Epoxy TB ???
02-14-2006, 09:19 AM
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Epoxy TB ??? Getting ready to port TB and have seen pictures of some with the idle air holes epoxied and then drilled out. Is it worth the extra work to do that? Any down side? What type of epoxy is being used? What size holes are drilled? Would it be better to used an appropriate sized tubing instead of drilling? Thanks 
02-14-2006, 02:46 PM
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Some say forget it, but I saw the ridges / pockets as
definite turbulators and wanted them smoothed. I used
J-B Weld, several layers over several evenings as the
stuff slumps a lot. I like J-B Weld's adhesion (given that
you prep the surface meticulously) since there are only
bad places for it to go, if it comes loose.
You should drill a large hole, years back the advice was
3/16" but this is -well- short of the area that the IAC
originally has authority over and the PCM expects; too
small makes for more probability of idle surge. I think I
drilled mine 1/4" but if I have it off the car again I will
go up to at least 3/8" (still well smaller and smoother
than the stock ports). PCV, you don't care, smaller is
probably better given the oil-slurping these motors can
do.
Potting in some tubing would be sensible and maybe add
some further strength to the epoxy. If you got a piece
of 3/8" aluminum from the Ace Hdwr hobby-metal rack
or something, that would be easy to work and cheap.
You'd want to be really sure no epoxy got onto the IAC
seating circle, or left loose ***** in that passage. I pressed
in aluminum foil dams before the first layer of epoxy, which
sealed things up for the rest. I had to pick out from the
back with a dental pick but was happy with the result (no
glop where glop shouldn't be).
There's no proof I've seen that doing all that work, buys
you anything. But I chose to trust my eye / gut, it just
looked like the right thing to do. But sometimes doing the
right thing, is only extra work and nobody notices.
definite turbulators and wanted them smoothed. I used
J-B Weld, several layers over several evenings as the
stuff slumps a lot. I like J-B Weld's adhesion (given that
you prep the surface meticulously) since there are only
bad places for it to go, if it comes loose.
You should drill a large hole, years back the advice was
3/16" but this is -well- short of the area that the IAC
originally has authority over and the PCM expects; too
small makes for more probability of idle surge. I think I
drilled mine 1/4" but if I have it off the car again I will
go up to at least 3/8" (still well smaller and smoother
than the stock ports). PCV, you don't care, smaller is
probably better given the oil-slurping these motors can
do.
Potting in some tubing would be sensible and maybe add
some further strength to the epoxy. If you got a piece
of 3/8" aluminum from the Ace Hdwr hobby-metal rack
or something, that would be easy to work and cheap.
You'd want to be really sure no epoxy got onto the IAC
seating circle, or left loose ***** in that passage. I pressed
in aluminum foil dams before the first layer of epoxy, which
sealed things up for the rest. I had to pick out from the
back with a dental pick but was happy with the result (no
glop where glop shouldn't be).
There's no proof I've seen that doing all that work, buys
you anything. But I chose to trust my eye / gut, it just
looked like the right thing to do. But sometimes doing the
right thing, is only extra work and nobody notices.
02-14-2006, 02:55 PM
#4
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Are we talking about the hole in the TB blade or the two holes in the top of the housing for the sensors? I seem a little confused by the replys compared to the question 
02-14-2006, 03:02 PM
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Originally Posted by 300bhp/ton
Are we talking about the hole in the TB blade or the two holes in the top of the housing for the sensors? I seem a little confused by the replys compared to the question
02-14-2006, 05:21 PM
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The guys who do alot of porting for other people Bo, New Era, Yak.....will all say don't do it as over time that epoxy could chip off and get sucked up into yer intake...That would be bad.
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02-15-2006, 07:46 AM
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Use an epoxy called "Marine-Tex". It is expensive but far superior to common autostore-stocked epoxies. I have a quart I purchased 15 years ago and still have half of it. Marine-Tex is used in the boat hull repair business. You can find it via Google.
02-15-2006, 07:53 AM
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I picked J-B Weld because of its high temperature
resistance; used it before on aluminum intakes etc.
I don't know what the marine stuff does when hot
and oily, one way or the other. Been a couple of
years on the car with no missing bits so far. I did
take some care to roughen the surfaces to be filled,
trying to give it some good "tooth".
resistance; used it before on aluminum intakes etc.
I don't know what the marine stuff does when hot
and oily, one way or the other. Been a couple of
years on the car with no missing bits so far. I did
take some care to roughen the surfaces to be filled,
trying to give it some good "tooth".
02-15-2006, 10:30 AM
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Marine Tex is rated:
Up to 250°F constant temperature in a dry environment, with spikes up to 300-325°F
Adheres to Metal, fiberglass, glass, masonry, ceramic, wood, most plastics
Can be applied under water
CHEMICAL RESISTANCE: Most common acids, alkalies and hydrocarbons (gas & oil).
Years ago (1988) used Marine Tex to patch a hole in the side of a Briggs & Stratton 5hp engine in my brother's go-cart. Rod broke and made a 2x2 inch hole. That same engine is running today. Marine Tex has NEVER let me down.
Up to 250°F constant temperature in a dry environment, with spikes up to 300-325°F
Adheres to Metal, fiberglass, glass, masonry, ceramic, wood, most plastics
Can be applied under water
CHEMICAL RESISTANCE: Most common acids, alkalies and hydrocarbons (gas & oil).
Years ago (1988) used Marine Tex to patch a hole in the side of a Briggs & Stratton 5hp engine in my brother's go-cart. Rod broke and made a 2x2 inch hole. That same engine is running today. Marine Tex has NEVER let me down.
02-15-2006, 11:38 AM
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02-15-2006, 11:48 AM
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I've used Devon aluminum putty in the few TB's I've ported, no problems what so ever. I do "pot" mine with aluminum tubing like like jimmy blue described as well. HTH's
02-15-2006, 04:11 PM
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Correct. I have done alot of R&D on a Dynojet and there is no gain in on with compared to without. If ya want to say youve done all that can be done to one then do it but thats all that will come of it- you can say its been done.
