Preparing cylinder heads for marine application

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11-29-2018, 01:34 PM

#21

Ryan00TJ

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Quote:

Originally Posted by Full Force

The heads are not going to be the same off shelf heads as cars/trucks. merc sets them up for marine use, casting is the same sure... not the rest.

I'll buy that on the Merc Racing blue motors. Everything I've read on the black production side is Merc used GM long blocks. I just can't see Mercruiser disassembling and performing a valve job on every black production engine before Marine izing. I actually pulled a set of 496 ho heads off this morning I will check the valve guide clearance and post back to results.

My 496 ho with a Whipple tune and hundred twenty degree thermostat runs around 140-160 coolant temperatures.

11-30-2018, 12:45 PM

#22

getrdunn

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Not a true comparison auto vs marine clearances but....

https://www.hotrod.com/articles/engine-oil-temperature/

12-01-2018, 06:15 AM

#23

Full Force

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Quote:

Originally Posted by Ryan00TJ

Not 100% sure on all of them, but the Merc420 came with Inconel valves, that there tells me they did something..thats why I say I figured they would.

12-01-2018, 08:47 AM

#24

Camalot

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Originally Posted by payuppsucker

I'd suggest contacting adk61 here on OSO. Top notch marine engine guy up in your neck of the woods.

Thanks I will looking into him!!

12-01-2018, 08:50 AM

#25

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Quote:

Originally Posted by mira boater

A&j automotive Alyn Armstrong in Kingston NS has done some marine engines as well as Sussex engines in NB

I have spoken with Armsrong in the past, not will to give any secrets away lol.

12-03-2018, 09:47 AM

#26

Ryan00TJ

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Quote:

Originally Posted by Full Force

Not 100% sure on all of them, but the Merc420 came with Inconel valves, that there tells me they did something..thats why I say I figured they would.

Ok, 496ho valve stem clearance spec....#30 FSM

Intake. .001-.0029
Exhaust. .0012-.0031

Have not pulled one apart yet to confirm.

12-03-2018, 09:58 AM

#27

Full Force

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That’s a huge range .. I set my raw water cooked at .0020-.0022

12-03-2018, 10:14 AM

#28

Camalot

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Quote:

Originally Posted by Full Force

That’s a huge range .. I set my raw water cooked at .0020-.0022

How do you set the clearance....guide or valve stem?

12-03-2018, 12:47 PM

#29

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Quote:

Originally Posted by Camalot

How do you set the clearance....guide or valve stem?

Okay I just found my own answer lol, didn't realise you could get such a large variety of guide reamers.

12-03-2018, 01:24 PM

#30

Full Force

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Quote:

Originally Posted by Camalot

How do you set the clearance....guide or valve stem?

guide, but some valves are machined a tad smaller like AFR valves.

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