Mopar Muscle Association UK

Glad to see we are starting to convince you


Flex hones are good, I have one in the garage. Its all about the right tool for the right job.

It's more critical with gapless rings if you think about it. It there was a tiny tight spot.......

re hone 50 quid cash Guards Auto Engineering Rayleigh Essex cant grumble at that not worth me getting my hands dirty at that price and half the price of a flex hone. Grateful you twisted my arm

There you go
While they have it in the shop get it properly measured, bore sizes, deck heights etc. bet it's only another 20 quid
Remember to take the pistons......

I wasn't going to take the pistons as its only a hone to break the glaze for ring seal, but I could get them to gap the rings and fit them on the pistons I guess saves me another job.

If you don't take the pistons how are you goin to accurately work out the required piston to bore clearance ? If the piston to bore clearance is much in excess of say .006"-.007" on a 2618 alloy forged street piston you'll have excessive piston slap and excessive oil consumption, not to mention ring blow-by and possible ring land damage.
You're goin this far Carl, you may as well get it checked for your piece of mind. Or worse to find out its a a non starter ...... hope not!

Carl, its not a hone to break in for ring seal at all, I thought you took on board previous comments?......as Ade says, everything you do to eachbore
depends on the size of each of the Pistons. you need to end up with each bore 008" larger than the piston you are putting in it, .004 per side, or whatever the required PTW is for your type of piston. According to the link you provided it was .004?

That was the whole point of it all, whether you had enough room left to get rid of the scoring so you end up with the correct PTW, thats probably why the pistons look the way they do now, you only had .0025 before according to your figures.

You seemed to have .003 left to go on each bore to get rid of the scoring and clean up to the ring finish required, thats why I said looks like you've been given a second chance.

Les

Fair point Les and Ade I assumed we where talking about not being able to take it out any more due to the excessive over bore and a re hone would give me enough, I must of miss read the posts

But the point is that they will NEED the pistons to tell you that
You need as much practical information as you can to make an informed decision on how you proceed with the build, you've got a professional to do the work so use 'em

no matter, just get each piston checked for condition and measured exactly, allow .004, or .0035 if thats what the correct PTW clearance is per side. Then either add .008 or .007 to the piston size and that is what your finished bore for each piston needs to be honed to.

Your bores were .005 larger than your pistons, giving .0025 PTW, which was too tight. You now need to go out on the bores 2>3 thou whichever you decide is the correct PTW, thats why you got a chance at the clean up.

Make sure these guys know exactly what you are talking about, just cos its an engineering place don't mean they do!!...if it sounds iffy, go to Johns Engineering, they should do!...and if I might add, forget about how cheap this is or not to a point.....you got 1 chance as you said to get this right.

A quick flick across the Decks would not hurt either.

Les

Okay tis what shall be done. For some reason I thought I read it as the ptw was ok hence why I thought taking another 6 or 7 thou off will be too much. Thanks again

Blue gave you the clue on page 3 of this thread.....

Glad its getting sorted and hope no other damage is identified - make sure the Ring Lands are OK and do not pinch the rings......

All the best with it

Cheers Pete

This is from the Ross site....

THE FOLLOWING RECOMMENDATIONS ARE FOR OUR STANDARD DESIGN
PISTONS FORGED FROM 2618 T-61 ALUMINUM. MANY SOLID (WATER
JACKETS FILLED) BLOCKS AND AIR COOLED ENGINES WILL REQUIRE
ADDITIONAL CLEARANCE AS WELL AS ENGINES WHICH HAVE BEEN HONED
WITHOUT TORQUE PLATES. AIR-COOLED ENGINES WITH PLATED OR
SLEEVED ALUMINUM CYLINDERS MAY REQUIRE LESS CLEARANCE.

Normally aspirated street cars
Bore size 3.475 and under..................................... .003
Bore size 3.476 – 4.499......................................... .004
Bore size 4.500 and above..................................... .006
Modified type engines, including drags,
circle track, and road race.................................. .004 to .005
Turbo engines, small bore.............................................. .006
Marine applications add................................................ +.002
Nitrous over 250hp V-8 add.......................................... +.002
Nitrous over 100hp 4 cyl add........................................ +.002

As I doubt they will use a Torque Plate I will need to add x amount of thou to their recommendations.

If my calculations are correct, piston is 4.095 + .007 = 4.102 + .004 + .004 = 4.110 so it needs to be honed out 10 thou if bores are 4.100

That will give 5thou both sides

Bore = 4.100.5 = +60 over

Piston = 4.095.5

___________


No Carl, add 10thou to your piston size if you want .005PTW?.....and your finished bore needs to be 4.1055, which is 4.0955 piston+ .010PTW.....so you now have .005 to clean the bores up to good=4.1055-4.1005 current=.005.

Bore size is dictated by the Piston size+ your preferred PTW clearance...current bore size is irrelevant, its only good to know how much you have left in it for the clean up after working out what your max bore size needs to be.....yes....what you are forgetting by your post is that your pistons are smaller than your bore size.

someone confirm please.

Les