135psi heads

[hawk232]

Previous owner told me that the heads were milled. I checked the compression and they are at 130-135. I would like to get the compression up to 145 or so. Can this be done with thinner gaskets or do I need to have them cut more?

[HStream1]

If it's a 2.5 L you will need to have the heads cut to 34 cc's to acheive 140/145 psi, assuming you have good cylinder leakdown. <8%<

[T-REX]

If U use tha .075 hed gaskets, it will drop comp around 10#s(if it haz tha smaller comb chambers)

[mach351]

Stock gaskets are 1.2mm - like Rex said, .075mm are an option - they do make 1mm ones also. Some people don't like the .075's, but the 1's were stock on 260's, so merc must think they are ok. I myself have used .075's in the past without a problem.

[ZonkaRacing]

Stock gaskets are 1.2mm - like Rex said, .075mm are an option - they do make 1mm ones also. Some people don't like the .075's, but the 1's were stock on 260's, so merc must think they are ok. I myself have used .075's in the past without a problem.

Does this apply to the 2.0L XR2 also?
And what cc heads are needed for 135 compression on a 2.0L?

[mach351]

Does this apply to the 2.0L XR2 also?
And what cc heads are needed for 135 compression on a 2.0L?

I don't think thin gaskets are avialible for the xr2 because it's a 2.0L and has a different bore (3.0") than a 2.5 (3.5"). Rex will know for sure and he will also know what cc will put you in the ballpark on them "little" motors.

[ChrisCarsonMarine]

2.0 litre is 3.125 bore,2.4 is 3.375 2.5 is 3.5...

[mach351]

2.0 litre is 3.125 bore,2.4 is 3.375 2.5 is 3.5...

Dang Chris you got me - brain not working right today.....

[hawk232]

I was told that it was pro max heads. Do these have the small chambers? Sounds like head gaskets may be the easiest option for me.

[T-REX]

They made thin gaskets for tha 2liter, but I don't know if they still avalible???...Tha F-1's had thin gaskets, but like rings, 2liter F-1 parts are gitt'in hard to git!!...

If I remember rite, tha 200 PM had tha small chamber heds, but tha 225PM had bigger ones...Mercury had so damm many heds, wit differnt cc's, tha only reely wat to tell what ya got iz take them off, and cc them!!...Quess'in will sumtimes cause ya more problems than juss bite'in tha bullet, and popp'in off tha heds!!

Hawk, I have a pile ov heds, I'll see if I have sum that will put ya wher ya wanna be...If so, I'll juss swap ya out, thoze heds U have make a good fish'in mota hed!!:thumbsup:

[hawk232]

T-Rex, that will work. Either that or I will just suck it up and pull on of em off and cc it. I was just hoping to avoid wasting a gasket (not ready to send them off somewhere to be milled, so if it was big chamber heads I would have to put them back on until I was ready).

[Baja16]

Hey Hawk i know this is bit off topic what kinda speed numbers you gettin with your laser? Looks like shes aired pretty good in your sig pic!!

[hawk232]

Hmm I replied but it disappeared!!

In that pic, 78. Best so far is 81. Still have some setup left to do too

[Baja16]

Hmm I replied but it disappeared!!

In that pic, 78. Best so far is 81. Still have some setup left to do too


nice:cheers: My uncles got a beautiful 85' 380 Ray Sig hes thinkin about getting rid of. Hes had the boat since the early 90's and only used it for five or six seasons maybe, and im pondering the thought of gettin it from him. Id probly run similair power but a Johnrude:)... thanks man

[hawk232]

I LOVE the boat. I didnt know anything about it before I got it (new to fast boats) but after riding in other boats, the is the only v-bottom that I have found that I would own. it does EVERYTHING well, chop, turns, acceleration, top end...

also just found out that I have some decent chips on the pad, hoping that fixing that and sharpening the back of the boat will pick up some speed too!!