ABF Pistons in 6a block ?

Took the head off the 6a today to find piston crown damage



Would the ABF Pistons fit the 6a block, I took one out to find the Conrods are longer, so if I fitted the ABF Pistons to the 6a rods, would this work ?

Con rods are longer cause the abf is a tall block, gives a superior con rod length, I reckon you will need to try and measure the pistons accurately.

Little end pins are different diameters

6a   20mm
ABF 21mm

So won't swap over, back to the drawing board, best get my thinking cap on !!!

9a pistons fit

Whilst it doesn't look pretty it doesn't look like an issue in the pic. As long as the rings or ring grooves arnt damaged or there's no protruding damage likely to mark the bore it'll be fine. Looks like it's very old damage from a broken valve or something in the past. Clean them throughly before re fitting and change the rod bolts…they're a stretch bolt…If you've only pulled 1 piston just change the 2 and don't touch/try to re torque the others…If you've pulled all 4 you'll need a full set.

Thanks for your reply mate on this thread and my other one, I didn't know the big end cap bolts were stretch so cheers, I'll bear that in mind

As for the damage to the piston, if you zoom in on the photo you can see the top coat on the top piston ring has started to break up (on the right hand side of the photo it's ok and the smooth surface of the ring is visible, but the rest of the top ring looks black as the top coating has broken away)

I did take all 4 Pistons out to check them, and 1 of them had the tiniest bit of  damage to the edge of the crown, and when I looked at the top piston ring there was a small piece of the top coating (about 3mm) that had broken away

There is no damage or marks on any of the cylinder bores, they look like brand new to me (but I'm no expert !!!)

I'm tempted to get a new set of rings and put the Pistons back in, would I have to get the bores honed if I were to do this ?

Cheers

Gav

No problem at all Gav.
I can see the marks you mean. Ring's don't have a coating on them so it's either bits of carbon chipped off or whatever marked the pistons has marked the top face of the rings. That isn't too much of an issue if it's just an isolated area as the ring seal against the bore is the main thing, unless the ring is sloppy up and down in the groove.

New rings will need a honed finish to bed into so yes indeed to your question. The debate then is do you look for a better engine or proceed with that one….New rings and rod bolts are going to cost approx £200, plus a hone at around 40 quid. Then the block will need stripping and cleaning properly. .great if you want to get "hands on" or suffer the consequences of honing grit circulating the engine when it's back together…The only way is the right way.

Like this…

I found nevlock engendering very helpful and good prices when I rebuilt my Abf block 

I did say on facebook nothing wrong with the piston.