[mbardeen]

My luck doesn't seem to be getting much better with my car.



The story so far -- the car had some cooling issues, so I pulled the cylinder head to find a "homemade" head gasket and unknown valves in the head. I've since bought all new valves, seals, and keepers.



Today, I took the cylinder head to the best machine shop in Chile, who did some measurements and found the measured thickness of the head is 146.5mm. The maximum wear limit for the head is 146.6mm according to the manual, and requires the use of the 1.4mm headgasket.



So, what are my options? Anyone know of someone selling a slightly thicker headgasket? Or that has a good cylinder head casting for relatively cheap?

Partial Post: Please Login or Register to read the full post.

[paulzebo]

I would check the valve clearance and if it's acceptable, use the head.

Partial Post: Please Login or Register to read the full post.

[MCL968]

I agree. An earlier post indicated that there are several gasket options to lower the CR, given how much the head has been shaved, a thicker gasket should get you back to close to stock. At least it sounds like there is a solution, so a new head is probably not a necessity as yet.

See the MLS Head Gasket thread. Flash has some great info in there!

Partial Post: Please Login or Register to read the full post.

[banditsc]

1.4mm is actually one of the factory sizes and even has a part number.

http://www.lindseyracing.com/mm5/merchan...GASKETS968

Partial Post: Please Login or Register to read the full post.

[mbardeen]

My fear is that the machine shop will have to shave a little more off the head to get it flat. 928 Motorsports offers a GCS headgasket that is almost 1.6mm, that seems like it should do the trick if all else is good. Any other dangers to having the head shaved .2mm below spec?

Partial Post: Please Login or Register to read the full post.

[flash]

cometic makes them too.

Partial Post: Please Login or Register to read the full post.

[mbardeen]

I saw that, but I've also seen many comments that mention that the MLS gaskets need very specific surface prep to be used succesfully. My block is still in my car and I really didn't want to take it out, so any gasket that I use will have to seal not-so-great surfaces. Is the fine machining of the head something that's only really necessary in race/high-boost engines?

Partial Post: Please Login or Register to read the full post.

[flash]

it's never a good idea to have a "not so great" surface.



i would either surface the head, run the 1.4, and live with slightly lower compression, or replace the head. since somebody had been messing around in there already, it seems like a better idea to replace it anyway, and have your new valves put in it.

Partial Post: Please Login or Register to read the full post.

[mbardeen]

My cylinder head is finally on it's way back from the shop, but the surprises don't end. Evidently when boxing up the cylinder head, they noticed a crack on the retainer lip of the intake camshaft.







The shop manager recommends replacing the camshaft, even though it doesn't appear like the crack is very deep. My feeling is the same, but second/third opinions are welcome. The rest of the camshaft seems to be in good shape.

Partial Post: Please Login or Register to read the full post.

[speedysprocket]

[quote name='flash' timestamp='1404578529' post='159618']

it's never a good idea to have a "not so great" surface.



i would either surface the head, run the 1.4, and live with slightly lower compression, or replace the head. since somebody had been messing around in there already, it seems like a better idea to replace it anyway, and have your new valves put in it.

[/quote]

Wouldn't surfacing the head and using that thicker gasket give him the same, if not higher, compression?

Partial Post: Please Login or Register to read the full post.

[flash]

no - there is a misread going on here.



it says that if the minimum thickness is exceeded, then you use the thick gasket. that thickness is 146.6. anything thinner than that uses the thick gasket, but anything up to and including that point uses the stock gasket.



the stock gasket is 1.1mm. the thick one is only 1.4mm. the head is already shaved .1mm too far for the stock gasket. the spec assumes a stock gasket. using a 1.4mm thick gasket on a head at the limit will leave a .3mm deficit, which means the same compression.

Partial Post: Please Login or Register to read the full post.

[KRAG50]

I've been running the Cometic MLS gasket for two years now ( with SC) previously I had blown two of the wide-fire gaskets ( because of denotation issues that have been dealt with, Thanks Flash) I really never did anything special for surface finish, The real key is flat and matched, the engine never came out, it was lightly stoned, and the head resurfaced. No problems and I track my car.

Partial Post: Please Login or Register to read the full post.

[mbardeen]

Head was already 0.1mm below minimum height. Correct me if I'm wrong, but I'd assume that a 1.4 mm gasket on a shaved head will have a bit more compression than a 1.1mm gasket on a stock head. Regardless, I've made my mind up on the 1.65mm gasket that 928motorsports offers. I'd rather have slightly less compression than risk any interference.



Question now is regarding the crack in the camshaft retaining lip.. replace, repair, or run as is? Since I've got so much money tied up in this already, I feel like I should do it as right as possible -- so I lean toward replace.

Partial Post: Please Login or Register to read the full post.

[flash]

lol - ok - getting dizzy now



1.1 is the stock gasket thickness. 147mm is the stock head thickness.



on a stock head, with stock thickness, and a stock gasket, you would have stock compression.



1.1 gasket on a shaved head, at the limit, will have a .3mm change, and will raise compression. on a head shaved .1mm beyond the limit will raise it even more.



1.4 mm on a head that is shaved .1mm beyond the minimum spec will raise compression slightly.



given your location, and the complete lack of support many have gotten with that company, i cannot say with confidence that you will be happy.



raising compression is not necessarily a bad thing. if you have the octane to handle it, it can mean more power. if it were me, and everything else in the motor was good, and i had at least 98RON (93 RON+MON/2) fuel available, i'd run the widefire stock thickness and say "woohoo!"



this all assumes you are normally aspirated

Partial Post: Please Login or Register to read the full post.

[Bulti]

"Head was already 0.1mm below minimum height. Correct me if I'm wrong, but I'd assume that a 1.4 mm gasket on a shaved head will have a bit more compression than a 1.1mm gasket on a stock head"





Stock head + stock gasket = (147 + 1,1) = 148,1 mm



Shaved at 146,5 + thick gasket = (146,5 + 1,4) = 147,9 mm





So the second option has more compression and Matt is correct? Or am I missing something here?



I just want to understand what's what...

Partial Post: Please Login or Register to read the full post.

[banditsc]

On the question of the camshaft, yes, I would look at replacing that one or trying to have it fixed.

Partial Post: Please Login or Register to read the full post.