Air intake system parts compatibility

RimfireJim · Post by **RimfireJim** » Fri Mar 04, 2011 4:16 pm

Our efforts to get my M38 drivable again so that it can be handed down to my son have 1) turned into a bigger (aka "more expensive") project than we expected it to be (surprise, surprise, huh?), and 2) turned into a bit more of a restoration project than originally intended.

Part of the project is getting a functional air intake system on it. When I bought it many, many years ago, it had none of the original air and fuel system. Mechanical pump had been replaced with an electric pump which did, and still does, work just fine. Carb is a WO. Upstream of that, though, is worse: a hole had been cut into the hood above the carb and a sheetmetal box welded on to clear and cover a dome over the carb. Under the dome was just a screen for a filter. I found a 4" Mr. Gasket aftermarket paper filter to replace the screen, then later found a lower-profile 6" Mr. Gasket filter that allowed me to patch in the hole in the hood and get rid of the ugly box.

But nowadays that thin 6" filter isn't available, so we're on Plan C (or is it D?). We bought an original oil bath air cleaner from a forum member, and I found brackets for it on ebay. A correct YS carburetor is out of our budget at the moment unless we get lucky, so the WO will have to suffice. So, finally, the compatibility questions:

1. If we use an MB-style air horn elbow on the WO carb, is the inlet diameter of the elbow the same as the outlet of the M38 air cleaner, allowing us to connect the two with a hose or duct?

2. If we add an M38 crossover tube in the path, is there any problem connecting it to an MB carb elbow? Would the MB rubber hose work? Length issue, maybe?

3. If we do score a YS carb, do we need a M38 fuel/vacuum pump to make it work correctly? I'm thinking vac-operated accelerator pump, for example?

Any answers and other insights would be appreciated.
-Jim

Oldsalt · Post by **Oldsalt** » Fri Mar 04, 2011 11:47 pm

My M-38 has had a WO carb on it ever since I got it almost 40 years ago. If the pic I posted works you can see that it is hooked to the air tube and oil bath air cleaner. I think they are all original. The fording vent valves are all hooked up too.

I never realized that the WO was not the correct carb for my jeep. I have no idea what type of jeep the air horn came from if it is not what came with it.

If the picture does not work in this messge, it is in my photo gallery.

Post by **wesk** » Fri Mar 04, 2011 11:55 pm

1. If we use an MB-style air horn elbow on the WO carb, is the inlet diameter of the elbow the same as the outlet of the M38 air cleaner, allowing us to connect the two with a hose or duct?
If accuracy is not an important issue for you then just use the thin flexible wire reinforced Scat tubing. It is flexible enough to get it sized for the larger pipe and can easily be necked down to the smaller pipe. I don't think they differ more than 1/8" M38 air cleaner to crossover is 2 1/8". I think the carb side is 2 1/2"
http://www.brownaircraft.com/searchresults.asp?cat=106

2. If we add an M38 crossover tube in the path, is there any problem connecting it to an MB carb elbow? Would the MB rubber hose work? Length issue, maybe?
You are best off measuring what you have and fitting the appropriate size hose.

3. If we do score a YS carb, do we need a M38 fuel/vacuum pump to make it work correctly? I'm thinking vac-operated accelerator pump, for example?
No. She'll work just fine without the dual fuel/vacuum pump.

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Zane · Post by **Zane** » Sat Mar 05, 2011 10:07 am

A wo carb will clear just fine on an m38 engine, as far as cutting a hole in the hood for clearance it sounds like somebody stuffed an f-head 134 overheadvalve engine from an cj3b/5/m38a1 in it, which means it has a yf carb not a wo.

Post by **wesk** » Sat Mar 05, 2011 11:02 am

He has an L134. The old style larger pancake aftermarket aircleaners did not fit between the WO and the hood and that is why the hole was cut years ago in the hood. He eventually found a shorter/thinner aftermarket air filter and plugged the hole in the hood. No F134 thing going on here.

The level headed approach to air cleaner/carb room on the F134 in a flat fender low hood jeep was to use the Ford Falcon Carb.

Zane · Post by **Zane** » Sat Mar 05, 2011 3:30 pm

No the level headed approach is to not put the f134 in a jeep that has a l134 to begin with.

RimfireJim · Post by **RimfireJim** » Mon Mar 07, 2011 1:27 pm

Thanks for the answers, guys. Looks like we should get an M38 crossover tube and M38 air cleaner-to-crossover tube hose, an MB horn (elbow) and seal and adapt between the latter two for now, and keep our eyes peeled for a good deal on a YS.

Yup, no f-head ever in this puppy. It has an RMC engine in it, but unfortunately all the original ancillaries were replaced with civilian or aftermarket devices.

kenperkins · Post by **kenperkins** » Mon Mar 07, 2011 5:07 pm

might look at using an mb crossover tube, there around 30.00+

mckim · Post by **mckim** » Mon Mar 07, 2011 5:20 pm

The long-term goal will be to have a correct M38 carb, so it probably makes more sense to put an M38 crossover tube on now. Otherwise, I'd have to replace it once I find the correct carb. (I'm the "son" in the son-father project).

Post by **wesk** » Mon Mar 07, 2011 9:05 pm

No the level headed approach is to not put the f134 in a jeep that has a l134 to begin with.

The problem here is we have not defined the term "Level Headed".

There are plenty of good reasons for folks to put F134's into flat fender (LOW HOOD) jeeps.

12 more horsepower
Better throttle response
Cheapest upgrade since it bolts right in and radiators and trannies bolt right up.
They had a F134 sitting there and an empty engine compartment in their Low Hood Flat Fender.

Being level headed would be weighing your options, checking your wallet
and than "Having it yourway "

Once the level head is used to determine the feasability of the F134 installation then if the fellow continues with the level headed approach he will not cut a hole in the hood

Not everyone's wallet, skills and tooling are equal.