Technical Question about Cylinder head with no gasket

[fiat500]

It's not really directly about that but I'm bored with the tennis so musing about plans for next week, such as re-torqueing the head after passing the deadline by about 700 miles.
I've previously questioned how important it is when you have a gasket and although satisfied by the excellent answers:

https://www.fiatforum.com/500-classic/357803-retorqueing-cylinder-head-nuts.html

I never actually did it in nearly 16,000 miles on the 499 engine.

Although I know that if you are one of that elite band who have no gasket, your care in preparing the mating surfaces and that actual lack of a gasket means you probably eliminate the need for retightening. Using a thin gasket presumably gives you some leeway and it just seems that if you can really get a seal without a gasket surely a couple of foot-pounds of torque is no biggie between friends.

 

[the hobbler]

Evening Peter; The expression 'Gasket free' is not very accurate because whilst one does away with a 'gasket' (in the normally accepted meaning), you still have to use what is known as 'liquid gasket'. Your mating surfaces have to be very clean and flat, but rest assured--they are NOT put together 'dry'

 

[Bigvtwin996]

Evening Peter; The expression 'Gasket free' is not very accurate because whilst one does away with a 'gasket' (in the normally accepted meaning), you still have to use what is known as 'liquid gasket'. Your mating surfaces have to be very clean and flat, but rest assured--they are NOT put together 'dry'

Never had cause to question any of Toms replies......

I have friends who build racing bikes and lap the heads to the barrels and it is a big "no no" to put anything between the head and the cylinders (other than the tiniest smear of light oil you cannot even feel), doing so on such bike engines will always cause failure.... I know again VWs do not have head gaskets, some people confuse the copper rings that were used to deck the piston height correct as gaskets, these were removed from later head designs and replaced with a ring under the barrels.
The logic being that the head gasket or any compound reduced the heat transfer between the surfaces and lack of gasket reduced the need for re-torquing the head bolts due to the gasket compression. (Early Harleys never had them either).
So if no head gasket is to be used then there should not be any compound present but the lapping of head is very important and can take up to an hour even if the head is quite good condition.....
I confess to having never done this on a 500 (not had an engine fail - ain't broke don't fix it) but a said my friends lap heads to barrels on bikes all the time, and often people machine off the gasket locating rings on bike heads and run gasket-less, partly to gain slightly higher compression bit also as said to improve heat transfer.

 

[AndrewHarvey]

I have a "dry" gasketless 695. Time will tell regarding its longevity.
Gas ring was machined out - running 10.5:1 CR using an Apollo kit.

 

[fiat500]

lack of gasket reduced the need for re-torquing the head bolts due to the gasket compression..

That's the logic I was thinking of BVT. Not that I have even the slightest intention of trying to run without a gasket, just thinking laterally about head tightening in general.

 

[Bigvtwin996]

I think if you look back there were many engines that ran gasket-less...
lots of motorcycles and even air plane engines.. huge diesel engines and Offenhauser Indy engines..
Probably because they were mostly aircooled and needed the better heat transfer so lapping and machining may have been better...
where as modern water cooled stuff is slap happy with water jackets and radiators for cooling so not as important to get things right...
a Good topic for people who run gasket-less to keep everyone updated...

I personally am not one for all these modern gasket materials either... I have seen the effects of a piece of squid-ed out silicon block an oil way.. no need to slap stuff on till it comes out when tightened... it squeezes out both sides so not just the one you see... Lets see who remembers... I used to use "Wellseal" on my old engine with paper gaskets....

 

[Bigvtwin996]

That's the logic I was thinking of BVT. Not that I have even the slightest intention of trying to run without a gasket, just thinking laterally about head tightening in general.

As you do the most miles I nominate you to do the testing of all our theories etc...
I'm sure we can all sort you a spare engine...
so you need to run gasket-less.... we need to build up a list of "things to try" for you and you can report back...

do you know of the head temp gauges that you run via a connector under the plugs.. you can monitor each cylinder temp... so you need to get one and accurately record your findings too.. we have so many things for you to test...

with without head gaskets
exhaust wrap
different exhausts
Richer running,
different sumps
different oils
different fans
with without tin wear....

ohhh what fun you will have..
Only you do the miles!!!

(Ps have you all noticed I don't seem to have much to do these days .... hence more replies and posts)

 

[fiat500]

(Ps have you all noticed I don't seem to have much to do these days .... hence more replies and posts)

You will know that I dont have much to do at the moment and the balls-up that has made that the case!

Sean has commented before that I seem to think it's my job to continue the factory road testing that was finished probably 50 years ago.

Overall, after nearly 18,000 miles and 32 months of solid motoring I have concluded that there is nothing on the 500F that needs to be changed either in the engine, cooling, drive, steering or brakes.

The only changes I have made that I think are really useful are additions...spot-lights with relays, hazard lights, power supply for my mobile and a checkered sunroof....only the last one makes it go any faster.

The bigger engine is nice but I think that's when you start wondering about the brakes and corner handling.....start of the slippery slope.

But seriously, I would try any modification that was undo-able and for which the intention was to make the car even more driveable and more likely to be driven if adopted by others.

 

[Bigvtwin996]

Sean has commented before that I seem to think it's my job to continue the factory road testing that was finished probably 50 years ago.
I would try any modification that was undo-able and for which the intention was to make the car even more driveable and more likely to be driven if adopted by others.

I agree entirely... it sometimes takes a long time to Iron out the faults with a design, and I'm sure Fiat will appreciate your road report...

My own view on my cars are .. I want to be able to open the garage door (when it has a roof) and jump in and drive.. without having to mess about plan a week ahead check the car over, will it start.... because I may not have driven a car for months... I no longer than the time to "tinker" every week with points and brake shoes etc Yes i have the luxury of more than one so I can have an original spec but also a car that has the heart and soul... but I can almost drive with the confidence of a modern car..
If Peters high mileage experiences and the feedback from everyone else makes these little cars seen more often then it will bring more smiles..I envy Peter being able to use his car the way he does, and perhaps I may get to that point...
So it looks like it has fallen on Andrew to report back on the gasket-less testing..
..

 

[124spiderman]

I believe some Porsche have no head gaskets

 

[Bleeding Knuckles]

Greetings All, I have the honour of (in the past) being 'gasketless' but, the motor was running with a crazy C/R so I now run a 0.5mm copper gasket and a 1.0mm base support plate to hold everything together and lower the C/R. If I had left it all as it was the detonation alone would have made the thing 'grenade'
The original joint was dry and showed no signs of blow by at all, but I'm a mechanical sympathy chap nowadays and have hopefully extended the life of the motor some

Ian.