[67ragtopStang]

I have a Holly Carburetor with a tag that reads:

Motorcraft D2JL C / A 3M10

As far as I know, this means:

D2.......1972
J.........?
L........ ?
C.........engineering version
A......... ?
3M10.... December 10? (not sure what the 3 is.)

Am I wrong? Can anyone help me fill in the blanks?

Is the tag enough to identify what carb model this is?

It's not in a Mustang, but is on a 1971 302 engine in my boat.

[67ragtopStang]

Here's a couple of photos of the carburetor.

[Boomyal]

It's a Ford Holley carb. Not sure when exactly ford used them but if it has a motocraft name/tag on it, that's what it is. If your 289 is a run of the mill motor, the carb is probably a 450 cfm carb. There will be a list number stamped into the choke horn, you could call Holley with it and they will give you all the specs plus the original application.

EDIT: I just re-read your original post and saw that it was on a boat. It was common to use Marine Holleys on boats but they were never the Motorcraft variety. Yours is an auto carb, not a marine carb. Not the very best idea as the auto versions are not coastguard approved for marine use. However, like yours, I'm sure there are countless numbers of them used that way.

Some factory installed marine carbs on SBF's were 450-500 cfm. That would have been a proper size. 600 cfm's are much more common and can be had off the shelf, supposedly jetted for SBF's but they are really a compromise size and ideally too big for the SBF.

I have a 600 cfm Marine Holley in my 302 BUT it is really a 9.0:1 compression 5.0 liter with a slightly hotter roller cam and GT40P heads so it can make use of the 600 cfm. I also have a 450 cfm Marine Holley that I plan on putting on a dead stock Merc 888 2bbl 302. A perfect match for a stock marine or auto 302.

I also see the number 225 on the valve cover of your boat engine. That, plus the black color tells me that your motor was probably a Merc motor that originally came with a 4 bbl. I just do not think that the current carb was original.

Like I said, Holley can tell you the size, the jetting and the original application.

[67ragtopStang]

What's the difference between auto and marine carburetors? What's does SBF mean? What is the choke horn?

The engine has a '71 block/intake, '72 Carb and the boat is a '74. The boat was used in fresh water for 30 years. I figured the setup was original to the boat since it shows little of the wear and tear 35 year old boat would normally show.

I've haven't come across anyone that has seen a Ford/Mercruiser Marine 302 engine before, but the original Mercruiser serial number tag is still there. I should check to see if they have records that old.

I'd like to find out the model number of the carb, so that I can buy the right rebuild kit and overhaul it over the winter.

[Boomyal]

Merc used 302's up until the late '70's, then switched to the 305 and 350 chevy. SBF ='s Small Block Ford, ie, the 221 cid, 260, 289, 302 and 351w. All refered to as Windsor motors.

Marine Holley's have a more corrosive resistant finish, the throttle shaft bushings are made to seal in any fuel weepage and the float bowl vent tubes are hooked so they would dump back down the venturis if any fuel exited them.

The choke horn is the raised wall around the primary opening that houses the choke door at he top.

Your block may or not be an original Merc block. There was no difference between an auto block and a marine block except for the brass freeze plugs. Many replacement motors started out as an auto engine. If it retained the Merc/ford cylinder heads, they would be 351w heads that were only drilled (1/2") for the 302 head bolts. The cam would have been marine specific, to keep the torque curve down low, and would have had a 351w firing order.

Again, I encourage you to call Holley Tech with all the numbers you have, including those on the choke horn. They will tell you exactly what you have and what you need for a rebuild.

You could post your engine number here: Someone will be able to tell you the year of the Merc motor, at least as far as the number on the valve cover represents.
Mercruiser, OMC, Volvo & other I/O & Inboard Engines & Outdrives - iboats Boating Forums

Keep in mind that the number on the valve cover would only represent what the motor originally was. It could have been an original merc that came out of a donor boat, or considering that your boat is a 74 and you know the block to be a '71, the original valve covers could have been used on a replacement longblock or shortblock.

[67ragtopStang]

I'll try contacting Holly, now that I know where to look for the numbers. Thanks!

[67ragtopStang]

I figured that out it's a 1972 Holly 4160, 450 CFM Carburetor.

Thanks for the help!