20v head wanted no cracks

[retropower]

Hope I'm not looking for the impossible!

We're currently rebuilding a customer's engine and following chemical cleaning I have discovered a few combustion chamber cracks, one of which looks to be more serious than either I or the customer are keen to accept.

Anybody got an uncracked 20v head available in the uk?

cheers

Nat

[Rusty]

Hen's teeth...

What is the engine you are working on? 7A, 3B, ABY, ADU, AAN?

[retropower]

Without wishing to sound like a complete moron.......how do I tell!

The block and head are from different engines and it has a steel crank, arrow rods and accralite pistons. Fabricated inlet, fabricated exhaust - Not much of it is as Audi intended!

The numbers on the existing head are: Cast-in 034 103 373 and stamped-in RR 001 516

[terrybullwon]

How does the motor pick up the hall signal is it still on Motornic?

[Kieron20V]

That'll be a RR out of a 20V Urquattro.

Most likely source for an uncracked head would be a 7A out of a normally aspirated 20V 90 or coupe, but then youd need to have the head machined to accept the turbo versions water manifold.

A 3B head should fit directly, but again, due to age and turbo use, most are probably cracked. I believe the bently states that as long as the cracks dont extend to a valve seat or into a water jacket then its still useable. I'll have a nosy when I nip to the garage.

[AndyP]

Without wishing to sound like a complete moron.......how do I tell!

The block and head are from different engines and it has a steel crank, arrow rods and accralite pistons. Fabricated inlet, fabricated exhaust - Not much of it is as Audi intended!

The numbers on the existing head are: Cast-in 034 103 373 and stamped-in RR 001 516

Looks like an RR engine from the last of the 20v Ur quattros.

Does it have distributor ignition and use the waterpump to tension the cambelt?

[retropower]

It does have a distributor (its running Motec now but still running mechanical spark distribution rather than COP) and yep the pump tensions the cambelt

I'm guessing a normally aspirated head is the way to go, how much machining work is involved? I'm guessing it can't be that much in the scheme of things?

[Kieron20V]

Its 3 holes into water jacket on inlet side of head and 3 bolt holes to match up.

Theres dimensions and a template floating around somewhere on here I believe.

[retropower]

cool ok, no problem there then.

Anybody got a good n/a head in the uk?

[Rusty]

Spink is your man.

Exhaust valves are sodium filled on the turbo heads, so you'd want to swap them over.

[AndyP]

I'd advise buying a new set of exhaust valves, I re-used some old ones and had one snap and it destroyed the engine

They are not that expensive from Audi, but if I were to rebuild the head again I'd buy these

http://www.ebay.co.uk/itm/2905577457...84.m1423.l2649

[retropower]

Ok, thanks, will get a new set of valves, on a used head I'd want to fit new guides anyway, and recut the seats.

If non standard, What valve/guide materials are best to go for? (I'm guessing stainless valves and colsibro guides, but I'm not expert on these!)

[retropower]

Thanks folks! Looks like Spink is able to sort something