SAAC Forum

That would save me a ton of time....

I do need to get those from you and scanned. I am a data nerd. I just love reading about how and why they did what for a specific purpose. Both to learn from and replicate as needed.

Been busy, 98 carbs in 76 days has been exhausting.

Pre Colt Ford throttle shafts are brass.

Quote from: vtgt500 on May 15, 2021, 03:23:44 PM
I'm see a lot of hype, but no substance.  Generally, on well used carbs the bores for the throttle shaft(s) will wear egg-shaped.  Vacuum leaks become serious.  Where a new throttle plate assembly is not available, necessary to use a small, jig bore to pic up on the original center line, and bore over size.  Index to the opposite side and bore in perfect alignment.  Lathe turn a bronze sleeve, slip fit into the new bores using Loctite.  Finally, ream the bronze repair sleeves in place for .0002 clearance with new throttle shafts.  Any less is just aesthetics.

A few questions:
-Was this directed at anyone in particular?
-In a Holley baseplate, what wears first, the baseplate or the brass throttle shaft?
-these shaft vacuum leaks. What overall effect does one have on an engine?

Oil fill makes a straight fitting pretty hard to use.

I had an 81 Dodge Aries when I was a kid.
I was wanted to get another and make it a dedicated drag car with a blower motor.
Ford engine, put chevy SS emblems on it.

Would be the ideal "funny car."

Bob, what works works!

67gt350, sounds like a lil trash got flushed out the seat.
Fun story.... so I daily drive a 76 F100 with a 390FE and a holley.
Well, driving to the airport to go to work at 2am. Dark South Georgia road, middle of the swamp. Real dark.
Anyway, cruising at 60mph and I feel the engine wanting to die. I realized a bowl had a stuck float.
Well, if the float drops it normally flushes out the trash, so no cars for miles, I floor it.
100mph and my crappy truck shakes bad.
I hit the railroad tracks at 112mph.
Anyway, no more issues. Rest of the trip was smooth.


Also of note on old Ford downleg carbs. There is no killbleed. The siphon break is in the emulsion tune feed. So can have an issue if blocked.

Three variants I have seen from 3259 to -1 have massively different idle circuits.

I won't jump on you. Don't particularly care what you think.


As I said Bob, toss it on and see. Ran normally for me, and I'm fond of the size, but the true test is always on the street.

Dunno what it is, but I kinda am lusting on it pretty hard.

Quote from: gt350hr on March 08, 2021, 12:18:27 PM
Drew ,
    I am still AMAZED at how little people REALLY know about carburetors! The FIRST thing they do not understand is the "principal" of how they WORK. MANY talk about "flooding" an engine with a 715-750-850 etc. In truth , a given engine will only flow what the cubic inches , intake and exhaust efficiency and RPM allow. Bolting on a 600 may be an easy way out for some , but I'll take an expertly optimized carburetor any day.

To this day, one of my most thrilled customers argued with me about what he needed for months.  350 Chevy with a 600 double pumper, ran like poop everywhere, got horrible economy, etc etc.  He finally relented and I sent him a 780cfm carb that I custom tweeked.  Better economy, ran better everywhere.  He went from ready to sell the car, to wanting to sell his daily driver so he could drive his corvette more.  Lol.  I mean, the guy was fanatical, sent me all sortsa gifts, etc....  kinda funny actually, tho I pondered a restraining order for a little bit.

Agreed with the flooding comment.  You are much more likely to have overly rich issues with a 390cfm carb than you are an 800.  I'm not sure how people do not understand what I consider to be common sense, but I also ignore a lot of people.  I have one of the greatest books ever written about carburetion, by Walter Larew.  I gave a copy to a competitor.  With some of the best info in his hands, he misread it and came to mostly wrong conclusions. The same is present here in this thread.

Ohh, Randy, I sent you an email regarding the carb from the Original Poster.... it is super cool, check it out and save the photos for your records.

Drew

I can.... but shipping a carb to me for 5 minutes of work is expensive.

Enlarge IAB to .070, reduce ifr to .031
If cam over 245@.050 .067/.033 works better.

Be sure the burning eyes is not a lean misfire, lots of folks head the wrong direction.

Quote from: shelbydoug on March 06, 2021, 03:38:52 PM
What's great about Holleys is that there is such a variety and you can keep trying different combo until you find the right one. What you like someone else may not.

Mind you, I am coming from a vastly different place compared to most.
I find the "wheel of carbs" to be annoying.  There is a specific reason one works better than another.
I would rather change bleeds and make the fuel curve appropriate for my usage.  The 650 double pumper mentioned, it seems like the right choice.  Only negative is the majority of them have a tiny PVCR and oversized jets as they were meant for racing.  For street car usage you will juggle between having a fat cruise and being underfueled at wide open throttle.  The only solution is to drill PVCR's and jetting down, of course this brings us back to just make the carb work for your setup in which case who cares what you started with?
The only benefit of swapping to another carb would be that it being a generic vs a valuable original, you could molest it sufficiently to work perfectly in all conditions.

I simply like the 715cfm as the venturi to throttle bore size is very favorable in regard to optimal tube.  (optimal tube being 30 degree inlet, 7 degree outlet, vena contracta being a specified fraction of the outlet).
All of this said, there is a very specific reason that Ford used the 1 5/16, 1 3/8 venturi, 1 11/16 bore combo on so many carbs.
C3-B, CU/CV, BC/BD, 3259, etc.  It simply works very well.  Not big enough?  run two of them.

Bob's 715 probably would have run like poop as delivered to me.
Idle feed is massive, carb was hand made into a double pumper, the details of such are very fascinating to be honest.  Someone tossed a newly minted baseplate on it, which aside from hanging the throttle open, it defeated the purpose of the original modifications.
I'll put it back to stock specs and it should run just fine as is.

of course I could be wrong..... 

You should try the 715 when I'm done before making any other decisions.

Zinc survives 12 hours in a salt spray cell.
Yellow chromated zinc survives 250 hours.
Clear chromate survives 175.

Zinc plate, yellow chromate, use a sodium carbonate leach back for clear look. 250hours.
Or just dip a bolt in acid and lose 95% of it's protective coating.