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GMC V6 and V12 Engines Engine repair and rebuilding

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  #11  
Old February 3rd, 2018, 01:35 PM
Otto68 Otto68 is offline
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Default Re: Head gaskets 351

Thanks, Dave.
I just looked them up and will be calling them on Monday to get more info. There is a good chance by the end of the week he will have a 351 gasket to reproduce for us. I was going to call Cometic up and see what type of numbers I would need to make it worth it for them to do a multilayer. Still might who knows.
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  #12  
Old February 3rd, 2018, 02:06 PM
Motiv8 Motiv8 is offline
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Default Re: Head gaskets 351

Otto, It's my understanding that a while back asbestos was eliminated by law in gkt mfg. Stock on hand could be used until depleted. Molina had a good stock and hopefully can accommodate you. Other mfgs have gone to these various modern methods which are very good. Nitrous, Harleys, etc, they're great. the old asb/ coper clad probably best for you. Forget the solid copper and O ring thing for you. I deal w/ solid copper gkts on British bikes and other special applications. They can be annealed, if desired.
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  #13  
Old February 3rd, 2018, 02:27 PM
Motiv8 Motiv8 is offline
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Default Re: Head gaskets 351

Otto, The GMC V6& V12s I've dismantled had steel shim clad asbestos gkts. Probably cheaper to make. Or they figured the steel could take more combustion heat at thr "fire ring". (The offshore racing blown big block Chevs I build use Stainless Steel fire ring head gkts.) Joe may have already made the ones you need and could be a reasonable cost. Reminds me to ck my stock and reorder. Would you like a Felpro part # to reference? David
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  #14  
Old February 4th, 2018, 12:56 AM
Otto68 Otto68 is offline
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Default Re: Head gaskets 351

David, So what your saying is forget about the multi layer and go with the stock style. Both of mine here copper clad with a GMC stamp in them. If you think the Fel# will help, but I have no problem shipping him out a gasket.
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  #15  
Old February 4th, 2018, 02:42 AM
Motiv8 Motiv8 is offline
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Default Re: Head gaskets 351

Otto, I opened a Felpro V12 full gkt set today. The head gkt# 7962-SB was prox .060 thick, steel clad with a thin mat'l sandwiched within. Felpro offered a double thick head gkt (7962-SB-3) to lower compression. Wonder how that would affect intake manifold alignment. Only reason for my responses was I thought Molina could be a lower cost alternative to the prices you posted. David
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  #16  
Old February 4th, 2018, 05:35 PM
Otto68 Otto68 is offline
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Default Re: Head gaskets 351

The ones I pulled are between 51 and 53 thick now. I want to raise the compression not lower it. I only had a problem with the 1000$+ for the multilayer gasket, the 240$ wasn't a problem just always thought copper was more suited for high compression race when you are pulling the engine apart all the time. Plus I wasn't keen on doing the ring job to make them seal better around the cylinders. I have no problems with the asbestos clad gasket. The one engine i pulled apart had over 150,000 on it and it was in good condition.
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  #17  
Old February 5th, 2018, 11:57 AM
massey478 massey478 is offline
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Default Re: Head gaskets 351

I see a lot of thought about high compression racing engines going into this discussion. I propose that there are parallels but not so much because of compression ratio/cylinder pressures. The V-6 motors do not have high compression ratios and high cylinder pressures. When I go with the jet cut soft copper gaskets, especially for the gas motors, I will not be using compression rings. I will be very sure all surfaces are flat and will use ARP studs. I will coat the copper gasket with a light coat of Hylomar and hot re-torque. The solid copper to cast iron interface bleeds away heat very efficiently, that does not happen as efficiently with a sandwich gasket. Copper does not burn so there will be no torching through with them in these low compression motors without fire rings. The shop could not cut it with a laser cutter for that reason. Also you can change compression ratio a bit by how thick the copper is you use for the gaskets. McMaster Carr, an industrial supply house out of Chicago and other locations I buy from has the soft copper for head gaskets in sheets. With all of the problems I see happening here getting gaskets I am now even more convinced I will be doing it. If it does not work, fine, I will fix it another way but I am quite sure I will not have to. I have been in the engine building business, both stock and race, for over 50 years as a one time full time job and now as a sideline to a design engineering job. We have the capability here on the farm in our shop to do everything needed except boring and crank turning. In the 50 year time I have seen a lot of gasket failures so I have a good idea of the mechanics of it along with the curing of it, drawing on that experience to set the pathway for this concept I am going to follow. So, your good wishes for my success with this low cost alternative will be helpful!
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  #18  
Old February 5th, 2018, 04:21 PM
Otto68 Otto68 is offline
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Default Re: Head gaskets 351

Massey,
Everything you said complies with all the research I did on copper gaskets when I was first told that was my only option unless I wanted to spend 1000+ on a head gasket. Well except the compression ring. Even the Gasket makers say to use one. Well, I Decided to google copper gaskets without o-rings and you are right I found a lot of posts about just using a spray sealant on both sides for street and some performance engines. The only thing that they don't agree on is how many coats and set time before installing. At the moment I'm waiting for my engine builder to get back to me on the thickness of gasket to get my compression between 8-9. I would prefer to take as little off the block and heads as possible to reach that goal. Good luck with your endeavors with a low-cost gasket. If you come up with one before I need it I'll get it from you if your willing to sell me one. My engine builder does a good part of the racing engines around here so he only gets to mine when he is in a lul. Needless to say, it been a year but a lot of that was hunting down parts when we found out what I needed and I'm in no rush since the engine in the truck runs just fine. Its easier to build one of these engines when you don't need one then when you do.
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  #19  
Old February 5th, 2018, 08:35 PM
jrmunn jrmunn is offline
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Default Re: Head gaskets 351

I have a GMC 351E engine that will need rebuilding before putting it in a 1964 1500 pickup, and have what is a dumb or at least uninformed question. Are the head gaskets the same for all the GMC 351 V6 engines? I expect that the intake and exhaust manifold gaskets are different because of port sizes, but have not heard or seen anything about the head gaskets. It sounds like it is going to be hard finding gaskets of any sort, so I at least need to be looking for ones that fit.

JRMunn
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  #20  
Old February 5th, 2018, 08:55 PM
Otto68 Otto68 is offline
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Default Re: Head gaskets 351

Jrmunn,
Head gaskets are the same for all of the 4.56 (351) bore pistons I think. The intake and exhaust gaskets for the 351E you can get from Cometic. I sent them all the gaskets I could from my engine to remake for the ones I couldn't find easily online. They have the head gaskets in copper so it's not a problem there. After reading the post from Massey unless Molina has them for less than 200 I will probably get them from Cometic. I haven't heard back from Molina when I called them this morning. I'll try them again tomorrow.
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