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Jagtec1 · 03-07-2005, 07:37 PM

I'm working on port matching my RPM intake to my 670 heads with port opened to RAIV specs. Needless to say, the gasket alignment on the RPM is not correct, and I need to "build up" very small areas on one side of each runner divider, and grind the other side. Jim Hand refers to this process in his book, and recommends a "good fuel resistant epoxy". What should I use? I bought some JB weld, but am nervous to use it. Anyone done this without TIG welding it? I don't really weld, nor do I have access to a TIG. I really don't have the $ to pay to get it done. Any ideas/suggestions would be appreciated! Thanks!

Jagtec1 · 03-07-2005, 07:37 PM

I'm working on port matching my RPM intake to my 670 heads with port opened to RAIV specs. Needless to say, the gasket alignment on the RPM is not correct, and I need to "build up" very small areas on one side of each runner divider, and grind the other side. Jim Hand refers to this process in his book, and recommends a "good fuel resistant epoxy". What should I use? I bought some JB weld, but am nervous to use it. Anyone done this without TIG welding it? I don't really weld, nor do I have access to a TIG. I really don't have the $ to pay to get it done. Any ideas/suggestions would be appreciated! Thanks!

critter · 03-07-2005, 07:46 PM

JB Weld or Devcon Marine Epoxy should do the job. I think Jim reccomends the latter for filling the well plugs on Qjets so it should resist fuel permeation very well.

tom s · 03-07-2005, 08:05 PM

Mendoza uses a marine epoxy called splashzone.Works real well.Tom

Bill Bolin · 03-07-2005, 08:25 PM

I've used Devcon Titanium Putty for that same application with great success. Devcon makes a full line of epoxies. www.devcon.com

pontiacjeff · 03-07-2005, 09:25 PM

ould your port line-up problem be fixed by separating the crossover and moving the intake forward/rearward?

Jim Robertson · 03-07-2005, 10:13 PM

Splashzone aka Z-Spar is by far the best epoxy we have ever used. Put it in and forget about it. If surface is prepared correctly it will also handle alcohol fuel.

Jagtec1 · 03-07-2005, 10:30 PM

I referenced the port opening areas on the heads and intake using the outer holes with dowels. The issue is the when the gasket is layed across the intake port outlets, there is slight overhang on one edge. The head side is fine, as it was already gasket matched and ported. The only way I see to remedy it would be to build up the area behind the overhang. The water crossover is separated, and there will be reference marks on the gasket, head, and intake to ensure proper port alignment.

buwalda · 03-08-2005, 04:23 AM

Jagtec,
I found the same problem with my RPM. It was so far out of alignment, I had to elongate the mounting holes; even then, when you lined up the ports on one head, then the other side was out. I used Devcon to build up the openings. I also use Devcon to fill in the threaded accessory holes in the runners, so that the runner roof is flush.

tempest455 · 03-08-2005, 11:29 AM

Most two part, room temp curing epoxies when cross linked, are resistant to gas. There are various types and some better than others.

However, even some of the best will soften with exposure to Methanol.

ponchobob · 03-10-2005, 07:46 AM

FWIW, I put some samples of fully cured JB "industro weld" immersed in methanol for 36 hrs. Surface was still firm, and still had exellent bond to aluminum. Only change was went from brittle to a very hard rubber consistency. I feel it is more than adequate for "necking down" the runner sides on my "Gutsram" based Enderle injection system. Should perform with gas even better.-Bob.

tempest455 · 03-10-2005, 11:39 AM

Bob, did you heat the solution? Additionally, 36 hours is not enough time to determine failure.

The reason I ask, it takes some heat to soften. We came across this a number of years ago when I worked as an R&D Chemist and we needed to remove cured epoxy from aluminum. I consulted with BF Goodrich (who at the time was the largest epoxy mfg) and they suggested Methyl Alcohol as a primary constituent. They found out the hard way on an auomotive application for the "big 3".

Eventually we found a combination of compounds that when used in conjunction, were greater than the sum of their parts. Cured epoxy would completely remove from aluminum within a few hours at elevated temperatures. I was under contract at the time, so I cannot divulge the compounds or ratios.

I can see where the JB Weld product will work for your application, that was not the intent of my post. My point was, it will soften eventually and heat will accelerate the process.

That being said, epoxy has been used for many years in your application.

fasteddy · 03-10-2005, 11:52 AM

Bottom line--IMHO--use the JB Weld. Be sure to rough up and clean with brake cleaner before applying. I used JB on my HSD modifications--2 years-no problems--looks like the day I put it there. Methanol? Gasoline--yes.

Jagtec1 · 03-10-2005, 03:35 PM

Thanks for all the replies! Motor will be run on 112 race gas. Unless you advise otherwise, I'll go ahead and use the JB Weld. I'll wait to see what is said about it's use with the 112....and I'll certainly rough up the surfaces and clean thoroughly. Let me know if you think that will work....I'm guessing so, but it's always nice to have reassurance. Methanol....like alchohol?? I'm assuming race gas at 112 isn't methanol??

Thanks!

gobrdgo · 03-10-2005, 03:36 PM

I read Hand's book, Great stuff, I gotta say I'm weary of putting the epoxy in my intake ports. I'm too afraid of it breaking off and maybe taking out an intake valve. My intake alignment does necessitate this solution though.

Jagtec1 · 03-10-2005, 03:59 PM

GOBRDGO, yeah, I'm a little leary of putting the stuff in there as well, but unfortunately, to do the matching, it's required. If I could TIG weld, or could get it done cheap, or free, I would build it up that way....but I don't and can't, so I'm left with the epoxy solution. I can't believe more people have not done it that way. I must be the only poor one!! LOL

slowbird · 03-10-2005, 04:13 PM

I have heard (and know of) of problems with epoxy when used on a mating surface with a gasket in between. The pressure from the gasket (when the to mating sufaces were tighten up) was strong enough to break the epoxy loose. This happen to a good friend of ours. He now weld the entrances up and then epoxy up behind the weld so there is pressure being put on the epoxy.

ponchobob · 03-10-2005, 04:28 PM

BTW, samples soaking in warm (145deg) alky showed no significant softening yet.(8+hrs.)-Manifold usually was COLD when running anyway!-Bob.

gobrdgo · 03-10-2005, 05:12 PM

Jagtec, I could weld mine, I never really thought of that. LOL. I really only need to fill what the gasket should, or would not before I cut it to fit. I'm going to do a little thinking before I make a move. The engine is in the balancing stage anyway for now. I'm shooting for an honest 600 horse this time, assembling it myself. Lofty Goals? We'll see.

Bill Bolin · 03-10-2005, 07:25 PM

Loctite is also a full line epoxy manufacturer now. I sell their line and Devcon. You can feel free to call 1 800 LOCTITE and talk to the technical guys about your specific application. They are great to deal with and can answer any question you may have.

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