The year of the carb...

Has anyone here actually replaced the carb on their 302 HM from the autolite to a new 4bbl or 2bbl marine? Replaced without changing cams or heads? If so, what were the results?

When I was discussing this with my brother he said, "you want MORE power in that thing?".

a few years back, in an old Mach one, (this is from memory) so please do correct me if im wrong. it had a 351 with 2v heads and being not so wise, i bought a 2v manifold and 4 barrel....it ran worse once installed...the heads couldnt take that much gas. I still have the old manifold up in my attic and need to take a look at it

I would think that you can tweek your current fuel line to get it to work, that is unless it's a little to short. Another option is a braided flexable hose with AN fittings on each end.

Yes, the 2bbl Holman Moody came with a 500cfm carb. Thats why it was rated at a strong 210hp- the same as the 4bbl Interceptors. The 2bbl Interceptors used the smaller carbs, I believe- as they were rated at 165-190hp.

Im not quite certain what the V stands for, but yes- 4v indicates 4bbl. Im assuming your hand slipped off the 2... Ive never heard of a 3bbl!

I think youre correct- the only 2bbl H-M's Ive seen or heard about were from the mid 60's through '70. Everything newer than that was a 4bbl- the 302 being rated at 235hp and the 351 being rated at 290.

I dont think that H-M manual is on the site... would you care to scan it and share it with the rest of us?

vondy wrote: I assume my Autolite is 500 only because that's what everyone on this thread has been saying.

Not me and I still have it here in my garage. It's float bowl is marked 1.14 which makes it a 300 cfm. It's definitely the original and the same as the picture you posted in the past David.Look on the float bowl under the push rod for the accelerator pump

Here is what I finally found-


This is the Autolite 2100
series two-barrel
carburetor. Look for throttle
bore size cast into the body
. The type of carburetor is determined by the venturi diameter size which is cast in the left-hand
(driver’s) side of the carburetor body beginning in the 1960 model year. What you can expect to
see are numbers like .98, 1.01, 1.02, 1.14, 1.23. This is the venturi diameter in inches. The higher
the number, the larger the venturi diameter in inches. The 221ci small-block was fitted with eight
possible 2100 types, all with .98-inch diameter venturis (190cfm ). The 260 and 289ci engines were
fitted with 2100 carburetors with 1.01 (245cfm ) and 1.02-inch (240cfm) diameter venturis,
depending upon application. Venturi size originally depended upon transmission, vehicle
application and original sales district. California emissions carburetors, for example, were jetted
differently. This was also true for vehicles delivered to high elevation areas like Denver. For 1964,
the 289 received a larger throttle bore 2100 with 1.14-inch (300cfm ) venturis. This gave the 289
improved low-end torque.

About the manuals,the parts manual has all models in it,only the owners manuals are seperated by size.

Back to square one.

I'll take a look when I get home tonight and see what's on there.
If it is 300 cfm. I assume I should stay 300?

If this is the case then the 450 cfm 4 barrel would have been closer than the 500 cfm 2 barrel huh?

The tag says Autolite C9ZFG A949. That's the only info I have at work on it.

Guess I figured there were plenty of HM 302s out there that people would have changed out the carb on. I knew Gary had but he also upgraded more than I plan on.

Gary did you ever install your new fuel pump? Remember, way back when, I got mine and the vent tube was hitting the oil pressure sending unit? I still have not addressed it.

Curious if you ever did yours.

Old Post

No David,I'm keeping it as a spare, I rebuilt my old one for now.

Tim here is a pic, the carb is more like an Edelbrock in that the top comes off and the bowl is cast as one with the venturies and base. You can see on the bowl the number cast into it. I thought it was a pretty cheap carb,but I see on some Ford sites,they were well thought of. When I changed over to the Holley it runs so much better particularly after sitting for a few days.One thing I just thought of, is mine started out as a 289 which was rated at 200 hp with the 2v,the 302 was 210 hp. I wonder what Davids is? Can you post the serial # off the bellhousing David? Then look at the carb's float bowl to see what size it is.Reid is probably right as the parts book dated 9/74 also a holley type carb,does not say Holley,but sure looks like one, they might have been changed for later models.

Now that is confusing,a bigger engine,higher compression and a smaller carb not even listed! Must be a different listing for the 302's,but it must be less than 300 cfm. My opinion would be to go with the 4bbl 450cfm and manifold,you'll cruise around on the smaller 2bbl side and when you want to open it up the secondaries will kick in.

for some reason i can remember 2v or 4v stamped on the heads somewhere, dont quote me cause in no way im a ford genius, but from what i remember the engine couldnt handle the 4 barrel, i blew black smoke when the secondaries opened, but nothing like experimenting

My search is showing the 1.08 to be 287 CFM. And apparently, like Gary said, these Autolite carbs are highly thought of.

[QUOTE=vondy] So sounds like the 2 barrel Holley 300 cfm might be the way to go.
[QUOTE]

Not unless you like a slow boat.
Like tim sez, above 4000 rpm, you'll be making unneccesary manifold vacuum. While you would likely exceed 4000 or more rpm, it will be like having a restrictor plate on, and the power will go flat for no good reason.

I feel 300 is just too small.

if you can acurately measure the carb, then we might be able to verify the research so far and be 100% right. But there is a possibility that the carb was changed at some point in it's life. What does HM state should have been on the motor? the 500 cfm? has anyone actually seen this in print form in a manual?

Seems like a very small carb for a high compression engine.