Mopar Muscle Association UK

As said many times, it comes down to measuring carefully as in this instance we are effectively using 2nd hand parts.

Therefore you need to hone the bores to suit with the existing pistons plus the desired PTW clearance.

This is why it is essential to take the pistons with you when you are getting the Bore Honed.

When you order new Pistons they already take into account the PTW clearance (+.030, +040, etc) - BUT you still finish the bore to suit.....

Its not so easy to understand if you haven't done it a few times already, albeit 25yrs ago!!

Les

Yes I did work it out wrong I added .007 to piston then added .004 + .004 on top of that

Les Szabo wrote:Bore = 4.100.5 = +60 over

Piston = 4.095.5

___________

someone confirm please.

Les

Spot on mate

mopar_mark wrote:

Les Szabo wrote:Bore = 4.100.5 = +60 over

Piston = 4.095.5

___________

someone confirm please.

Les

Spot on mate

I meant the rest of it Mark

Les

Les Szabo wrote:

mopar_mark wrote:

Les Szabo wrote:Bore = 4.100.5 = +60 over

Piston = 4.095.5

___________

someone confirm please.

Les

Spot on mate

I meant the rest of it Mark

Les

It wasn't intentional, it's all good

I popped a piston back in today and this is what I found

All cylinders are around .003 and .004 with one side against the cylinder wall

At this point, I would suggest you take your block and pistons to a professional engine shop that is used to dealing with V8's, preferably a knowledge of high performance motors, but not absolutely essential.....get them to measure everything up properly and get their advice on how best to continue from their results for the type of use you want from it before doing anything further or spending any money.

Les Szabo wrote:At this point, I would suggest you take your block and pistons to a professional engine shop that is used to dealing with V8's, preferably a knowledge of high performance motors, but not absolutely essential.....get them to measure everything up properly and get their advice on how best to continue from their results for the type of use you want from it before doing anything further or spending any money.

Perfect post from Les

Yes I agree, im going to have to come out at least another 6thou to make the engine serviceable, and I don't think its got it in it.

Carl wrote:Yes I agree, im going to have to come out at least another 6thou to make the engine serviceable, and I don't think its got it in it.

I don't recall how big the gouges are in the cylinder walls ?

But you have quite a few thousands to come out, so all may not be lost. it depends what you intend to do with the motor ?

This is not meant as being disrespectful, but the way you are approaching the build, its never going to be an all out race motor living on the edge. So sort out narrows it down to a reasonable street motor & a bit of track fun here & there.

A few tiny nicks will be fine in a regular street driven motor & would seem to be a good option for a cheap route. A final hone & some rings is cheap in comparison to a new build.

You cant measure bores clearance as you are showing with feeler gauge. You cant beat a bore mic & regular mic for checking pistons & obtaining accuracy. A cheap digital vernier is more accurate than those feeler gauges.

Take up Les's advice & visit a decent engine machinist, take the block & pistons with you. If its a reputable or decent shop, they should be able to advise you & will also be able to measure the bores correctly. They should also be able to advise you the max upper clearance tolerance on Piston to bore, based on actual experiences v Manf stated figures.

Sorry if I'm being dim. But if your showing .003 as pic then isn't that a PTW of about .0025 ? Which was considered too tight ?
Then what is the prob with honing to desired PTW ?

Mossy68 wrote:Sorry if I'm being dim. But if your showing .003 as pic then isn't that a PTW of about .0025 ? Which was considered too tight ?
Then what is the prob with honing to desired PTW ?

Hard to tell from the picture, it look as the piston I being pushed against the cylinder wall & the opposing gap is being measured with a feeler gauge. If this is the case, the 0.003" should be halfed, making 0.0015" PTW.

This method of measuring is not accurate, you need to know the if the bore is round, if the piston is round (not that piston are fully round, along their full length) & their respective diameters. This should be done to all 8 pistons & to all 8 bores

mopar_mark wrote:

Mossy68 wrote:Sorry if I'm being dim. But if your showing .003 as pic then isn't that a PTW of about .0025 ? Which was considered too tight ?
Then what is the prob with honing to desired PTW ?

Hard to tell from the picture, it look as the piston I being pushed against the cylinder wall & the opposing gap is being measured with a feeler gauge. If this is the case, the 0.003" should be halfed, making 0.0015" PTW.

This method of measuring is not accurate, you need to know the if the bore is round, if the piston is round (not that piston are fully round, along their full length) & their respective diameters. This should be done to all 8 pistons & to all 8 bores

Sorry Mark. Meant 0015. Halved it but typed it wrong !!
I understand it is inaccurate however this is still showing the PTW is too tight. Correct ?
If so why could it be a problem to hone to correct PTW ?
Sorry chaps. Just interested.

I did initially mesure the bore and piston with a digital vernier to get measurements of for bore 4.100 and pistons 4.0955 I was just checking the gap out of curiosity, to measure accurately I really need a bore gauge to measure the bore all the way down.

But you are correct mark and no offence taken, the car isn't an out and out race car so my tolerances arnt going to be as critical but at the same time I want it serviceable for my needs bit if street/strip.