Technical RE: Headgasket Job

Currently reading:
Technical RE: Headgasket Job

pachadwick1

Member
Joined
Feb 13, 2012
Messages
29
Points
61
RE: Headgasket Job

I have the classic symptoms of failed head gasket, losing water, lumpiness on start-up. So I am planning to replace the gasket on my 1108cc sporting, it's done 91K so will do the water pump and cam belt kit as well

I am thinking I might try and get a little more performance since I am going in the engine bay.....Can anyone advise me about taking the compression ratio from 9.6:1 to 10.0:1 I tuning guide suggested a 1mm skim off the block and head. Is that right?

Thanks Paul
 
Re: Headgasket Job

You can skim the head to it's markers, skimming the block would require removing the engine and would be a waste of time for the performance gain. It also wouldn't be recommended unless you'd taken measurements and knew exactly what you were doing. It could also remove the benefit of having a non interferance engine and would need to be run on high octane fuel to prevent detonation... We don't fit thicker gaskets on Seis Ziggy, just go a bit faster. :D
 
Re: Headgasket Job

Thanks everyone for your helpful replies. What I understand now is that for a high mileage motor increased compression can come with additional issues. Generally this engine runs very well, I've maintained it since 36K and done regular oil changes. I chipped it at 50K for a couple more bhp and that's been fine.

I've thought about the other tuning improvements:
  • High lift cam seems to be £250, quite a lot more than £25 for a head skim
  • Porting and polishing, well that's just hard work.....:-(
  • Exhaust manifold, slightly more tempting for the hight flow at £250 for a stainless supersprint product.
Thanks for the tip on a new thermostat, I had one jammed closed at 45k and the engine overheated so I know about that problem.

I'll probably have 0.75mm taken off the head alone and see how that suits.

Cheers Paul
 
Re: Headgasket Job

If you've an SPI car, you can gain a lot by bunging in a P75 cam (they're cheapish, and sometimes you can find them pre-attached to P60 engines for less than £100, which gives you extra capacity, too......,
a bigger TB (tricker or tricker alike recommended, but there are suitable TBs of about 38mm attached to some Pugs, and P75 TBs can be made to fit) and a chip.

Don't neglect the valves -- they're the most important seal (in terms of power) on the whole engine.
 
Re: Headgasket Job

Skim head to max mark, fit 75 cam. That would be the best bang for buck really.

Unless the engines been run low on oil or had very infrequent changes then the rings should be fine. Even when driven like Mansell they hold up well with decent maintenance. The only other damage occurs normally if the car has been heavily overfuelling for prolonged periods and it sucks through the rings which flushes the lubrication from the cylinder walls.

My old 1108 mpi engine looked like new inside after 84K when we took it to bits and swapped it out for the 16v.
 
Re: Headgasket Job

Many thanks again, thinks are even clearer for me now:

  • Find a camshaft in good condition from a Punto 75 (1.2L)
  • Reseat the valves since I am taking them out to skim the head and fitting new valve seals from the gasket kit
  • Skim the head down to the minimum mark

If things are going well I might get a manifold as well..
 
Re: Headgasket Job

Hello All,
Please can anyone advise me over my lovely Xmas break, I am avoiding the family whilst I do this head gasket job in the garage. I've got the cam cover off and measured the cam lobes in on the original engine 1108cc SPI. They appear to be a total average diameter of 38.35mm, I know that this is a really simplistic gauge for all the measurements on a cam but it is all I can do in the garage.

When I compare the measurements of the Punto75 cam I sourced from a breaker it has cam lobe measurements of only average 37.65mm.

I was thinking that the Punto would have higher cam profiles (more total dia) and perhaps longer duration? Does anyone know? I makes me think that the "P75 cam" I have to swap in may not be the right thing.

Someone with more experience may be able to tell me whether I am doing this right thing. My auto shop is worried about skimming the head down to the minimum for more compression if I am putting a higher lift cam in place. This does not seem to be a worry at present....

Paul
 
Re: Headgasket Job

Hi

Unless you have had a auto from new, what cam it has is not necessarily standard. And Fiat are not necessarily religious about engine build standard, if they don't have the correct cam, and the need to build engines...

I'd not skim an engine that I used for getting to work, more then necessary, any over heat transgression may require a new head gasket and a further skim, and an interference engine needs more care.

New pump, new belt, new belt tensioner, grind in valves (if the valves and seats look ok), hope the bores and rings are ok, ... will keep you busy. You could inspect the bores when the head is off, they well be well nackered.

I'd tell the ins company that the cam has the wrong lift, if it is different from the manual...

If it a track auto it is a different thing.

Noel
 
Back
Top