Overkill????


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By lovefordgalaxie - 15 Years Ago
After a while, I'm back to the forum.
My 292's rebuild was a success, and the engine is running like a champ.
I'm using a Autolite 2100 (1.08) carb now, and the engine kind of asks for more "go power" at high revs.
During the rebuild, I instaled a Iskenderian cam (ref 301444) of 260X260. The cubic capacity is about 300 ci, due a 0.060 over piston swap (Clevite)
I just bought a brand new 1.23 Autolite 2100 carb, and I'm planning to install it.
The question is: May it be too big?
Another thing: Even the carb being new, it was missing the secondary ventury assembly, wich I replaced with a NOS part out a NOS 1.08 Autolite 2100.
What do you think guys? Will it work, or is it a overkill?

Here is a video of the engine working:

http://www.youtube.com/watch?v=b2Eisiqb2Z0

Thanks for any help!!
By crenwelge - 15 Years Ago
The 2100 is a very good carburetor, but unless you are looking at top end performance, it may have a flat spot at lower rpm. Carbs need velocity to suck fuel out of the fuel bowl. A larger carb will decrease the velocity and result in a lean mixture at lower rpm.
By lovefordgalaxie - 15 Years Ago
Thanks a lot Kenneth.



I did instal the carb to see what would happen. There were a slight hesitation when I pumped the gas, and I had to run the mixture screws all open. The top end performance increased, but not enough to compensate living with the hesitation. City driving became a real pain. This night I installed my "old" 2100 back, and for real, is not that different.
By 46yblock - 15 Years Ago
lovefordgalaxie (8/16/2010)
After a while, I'm back to the forum.
My 292's rebuild was a success, and the engine is running like a champ.
I'm using a Autolite 2100 (1.08) carb now, and the engine kind of asks for more "go power" at high revs.
During the rebuild, I instaled a Iskenderian cam (ref 301444) of 260X260. The cubic capacity is about 300 ci, due a 0.060 over piston swap (Clevite)
I just bought a brand new 1.23 Autolite 2100 carb, and I'm planning to install it.
The question is: May it be too big?
Another thing: Even the carb being new, it was missing the secondary ventury assembly, wich I replaced with a NOS part out a NOS 1.08 Autolite 2100.
What do you think guys? Will it work, or is it a overkill?

Here is a video of the engine working:

http://www.youtube.com/watch?v=b2Eisiqb2Z0

Thanks for any help!!

Congrats on your new engine.  The 1.08 is a very good carb for 292's.  I have one in my .060 over now.  About the biggest you can go in the 2100 series is 1.14.  They give a little more power, at the expense of a little less mileage.  Jet size would need to go to 51-53 in the 1.14, compared to 47-48 in the 1.08.  A 1.23 is most likely not going to work well.  Think they were used in 428's.  Transition will be a problem, bad mileage, bad deal.  Swapping around different venturis almost never works either.  I have the rebuilt 1.14 which was going on to ebay fairly soon if you are interested.  Also have 1.21s, but they are too big for the 292 also, being used on 351 Cleveland and other engines.  The 1.08 and 1.14 were found on 302 and 352 powered vehicles.  Both are more adaptable to use in nonoriginal applications than the smaller or larger models.

By lovefordgalaxie - 15 Years Ago
Yes Mike, What you said, was just what happened. I had a 1.08 on the Galaxie, and reinstalled it after some testing with the 1.23.

I also have a NOS 1.08, never used, that I'm saving for "spare" for my Galaxies, since both use this carb (302 and 292).

The 1.23 I got as part of a parts lot I bought. The carb was missing the secondary ventury, but otherwise complete. I got interested to see if it would imimprovehe 292, but it was really a bad momoveMy NOS 1.08 is actually a Motorcraft, so I think the correct would be Motorcraft 2150, but it's basically the same as my Autolite 2100 1.08. The sensecondaryntury from the Motorcraft fit the Autolite like a glove, but it didn't stay there for long.

I believe I'm gonna end selling the 1.23 (missing the sec ventury), or maybe trading it into something.
By yalincoln - 15 Years Ago
just a thought, i allways used 350 cfm holley 2bbl's on all my ford pickups with 360's. they ran better and got better mileage with no hesitation.
By lovefordgalaxie - 15 Years Ago
Just remembered a detail. When my engine was being rebuil, I sent the carb to a friend who said would increase the flow capacity. He told me the carb would flow 400 CFM after the job. It's a 1.08 Autolite.

Well, when I instaled the Autolite 1.23, the car didn't like it. I saw an article on Autolite carbs, that informed that the 1.23 flows 356 CFM.

I believe there's somethink that don't smells quite right. How can a car run with a 400 CFM perfect, and a 356 be too much?

Or my "friend" did a nice job doind nothing to my carb, and doing something with my pocket, or the 356 CFM rating is nor right for a 1.23.

Does anybody knows a formula to calculate the carb CFM?



About the Holley, I like the Autolite/Motorcraft better, but that's personal taste, the Holley is a very good carb. I never coul stand Edelbrock carbs. Every single one I saw had some sort of problem. Maybe they are sensitive to the Brazilian gasoline, that has 25% of alcohol.
By charliemccraney - 15 Years Ago
The overall design of the carb has more to do with how well it works than the cfm rating alone. It is possible that a 750 will out perform a 390 throughout the entire rpm range if the design of it is better suited to the particular combination. The 1.23 as a whole simply may not be a good match.
By 46yblock - 15 Years Ago
Getting 400 cfm from a 1.08 needs to be documented, meaning it is very questionable.  I removed all the choke from mine, including plate and shaft.  Was just curious about there being some gain in the flow.  Cant tell any difference.  It still works well, with a little decrease in responsivenss at highway speeds, compared to the 1.14.  I'm going to change to a 4V sometime soon.  Kind of reluctant to do so since the spark plugs are showing so perfect currently, plus the good mpg is nice.
By lovefordgalaxie - 15 Years Ago
I agree with Charlie. The CFM itself is not a good measure of the carb, but, like Kenneth said, the speed of the air is very important. With a two barrel carb, you can only increase CFM by increasing speed, or volume. With the larger venturys of the 1.23, the flow got higher, but the speed decreassed. This fact turned the 1.23 too much for my engine, from what I could understand. Since both, the 1.08, and the 1.23 are twoo barrel carbs, and the engine is the same, logic says my "improoved" carb don't have 400 CFM, and the guy only ate my money.

I took the carb from the engine, and did what I should have done long ago, and compared it with my NOS 1.08, and the result was the expected. The venturys are the same diameter, and my old carb was only rebuilt, not modified. I suspected that my "friend" didn't have the expertise to actually modify a carb to the point of improoving CFM, recalibrate jets, etc, without at least a machine to measure the flow. The improoved performance of the engine came from the cam, bigger pistons, more compression, etc, things that were actually done, by me, and Maycon, a real friend, that warned me about the carburetor guy.

The car needs more go power, and since the 1.23 is too much, and a four barrel intake manifold is near impossible to find for an Y around here, I'm looking for a decent 1.14.