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question about head gaskets
General_Failure - August 23rd, 2005 at 05:44 PM

Hi everyone!

I was just cleaning up an old spare 1800 type4 head and noticed something.
It has 2 head gaskets on each chamber.

Is there any reason for having 2? I can see it lowering compression, but that'd be about it.
I believe the head was in a motor with domed pistons.


Kombi_Rescue - August 23rd, 2005 at 06:46 PM

You hit the nail on the head,who ever fitted 2 gaskets did so to prevent the ol pinging prob.....domed 1800's pinged their nuts off....to use these pistons you require a lower compression ratio..these were developed for the 412 1.8 carby engine running at 85hp....they ran a 1700 grind cam with larger carbies compared to a type 2 set up ..manifolds were very short and the valve sizes were the biggest vw produced..my old 412 LS variant would hit the ton only to scare the tripe out of me when a gust of wind hit...hang on!!!! cheers steve


General_Failure - August 24th, 2005 at 11:53 AM

So when I do the next rebuild to fix the massive compression leak should I put back my original proper pistons (+1 to replace the mashed one) or keep the domed ones and go for 2 headgaskets, or even the originals with 2 headgaskets.

With the various doping of petrol now I'm not sure where the actual octanes are hovering.


General_Failure - August 25th, 2005 at 12:24 AM

Just for the sake of it. Heres a pic of the head I cleaned up, still with old gaskets. note the scary inlet valve seat. See how you can see the outer edge of it? I discovered liquids can leak through that.


vw54 - August 25th, 2005 at 06:59 AM

yes you havea loose valve seat and it will drop out when you least expect it

Time for some NEW cylinder heads


mnsKmobi - August 25th, 2005 at 09:24 AM

Quote:
Originally posted by General_Failure
So when I do the next rebuild to fix the massive compression leak should I put back my original proper pistons (+1 to replace the mashed one) or keep the domed ones and go for 2 headgaskets, or even the originals with 2 headgaskets.

With the various doping of petrol now I'm not sure where the actual octanes are hovering.


From my reading on TheShopTalkForums it seems the go is to leave out head gaskets and lap the cylinders into the heads like you do valves. If you need to adjust the compression/deck height put shims under the cylinders. And if it's non-stock you will need to check your rocker geometry.


Kombi_Rescue - August 25th, 2005 at 10:20 AM

some good advice here ..not sure about running no gaskets though...barrel fin to cylinder face is a critical measurement due the the various expansion rates of materials...take into account most heads have been machined once or more times this also alters the comp ratio..go new heads it a safer bet if you can afford it. cheers steve


General_Failure - August 25th, 2005 at 10:55 AM

I wish I could afford new heads. Or even reco'd ones. I can't even afford a new battery :(

I remember reading about leaving out the head gaskets. I can see the pros and cons of it. I think the biggest argument against doing away with them is precision. Sure everything needs to be accurate, but everything needs to be absolutely spot on if you have nothing to compensate for slight abnormalities.
It'd be fine on a completely rebuilt o new engine but on my old monster maybe not so hot.

Cylinder base shims are the most logical approach. It lessens the amount of possible places for compresssion to leak out.
Rocker geometry. I didn't even think of that. Thanks for the reminder.

In all honesty, given the chance I'd build a high compression engine and run it on optimax.
In reality I think I want to build a low compression motor that's capable of running on the garbage fuel that seems to be more common, and less expensive.


vw54 - August 25th, 2005 at 11:14 AM

Quote:

I wish I could afford new heads. Or even reco'd ones.



If you want to rebuild your engine after a few thousand Klms sure fir some RECODED heads on Waste your money twice as fast

Type 4 heads DONT recondition. There Throw away


General_Failure - August 25th, 2005 at 11:38 AM

I'm inclined to agree about the throwaway nature of type4 heads. The reco ones fail a little too fast for my liking.

Purists may scream in horror, but I hate the type 4 heads with a passion. They are the major weakpoint of the motor, which apart from that problem I think is excellent.


vw54 - August 25th, 2005 at 06:05 PM

Nail on the head dont even think reco 4 2 seconds there JUNK

Bit the bullet n go new even S/H ones r F U c k ed


General_Failure - August 27th, 2005 at 12:19 PM

Believe me, if I coud afford new ones I'd get them. Maybe I'll be able to get some after I move, eventually.

In all honesty, I just want to fix the engine enough that the van can make it about 200 kms to the new place. As it is it struggles in 1st gear currently I doubt it will get there like this.