mercruiser head gasket

[MBAKER]

Can anyone tell me on a vortec 5.7 around a 2000 vintage, or even a new one, are the head gaskets the typical GM head gasket .028 thickness like was used on the trucks? Or is it something different?

Next question would be is the MErcruiser replacement an actual GM gasket with a merc# on it. I cant seem to find any specs online about the Merc gasket, but read a post where it was stated that the Merc part number was labeled over the top of the GM #.

 

[wrench 3]

Re: mercruiser head gasket

The marine vortec uses a thicker composite gasket. The trucks also changed to a composite gasket. But why would you want to know?

 

[MBAKER]

Re: mercruiser head gasket

Going to be putting together a new engine, and looking at what head gaskets are out there and what thickness. I had heard that the Merc gasket was in a GM wrapper with a different part number sticker on it is all. I just wondered what GM gasket they were using. Trying to figure out how much i might need to deck the block to keep quench right with a rebuilder piston, and commonly available gasket..

 

[RogersJetboat454]

Re: mercruiser head gasket

Going to be putting together a new engine, and looking at what head gaskets are out there and what thickness. I had heard that the Merc gasket was in a GM wrapper with a different part number sticker on it is all. I just wondered what GM gasket they were using. Trying to figure out how much i might need to deck the block to keep quench right with a rebuilder piston, and commonly available gasket..

Hard to say.
Keep in mind any head gasket used by GM in a truck was intended to have a water/antifreeze mix in contact with it. Because of that, the gasket may have carbon steel as either the skeleton of the gasket, or it may just be the full gasket (such as the MLS gaskets). GM may have made gaskets that would be happy with raw water cooling in a salt environment, but again it's hard to say.

If you wanted another option over the Mercruiser replacement gaskets, Fel-Pro marine gaskets should fit the bill. If you are running closed cooling, or are in fresh water only, the automotive gaskets may work.

 

[wrench 3]

Re: mercruiser head gasket

If you are using the correct pistons why would you want to change the deck hight, unless you are trying to increase the compression.

 

[MBAKER]

Re: mercruiser head gasket

Most rebuilder pistons have a reduced compression height 1.54 or 1.55 instead of 1.56 which puts the piston furthur in the hole. If you dont deck the block, use the rebuilder pistons and stick a .040 gasket on it you could end up with .080 or more quench. If I could find a Marine suitable gasket that was .025-.030 like I thought GM was using new, then it would save deckign the block another .010-.015.

The mahle pistons im looking at are 1.55 compression height, so with a stock rod and crank I end up with 8.990 piston height, and a stock block is going to be 9.025+ to the deck. To get to .045-.050 quench If I use the fel pro .040 gasket I would need to take the deck down to 9.000, which still leaves the piston 0.010 in the hole. If I find a .025+/- gasket then I only need to take .010 or .015 off the deck.

 

[Bondo]

Re: mercruiser head gasket

Most rebuilder pistons have a reduced compression height 1.54 or 1.55 instead of 1.56 which puts the piston furthur in the hole. If you dont deck the block, use the rebuilder pistons and stick a .040 gasket on it you could end up with .080 or more quench. If I could find a Marine suitable gasket that was .025-.030 like I thought GM was using new, then it would save deckign the block another .010-.015.

The mahle pistons im looking at are 1.55 compression height, so with a stock rod and crank I end up with 8.990 piston height, and a stock block is going to be 9.025+ to the deck. To get to .045-.050 quench If I use the fel pro .040 gasket I would need to take the deck down to 9.000, which still leaves the piston 0.010 in the hole. If I find a .025+/- gasket then I only need to take .010 or .015 off the deck.

Ayuh,.... Go with Fel-pro gaskets,...

I don't think you can get a composite gasket at .025",.... That's why ya deck the block..

Don't what those pistons yer lookin' at are, but I'd go with a D-dish, or inverted dome to tame the compression ratio, 'n use the full benefit of the Vortec heads,...
'n Deck the block to bring the pistons flush, or nearly so...

 

[MBAKER]

Re: mercruiser head gasket

The pistons are Mahle stock replacement types. Look identical to the stock piston, has a small dish in the middle and flat ring around the outside.

 

[Bondo]

Re: mercruiser head gasket

Ayuh,... If yer goin' so Deep, Why wouldn't ya go with the Better choice,..??

 

[MBAKER]

Re: mercruiser head gasket

I was just responding to what type piston they were, Im still open to anything, but have had trouble finding a 'd' shape dished piston.

 

[RogersJetboat454]

Re: mercruiser head gasket

I was just responding to what type piston they were, Im still open to anything, but have had trouble finding a 'd' shape dished piston.

Have fun!

CHEVROLET 5.7L/350 Chevy small block Gen I Pistons - Dish, with a D-shaped cup Piston Style - SummitRacing.com

 

[MBAKER]

Re: mercruiser head gasket

I guess I should have clarified, I had trouble finding many that were not forged. Its just a stock rebuild so Im not going to put 4-800$ set of pistons in it.

 

[Bondo]

Re: mercruiser head gasket

Ayuh,... ya don't need forged, Hyper-tetics are reasonable for what they are,.....


did ya get my pm's,..??

 

[MBAKER]

Re: mercruiser head gasket

yes i did... havent read through it all yet though.

 

[MBAKER]

Re: mercruiser head gasket

Old 305 is out, not torn down yet but looking at the head gaskets they look like regular steel shim type gaskets, .015-.020 thick maybe. I guess this is why I was askign about the merc replacement whether or not it was a thicn shim type gasket or a thicker composite gasket.

 

[MBAKER]

Re: mercruiser head gasket

Does anyone know if the GM gasket is a stainless core with graphite facing, or is it just a punched steel core.