I'm getting ready to order some spare needle/seats to keep in the tool bag. I see there are several options for needle material, steel, viton, SS, titanium, ect....

What is the best all around needle material for pump gas?

Viton. This place has excellent prices. Ive had great luck buying all my carb parts from them.

http://www.allcarbs.com/detail.php?p...ctgn=38&stt=15

Holly? you will also need to know what the flow rate is..they come in differant sizes... .120 and up ..

Yes, Holley 4150 750CFM. There are'nt any numbers or markings that I can see stamped into the originals.

The link I posted is the .110 Viton needle and seat. It comes standard in most holley carbs. 750, 800, 850, etc. Holley part #6-504

mt 4779 4150 style had .120's in it..

My holley master book shows the 110's for the 4779, 4780, 4781, etc. Even the 1050 and 1150 dom's. My 850's were used, and the ones I pulled out were stamped "h". Forgot what H stands for? but I replaced them all with ''.110'' when I was rebuilding them. The smaller 600,650 carbs call for .097 needles.

But, to get back on topic, you want "viton'' because they seal better, and a little more resisitant to dirt. Steel needles are for alky. With alcohol, generally you go larger with needle and seat size, than you would with gas. Putting a .150 needle in a typical 750 or 800 wont do anything. Unless your running a single carb application and making 1000HP or more. Hence why the single carb'ed blow thru stuff making over 1200hp requires dual needle and seat bowls. Saw that first hand on my buddies engine on the dyno. Sucked the bowls dry at 6000RPM. The best fuel pump in the world wasn't gonna fix that issue. Fixx knows that story

Thanks for all the help guys.