Dual carbs with a Load-O-matic distributer

ChuckinNH

ChuckinNH

Active member
My recent aquisition is setup with an Offy 2 pot manifold on a 215". There are 2 Holley 1904s on it. The vacuum from the front carb is hooked up to the Load-O-Matic distributer. I can feel a bucking at cruise at any speed above 25MPH. It runs strong when I'm on the throttle. I am suspecting the carbs should be rebuilt. I do have a couple questions about the Load-O-Matic. Should the vacuum signal from both carbs be fed to the distributer or is it normal to use only one? Can the Load-O-Matic be run off manifold vacuum?
 
I would say just plug the carb port that does not have the vacuum line going to it. Why would you need to "tee" that line and run it to both carbs. The vacuum source is the manifold, not the carb.
I would check the operation of the vacuum advance, engine not running, distributor cap removed using a mityvac connected to the line going in to the vac advance. Dont pull the trigger too hard. Watch the distrib breaker plate while pulling the trigger. If the breaker plate moves, your vac advance is good.
 
The LOM distributor is designed to work with the modified vacuum signal that comes from the Spark Control Valve (SCV) port on the OE carburetor. It has no centrifugal advance. In reading about '49-'53 flatheads; pre-'57 Y-blocks; and Falcon sixes, my understanding is that a LOM dizzy won't work right on manifold vacuum or on the signal from just one carb in a multiple-carb setup. I'm not sure if tee-ing the SCVs together would overcome that. Period hot rodders would switch to an aftermarket distributor (often from Mallory), and today many adapt a conventional distributor from an earlier or later engine. I'm not sure what your options are with the 215, to be honest.

-Dave
 
Thanks Guys,

Already checked the operation of the vacuum advance. Its OK. Also tried manifold vacuum. Ran worse hooked up there. That lead me to the question of dual carbs and the LOM distributer. I thinking I'm in the same position as the late flathead guys. Not being able to get the LOM to work with multi carbs. At least they have the Chevy distributer conversion as a fix. Research continues.
 
Okay, you inspired me to do a little reading on the “second generation” Ford sixes. They were produced up until 1964, finishing their run in Heavy Duty Ford Trucks as a 262ci engine. The “fourth generation” (240/300) sixes that replaced them used a conventional distributor, and I wonder if Ford had dumped the LOM by the last couple years of production. It might be worth looking around to see if 262 or late 223 distributors might have centrifugal advance and no LOM.

Or start poking around the HAMB and guys who have old collections of hot rod magazines. Since you’re using a vintage dual intake, you aren’t the first person to encounter this problem. Mallory doesn’t list a conventional distributor for the 215/223/262 right now, but maybe they produced one at one time. That seems to have been the period answer. Perhaps eBay may be a good route.

One last thought: I recently read that the SCV was used in Ford dual-quad setups to synchronize the secondaries on the old “teapot” Holley four-barrels. But, I think that Ford only started using dual quads on the 312 in 1957, which (perhaps not coincidentally) was the year they switched to a conventional distributor on the Y-block.

-Dave
 
From here:

I'm eventually going to use a 300 distributor in mine. You can modify the 223 distributor gear to fit the 240/300 shaft and match it up with a '64 223 oil pump. The '64 223 used the same size hex drive as the 240/300, which is slightly larger than that of the earlier 223.
Click to expand...

-Dave
 
A more-detailed reference to a fourth-generation distributor in a second-generation engine here:

I went a different route and had a machine shop modify an early 80s Duraspark-II distributor from a 300 to fit my 223. To do that, you have to bore out the 262 distributor gear to fit the 300's shaft. The 300's hexagonal oil pump drive shaft may also need to be shorted by about 3/4". If your 262 is from 1961-63, the oil pump probably uses a 1/4" drive shaft, so you'll either need to use a 1964 oil pump (Melling M-67A), which accepts a 5/16" shaft, or have the shaft diameter machined down to 1/4" to fit the earlier pumps.
Click to expand...

-Dave
 
Thanks for those links. I had seen the first one before. That may be the direction I go when I get the cause of bucking at cruise problem nail down. I'm not yet totally convinced its a problem related to the LOM. I believe this system was put to gether about 15 years ago. So I have trouble believing its always had the buck. I will post what I find and the fix here.
 
Even if you could get the proper vacuum signal by running a "t", the Loadamatic is not very tuneable. Since you are obviously trying to get some performance (dual carbs), I would definitely either find an aftermarket distributor, or modify another distributor that has mechanical advance to work on your motor. You will be much more satisfied, and can better realize the power potential of your carbs and any other mods.....
 
Mallory did at one time make a Centrifical advance only Dist to fit the Earlier generation Ford Six engines. I don't remember what model it was, but I bought one off EBay that I was going to use on my 62 F100 223 if I ever changed carbs from the Holley 1904, but I never got around to using it and it went with the pickup when I sold it.

Fred
 
fmartin_gila":2uw5jvna said:
Mallory did at one time make a Centrifical advance only Dist to fit the Earlier generation Ford Six engines. I don't remember what model it was, but I bought one off EBay that I was going to use on my 62 F100 223 if I ever changed carbs from the Holley 1904, but I never got around to using it and it went with the pickup when I sold it.

Fred
Click to expand...


Speedway Motors has a couple of N.O.S. left in their garage sale. Check here:
http://www.speedwaymotors.com/Garage-Sa ... 52078.html

It's the old YC dual point model. Rotor, points, and a substitute condenser are available as replacement parts. Distributor caps have been discontinued by Mallory and I don't know of a suitable replacement. I believe Speedway has 3 left in stock.

Lou Manglass
 
Thanks to Lou for the Speedway link. I have a YC dizzy coming.
This weekend I tried running with the vac advance blocked off. It ran about the same performance wise as when connected. Cruising along with light throttle was smoother although the buck/stumble was still there.
I did find the carbs are not matched. The front one is a 1904 while the rear appears to be a 1920 as used on 225" Chryslers. I am not really liking how these are set up. Linkage is direct. I think that part is OK. The accelerator pump link is removed and the vac port capped on the rear carb. The front AP is set for the lightest shot. Choke is active on the rear only. Probably Ok because it cold starts. I've haven't come across anything quite like this before. Any opinions?
I'm thinking I need to find another 1904 of the same list # to start.
 
Second update:
I messed around some more with the mis-macthed carbs. Was able to get a smooth cruise mode by cutting 4 coils off the economizer spring on each carb. Doing so basically reduced the spring pressure by about 50%. I figured that would be similar to the 3.5 PVs in the 94 carbs on my 41 V8.
There is a swap meet in the area a week from Sunday that I'm hoping to get a match for the 1904 to replace the 1920. Got the Mallory from Speedway. Looks like I need to replace the oil pump to a 223 hex drive to use it. The 215 and the '55- '59 223 OP look the same except for the drive. I'm wondering if I could get away with a rebuild kit for a '55 -'59 OP.
 
Update 3:
The weather has been agreeable to play with the old cars and carbs. I now have a matched pair of 1904s. These are list #1350. Both are setup with a new power valve plunger. No spring modification. both are jetted with #62 main jets that were in them. According to the Holley parts list they should be #69s. The AP link is set for the largest shot on both. I believe the carb issues are put to bed. The 215 is running better than it ever has since I aquired it. I runs best with the vacuum advance disconnected and the timing set at 12° BTC. This distributer does not play well with multi carb set ups. Next up is to install a new oil pump and the mallory dual point.
 
I still haven't done the oil pump change to use the 223 Mallory YC distributor. I'm having too good a time driving it. I am contemplating another approach to get the benefits of both vacuum and mechanical advance. Has anyone on this forum used a Chevy 6 distributor adapted to a Ford 215". Or is there a better Ford 6 points type distributor with vacuum and mechanical advance systems that will work better than straight mechanical? I realize I may need to change the pump to get the hex drive anyway. I would like to retain the 6 volt system, so I don't want to go to a later Ford electronic.
 
The 240 & 300 distributor can be adapted the 68 up units have mechanical & vacuum advance, any 12 volt distributor can be used as a 6 volt one when wired correctly :nod:
 
Excellent am glad you got it running good! (y) One of these days hope to find a pair of the Holley 1904's with glass bowls to go with a new Offy I picked up. :nod: Take care
 
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