Slant Six Carb Issues

[SpriceyStuff]

Hey guys. I’ve been having some carb issues lately and I’d like to see what you guys make of it. I got a Slant six with a Holley 1945 1bbl carb. Recently, it died on the side of the road, just pouring gas down the manifold. Had to readjust the floats on the side of the road and get it home. It ran great then. Now, it seems to be running rich again. In order to get it to idle relatively well, I have to turn the idle mixture screw all the way in, but it still doesn’t run or drive great. What do you guys make of this? I want to get it running good again so I can drive it to my uncles house and work on the body some.

Thanks in advance.

 

[RustyRatRod]

I stopped reading at Holley. There's your problem. At least, in my opinion.

 

[Bewy]

I stopped reading at H....

 

[slantsixdan]

Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.

 

[chryslercruiser]

Is the float absorbing fuel and getting heavy? That would be my first guess... especially if you have already readjusted it once, and it continues to be start running rich over time..

I replaced the plastic-foam float in my 1945 with brass.. NOT sure that such is a good practice, as it was difficult to get the float level adjusted correctly, as the brass ones do not float quite as high on the fuel level... Still not sure i have it correct!!! But they do solve the fact that the foam ones can absorb fuel over time..

 

[SpriceyStuff]

Is the float absorbing fuel and getting heavy? That would be my first guess... especially if you have already readjusted it once, and it continues to be start running rich over time..

I replaced the plastic-foam float in my 1945 with brass.. NOT sure that such is a good practice, as it was difficult to get the float level adjusted correctly, as the brass ones do not float quite as high on the fuel level... Still not sure i have it correct!!! But they do solve the fact that the foam ones can absorb fuel over time..

Thanks for this. I may actually do that at some point. It turned out that there was a brass piece inside that had fallen out of its slot during my last endeavor into the carb. I took it all apart and put that piece back in and now it’s fine

 

[SpriceyStuff]

Thanks for this. I may actually do that at some point. It turned out that there was a brass piece inside that had fallen out of its slot during my last endeavor into the carb. I took it all apart and put that piece back in and now it’s fine

Wrong. Tried to drive it to get some oil for the daily and it did it again. The floats are definitely boned. Ordered a NOS set on eBay.

 

[Jim Kueneman]

My experience new fuel pumps will put out 8-12 PSI and rumors are Hollys are sensitive to fuel pressure. I used Daytonas on my dual carb setup which are Holly knockoffs from Argentina. They would occasionally flood over at idle. I found an original rebuildable Carter pump, bought a rebuild kit from Then and Now which has the same issue, 12 lbs of pressure. I bought an assortment of springs and found a spring light enough to give 4.5 lbs at the input to the carbs and it has run flawlessly for the last 3 years.

 

[SpriceyStuff]

My experience new fuel pumps will put out 8-12 PSI and rumors are Hollys are sensitive to fuel pressure. I used Daytonas on my dual carb setup which are Holly knockoffs from Argentina. They would occasionally flood over at idle. I found an original rebuildable Carter pump, bought a rebuild kit from Then and Now which has the same issue, 12 lbs of pressure. I bought an assortment of springs and found a spring light enough to give 4.5 lbs at the input to the carbs and it has run flawlessly for the last 3 years.

That’s an interesting anecdote. I have an electric pump already so maybe I’ll just shell out and buy a pressure regulator and not worry about it again.

 

[Jim Kueneman]

That’s an interesting anecdote. I have an electric pump already so maybe I’ll just shell out and buy a pressure regulator and not worry about it again.

Measure your fuel pressure at the carb input and see what you have. An electric could easily put out enough to give you this problem.

 

[SpriceyStuff]

Measure your fuel pressure at the carb input and see what you have. An electric could easily put out enough to give you this problem.

Welp I hooked up my pressure gauge and I’m pushing 8lbs just from the starter. Not even running. So sounds like it’s regulator time.

 

[slantsixdan]

Welp I hooked up my pressure gauge and I’m pushing 8lbs just from the starter. Not even running. So sounds like it’s regulator time.

Well…yeah, you could shove a cork in the tailpipe and kindasorta stop the exhaust smoke, or you could fix the actual problem: it's time for a fuel pump built to correct specifications.

 

[SpriceyStuff]

Well…yeah, you could shove a cork in the tailpipe and kindasorta stop the exhaust smoke, or you could fix the actual problem: it's time for a fuel pump built to correct specifications.

I can’t afford to just Willy Billy start buying new pumps and hope to god that it works the way it’s supposed to. They don’t even put that information on the box. So like if the catalog says it’s for my engine that’s all I get. What I can afford to do is by a cheapy pressure regulator and set it to 5lbs or so and call it a done deal. It’ll be sufficient until I have the funds saved up to replace this intake entirely.

 

[slantsixdan]

I can’t afford to just Willy Billy start buying new pumps and hope to god that it works the way it’s supposed to.

Well, yeah, fair. My point is that the current-production pumps for Slant-6s are improperly-built garbage. This would be a better pick.

Budgets are budgets, and dollars that don't exist don't exist, but "cheapy" and "fuel delivery system" can easily add up to "suddenly hideously expensive".

 

[volaredon]

I bought 2 of them about 3 years ago from eBay, genuine Carter (I think that's what they used on the assembly line even) brand new in their boxes, and pretty cheap as I remember. Gotta do a lil digging, as of there's 10 listings for whatever the prices are all over the place for the same exact thing

 

[volaredon]

I sas that listing Dan posted and it looks like a crimp together style. Not a screw together style of fuel pump. I didn't know they ever "remanned" the crimp style pymps

 

[SpriceyStuff]

Well guys, I found my culprit. Turns out, it was my needle and seat. Rubber-tipped needle had begun to come apart after 3 years of ethanol gas usage. I robbed one off my old 1920 carb. I also robbed a check ball, because I had lost mine at some point. It is a little surprising how much can be taken from a completely different model carb and used in mine. Anyway. It seems to be running okay now. I also ordered a new needle and seat to keep on hand, because my 1920 is a couple years older even than my 1945, but at least hadn’t seen as much ethanol usage. So after all that. After dropping the $30 on a pressure gauge, $20 on a new float, and another $35 on a regulator (which didn’t fix the issue at all), it turned out that the real problem all along was none of those things. It seems to be running okay now. It idled for a solid 20 minutes and didn’t flood. Haven’t tried driving it yet, because I’m still a little scared to, but maybe soon.