Performance Boats Forum banner
1 - 18 of 18 Posts

·
Half a bubble off
Joined
·
2,467 Posts
Discussion Starter · #1 ·
The Dual 4's thread got me thinking and I didnt want to thread jack it so I'm posting it up here.

Given the number of folks that are squeezin the hell out of their motors with multiple bottles or running massive amounts of boost and using big pumps to feed all of it, what is everyone running for inlet sizes?

I've been running .150's which is likely overkill for my tub but curious what others are doing. When you look at Travis's turbo motor, that carb is running two inlets per bowl which is certainly needed for that monster but what about the rest of us?

.097s, .110s, .120s or .150????

Okay gents......flame away.....and thanks....john :D
 

·
Administrator
Joined
·
16,894 Posts
Float needle seat size? 110 prolly good enough for a lake boat gasoline deal.

The biggest issue to enough fuel I have seen is as SuperDave mentioned. Tank outlet too small or restrictive.

The Dual 4's thread got me thinking and I didnt want to thread jack it so I'm posting it up here.

Given the number of folks that are squeezin the hell out of their motors with multiple bottles or running massive amounts of boost and using big pumps to feed all of it, what is everyone running for inlet sizes?

I've been running .150's which is likely overkill for my tub but curious what others are doing. When you look at Travis's turbo motor, that carb is running two inlets per bowl which is certainly needed for that monster but what about the rest of us?

.097s, .110s, .120s or .150????

Okay gents......flame away.....and thanks....john :D
 

·
Administrator
Joined
·
16,894 Posts
Oh and some may never have thought about it but the bigger the
float needle seat, the easier it is for pump pressure to force it open. If you are pushing the max for fuel pressure.

force = area x pressure
 

·
Half a bubble off
Joined
·
2,467 Posts
Discussion Starter · #4 ·
Thanks very much Ron. In my setup anything would probably work but after seeing Travis's dual inlet bowl setups on that badass turbo deal and factoring in everyones use of big pumps to feed these carbs, it got me thinking about what's really needed.

I admit my 150s are overkill but I thought the discussion was worthwhile here. Huge pumps, huge carbs but I've never seen any discussion on inlets.....

Thanks again for not flaming me.........:D...........john
 

·
Resident Ford Nut
Joined
·
10,102 Posts
Thanks very much Ron. In my setup anything would probably work but after seeing Travis's dual inlet bowl setups on that badass turbo deal and factoring in everyones use of big pumps to feed these carbs, it got me thinking about what's really needed.

I admit my 150s are overkill but I thought the discussion was worthwhile here. Huge pumps, huge carbs but I've never seen any discussion on inlets.....

Thanks again for not flaming me.........:D...........john
As Ron stated the .110's will handle 90% of river racers. The 565 has .120's never had a problem. The needle and seat is something that is over-looked by people. I know a guy who burned up a blown 496 3 times before he figured out the .080 needle and seats was the problem :mad:

S CP :D
 

·
E-7 Sheepdog (ret)
Joined
·
6,834 Posts
For some hard data for here, dug out my Holley manual (Copyright and chapter/page info available on request ;) ).

It rates flow for the seat assy's as follows (left off the smallest sizes and lowest fuel pressures, 'cause I didn't want to type it all).

Flow numbers in Pounds fuel per hour.
Seat Diameter and type ................ Flow @ 4psi ........ Flow @ 6psi
.110" holes ...................................... 230 ................... 275
.110" windows .................................. 232 ................... 295
.120" windows .................................. 236 ................... 305


To convert to GPM, divide by 390 (or divide by 6.5 (pounds) and divide by 60 (minuites per hour).

My book aparently predates the .150" window seats, and I am having trouble finding chart data on Holley's site.

BTW, 305 lb/hr = .78GPM, or 46GPH

The viton-tipped needles are only up to .120" size, and are the only ones advised for gasoline, and for 90+% of uses. the Steel ones are for "exotic fuels" (per holley) that swell up the viton seal tips. The steel ones scar easilly from unclean fuel and tend not to seal well. They now make Titanium needles apparently, same as steel, race-use only advised.

Keep in mind, that is for EACH SEAT, so a 4-barrell with 2 bowls, is double, 2x4v setup is multiple of 4 of course.
 

·
E-7 Sheepdog (ret)
Joined
·
6,834 Posts
As Ron stated the .110's will handle 90% of river racers. The 565 has .120's never had a problem. The needle and seat is something that is over-looked by people. I know a guy who burned up a blown 496 3 times before he figured out the .080 needle and seats was the problem :mad:

S CP :D
0.082" seats:
153 lb/hr @ 4psi ... 204 lb/hr @ 6psi
Yea, not much to feed a big blown motor at high revs, probably had great fuel pressure, 300GPH or so pump? :D
134gph flow for 2 carbs.
 

·
Half a bubble off
Joined
·
2,467 Posts
Discussion Starter · #8 ·
The needle and seat is something that is over-looked by people. I know a guy who burned up a blown 496 3 times before he figured out the .080 needle and seats was the problem :mad:

S CP :D
Ouch! That would suck and is zactly why I wanted to get this thread going. I see guys with -12 and -16 lines from their tanks to massive pumps and bigflow regulators and can't help but wonder about the needle&seat inlets.

For some hard data for here, dug out my Holley manual (Copyright and chapter/page info available on request ;) ).

It rates flow for the seat assy's as follows (left off the smallest sizes and lowest fuel pressures, 'cause I didn't want to type it all).

Flow numbers in Pounds fuel per hour.
Seat Diameter and type ................ Flow @ 4psi ........ Flow @ 6psi
.110" holes ...................................... 230 ................... 275
.110" windows .................................. 232 ................... 295
.120" windows .................................. 236 ................... 305


To convert to GPM, divide by 390 (or divide by 6.5 (pounds) and divide by 60 (minuites per hour).

My book aparently predates the .150" window seats, and I am having trouble finding chart data on Holley's site.

BTW, 305 lb/hr = .78GPM, or 46GPH

The viton-tipped needles are only up to .120" size, and are the only ones advised for gasoline, and for 90+% of uses. the Steel ones are for "exotic fuels" (per holley) that swell up the viton seal tips. The steel ones scar easilly from unclean fuel and tend not to seal well. They now make Titanium needles apparently, same as steel, race-use only advised.

Keep in mind, that is for EACH SEAT, so a 4-barrell with 2 bowls, is double, 2x4v setup is multiple of 4 of course.
Thats the info I was looking for. Thanks a bunch. I haven't had any problems so far with the Titanium 150 but now you have me wondering and for sure I can see that a .110 or .120 would be all I need at the max.

Thanks again guys......john
 

·
just a ski boat with bark
Joined
·
2,811 Posts
I'm just running .110 viton tipped ones with windows but I have 4 with the dual 750s so they work just fine for me. Actually think I only had .120s in my big single 4bbl.
 

·
Registered
Joined
·
262 Posts
The Dual 4's thread got me thinking and I didnt want to thread jack it so I'm posting it up here.

Given the number of folks that are squeezin the hell out of their motors with multiple bottles or running massive amounts of boost and using big pumps to feed all of it, what is everyone running for inlet sizes?

I've been running .150's which is likely overkill for my tub but curious what others are doing. When you look at Travis's turbo motor, that carb is running two inlets per bowl which is certainly needed for that monster but what about the rest of us?

.097s, .110s, .120s or .150????

Okay gents......flame away.....and thanks....john :D

.130 on my stock 429 :D
 

·
21' Daytona
Joined
·
395 Posts
Jim Guthrie set my carbs with .120's Johnny Show, you know how well they work :D. It was mentioned that having the n/s too large doesn't always mean better. The theory was it was best to have a 'balanced' system. To small means not enough fuel. To large means the n/s are bouncing open/close open/close. Getting the right size n/s means the fuel level stays more consistant in the bowls. That what I was told at least......................
 

·
i got skiillllzzzz....
Joined
·
977 Posts
reading this thread made me think about the needle and seats that are in my carbs.does anybody know what size does my 750 hp's part#0-80528-1 come with from holley?.i have a high flow pump and big lines in my fuel system.im thinking they are to small.
 

·
E-7 Sheepdog (ret)
Joined
·
6,834 Posts
reading this thread made me think about the needle and seats that are in my carbs.does anybody know what size does my 750 hp's part#0-80528-1 come with from holley?.i have a high flow pump and big lines in my fuel system.im thinking they are to small.
Do you have any sustained high RPM operation problems (from the bowl fuel levels being pulled down)?

If not, then they are not too small, period.
 

·
Half a bubble off
Joined
·
2,467 Posts
Discussion Starter · #15 ·
.130 on my stock 429 :D
Okay Vern, so let's see. If your "stock 429" uses .130's, then the 700" motor in your CP must be using 1/2" gate valves.....sandbagger..:)hand

Jim Guthrie set my carbs with .120's Johnny Show, you know how well they work :D. It was mentioned that having the n/s too large doesn't always mean better. The theory was it was best to have a 'balanced' system. To small means not enough fuel. To large means the n/s are bouncing open/close open/close. Getting the right size n/s means the fuel level stays more consistant in the bowls. That what I was told at least......................
Ya Droppy,the skin on my face has finally returned to where it was before you took me in the rocketship of yours. I think I'm gonna send my carbs off this winter to have them set up.
 

·
Registered
Joined
·
30 Posts
Good topic :)devil, haven't seen anyone discuss this previously. I've always had good luck with .110s and keeping constant 5 1/2-6 PSI . Go with the smallest that suits your HP rating . Too large an inlet valve is a bad thing in some racing applications .

There's plenty info out there on Holleys , I have a great book on Holley carbs , published by HP books , a must for serious Holley tuners . Cuz nobody knows all there is to know.......:D

HP Books # 339 . It's still only $15.95
 

·
Registered
Joined
·
262 Posts
I think I'm gonna send my carbs off this winter to have them set up.[/QUOTE]


HIGHLY recommended doing this. I had a "professional" set up my 2 750's and my dominator. Both work flawlessly idle to WFO.
 

·
Half a bubble off
Joined
·
2,467 Posts
Discussion Starter · #18 ·
HIGHLY recommended doing this. I had a "professional" set up my 2 750's and my dominator. Both work flawlessly idle to WFO.
Hey Vern, shoot me a PM with who you used iff'n you don't mind......:)
 
1 - 18 of 18 Posts
Top