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Re: Trying Daytona Universal Carburetor UN2
ClassicsR4Me #1341344 Fri Jan 10 2020 02:19 PM
Joined: Mar 2002
Posts: 8,950
Master Gabster
I understand from the writeup that it has an adjustable main metering jet. That could make a big difference I think.


1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed


My Chevy Master 4 Door is on the Road!
Re: Trying Daytona Universal Carburetor UN2
panic #1341345 Fri Jan 10 2020 02:20 PM
Joined: Nov 2002
Posts: 1,982
C
Carburetion specialist
Originally Posted by panic
I don't think quality control is the problem, it's the idea that a few variants can be as close to the original mixture requirements as the many, many OEM carburetors. L6 engines of the same size will not require the same carb except by accident.
They may have developed the throttle disc size, venturi, jetting, vacuum setting, pump discharge, idle and transition hole sizes and locations, etc. on a specific engine, and will give good results... on that engine.
As your engine begins to differ from their model (displacement, CR, port size, cam timing, spark advance curve, valve area, overlap, rod ratio) the results will be worse - but perhaps tolerable.
Now, the 235 is an excellent model for this due to long use with very similar tune-up specs, so we certainly would like to hear results.
TIA



Totally agree.

Additionally, I have been unable to find any specifications of the items mentioned above by Panic. But my real issue is: where does one get parts????? One bad tank of fuel, the carb idle circuit is plugged, and the carb needs to come apart for cleaning.

If you need any verification of the parts issue, just find someone with a mid-1980's or 1990's I.H.C. tractor which was imported and renamed. We finally got enough requests to tool up rebuilding kits for some of them. This (I.H.C.) is a MAJOR brand, and information was available, just no parts.

I realize many today live in a throw-away world, but I don't!

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: Trying Daytona Universal Carburetor UN2
carbking #1341376 Fri Jan 10 2020 04:19 PM
Joined: Feb 2016
Posts: 197
C
Gabriel Sandoval
They say they stock all components replacement parts, which is another plus. Heres what Mr. Hewitt wrote regarding adaptability : "Since the carburetor manufacturers could not continue to make each factory specific carburetor model, they would make a Universal to retro-fit original applications and unlike factory carburetors with fixed jetting and fixed throttle throw, the Universal models allow the full adjustment of the throttle lever to suit different hookup's; slotted base bolts to fit the small base US standard 1bbl (2 11/16") and also the larger flange (2 15/16"). The Universal carburetors also used a external adjustable high speed main jet to allow the fine tuning of the high speed circuit so you can match up the main jet orifice size to suit your particular engine, without tearing the carb apart and guessing at a correct jet size. This is a simple process based on the manifold vacuum your cylinders produce with the throttle open and the engine running at speed (2000-2500 rpm). Same principal as adjusting a idle circuit, except on the high speed side"

Last edited by ClassicsR4Me; Fri Jan 10 2020 04:20 PM.
Re: Trying Daytona Universal Carburetor UN2
ClassicsR4Me #1341379 Fri Jan 10 2020 04:42 PM
Joined: Feb 2004
Posts: 19,910
H
Boltergeist
Most carburetor manufacturers like Carter, Rochester, Stromberg, Zenith, etc. stopped using adjustable main jets back in the late 1930's or early 40's. Think of all the research and development money they could have saved by simply continuing to use technology that existed back when engines had 6:1 compression ratios, Babbit bearings on the crankshaft, and needed to be rebuilt every 30,000 miles! How does the power enrichment system get adjusted for such things as automatic or standard transmissions, different rear axle ratios, and other variables that aren't directly affected by either idle or main jet adjustments? The "one size fits none" approach has been tried repeatedly, and failed every time. Maybe this time it will be different. I suppose some people will be willing to accept mediocre performance from a universal carburetor because they don't know any better. Growing up eating 30% fat content hamburger is OK as long as somebody never gets served a prime quality steak, also.

I wonder if the average purchaser of one of these carburetors will have a 4-gas exhaust analyzer and a chassis dynamometer to help get those adjustments done correctly?
Jerry



The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: Trying Daytona Universal Carburetor UN2
ClassicsR4Me #1341389 Fri Jan 10 2020 04:57 PM
Joined: Nov 2002
Posts: 1,982
C
Carburetion specialist
Gabriel - that is an interesting answer, that really doesn't tell us much, other than you can order parts from Daytona at this time; how about elsewhere.

I have no issue with adjustable main jets, and consider them a bonus; however, they are NOT the major criteria in selecting a replacement carburetor. Internal size IS the major criteria, which is one of the issues to which Panic was referring in his post. One really great application of the adjustable main metering jet is the ability to temporarily retune an engine on a trip. As an example, if I were to leave Missouri (elevation where I live approximately 800 feet) and make a trip to Denver (elevation about 5500 feet).

When a customer asks us for a replacement carburetor; we have a list of questions.

(1) flange size (Daytona covers this)
(2) engine displacement and engine modification. These are critical in selecting the proper carburetor, as they give us information to determine internal venturi size, which is what determines the airflow characteristics of the carburetor. If it is determined that a specific engine requires a 24 mm venturi, and one installs a carburetor with a 27 mm venturi; one can adjust the adjustable main jet from all the way in to taking it out and putting in one's pocket, and the engine will always be sluggish at lower RPM. Conversely, if the engine requires a 27 mm venturi, and a carburetor is selected with a 24 mm venturi, then the engine is going to be sluggish at higher RPM, and in effect, the venturi will be a rev limiter.
(3) once the proper venturi is selected, then the adjustable main metering jet is useful to "tweak" the mixture for the volumetric efficiency of the given engine; but it will NOT compensate for using the wrong size venturi. Generally speaking, our customers never need to adjust the adjustable jet (if the carb we sell has one) more than plus/minus 1/4 turn (generally less) from the standard setting. And other tuning components are useful as well. As an example, Carter offers at least 5 different vacuum springs to help tweak the mixture for different engine vacuum profiles. This is not possible with a carburetor with an adjustable main jet UNLESS the adjustment is connected to a dial on the dash and may be adjusted "on the fly" by the driver.
(4) next question is cost versus performance. Not everyone wants to pay for good performance and reliability (one reason the Rochester B's are still somewhat popular). The Daytona carburetor certainly fits the "less expensive" criteria.
(5) we also ask about the terrain traveled by the customer, as there are some less expensive carburetors that may be used successfully if one drives in an area that is virtually flat.

But the key for you is that if you are totally happy with your purchase 5 years from now, then that becomes the ultimate criteria.

Jon.

Last edited by carbking; Fri Jan 10 2020 05:05 PM. Reason: Typo

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: Trying Daytona Universal Carburetor UN2
carbking #1341391 Fri Jan 10 2020 05:15 PM
Joined: Feb 2016
Posts: 197
C
Gabriel Sandoval
You know allot more about carbs than I do Jon. I appreciate the information. I just thought id try it out and see how it worked. Im sure it wont be the best, but if it gives me decent performance then ill be happy. If it doesn't, then ill go back to my Rochester carb. Its just that nobody has tried it out and seen what it can do, so I thought id do that. Ill be working on it some more today, hopefully I can get it hooked up soon. It will take me a while of driving to see its response and fuel consumption. Another reason im trying it is my Rochester was starting to give me problems. It was leaking down fuel. I saw the intake manifold was wet with fuel and the carb bowl was low. So I would have to have addressed that sooner or later. Do you know what usually causes that problem?

Re: Trying Daytona Universal Carburetor UN2
ClassicsR4Me #1341402 Fri Jan 10 2020 05:51 PM
Joined: Nov 2002
Posts: 1,982
C
Carburetion specialist
Gabriel - much as I enjoy throwing rocks at the Rochester B's ( wink ); the carburetor probably is not the issue here. Rather it is the volatility of modern fuel. The Rochester B can leak down, but only if you park the truck on its roof (upside down wink ) Leaking down is a function of Holley carburetors, with the diaphragm type power valves, and a gravity passage direct to the intake.

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: Trying Daytona Universal Carburetor UN2
ClassicsR4Me #1341417 Fri Jan 10 2020 06:43 PM
Joined: Nov 2002
Posts: 1,982
C
Carburetion specialist
Gabriel - see my new thread.

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: Trying Daytona Universal Carburetor UN2
ClassicsR4Me #1341569 Sat Jan 11 2020 03:22 PM
Joined: Jun 2008
Posts: 1,313
S
Shop Shark
Gabriel, I’ve enjoyed reading this thread. I appreciate you biting the bullet and buying this new Daytona carb so we can all learn from your experience. I’m really looking forward to reading about how it performs. Please post frequently.


Chuck
1950 Chevy 1/2 ton (original)
1951 Chevy 1/2 ton (future streetrod)
1941 Chevy coupe
1938 Chevy coupe streetrod
Re: Trying Daytona Universal Carburetor UN2
Spotbiltxo #1341606 Sat Jan 11 2020 09:39 PM
Joined: Feb 2016
Posts: 197
C
Gabriel Sandoval
Thanks Chuck, I appreciate it.
Here's the latest update. I installed the Carburetor with a temporary setup. I tried to put the old school glass bowl filter as I had it before, but was not able to find the correct fittings so I went without it for the moment. I installed the fuel filter that comes with the carb right after the fuel pump. Prior to connecting the fuel line I ran the fuel pump for about ten seconds until I could see clean fuel coming out as the instructions say. This seems to be an important step as the main reason for initial failure is that the carb gets debris inside and floods the carb. The engine started right up, idles perfectly, (as my Rochester did). Only downside I see so far is that I wont be able to use my original heavy duty air cleaner, as the mount is quite a bit smaller. The regular auto air cleaner (non heavy duty) fits right on there. I just happen to have an extra and will run that one in the meantime. Response feels nice and crisp when I touch the pedal. Now to wait for some sunny weather so I can feel if it has the same power, and see how it is on fuel consumption. I don't think ill have to worry about leaking the fuel out of the carb while it sits like my Rochester was doing.

Attached Files
Daytona 6.jpg (123.75 KB, 235 downloads)
Daytona 7.jpg (105.25 KB, 237 downloads)
Daytona 9.jpg (103.45 KB, 233 downloads)
Daytona 9.1.jpg (87.74 KB, 237 downloads)
Daytona 9.2.jpg (106.64 KB, 230 downloads)
Last edited by ClassicsR4Me; Sun Jan 12 2020 06:34 AM.
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