Serious stumbling from off idle through cruise. Runs like a champ at WOT. ??

[bigoilman]

1977 Chevy C30 dually.  Stock 454/TH400.   
Carb # 17056212ABH

Back story...Truck ran fine but would take forever to crank after it sat more than 4-5 hours.  Suspect leaking bowl plugs.  Ordered plug kit from Cliff's and installed.

Put carb back together but now it runs very, very rough until you go to WOT, then it runs better than it ever did.

I should've just put it back together but....

1. I adjusted the float
2. I reattached the linkage on the vacuum pot
3. I bent the pin that engages the secondary lockout so that it would engage the linkage (previous owner had bent it out of the way so they wouldn't engage.

Any suggestions are appreciated.

Richard

[bigoilman]

Update:  Disconnected linkage going to the vacuum actuator and it runs like it did before.  Maybe that's why it was unhooked?  I just like for things to work as designed. 

[bigoilman]

Another update.  This morning it takes forever to even fire, just like it did before I epoxied the bowl plugs.  Carb appears to be completely empty.

Could a weak fuel pump cause it to take so long to get fuel?  Then run fine once it is up to temp?   Carb is missing the spring and filter on the inlet, btw.  Previous owner removed and added inline filter between tank and pump.

[Jeffs68]

Have you tried replacing the inline filter yet?
Any particular reason you adjusted the float?
You might want to spring for a complete rebuild kit from Cliff if you don't know how long it's been since the last rebuild.

[bigoilman]

I haven't replaced the inline filter.  It flows fine once flow is established.  I could replace it though, it's a cheap thing to try.

Float position didn't match what was called for in the table I referenced.   That's why I adjusted it.

It was rebuilt around 2000 miles ago per the previous owner.  Appearance of gaskets and other internal parts would support that.  I bought an over the shelf kit but just used the gaskets, still have the rest.  I realize I should've bought Cliffs kit but was in a hurry.  I'm in the middle of Cruisin' the Coast.

If the bowl plugs aren't leaking (they aren't) why is the bowl empty in the morning?  Only one other place for the fuel to go, right?  Back the way it came, toward the fuel pump.

[Jeffs68]

The fuel does have an easy path back out of the carb if there is no filter in the inlet. Some have a check valve built into the filter. Also, and don't quote me on your specific carb, but the fuel inlet needle can either be hooked on the float arm or not, if it is not it may help with fuel drain back by keeping the fuel inlet seat sealed.

[bigoilman]

Thanks, Jeff.  Needle is attached to the float arm.  It was before, too.   Should it not be?

[Jeffs68]

Cliff has said he prefers it not to be. I have it attached on 2 carbs with no issues, but it may be something to try. But I would recommend getting his SR rebuild kit, it has VERY high quality parts including a new needle and seat for the fuel inlet.

[Cliff Ruggles]

The HD/Motorhome carburetors are very specific, and take different gaskets than any other carburetors.

I would install one of our kits, and I'm betting your issues will go away.  Very little in the over the counter kits will be correct or work well in one of those carburetors.....Cliff

[bigoilman]

Thanks, Cliff.  Didn't realize they were "oddball" carbs.  I'll order a kit.  I've got the book.

[bigoilman]

I'm curious to how a needle works if it isn't attached to the float?

[Jeffs68]

The fuel pressure just pushes it up and then when the bowl is full the float arm keeps it shut...rinse repeat.

[77cruiser]

I just throw the clips away.