# Bubble Block: 220mm 3A build



## fwdvw (May 12, 2000)

I'm in the process of building up my 3A. Full rebuild I hope to highlight and may become a definitive guide to the 3A.

This was suppose to be a simple low cost rebuild but has become a money pit. 

I'll update this as I proceed but first the Most Basic part of the build are the pistons. 

AEG 83mm 20mm pin pistons will not work with 3A rods



Currently your only options are the aftermarket forged 83.5mm pistons (if you want to keep the 10.5:1 compression)

The standard part numbers in 83mm 0.5mm overbore (There is a 0.25mm overbore also)

Audi	053107081
Audi	053107081E
Audi	053107107
Kolben 93998620
Mahle 034 84 02
Perfect Circle	56 01778 1W
VW	053107081
VW	053107107

These pistons are impossible to find. And when all is done, one might be better off using an ABA. 

I'll be updating the specs and the build in as I progress

The project will be:
Audi 3A 83mm oversize
Audi 3A head with 7mm ABA valves
AGB Transmission

Some introductory pictures for you:

This is the point where i discover the pistons will not work. A little late to find this out.


Scat Rods: 144mm


Block already bored for 83mm Cast pistons


The Injector set on the 3A head: Besides some performance advantages, its a dream to swap injector holders and seals.


And Preloading my AGB


Stay tuned


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## fwdvw (May 12, 2000)

*Pistons*

There is some speculation that AEG pistons using the 20mm wrist pin are viable options for the 3A.

But as this picture shows, the head of the standard rod for the 3A does not fit in the piston pin area.


From what information I've read, VW has apparently gone light weight on us. 

Observations:
1) Seems the head on the AEG rod is much slimmer
2) AEG pistons skirts are very shallow, and I bet the cylinder inside the AEG block are not as deep as the 3A Bubble block. The reason I say this is because the AEG pistons are also Clarence for squirters, but if they were put into the 3A block, that clearance is much more than necessary to clear the 3A squirters. 
3) Piston pin area on the AEG piston is thinner and the pin itself is not as long as the 3A piston pin.

So it does seem that VW has gone light weight on us.

There are several options I'd considered. To shave the rod head to fit or mill the piston to clear the rod head. I feel that with such a thin piston pin, milling the piston would not be wise.



At this point i had already had the block bored for 83mm cast pistons, so my forged options and or going 83.5mm would mean i'd have to spend another $1,000 . Forged Pistons even in 83mm would have required me to bore the block again. $600 or so for pistons and $300 for boring. So because of this mistake on my part, sourcing the OE cast pistons would have been cheaper and salvageable.

So the good news is I did find a set of 053 107 083E pistons. They should arrive next week, but it was a long journey to find them. I sourced a set in Australia but when they did the stock check the box only had 2 pistons. The set in the UK I found was apparently found in Asia as overstock and then bought from a distributor in the UK, as overstock.


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## fwdvw (May 12, 2000)

*Pistons Part 2*

Finally got my elusive pistons.


Audi may not have made very many of these since they are 2nd oversize. I was only able to find 2 sets and one was partial. I don't think any Audi 80's made it to the point of getting to 2nd oversize. I learned these went obsolete around 2004

Piston Cylinder Bore
std 82.48mm 82.51mm
1st 82.73mm 82.76mm
2nd 82.98mm 83.01mm


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## L33t A2 (Aug 5, 2003)

*FV-QR*

i'll be keeping my eye on this one :thumbup:


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## Vedubauman (Sep 20, 2001)

Good information. I'm hoping rings will solve my issues on mine. I don't want to scrap this engine. I'm just hoping to find mine is a late 3A with the 9A rings on it.


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## fwdvw (May 12, 2000)

Vedubauman said:


> Good information. I'm hoping rings will solve my issues on mine. I don't want to scrap this engine. I'm just hoping to find mine is a late 3A with the 9A rings on it.


I think your only future option is to use AEG rods and pistons. 

but if you still want to maintain the 220mm block, overland has this which i've never seen. The modify the new blocks to fit our 8V and 16V heads. Eliminating the water pump on the side you can use their dry sump kit too. It includes the motor mount bracket for the Mk1.


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## fwdvw (May 12, 2000)

I think this says the dry sump kit for 4cyl is $700.


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## RGARDGTIR (Aug 23, 2013)

What is the main purpose of your build? what do you want to get out of it?


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## Picmas (Mar 11, 2021)

fwdvw said:


> I'm in the process of building up my 3A. Full rebuild I hope to highlight and may become a definitive guide to the 3A.
> 
> This was suppose to be a simple low cost rebuild but has become a money pit.
> 
> ...


Long time ago - I know...
I joined just to advertise a set of KOLBENSCHMIDT 93 998 620 I have for sale. Its a set of 4 pistons with pins, clips and rings never installed and still in box.
I got them with 2 other stes of VAG pistons in a lot of parts. I have absolutely no use for these.

I havent advertised them anywhere else yet.

Shipping from Denmark.

Anybody interested?


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