removing even more material another 6 or 7 thou probably, doesn't sound much but is when your at the limit.

Mossy68 · Post by **Mossy68** » Thu May 15, 14 9:18 pm

Off topic a bit ( sorry Carl )
But I found out today that modern Bentleys have flared split skirt on their pistons. The bottom of the skirt is virtually tight in the bore from cold but on warm up it reduces in diameter due to the split. This is done so that on fire up from cold the engine is quiet , no piston slap !
All clever stuff

Carl · Post by **Carl** » Thu May 15, 14 9:25 pm

Yes mate, but nothing new they have been around since the 20's

Mossy68 · Post by **Mossy68** » Thu May 15, 14 9:32 pm

Carl wrote:Yes mate, but nothing new they have been around since the 20's

Another new thing I've learnt today then !

Carl · Post by **Carl** » Sat May 17, 14 5:58 pm

Its just a thought, ive personally not heard of it being done but is it possible to have the pistons taken down a bit to gain the correct PTW instead of the block taken out, then just give the bores a light hone?

Pete · Post by **Pete** » Sat May 17, 14 6:10 pm

No. The sides of the pistons are not parallel
parallel.

Carl · Post by **Carl** » Sat May 17, 14 6:20 pm

Thought it couldn't be done was just an idea. cheers Pete

Mossy68 · Post by **Mossy68** » Sat May 17, 14 6:37 pm

Me being dim again probably.
But. When stroking a motor do you follow a set "kit" as for piston size etc for the size of stroke you require. Ie 340 to 416. 360 to 426 etc ???

mopar_mark · Post by **mopar_mark** » Sat May 17, 14 9:00 pm

Mossy68 wrote:Me being dim again probably.
But. When stroking a motor do you follow a set "kit" as for piston size etc for the size of stroke you require. Ie 340 to 416. 360 to 426 etc ???

No, the stroke is determined by the crank, the bore is dependant on what you want to achieve, you also have rod ratios to consider, length of rod, piston gudgeon pin height, etc, etc. A lot of shops offer kits, with some of these things already considered.

Mossy68 · Post by **Mossy68** » Sat May 17, 14 9:43 pm

mopar_mark wrote:
Mossy68 wrote:Me being dim again probably.
But. When stroking a motor do you follow a set "kit" as for piston size etc for the size of stroke you require. Ie 340 to 416. 360 to 426 etc ???
No, the stroke is determined by the crank, the bore is dependant on what you want to achieve, you also have rod ratios to consider, length of rod, piston gudgeon pin height, etc, etc. A lot of shops offer kits, with some of these things already considered.

Thanks Mark. Appreciate you taking the time to answer my questions mate
I have hell of a lot to learn

So in Carl's case the pistons could in reality be too big a diameter to start with hence the reason for the bore having not enough " meat " left in them to obtain correct PTW ?

Pete · Post by **Pete** » Sat May 17, 14 9:51 pm

Nope.
The pistons are the pistons (as I said earlier).

In my opinion (which counts for nowt) I do not think the bores were correctly finished (i.e. finished with sufficient working clearance) in the first place when the Stroker was built - hence Blue's comments about wear / galling on the Piston Skirts.......

I suggest you buy the "How to build Mopar Big Blocks / Small blocks" book and have a good bone up on basic principles, it will give you a better overall understanding.

Mossy68 · Post by **Mossy68** » Sat May 17, 14 10:08 pm

Pete wrote:Nope.
The pistons are the pistons (as I said earlier).

In my opinion (which counts for nowt) I do not think the bores were correctly finished (i.e. finished with sufficient working clearance) in the first place when the Stroker was built - hence Blue's comments about wear / galling on the Piston Skirts.......

I suggest you buy the "How to build Mopar Big Blocks / Small blocks" book and have a good bone up on basic principles, it will give you a better overall understanding.

Cheers Pete. I do understand I can be a pain in the arse on here ( well I try my best !!)
No seriously. What I am finding hard to understand is that like you said the bores were not correctly finished to get the correct PTW in the first place.
So why then as Carl says is there not enough left in the bore to hone to achieve correct PTW ?
Assuming that obtaining the correct PTW will remove scoring etc.

Does that make sense ?
Its a bit like me trying to chop a 3 7/8 "tenon into a 4"" timber !!!
You just wouldn't do it !

Pete · Post by **Pete** » Sat May 17, 14 10:24 pm

It is not a question of being a pain, it is just a case of getting your head around it.

You did not pick up a tool and cut a Tenon without either studying or being shown how.........

Mossy68 · Post by **Mossy68** » Sat May 17, 14 10:31 pm

Fair comment. Time to shut up and study !

mopar_mark · Post by **mopar_mark** » Sat May 17, 14 10:45 pm

Mossy68 wrote: What I am finding hard to understand is that like you said the bores were not correctly finished to get the correct PTW in the first place.
So why then as Carl says is there not enough left in the bore to hone to achieve correct PTW !

As Pete said, most likely the bores were not correctly finished to give the correct PTW.
Lets assume they were too tight, this would of caused the piston to pick up/scuffing the bore causing damage. There's lots of assumptions as we don't know the whole story, actual PTW, Ring clearance, etc, etc.

I am assuming the damage to the bore is greater/deeper gouges than the amount of material to be removed to get the correct PTW ?