Viton vs steel needle for demon carbs; size?


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By rgrove - 15 Years Ago
Hi all,

I recently picked up a demon jr 525 carb for my 56 sunliner.  I had read up on here about swapping out the viton needle for a steel one due to alchol in the gas softening the viton tip and the needle sticking.  Well, I checked an older holley and sure enough, the needle tip was soft, so ive decided to swap to steel.

After reading on here, someone else (I apologize i dont recall who right now) had said they swapped to a .130 steel needle, so i ordered a pair.  Went to put them in today, and hte needles i took out looked to have "111" stamped on them.  Curious, I checked out barry grants website, and their spec sheet lists the demon jrs as taking a .097 needle.  So question is: should i stick with the .097?  What is the downside of sticking with the .130 I just put in (seeing as how the .097 in steel is nearly $40!!!).

Any and all comments are appreciated!

BTW, Barry grants website has a sweet looking Y block on their home page promoting their 98 series carbs....

THANKS!!!

By paul2748 - 15 Years Ago
Why work with second hand info. Call barry grant and get it from the horses mouth
By Ted - 15 Years Ago
rgrove (2/17/2010)
What is the downside of sticking with the .130 I just put in (seeing as how the .097 in steel is nearly $40!!!).
The down side to using the larger sized needle seats is that they are more prone to being unseated due to the increase in surface area if the fuel pressure is high.  With 5 ½ to 6 psi pressure, you’d see no problems though with a 0.130” Holley style needle and seat assembly.  But if the engine is hot soaked and the fuel pressure in the line increases with the normal expansion that occurs with this heat, then the carb could see some potential for flooding with these larger seats when shut off whereas it wouldn't happen with the smaller sized ones.
By rgrove - 15 Years Ago
paul2748 (2/17/2010)
Why work with second hand info. Call barry grant and get it from the horses mouth

Not working with second hand info; trying to resolve conflicting info.  Barry grant says to use a .097, someone here recommended .130.  Trying to understand pros/cons, etc.  the .097 steel needles are about $40 at summit vs. about $12 for the .130.  I ordered the .130s based on comments here, and was wondering what the implications were, etc.

Ted, your comments make sense.  I dont run a carb spacer, but havent had any problems with heat soak or vapor lock with any carb setup ive tried before.  Maybe ill just try it with the .130 and see what happens?  If it has a problem, I can spend the extra $$ and make the switch, but it sounds like its not likely to be a problem?

Thanks!

By GREENBIRD56 - 15 Years Ago
I'm the one who put the .130's in - they solved my problem (immediately) and they've never "percolated" that I know of. And they've gotten more than a few Arizona meltdown tests. Its got a 1/2 phenolic spacer under the carb and restricted (truck style) heat riser intake gaskets.

Myself, I've never heard of anyone having a problem with the .130's and a standard sort of fuel pump.

This photo shows the engine sitting from a hot stop (about 5-10 minutes) - and it still has 5 psi showing on the gauge....

By rgrove - 15 Years Ago
THANK YOU Steve!  Glad to hear it should be ok; as i mentioned, the 130s are much cheaper than the 097s.

Thanks again to everyone who chimed in!  I appreciate it!