Needle and seat O-rings

[Cs19]

WTF is up with these things? They seem to shrink,crack and go brittle way too often.
Does one type of fuel attack and destroy these o-rings? I run different fuels depending on what Im doing, this carb has seen pump,av,C-16 and Sunoco 116 (once)
At the IHBA world finals I was forced to run this Sunoco as they sponsored the race or something, anyways everthing was dialed all weekend long. After the race the boat just sat there for a few weeks with fuel in the bowls,the other day I turned the fuel pump on and saw a problem,finally diagnosed the o-rings being shot.When I pulled them off the needle they just disentigrated in my hand.SHOT! Saw the same thing happen on my 496.
It makes me think that the sunoco attacked the rubber o-rings..I also found that one of my XRP hose ends developed a leak (was not leaking all season) which just backs up my thoughts on the sunoco.
Or....maybe that new pump gas (ethanol) is attacking the rubber and its just a coincedence that both o-rings failed at the same time, and it has nothing to do with the 116.
Any thoughts on this?

[George Pataki]

CS-19 I've had this same Problem with my engines also.
I've had my Hot rod 57 sitting for two years. When I went to move it before winter, it started to act alittle funny like it was out of gas "It has Holley Electronic fuel injection" I checked the tank and noticed on the return line it was spitting black globs or chunks in the tank.:idea: :idea: I then went and changed the fuel filter. Thats when it got interesting!!!!! Pulled the Aeroquipt hose off and the inside of the hose looked like it was made out of Black Permatex goop. The Pump Gas Fuel "ethanol CRAP" Had sofftened the lines to the point they were Moosh.
So yes I beleive the Ethanol in the fuel had turned the lines bad from sitting for that time.
Damn Exotic fuels

[Infomaniac]

Yes you need alcohol compatible "o" rings

[wsuwrhr]

I believe PTFE Teflon is the material you need your O-rings made of.
Buna-N gets all worked up around alcohol.
Brian

[DEL51]

In Wisconsin, alot of our fuel has been 10 percent ethanol for quite some time. This is indicated at the pump. Pump gas unleaded at the BP station is as follows: 89 w/10% eth ,89 silver same price no eth, premium 93 no eth added. Do not let ethanol based fuel sit in a carb for too long. Cleaned a friends Dom that sat all winter with the blend. It was all chalky and attacted the zinc pot metal. Some premium unleaded at other stations will give a 94 oct level, I believe this is even higher ethanol or pemium 92-93 with 10 percent eth. anything over 10 percent should be labeled as such. I dyno'ed my engine on citgo 92 and tubo blue 110. very close in power production for my app.Ran richer on the 110. Did experiment on the lake. Running too rich on 110 at certain rpm's was bad.Added 10 percent denatured alky and it cleaned up. The new E-85 is available as well as a 20% eth mix. In my opinion it is all better than MTBE. I did not ever have a problem with my dominators with any gasket/o-ring/corrosion. I will be checking my carbs over soon and I'll post any negative findings. Maybe Blown 472 could give some input on our local ethanol recipes. Their might be more to this whole thing than ethanol and rubber.

[Blown 472]

In Wisconsin, alot of our fuel has been 10 percent ethanol for quite some time. This is indicated at the pump. Pump gas unleaded at the BP station is as follows: 89 w/10% eth ,89 silver same price no eth, premium 93 no eth added. Do not let ethanol based fuel sit in a carb for too long. Cleaned a friends Dom that sat all winter with the blend. It was all chalky and attacted the zinc pot metal. Some premium unleaded at other stations will give a 94 oct level, I believe this is even higher ethanol or pemium 92-93 with 10 percent eth. anything over 10 percent should be labeled as such. I dyno'ed my engine on citgo 92 and tubo blue 110. very close in power production for my app.Ran richer on the 110. Did experiment on the lake. Running too rich on 110 at certain rpm's was bad.Added 10 percent denatured alky and it cleaned up. The new E-85 is available as well as a 20% eth mix. In my opinion it is all better than MTBE. I did not ever have a problem with my dominators with any gasket/o-ring/corrosion. I will be checking my carbs over soon and I'll post any negative findings. Maybe Blown 472 could give some input on our local ethanol recipes. Their might be more to this whole thing than ethanol and rubber.
I ran e85 in my boat all summer and had no problems at all. Del is right we have had 10% for some time now and I never see any problems with my o rings in my car or my boat.

[Fiat48]

Viton is the O ring material you want. That said...I know guys that run alcohol carbs with methanol and they are not having problems with normal Holley needle and seat O rings.

[wsuwrhr]

Doesn't alcohol eat Viton like a chery pie?
Viton is the O ring material you want. That said...I know guys that run alcohol carbs with methanol and they are not having problems with normal Holley needle and seat O rings.

[Fiat48]

Several types of Viton material.
Also looks like there is a grade specifically for oxygenated fuels too.
http://www.pspglobal.com/nfvitongrades.html

[Cs19]

Viton o-rings got it!!
I should have taken pics of these things to clafiry how shot they were..Normally when you drop in a needle and seat you can feel the resistance from the o-ring when you slide it in, these things were so shrunk down there was no resistance from the o-ring..They were hard as a rock and all cracked when i removed them. Something definatly got to the o-rings.