[Damjan]

Hey there!

Since my stock AB 1300 dual port engine is on the stand, I’ve been considering upgrading it to something with a little more power without modifying the case and sacrificing reliability. Maybe a 1600. I know 1600 cylinders fit, and that I’d need new heads for it. Do I need to pay attention to anything else for such an upgrade?

I don’t want to modify any of the existing components, so I can restore it to stock in the future if needed.

Thanks!

 

[Bada Ben]

You will also need the 1600 carburettor and 3-piece manifold, also a flywheel from a 1500 or 1600 and a 200 mm complete clutch.

 

[Mr.Whippy]

And bear in mind the bottom end needs to be in really good shape otherwise you're building a new house on shaky foundations and it wont last as long.
How many miles do you do and how reliable does it need to be, long term ?
Without splitting the case there's not a lot you can do to check this, other than to check the endfloat is still within factory tolerances, and I assume it was running perfectly well before you took it out ?

Dave.

 

[Damjan]

The engine ran ok when it developed a clutch problem, but that was about 10 years ago. It hasn't been driven since. Now I am restoring the thing from the ground up.
I measured the end play at the flywheel, which is 0.2mm (a bit over the 0.14mm tolerance, but still not that bad?). I've decided to replace the main seal behind the flywheel as it was leaking, get a new clutch, remove the heads to see how they fare, check the cylinders, etc, but I'd rather not split the case.
I don't plan to drive it much, since I want to spare it bad weather, salty roads, etc, but I want it to be reliable.
Do I really need a 200mm clutch with a 1600?

 

[Mr.Whippy]

200mm clutches were introduced by VW for the 1500 engine, but it depends what vehicle you're putting it in, how hard you will drive it and what lifetime do you expect out of it ?
Refer to this recent thread which covers the issue - 180 mm or 200 mm clutch?

0.2mm is over the limit, and 99% of the time excessive endfloat is caused by the front main bearing becoming loose in the case, not because of wear between the crank and the bearing itself. Therefore, once the bearing starts slopping back & forth in the soft alloy case, the wear continues to accelerate and the larger gaps also lead to lower oil pressure. You cannot shim adjust this sort of wear out.
So if you're going to renew the oil seal regardless, remove it then remove the 3 shims behind it. Then you will see the front face of the front main bearing. If you press it in towards the engine hard with your fingers then push / pull the bottom pulley in & out with your other hand you might feel the main bearing move very slightly relative to the case. Ideally you'd use a dial test indicator for this (DTI). If the bearing shell has any movement whatsoever with respect to the case, then only a case split, accurate linebore and oversize bearings can fix this. Preferably a brand new case really as many linebore procedures are not accurate enough.

However...... given what you say above regarding your expected future use / mileage, and if the endfloat is only just over factory tolerances, you may find that the engine will be good for quite a few thousand miles yet (especially if sympathetically driven) without any major problems other than perhaps changing that oil seal more often than usual, as one of the main symptoms of excessive endfloat is oil seals failing prematurley, as they're not designed to cope with in & out motion.

Dave.

 

[Damjan]

Thank you very much for the in-depth explanation, Dave. I’ll keep it stock, then. One day, perhaps, I’ll just start over with a new engine altogether.