Grassroots Motorsports

Register Log in to GRM
- Community

Birthdays
Recently on the Classic Motorsports forums

Subscribe get a full year for only $23.95 Sample Free Test Drive—no strings attached

Login to post Forums » Grassroots Motorsports » Epoxy for intake port shaping?

March 13, 2011 8:15 p.m. ditchdigger HalfDork

Long story short I got burned on an ebay auction for a cylinder head. Along with some very good modifications this head has recieved some very bad porting on the intake and reshaping of the combustion chambers.

The combustion chambers are easy. Fire up the TIG and drop fill where material was removed, reshape and flycut. This I have done before so I am not concerned.

but the intake porting is a mess. I don't know a lot about this black art but I can tell that at least the short side radius on this head is a mess. Too much material has been removed and I can't get the TIG torch in there to add some back.

At this point I am thinking epoxy. I did some googling last night and found lots of references to a marine grade epoxy, JB weld and even something Moroso sells but it was inconclusive whether any of these would hold up to the mandatory 10% alcohol in our fuel.

So I turn to you again GRM'ers. Who has experience reshaping intake ports with modern man made goo?
March 13, 2011 8:49 p.m. FlightService Reader

Don't have experience with the epoxy part,but I will say this. Porting isn't a black art. CFD modeling software has taken all that out.

I did put the side of a block back together with JB weld once. Truck is still runing (bout 12 years of use.)
March 13, 2011 8:54 p.m. digdug18 HalfDork

I'd use devcon, Its more like metal and is recommended for use in repairing cylinder heads
March 13, 2011 10:28 p.m. Kendall_Jones Reader

digdug18 wrote:

I'd use devcon, Its more like metal and is recommended for use in repairing cylinder heads

I've used devcon as well for blocking off the balance tube on a spridget intake.

Kendall
March 13, 2011 10:29 p.m. JohnyHachi6 New Reader

Keep in mind that metal and epoxy can have very different coefficients of thermal expansion (they expand and contract at different rates as the temperature changes). After some number of thermal cycles, the epoxy will crack and come loose. How long that takes will depend on a lot of factors, but it could be days or it could be many years.

Personally, I'd be fine using it for a low-budget engine. Just make sure you get an epoxy that is recommended for the application and do everything you can to ensure the best bond between the metal and the epoxy.
March 13, 2011 10:56 p.m. jimbbski Reader

I used Devcon epoxy to fill in the intake port floor on a Ford 2.0L head. This was done per a book by David Vissard on building these engines for performance. You need to make sure the surface is clean and rough. A sanding roll or stone grinding bit should work. There is always the chance that the epoxy could break off. In fact this did happen to one of the ports. The engine was not effected at all.

The worse case would be for part of the epoxy to be caught between a valve and the valve seat. That could lead to a bent valve or worse depending on the engine design, etc.
March 14, 2011 2:08 a.m. digdug18 HalfDork
Found 3 possible mixes from the devcon site, I was surprised, they have more on there then I was aware of.

Wear Resistant Putty (WR-2)

Smooth, non-rusting, all-purpose epoxy putty for repairs requiring low-friction finishes, such as machine lathe beds.

KEY FEATURES
```
* Bonds to steel, iron, aluminum, ceramic, concrete, brass, and some plastics
* Contains wear-resistant fillers for low friction applications
```
Titanium Putty

High-performance, non-rusting titanium-reinforced epoxy engineered for making repairs to machinery and equipment that can be precision machined. Withstands heavy loads in hard chemical envirnoments.

KEY FEATURES
```
* Excellent temperature resistance (350°F)
* High compressive strength (18,800 psi)
* Resistance to chemicals and most acids, bases, solvents, and alkalis
* Qualifies under Mil Spec MIL-PRF-24176C, Type I
```
Plastic Steel® Putty (A)

Plastic Steel® is the original metal-filled epoxy putty used for hundreds of routine maintenance, production, and tooling applications. Patch and repair areas where welding or brazing would be undesirable or impossible.

KEY FEATURES
```
* Bonds to most metals, concrete and some plastics
* Cures at room temperature and forms a tough durable metallic mass that can be drilled, tapped, machined or painted
* Excellent resistance to oil, gasoline, water and many chemicals
```
I'm thinking the 3rd is the one you want, but you be the judge.
March 14, 2011 7:23 a.m. Travis_K Dork

I dont really know all of the details, but someone who used to sell ported turbo dodge heads used epoxy in the ports and I had not heard of any issues with this practice back when I payed attention to those things. Is that a head for the fiat engine? Or is it something else.
March 14, 2011 8:15 a.m. Streetwiseguy Dork

There was a tech question in one of the competitors magazines this month (Initials HR, April edition) about epoxy in a manifold that had been ported to a larger set of heads. The suggestion was that epoxy was usually good for race parts, but the repeated heat/cool cycles of a street engine made it tough to keep it attatched. Mondello Tech Center uses a product called A788 that works if the surface is properly prepped.
March 14, 2011 9:23 a.m. ditchdigger HalfDork

This head is indeed for the fiat motor.

The ebay auction listed it as a PBS 8 port head in very good condition

What I recieved was a modified 903 head that had been attacked with a die grinder. The actual 8 port mod is totally workable but the combustion chambers were brutally reshaped and the intakes were ported by someone with a bigger is better mindset.

I expressed my dissatisfaction with the buyer and he has stopped communicating with me. I am just trying to figure out now if it can be salvaged before I open a paypal dispute.

I really should just send it back but the allure of one injector per cylinder is too strong.

The factory intake for comparison
March 14, 2011 10:55 a.m. Streetwiseguy Dork

Well, you gotta admit even a bad porting job on the 8 port head is better than stock.....
March 14, 2011 9:03 p.m. digdug18 HalfDork

i think it depends on how much you paid. if you got a deal that you aren't likely to find again, or if the head itself is rather rare, then I'd use the epoxy. On the other hand, if its a common head, or you paid full price, or the going rate. I'd open the dispute.
Dec. 15, 2011 10:48 a.m. 44Dwarf Dork

What did you end up doing with this? Did you use Slash zone a-788 or another goo?
Dec. 15, 2011 11:18 a.m. Gasoline Reader

I would not be happy trying to make this head work great deal or not. How close did they hog out toward the water passages? Epoxy or not, a couple of heat cycles and you are back to junk.

I would have to start with a un-tampered head.
Dec. 15, 2011 1:44 p.m. ditchdigger Dork

I ended up filing a paypal dispute and sending it back after the refund cleared.

I took it to a machine shop who cleaned it up enough to see that most of the work done was with JB weld. The tubes were just pasted into place with copious amounts of JB weld and then sanded smooth. Even the intake valve seats were being held in with the stuff. Beyond sketchy. Glad to have seen it go.

I did post detailed pics and warnings in all the fiat mailing lists and forums in case he should try and sell it again.
Dec. 15, 2011 1:44 p.m. ditchdigger Dork

You'll need to log in to post.