1.5 head on 1.6 adapter specs needed

[CarlosA]

Does anyone have specs on this adapter that is needed? I am about to do a swap, but want to make the adapter on my lathe before I pull the head.

[libbydiesel]

What specs are you looking for?  You should *not* use a 1.5 head on a 1.6.  The pre-combustion chambers are sized relative the displacement.  Placing the 1.5 head with smaller pre-chambers on the 1.6 will result in overly high compression.

[CarlosA]

What specs are you looking for?  You should *not* use a 1.5 head on a 1.6.  The pre-combustion chambers are sized relative the displacement.  Placing the 1.5 head with smaller pre-chambers on the 1.6 will result in overly high compression.

I was looking for specs for this little adapter: http://www.vwdieselparts.com/1.5-1.6.htm

If the compression difference is that bad, hopefully my old head will be ok. The previous owner told me their mechanic thought it was cracked, and it does lose both oil & water - about a gallon every 1000 miles. Compression is good though, so who knows til I pull it!

[RustyCaddy]

i have one of those, will see if i can turn it up.  Like Libby said; the cylinder head it was used with appears to have cracked running from a precup.

[CarlosA]

i have one of those, will see if i can turn it up.  Like Libby said; the cylinder head it was used with appears to have cracked running from a precup.

Thanks. I picked up a 1.6 head gasket today, there is no way it can work - the oil return is larger even than the casting of the head. I will grab a 1.5 head gasket tomorrow and compare ... with that a simple return plug would be enough to seal it up it seems.

I am very curious about the 23:1 vs 25:1 compression - that seems like a big jump.

Worst case i`ll run it until I find a 11mm 1.6 casting to work on. I am using ARP studs and have had a lot of heads on & off over the past few years/cars.

[RustyCaddy]

Sorry this took till today, organized everything recently and so couldn't find it. 

Here are the specs:

12.1 mm high
22.37-22.55mm outer diameter
16.38-16.45mm inner diameter
3.06mm thick
1.77mm gap
steel

In case you didn't know, the guy at VW Diesel parts said to use a 1.6l gasket and put the insert into the block flush with the deck.

High compression Franken engine started very easily but the mpg dropped may be 10% compared to currently running a 1.6 cylinder head on the 1.6 block.

[camboscams]

I'll add my 2 cents, I currently have a similar setup your talking about except I have a 1.6 rotating assembly in a 1.5 block and head. Yes it does have hella high compression but I have only had one cylinder pressure related hg failure. And I've been running 15psi for the life of the engine, I have had multiple hg exterior oil leaks though but that is a unrelated issue.

I will say this, it starts amazingly in any weather! Although I would in no way recommend this set up as it uses the smaller 11mm head studs and with plans to run boost it is less than ideal.

[CarlosA]

Sorry this took till today, organized everything recently and so couldn't find it. 

Here are the specs:

12.1 mm high
22.37-22.55mm outer diameter
16.38-16.45mm inner diameter
3.06mm thick
1.77mm gap
steel

In case you didn't know, the guy at VW Diesel parts said to use a 1.6l gasket and put the insert into the block flush with the deck.

High compression Franken engine started very easily but the mpg dropped may be 10% compared to currently running a 1.6 cylinder head on the 1.6 block.

Thank you! With the 1.6 gasket sitting on the head the gap is pretty significant, I don`t see how it would seal even with the adapter pressed into the block. I can see the mileage dropping, almost makes me want to mill a little pocket in the top of each piston... this is all for fun anyway.

I'll add my 2 cents, I currently have a similar setup your talking about except I have a 1.6 rotating assembly in a 1.5 block and head. Yes it does have hella high compression but I have only had one cylinder pressure related hg failure. And I've been running 15psi for the life of the engine, I have had multiple hg exterior oil leaks though but that is a unrelated issue.

I will say this, it starts amazingly in any weather! Although I would in no way recommend this set up as it uses the smaller 11mm head studs and with plans to run boost it is less than ideal.

Makes sense, I do have 11mm ARP studs so that should help. I won`t ever be running a turbo or anything like that.

[VW Smokr]

...
Makes sense, I do have 11mm ARP studs so that should help. I won`t ever be running a turbo or anything like that.

So... if your 1.6L block has 11mm headbolt holes, then it must be an early 1.6L engine. Probably been said a million times, but chase the threads & thoroughly clean out those (shallow) 11mm holes in the block (before you thread in the studs); they are very susceptible to cracking out, whether due to remaining water expanding to steam, oil hydrolocking, or whatever (IDK). The 2 at each end of the block seem to be the weakest; makes sense that VW went to 12mm & deeper bosses for more threads in their castings for the later engines.

OTOH I'm glad to hear of camboscams' success, since my 1980 Dasher's next engine will be built in a NOS 1.5L block (oil squirters retrofitted) with a 1.6L rotating assembly, though it will also use a 1.6L head, and 11mm studs. Hoping it will hold up by sticking to factory boost pressures, large intercooler, and a much higher geared 5-speed (65mph@2400rpm). Goin' for economy!

J.R.
SoCal