ABY Engine Rebuilding

[Jon441cc]

Well it looks like the SPM group buy rods may have to be fitted sooner rather than later, so i need some advise.I will be changing main and big end bearings, but will this mean the crank will have to be reground to accomodate the new main bearings.

I will be using the old pistons as they seem to look in good order and just fit new rings which will require the cylinder bores to be honed, also will the crank and rotating parts have to be balanced as i am just replacing the con rods and they come as a balanced set.All in all i have never had a engine rebuilt and just need some advice.

The original honing marks are still visible on all cylinder bores after 159k

[mcandmar]

In the process of doing the same myself

You shouldn’t need to regrind the crank unless its very worn, only way to tell for sure is to use plastigauge to measure the clearance between crank and bearing shell. Mine was still within the specs with the old bearings. Fitting new bearing shells will close the gap, i will have to measure it again with the new bearings just to be sure.

From what i can tell Audi dont do oversize bearing shells for the 3B/ABY so if your crank is worn to the point your outside the specs your screwed. I may stand corrected on this one

As for crank rebalancing i was told yes, worth doing anyway if you’re doing crank bearing as it has to come out anyway. Have a read here,

http://www.s2forum.com/forum/showthread.php?t=13493&highlight=crank

Rehone and new rings should be fine, again it depends on the cyl bore wear, in my case it was bad and ended up having to overbore .5mm. Again Audi dont do oversize pistons for the 3B/ABY so you have to buy Mahle which are damn pricy, or go custom. I think i'm going to go with JE pistons on my build.

If your bores are fine and giving good compression i would leave well alone. If it aint broke dont fix it.

[Jon441cc]

that will do nicely.
i may go down the route of of cosworth custom pistons just dont know on the prices yet.

Does anyone know where i could source a set of ARP headbolts for an ABY avant.

[mcandmar]

Yes i was given contact details for a guy in Cosworth, never did get around to calling him. I'm flat broke after the rod group buy so i will check that out next month. ....i can sense another group buy coming on :mischeif:

[ottawa coupe]

I don't know how different the 7A and ABY engines are BUT the 7A uses the same bearing shells as a VW 16v (same individual part number), just one more of them obviously. i checked in my family album to confirm this. it would be worth checking out on your family albums as mine is an NA one and does not mention ABY in it. so if your crank is worn to the limit, i don't think you're screwed.

[mcandmar]

I'm fairly sure there not the same, i do remember seeing undersize bearings for 7A, NM and KV motors in ETKA but not for the turbos.

[SteveH]

Glyco do a bearing set for the 3B/ABY/ADU, they are very high quality sputter bearings. They also do oversize if you need the crank grinding. It's unlikely that a 5cyl crank will need grinding unless it's seen mechanical damage, spun bearing, etc or oil starvation.

[S2 Ant]

ARP head studs can be supplied by SPM (The rod group buy company) i believe they worked out to about £120 but cant remember exactly. Think they were the cheapest i came across tho as a supplier for these studs

[mcandmar]

Curious, any difference in quality with these vs the Audi parts. Are they any better than the ABY/ADU units?

http://www.elcome.ltd.uk/fm/index.asp?cat=0&lang=en&region=1

[SteveH]

Not sure about the difference between these and the ADU items. I should think the ADU shells are sputter too. The Glyco items are good for high output motors, I know of cars with 500-600hp running them without any issues.

[Jon441cc]

Well this is the whole reason the new rods can be fitted sooner rather than later.

[4WheelDrifter]

Ouch!

[mcandmar]

Nasty, how bad is the damage?

[Jon441cc]

i was expecting alot of damage to the valves and pistons but visually they all look ok but i will be stripping the head apart tonight so we will see.

[Jon441cc]

Im trying to source a 7A exhaust camshaft if anyone can help, preferably in the UK