merc i/o head gasket question

[freeone]

im about to put my heads back on. b4 jumping into it i would like to get some questions answered. i have a 83 merc 350 i/o closed cooling with alpha one. i use the boat in both salt and fresh water.
1. has anyone used the steel shim stamped type gasket b4
2. which is better composition or what i have(shim stamped)
3. did you use a sealant on it and what
4. does the shim gasket really raise compression

 

[Bondo]

Re: merc i/o head gasket question

Ayuh,... #1,... Not in many, Many years....
#2,... Composites by Far are Much Better....
#3,... Composites go on Dry....
#4,... Yes, by the thickness of the gaskets chosen....
You have to mathamagically figure it out, it varies by motor...

That said,...
Raising the compression on a, well lets say Older, motor, is a double edged sword...
Unless this is a fresh, Full rebuild,...
All you're doing it over stressing worn out parts...
If you just did a Valve job, plus the shim gasket,... You'll be Hammering those worn rings...
The motor might make abit more power, but at a cost of longevity...
What about those tired rod bearings,..?? Mains,..??

Unfortunately,.. I don't remember the Details of your issue from the start,...
Just throwing out an Idea in general motor fixin'.....

 

[freeone]

Re: merc i/o head gasket question

the gasket i have is 0.28". just got off the phone with basic power industries and the tech said that these gaskets go on dry they already have the (alumikote?)
im not trying to increase comp. just info i came accross while searching the pro/con of shim vs comp. and type of dressing if any.
the engine is not a full rebuild.
had coolant in #4&6 cyl warped heads(should i find out how much the machine shop milled off the heads? is that something i need to know for reassembly?) only info i know from the shop that heads have no cracks valves are good and there was a minor warp. they did replace the seals on the valves.
should i just call this set a loss and get the fellpro composition?

 

[John_S]

Re: merc i/o head gasket question

I assume you meant 0.028", but that is still rather thick for a steel shim gasket??? I'd only use a composite, and if you want to be precise, add the thickness back that was milled off.

 

[freeone]

Re: merc i/o head gasket question

I assume you meant 0.028", but that is still rather thick for a steel shim gasket??? I'd only use a composite, and if you want to be precise, add the thickness back that was milled off.

no its 0.28 here is where i got it. the machine shop said he took off .008 i went to two different part stores all they carry is the felpro blue paper with the steel rings.

http://bpi.ebasicpower.com/mm5/merc...Product_Code=DET59063HG&Category_Code=GASK-HG

 

[John_S]

Re: merc i/o head gasket question

no its 0.28 here is where i got it. the machine shop said he took off .008 i went to two different part stores all they carry is the felpro blue paper with the steel rings.

http://bpi.ebasicpower.com/mm5/merc...Product_Code=DET59063HG&Category_Code=GASK-HG

Well, that has to be a typo. Are you saying the head gasket is more than 1/4" thick? A 0.060" compressed head gasket would be considered a "thick" one. See: http://www.gmperformanceparts.com/searchsite/?q=head gasket

 

[freeone]

Re: merc i/o head gasket question

Well, that has to be a typo. Are you saying the head gasket is more than 1/4" thick? A 0.060" compressed head gasket would be considered a "thick" one. See: http://www.gmperformanceparts.com/searchsite/?q=head gasket

you are correct sir, has to be a typo. now that i think of it that way 1/4"? no way.

 

[Bondo]

Re: merc i/o head gasket question

Ayuh,... What was there when you took it apart,..?? How Thick was it,..??

 

[freeone]

Re: merc i/o head gasket question

composite, .034"

 

[Apollo75]

Re: merc i/o head gasket question

composite, .034"

I don't hear the torque wrench clicking

.008" a mere clean-up --- the head gasket is going to compress more than that.

Decide on a thin one or a thick one, tick-tock

I would go with the thick composition ones -- like .038 - to - .060"

Hurry I'm on pins and needles here

OFM

 

[dr_bowtie]

Re: merc i/o head gasket question

I would also use the composite gasket here....several reasons but the most important...they are more forgiving in an older engine where parting surfaces may be less than perfect...if you had both the head and the block milled for squareness then it may be fine...

but just for a head job I would solely go with composite..I prefer the blue fel-pro those are pre-coated...the blue coating is actually a thinned sprayed on coating of their Ultra-Blue Gasket maker material...

 

[Bondo]

Re: merc i/o head gasket question

Ayuh,...
.034 plus the .008 is .042.....That's the gasket you're shootin' for...

 

[freeone]

Re: merc i/o head gasket question

the verdict is in, I'm going to toss these aside and get a hold of some composite. thanx to all the input.

 

[dan t.]

Re: merc i/o head gasket question

be aware that you will loose the "quench" effect by going to a composite head gasket. if the motor came with a shim type gasket stick with it. by increasing the head to piston clearance you could very easly end up with preignition due to the loss of the quench,if both surfaces are properly clean and flat, spray the gasket with hi-tack,torque it to spec and you will have no problems

 

[Bondo]

Re: merc i/o head gasket question

Ayuh,... Dan.t,... It's an 83,... Quench is of little to No worry....
Beating up a worn motor Is...