replacing carb - Right CFM?
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From: Cary NC USA
replacing carb - Right CFM?
I also posted this in carburetor section.
I have a '69 F-100 with 360.
After difficulty with remanufactured Motorcraft carb I am thinking about buying a new one. Edelbrock sounds like a dependable choice but Holley's are readily available.
?? Size in cfm - the stock 2bbl 2100-123 is rated at 356 cfm. The Holley comes in 500cfm and I was told 600cfm but parts store said not in 2bbl.
Someone told me that each step bigger carb would burn more fuel. That doesn't make sense to me because the engine should only need a certain amount of fuel/air mix regardless of what the carb is able to deliver.
?Should I just look for a replacement 350 cfm or go bigger??
Thanks,
Richard
I have a '69 F-100 with 360.
After difficulty with remanufactured Motorcraft carb I am thinking about buying a new one. Edelbrock sounds like a dependable choice but Holley's are readily available.
?? Size in cfm - the stock 2bbl 2100-123 is rated at 356 cfm. The Holley comes in 500cfm and I was told 600cfm but parts store said not in 2bbl.
Someone told me that each step bigger carb would burn more fuel. That doesn't make sense to me because the engine should only need a certain amount of fuel/air mix regardless of what the carb is able to deliver.
?Should I just look for a replacement 350 cfm or go bigger??
Thanks,
Richard
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Joined: May 2002
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From: nc
replacing carb - Right CFM?
holley makes a 350 cfm 2v and a 500 2v both would work in place of your motorcraft 2v. a 4v conversion will include the intake manifold with will drive up the cost. i would suggest the 350 cfm holley. they can be found at most large chain and mail order houses. first i would exhaust my options on the factory carb, they are fairly bullet proof, and are very easy to work.
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From: Cary NC USA
replacing carb - Right CFM?
Thanks teschwab,
The 2100 on this truck was running ok but the accelerator hung up. Previous owner told me it was a scored shaft so I relaced it with a remanufactured twice, first one had a broken bolt and clips missing. Second makes the engine backfire and hesitate only upon acceleration. If ease into throttle it is ok. Previous owner also had timing retarded. The hesitation is worst at correct timing even after accelerator pump rod adjustments and I know I am getting a good squirt in both barrels.
After replacing the carburetor that came on the truck, it appears that possibly an unsecured kickdown lever was binding the accelerator not a shaft problem.
I can't get the remanufactured carb to idle below 800 rpm's even with every thing idle speed screw and choke screw backed out. I am trying to check for vacuum leaks and will even retry the carb that I took off.
Thanks for your input, if I buy new I will probably go for a 500cfm because I was told the rings were replaced and maybe it was bored out. I want to be safe and not replace it again.
Thanks,
Richard
The 2100 on this truck was running ok but the accelerator hung up. Previous owner told me it was a scored shaft so I relaced it with a remanufactured twice, first one had a broken bolt and clips missing. Second makes the engine backfire and hesitate only upon acceleration. If ease into throttle it is ok. Previous owner also had timing retarded. The hesitation is worst at correct timing even after accelerator pump rod adjustments and I know I am getting a good squirt in both barrels.
After replacing the carburetor that came on the truck, it appears that possibly an unsecured kickdown lever was binding the accelerator not a shaft problem.
I can't get the remanufactured carb to idle below 800 rpm's even with every thing idle speed screw and choke screw backed out. I am trying to check for vacuum leaks and will even retry the carb that I took off.
Thanks for your input, if I buy new I will probably go for a 500cfm because I was told the rings were replaced and maybe it was bored out. I want to be safe and not replace it again.
Thanks,
Richard
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From: nc
replacing carb - Right CFM?
ratwell, i would back the idle mixture screws all the way out and inspect for damage.if they are in good condition run them in until lightly seated and then back them out 11/2 turns. i like to make my final mixture and idle setting with the engine in gear and the parking brake set. you can use a non-conbustible spray fluid and with the engine running spray around the carb base and the intake mating surface if the idle changes theres your leak. ratwell if this is an automatic truck make sure you specify a holley with a kick down or the part# for the kit to add the kick down. my opinion is the 500 cfm will work fine, but you may see a slight increase in fuel consumption over the 350 cfm.
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From: Cary NC USA
replacing carb - Right CFM?
Thanks,
I got a spacer to manifold gasket at lunch and will put my "old" carburetor on this evening.
I don't feel real good about dismantling the remanufactured carb.
I will play with mine before ordering.
?? Big question? I see the 350 and 500 cfm holleys advertised as off-road. My truck '69 does not have to go through emissions test. Should I buy that or street legal??
Richard
I got a spacer to manifold gasket at lunch and will put my "old" carburetor on this evening.
I don't feel real good about dismantling the remanufactured carb.
I will play with mine before ordering.
?? Big question? I see the 350 and 500 cfm holleys advertised as off-road. My truck '69 does not have to go through emissions test. Should I buy that or street legal??
Richard
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From: Cary NC USA
replacing carb - Right CFM?
teschwab-
I might try the 350cfm because fuel economy is a good thing on my pocketbook. I just don't want to be undercarbed and deal with the hesitation and backfiring.
Richard
I might try the 350cfm because fuel economy is a good thing on my pocketbook. I just don't want to be undercarbed and deal with the hesitation and backfiring.
Richard
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From: nc
replacing carb - Right CFM?
ratwell you won't be under carbed with 350 cfm nor will you be over carbed with the 500 cfm. here in nc we have to pass a visual inspection which i believe includes the correct air cleaner with heat stove and a pcv system. if your emmissions decal is still in place check to see if it states the carb requirement. i think it will mention a 2v carb. so the holley should not cause a problem since it will be a 2v too.
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From: Texas Hill Country
replacing carb - Right CFM?
[updated:LAST EDITED ON 11-Nov-02 AT 10:12 AM (EST)]Question... I've been told over and over that replacing the 2bbls with a 600cfm 4bbl will increase my 352's gas mileage, not decrease it... Yes? No?
Next question... Will the 500cfm Holley bolt onto the stock 352 manifold?
Thanks!
GolferSA
67 Ford F100 Custom Cab
352V8 C6 Auto Factory Air
https://www.ford-trucks.com/user_gallery/displaythumbnail.php?&photoid=5688&.jpg
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Next question... Will the 500cfm Holley bolt onto the stock 352 manifold?
Thanks!
GolferSA
67 Ford F100 Custom Cab
352V8 C6 Auto Factory Air
https://www.ford-trucks.com/user_gallery/displaythumbnail.php?&photoid=5688&.jpg
golfersa@netscape.net
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Thread Starter
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Joined: Sep 2002
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From: Cary NC USA
replacing carb - Right CFM?
GolferSA,
I don't know about what will bolt on which engine. Just thought I would pass on info that I have read. All indications are that putting on a 4 barrel carb without replacing the manifold will not gain much benefit. I checked the www and an edlebrock 4 bbl intake manifold for a 360 was about $250. I read that junk yard intakes were available for $35 to $50.
I also READ that 4bbl was more fuel efficient if you kept your foot out of the #3 and 4 secondaries.
There has been much discussion about loss of efficiency if you go too big with the CFM because of total airflow and fuel atomization.
Holley tech reps told me that with STREET driving with my 360 FE that if replacing the original 2bbl 356 CFM Autolite with another 2bbl- their 350CFM would be sufficient and more fuel efficient than their 500 CFM 2bbl. There were calculations of volumetric efficiency and the capability of turning 8,000 rpms aith a 500 or 600 cfm. Not me.
Of course there are a lot of people who guffawed at putting on a 350 CFM replacement.
Just information as I have heard it.
Richard
I don't know about what will bolt on which engine. Just thought I would pass on info that I have read. All indications are that putting on a 4 barrel carb without replacing the manifold will not gain much benefit. I checked the www and an edlebrock 4 bbl intake manifold for a 360 was about $250. I read that junk yard intakes were available for $35 to $50.
I also READ that 4bbl was more fuel efficient if you kept your foot out of the #3 and 4 secondaries.
There has been much discussion about loss of efficiency if you go too big with the CFM because of total airflow and fuel atomization.
Holley tech reps told me that with STREET driving with my 360 FE that if replacing the original 2bbl 356 CFM Autolite with another 2bbl- their 350CFM would be sufficient and more fuel efficient than their 500 CFM 2bbl. There were calculations of volumetric efficiency and the capability of turning 8,000 rpms aith a 500 or 600 cfm. Not me.
Of course there are a lot of people who guffawed at putting on a 350 CFM replacement.
Just information as I have heard it.
Richard
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From: nc
replacing carb - Right CFM?
hey ratwell some folks think that a 4v is the answer to most 2v problems. i don't always subscribe to that logic. the holley 350 cfm carb will work really well without the extra cost for the intake. one upgrade that i would consider, would be to go the electric choke route.
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From: Cary NC USA
replacing carb - Right CFM?
I agree tescwhwab-
I cleaned up the 2bbl 2100 Motorcraft, fixed a few problems with it, adjusted tuning specs as mentioned earlier, and will run it on the street for a while. If I start drag racing in my old age I might do something diferent.
Richard
I cleaned up the 2bbl 2100 Motorcraft, fixed a few problems with it, adjusted tuning specs as mentioned earlier, and will run it on the street for a while. If I start drag racing in my old age I might do something diferent.
Richard
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replacing carb - Right CFM?
I have a F100 and F350 that both have the 2100 on. With the 72 with a 390 I get between 13 and 14 mpg. The F350 has a 360 and gets about 8 mpg, but for that size truck it is pretty quick. It will run 70 mph in the quarter and I haven't had time to do a good tuneup since getting it. The 2100 carbs are easy to work on and not too much can go wrong with them. If you continue to have problems with yours go to a salvage yard and buy one. The only thing to check is that the shaft does not have any side to side play in it.