2 deuces vers 0ne 4 barrel

Re the "165-185 cfm" I'm pretty sure I read a while back that these cfm numbers along with the often quoted 97 carb cfm, were flowed at 1.5" mercury like four bbls are, not the normal 3" mercury that two bbls are normally test flowed. Can anyone confirm this? Need someone with a flow bench and spare minute or two.
Martin.
 
scooder said:
Re the "165-185 cfm" I'm pretty sure I read a while back that these cfm numbers along with the often quoted 97 carb cfm, were flowed at 1.5" mercury like four bbls are, not the normal 3" mercury that two bbls are normally test flowed. Can anyone confirm this? Need someone with a flow bench and spare minute or two.
Martin.
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Martin,

I didn't realize they put the small throttle body with the 1 1/16" bowls in '55 either. The ones I've seen were like that. I have an old Holley manual with specs, but it doesn't list the throttle bore sizes. Just the venturi sizes.

I worked at the original Zenith Carburetor Co. in Detroit from '72 to '84 before they moved to Abingdon, VA in late '84 (to kill the union and reduce taxes etc.) since they were struggling to stay alive. They are still alive today. I worked in the engineering lab doing flow box work and engine dyno carb calibrations for new applications. I worked with some x-Holley carb people also and can confirm that Holley flows the 4 barrels at 2.0" Hg (28" H20) and the 2 barrel carbs at 3.0" Hg. Zenith flowed everything at 2.0" Hg.
With Holley flowing the 2 barrel carbs at 3.0" Hg makes it confusing. For example they have a 2 bbl. rated at 500 CFM, but if flowed with the same conditions as a 4 bbl., it would flow more like 375 CFM. It has the same venturi and throttle size as a 750 CFM 4 bbl, yet they rate it at 500 CFM ?

They make it confusing as heck. For example if you want a 500 CFM 2 bbl. for you're hot rod instead of a small 4 bbl carb, you are actually getting a lot less CFM capacity.

Sorry, but I do not have a flow bench to help you out, and don't know anyone at Zenith anymore. I do know they still use the original antique flow boxes from Detroit from at least the 1940's.

Sal
 
I could be mistaken. Holley may have flowed the 4 barrel carbs at 1.5" and not 2.0"Hg like I stated earlier. I love old age and foggy memories.

Sal
 
ok i think it will be a single 4bar how about a autolight 4100 i think a 108 is about 450 cfm and an old ford carb??? well it might be net looking??
 
4ford said:
ok i think it will be a single 4bar how about a autolight 4100 i think a 108 is about 450 cfm and an old ford carb??? well it might be net looking??
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I think an Autolite 4100 (108) is pretty close to 450 CFM. Probably no more than that. The Holley 390, Edelbock or the Autolite 4100 will all need an adaptor to fit a flathead manifold since they have a larger bolt pattern. Only old Holley 2140 & 4000 teapots, Carter WCFB's and Rochester 4G's had the small bolt pattern in the mid 50's that would match the pattern on a flathead intake.

The Autolite 4100 is an economical choice, and they are plentiful and affordable on EBAY if you rebuild. It's also a very easy carburetor to work on, and is dependable.

Sal
 
39topless said:
390 CFM is the max. Bigger ain't better with carbs. Speedway all the way!!!.
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We'll have to agree to disagree on carb size for a flathead.
Your right bigger ain't always better, unless the bigger one is the right size and the smaller one is a bit small.
Martin.
 
4ford said:
ok i think it will be a single 4bar how about a autolight 4100 i think a 108 is about 450 cfm and an old ford carb??? well it might be net looking??
Click to expand...

I have no experience of that carb, but Si seems to think it's ok.
Personally for a 4bbl, I'd be looking for a small bolt patter WCFB or Rochester 4jet, bolts on with no adaptor and more in keeping period wise.
Thats just my opinion though.
Martin.
 
I'm not a tuning whiz.....thus my experience has been with the Holley 390 4bbl.
Put one on my built 8BA flatty in my '35 slantback......ran great right out of the box.
I now have just installed one on my built 59A flatty for my '29 roadster. Have yet to fire it but I do not expect any surprises.
I also like the look of the multi 2bbl.......but I did my homework and the 4bbl seems to be the best setup for me.
 
well I gota get into this, considering the fact that we're not racing this engine, aesthetics come into play here as well. 2 Duces, do look good. However, for street, drivability and economy is more important. In my opinion, the 500 cfm Edelbrock is the best street carburetor. It has best tuning fetchers for both cruise and WOT. Now reguardless of what carburetor system you use, the ignition system plays a big part in both economy and WOT operation. AS far as airflow numbers are concerned, Holley can't get their act together. I bought an unknown 4150 from a friend and looked up the CFM and it was listed as a 390. However I have a 390 and the venturies are much larger. I called Holley, gave them the list number and they said it was a 390. So now I have 2 390 carbs with different size venturies. Go figger.
 
Hi 4ford, you started the thread indicating you have a stock '48 engine. Guys correct me if I'm wrong but that's a 100 hp engine. In his last post I read 4ford is still leaning towards a 390 to 450 cfm 4 barrel, even if you modify them to deliver the least amount of fuel., I think thats too much carb for that engine. You can go with the largest variety several choices in a two barrel, be it a 94, a Stromberg 97, or a Demon but unless you are gong to put a mild cam and enlarge the valves along with the milled heads I think any 4 barrel or multi carb set up is too much for that engine. I believe you'll be fowling your plugs and bogging the engine when you try to pedal to the medal it. not to mention again washing the oil off the cylinder walls with unspent fuel.
 
When I build my 8BA, (0.080 over, Max1,Offey 425 heads and intake, Mallory Unilite, Red's headers) I bought a 4160 390CFM Holley. It ran great, but wouldn't idle when cold. After struggling for 18 months I replaced the Holley with a 500CFM Edelbock. No problems since. I am beginning another 8BA build and plan to use 3 Holley 94's on this one.
 
It's time to buy JWL's book. And the stock out of the box 500 cfm Edelcrock carb has the #5 rod/jet combination which is very rich. not good for the rings.
These have to be tuned for the application.
 
I have a nonbranded 4 barrel manifold for my 59ab and just don't have the heart to put it on. Just like the two deuces better. Guess when you get old you also get stuck on some things.
 
guys.
i like all the info that you guys gave me on this.... heres what i am thinking, new heads offy 400s and leave the 94 carb on and drive it.....????

thank you for the advice

mike
 
Give it a go, the heads will up your torque at low (normal street driving) rpms. You may have to tighten the vacuum brake a bit, and you'll have to change the shorter head studson the engine, bottom two rows. As the heads are the same thickness all over, unlike the stock heads.
Then you could change the intake later, if you still want to.
High compression is the best bang for buck modification you can do.
Get John's (Jwl) book, lots of very relevant info in there.
Martin.
 
Have to agree with Ol'Ron. The Holley 390 I installed ran well out of the box and with a jet change was better. But after installing an Edelbrock 500 I found that the Edelbrock is far better at tune-ability.
With all the hoopla about having a 4 barrel carb. installed you are running on 2 barrels about 99.9% of the time.
 
4ford
For a stock engine, get the Offy 350 head, more compression. Also, Offies quality control is pretty bad. The 400 will not clear the L-100 or any other hi lift cam. They may have fixed this, but you never know till you check it out.
 
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