Well I need to replace the head gasket. Got some rot leaks in it.

I need some help on getting the right head gasket. The option I am seeing is a choice of a C ENG. VIN. or a 8 ENG. VIN. My engine tag dosnt have either one, neither dose my dash vin. Any help will go a long ways. thanks.

 

8 eng vin. C is for 91.5+ intercooled models, 8 is for non intercooled models. You need 8 for your 90.

 

thanks,

the guy at cummins didnt even know what i was talking about.

 

no problem...I just saw the two options listed at online parts catalog and researched to fig that out.

 

Call Cummins, and get it from them, there are 3 thicknesses,
stock/ +1/4mm// +1/2 mm thickness,
I went with the +1/2mm gasket
I am NON IC truck, and went for a bit lower compression, 1/2 point as i am told, Also you can order new head bolts, there are alot of them, But it will be about $100.00 for them all. The gasket should come with new injector washers.
Peter.

 

Did see these 'rot leaks' with the head off or externally? BTW, under no circumstances do you buy a headgasket from your local auto parts store (Felpro). Be sure to get it from Cummins! You only have 3 choices, stock thickness, .010 over, .020 over. They are ALL marine HG's, so don't ask for one of those. If I had the head off I would consider some valve work, possible port work, and have it checked for cracks and flatness. A good machine shop is a must. Most guys that pull a head, replace the HG, then put the head back on, usually are doing another HG job shortly after. Then after the machine shop takes X amount of material off the surface of the head, then chose which HG you want.

 

I agree with Bill- get the gasket from Cummins. I saw a Cummins vs Felpro comparison one time, and I wouldnt run a Felpro gasket if you paid me (unless it was enough $$ to replace it with a Cummins when Felpro failed). For gaskets and bottom end stuff, Cummins only. For fuel systems and injectors, aftermarket, which you cant get a NAPA anyway.

I got a .020 over gasket, and ended up taking .00925 off the head, so it was a good thing I got the thicker gasket.

Daniel

 

thanks for the advice bill. i was already taking it to the machine shop for a valve job and getting it re-surfaced.
then throwing new 60 lbs. valve springs on. also sending in the injectors to be re-built. ontop of that the exhaust manifold is getting re-surfaced and ported at bolth ends, along with the head. then sence its down a 3200 rpm gov. spring is getting added. then a re-built steering box and a borgosen steering shaft.
still with 300k nothing has failed on me. except the a voltage regulator, and a roted head gasket.
o'ya. i wouldnt get a gaket at any place except cummins. it just helps if the parts guy knew what the heck he was doing. but after a rough 40 min. on the phone i got my new head bolts, exhaust bolts, and valve collets.
waiting for the head work to get done before ordering the head gasket.

bob.

 

Be sure to have the head checked for cracks. 12v Cummins heads are notorious for cracking out around the injector holes, especially the old 9mm ones.

 

checking for cracks is included with the machine work

bob

 

Why would it matter if your head was shaved..?? Are the heads on the older motors not flat like 2nd gens??
If not I understand, but if they are flat, it makes no matter how much you take off the head, your not gaining any compresion. Only if you deck the block should you need a thicker gasket.

 

I think valve clearance is the issue.

 

I don't know if this is standard or not, but the guy who will be doing my head said he would "sink the valves" when he shaved the head (if the head required it).. I'm ***-u-me-ing (I know) that this would just be cutting the seats a bit deeper to match the head-plane..
I've just been told by several others there's no need to thicken the gasket unless you deck the block.. Trying to figure it all out.

 

I went with the thicker gasket to lower my compression ratio on the odd chance I someday get enough air to match my fuelling. It will also affect valve clearance, along with injector protrusion into the combustion chamber. I didnt notice any difference in the valve seating in the head- I had many hundredths left before even coming near the valve seat.

A 12v head is a 12v head, with the only difference being 9mm or 7m injetor bores. Some say the newer ones flow better, others disagree.

Daniel

 

Injector pattern isn't something I'd thought about... This would be beneficial if your running marine injectors wouldn't it?
Shaving the head and using thin washers would keep more of the fuel in the bowl...??