grrrrrrr...

[ilikevwdiesel]

lol I just picked up an 84 rabbit POS for the winter and it looks like the friggin thing has a 1.6 block and a 1.5 head!?! The head has the small drain hole but the one on the block is bigger and some of the gasket is exposed. it has a 17mm crank bolt. what the heck is going on here anyone else ever seen any geto hacks like this? the thing won't start now and there's coolant along the top of the block on the head gasket seam. guess I have to pull the head? lol sheet

[jaysen71581]

Yes, my brother had an '84, we had it for about a week before oil ended up in the coolant so we took the head off and had it gone through and redone only to discover that that PO had used a crap load of sealant and some goofy ass head gasket, still have the 1.5 head ....

[ilikevwdiesel]

I just gave it a shot of ether and it started...I wonder what the deal is it must be an 11mm block huh? unless someone made some custom head bolts? man what a pos glad I didn't pay much for it. 

[vanbcguy]

A friend of mine sent me pics of a car he was thinking of buying... it was a Mk III so it had an AAZ in it, but I guess they'd replaced the head at some point.  Head was off a 1.6, along with the 1.6 injectors (guess they were too lazy to remove them).  Stock AAZ fuel lines were bent over so they would reach the 1.6 injectors.  Guess it would start great when cold but that's probably about the only good thing one could say about that combination.

[ilikevwdiesel]

I pulled the head off it this afternoon, the block is a 12mm. my boys at the local napa had the gasket in stock so I put it back together and it runs, kinda weird the drainback on the head just covers the hole in the gasket but it can't last for long like that I'd think. anyone ever seen this kinda crap before? I just need this pig to make it till next april when I can drive my caddy again. the clowns that put that head on must have drilled out the bolt holes? they ground the washers down too otherwise they wouldn't have fit in the recess in the head. GE-TO

[RustyCaddy]

since you have the head back on this is a little late to post.  you can get machined reducers that fit into the oil return of the block.  Parts Place and VWdiesel parts.com sell two different ones.

i have a 1.5l head on a 11mm 1.6l block...got my insert from VWdiesel...it is removable but i don't know about the Parts Place version.   VWdiesels uses the head gasket for a 1.6l head, not the 1.5 l gaskets.

Not an ideal situation but manageable (for now)...id rather have had a 12mm block like you do and get a 12mm head if possible.

[Toby]

How is changing the head going to effect compression, when the head is dead flat? The only "combustion chamber" in the head are the valve pockets and I do not remember any noticeable difference between 1.6 and 1.5 heads other than the drain hole. I have seen aftermarket heads that have a drain hole that fits both, BTW.

[R.O.R-2.0]

How is changing the head going to effect compression, when the head is dead flat? The only "combustion chamber" in the head are the valve pockets and I do not remember any noticeable difference between 1.6 and 1.5 heads other than the drain hole. I have seen aftermarket heads that have a drain hole that fits both, BTW.

a DI engine, would not change compression..

but being that we got IDI engines, it does change..

[Toby]

The pre-combustion chamber is in the head and it is proportionately sized to the engine displacement.

And you know this how? Have you cced one or is this just supposition? While this is possible, I find it rather unlikely. It is much easier to alter compression with changes to the piston or head gasket thickness.  I will have to see if I have a 1.5 head laying about so I can cc it.

On second thought lets do a little "thought experiment".

If you do the math, the CC (Combustion Chamber) volume to get 21:1 in a 1.5 is 18.10ccs. In a 1.6 it is 19.05ccs. Less than 1 cc difference. The 1.5 CC volume of 18.10ccs on a 1.6 motor gives 22.1:1 compression ratio. Not very significant.

[theman53]

The pre-combustion chamber is in the head and it is proportionately sized to the engine displacement.

And you know this how? Have you cced one or is this just supposition? While this is possible, I find it rather unlikely. It is much easier to alter compression with changes to the piston or head gasket thickness.  I will have to see if I have a 1.5 head laying about so I can cc it.

On second thought lets do a little "thought experiment".

If you do the math, the CC (Combustion Chamber) volume to get 21:1 in a 1.5 is 18.10ccs. In a 1.6 it is 19.05ccs. Less than 1 cc difference. The 1.5 CC volume of 18.10ccs on a 1.6 motor gives 22.1:1 compression ratio. Not very significant.

I would say they probably know this as there are different parts for different heads. The compression ratios you have listed aren't correct for the engines anyway. Also in something that is 23:1 compression ratio I believe 1cc is a big difference.
I am PM'ing Malone to ask for an ignore function. I am PM'ing you toby *the new OM617 for my purposes* to not clutter the thread.

[Vincent Waldon]

How is changing the head going to effect compression, when the head is dead flat? The only "combustion chamber" in the head are the valve pockets

It is much easier to alter compression with changes to the piston or head gasket thickness. 

To look at this a different way, both of these statements are not quite correct *and* contradictory.. the combustion chamber is *not* the valve pockets, and head gasket thickness, in the presence of a flat head, has a barely measurable effect on compression ratios.... basically the area of the piston bore times the delta in headgasket thickness. Even a 1 cc difference in prechamber volume will be orders of magnitude more impactful.

Like others before me I'd recommend modifying your "lead with your elbows" approach to the discussion here...there's a wide range of knowledge and expertise available to all of us if we seek first to understand.

[R.O.R-2.0]

i boost my 11mm block religiously into the high teens, sometimes even to mid 20s..

1.6 CS engine.. out of an 83? vanagon.