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Re: Carb question [Re: JD1] #1321988 Thu Aug 15 2019 06:53 PM
Joined: Apr 2019
Posts: 121
J
JD1 Offline OP
Shop Shark
If I could get a consistent and better running carburetor I would have no issue running an electric choke.


1951 Chevy 3100 1/2 ton (1957 235, 4 speed, 411 rear)
Re: Carb question [Re: WE b OLD] #1321989 Thu Aug 15 2019 06:54 PM
Joined: Apr 2019
Posts: 121
J
JD1 Offline OP
Shop Shark
Originally Posted by WE b OLD
Langdon's is a good choice. Here.url=https://www.shop.cliffordperformance.net/68-Chevy-235-261-Combination-68C235.htm]Another choice but expensive.[/url].

The Langdon site references running a heated intake manifold.
Is the stock intake heated?


1951 Chevy 3100 1/2 ton (1957 235, 4 speed, 411 rear)
Re: Carb question [Re: JD1] #1322004 Thu Aug 15 2019 09:25 PM
Joined: Mar 2014
Posts: 1,064
J
Jon G Offline
Shop Shark
Yes, the stock manifold is heated by the exhaust manifold and heat is regulated by the flap and bi-metal spring. You should make certain yours is working correctly. The bi-metal spring for the 235 is rather expensive, but seems I saw where somebody was using one made for a Jeep which was much less costly and worked the same.

The Carter (at least in my experience) is more smooth running and consistent than the Rochester. A large part of the problem with any Rochester B or BC carburetor is the power circuit. There's a power piston in there which is controlled by manifold vacuum which passes up from the throttle body and from there through the float bowl and from there to the air horn where it sucks the power piston up off the valve ball. If this doesn't happen (which is common due to either a loss of vacuum from a warped carburetor casting or simply a stuck piston from ethanol-laced fuel), the carburetor will run as rich as it possibly can all the time you're driving. In this condition, your gas mileage will probably be in the single digits. The whole scheme with that circuit is that when the engine loses vacuum (in the case of greater demands on the engine from hills, acceleration, etc) the power piston will be forced down by the spring which controls it. Then when this happens, the power valve will open up and flood the mast with more fuel...a lot more. There's a restrictor in there, but it doesn't really restrict much. The carb will still run as rich as Croesus. In the days when the carburetors were new and we had real gasoline, these carburetors worked better. But today problems are not easy to avoid and the Rochester design was never heralded as a stroke of genius. If you see one leaking at the float bowl to air horn gasket, the casting is warped and/or somebody forgot to put a gasket between them. Last summer I spent a lot of time and effort showing what this warpage was and how it can be corrected rather simply with a piece of 3/8 inch thick steel, common bolts and nuts, a dial gauge, some patience and common sense and a gas grill. All that work is posted on this site. But I'm told by learned men that even if you correct it, the same situation will return in a few years.

The Carter design doesn't have this power circuit...it compensates for extra power needs in other and saner, more logical ways. I've never been a fan of trying to adapt 2 barrels or 4 barrels to a 235. Even though I've always liked the 235 a lot, it is a dandied up tractor engine and over-carbureting it isn't necessary or even wise in most cases.


Jon

1952 1/2 ton with 1959 235
T5 with 3.07 rear end
Re: Carb question [Re: JD1] #1322005 Thu Aug 15 2019 09:25 PM
Joined: Dec 2008
Posts: 1,306
P
panic Offline
Shop Shark
W/r/t "the float bowl (which carries the identifying marking of the YF model) can be swapped with throttle bodies and air horns of any model YF handy. This creates a mongrel carburetor which will never ever work as it was designed"

I agree.
Not speaking directly of that vendor (don't know them) but this problem exists throughout the industry. Many unsuitable variants can be made from interchangeable parts, whether innocently ("they came in the same box, so they must be from the same and correct carburetor") or deviously ("It's all I have left, and it's not going to anyone I know").

I write about the Linkert Model M (side-draft 1 bbl. for Harley-Davidson and Indian motorcycles) and some weird mix-n-match bodges have caused much grief over the years because of this.

Re: Carb question [Re: JD1] #1322123 Fri Aug 16 2019 10:56 PM
Joined: Mar 2017
Posts: 174
L
LeeD Offline
Shop Shark
I recently replaced my Rochester with a Carter 2100S from The Carburetor Shop and I have been mostly happy with it. It did not come with the choke cable bracket, but I was able to make just a slight modification to the bracket off the Rochester so that I could use it for the choke cable (and I can still use it on the Rochester if necessary). Unfortunately, the throttle cable part of the bracket does not line up correctly, so until I make a substitute, I have no throttle control. I drove it for a year without it before, so I am not in a hurry to adapt one. The problem I was having with the Rochester (leaking at the top gasket and some difficulty starting when hot) have gone away and the engine seems to run much smoother at cruise speeds. I have not driven it enough yet to check the mileage, so I cannot comment on the improvement that others have seen.

Lee


1956 Chevy 3200
Re: Carb question [Re: JD1] #1322126 Fri Aug 16 2019 11:02 PM
Joined: Mar 2017
Posts: 174
L
LeeD Offline
Shop Shark
I just re read your initial post and saw the question about ethanol; my understanding is that though you may still have some issues with gumming if you do not drive it frequently, any new seals and gaskets used in a new kit should be okay with the use of ethanol. At least the low percentage stuff anyway. That being said, if I could find ethanol free gas, I would use it.
Lee


1956 Chevy 3200
Re: Carb question [Re: JD1] #1323599 Mon Aug 26 2019 05:52 PM
Joined: Apr 2019
Posts: 121
J
JD1 Offline OP
Shop Shark
Thanks guys.
I ended up going with a 32/36 carb, spacer, gas filter from Langdon's site. I called the site and Tom answered the questions I had. He is a nice gentleman to talk to.

I do have a question for guys who are running the 32/36.

Did you cut up the hard gas and vacuum line for this new carb or do you just run hose from the fuel pump and distributor?
Having a combination of hard line and hose doesn't look as nice as the stock steel line, but I wanted to know what everyone has done.

Thanks,
JD


1951 Chevy 3100 1/2 ton (1957 235, 4 speed, 411 rear)
Re: Carb question [Re: JD1] #1323715 Tue Aug 27 2019 03:24 PM
Joined: Sep 2012
Posts: 51
D
Dcurtis Offline
Wrench Fetcher
Nearly $10.00 a gallon for non ethanol gas ? Are you sure your looking for the right gas ? 100 or 110 octane race gas or avgas is probably around that price. but non ethanol gas isn’t really anything special and is usually readily available if you look. there is also a website or app to help locate ethanol free gas in your area. Ethanol free gas is usually marketed as recreation gas or marine gas. And is usually around $1.00 more per gallon than the 10% ethanol gas.


Dan
Re: Carb question [Re: JD1] #1323738 Tue Aug 27 2019 04:59 PM
Joined: Nov 2002
Posts: 1,882
C
carbking Offline
Carburetion specialist
Generally, $10. gasoline is either racing fuel or aviation fuel. NEITHER should be used in your engine. Much better to run 10 percent ethanol than either of the other two.

I have no clue about the 32/36, but as Joe H. mentioned in an above post; the Carter W-1 will function well on the 10 percent, or even 15 percent.

Jon.


Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify
If you truly believe "one size fits all" try walking a mile in your spouse's shoes!
[image]http://www.thecarburetorshop.com/Avatar.jpg[/image]
Re: Carb question [Re: JD1] #1325792 Wed Sep 11 2019 07:11 PM
Joined: Apr 2019
Posts: 121
J
JD1 Offline OP
Shop Shark
RE: the $10 comments about gasoline above.

This is a great site for finding non-ethanol gas: https://www.pure-gas.org/

In my area there is only one local supplier of non-ethanol gasoline within 90 minutes. They are expensive but they are the only option. Yes, what I use is called "racing gasoline".
However, there are many different types of racing gasolines.

Here is what I currently use: https://www.sunocoracefuels.com/fuel/optima
Optima is referred to as a racing gasoline, but it isn't the same formulation as true "racing fuel".

I would rather use this gas than any of the 10% ethanol fuels that are available locally. Ethanol gas is a horrible fuel for engines and fuel systems that weren't designed for it.




1951 Chevy 3100 1/2 ton (1957 235, 4 speed, 411 rear)
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