The Stovebolt Site Forums The Shop Area Engine Shop Engine starting problems

Ladies and gents,

I’ve been helping A friend with his 54 3100 that has a pressurized 235. We were able to drive it, but there are a few issues.

First issue: I unhooked the choke because carb linkage was assembled wrong when it was assembled (new from local flaps).

Second issue: my vacuum gauge only shows 15psi when the truck is running. I adjusted throttle and attempted to adjust the fuel ratio, with no change. After replacing the vacuum advance with a known good part, it still doesn’t move. The lines are all clear between the carb and vacuum advance. (I need to check points still and all passages between carb and intake)

Third issue: in order to start it, we have to squirt fuel down the carb every time! After that, it runs for 20 minutes. (Float set wrong?)

My thoughts: I think this is a carb issue and here’s my reasoning. A [censored] at the factory assembled the carb wrong. I don’t think it’s a fuel pump issue since it runs. Timing might be slightly off, but again, it runs and is currently set to fire at TDC.

I am up for any thoughts on how to tackle this. We ordered a new carb already.

BTW, thank Sweet for helping us via phone to get it started.

Chris

Issue 1 - new or rebuilt carburetor?

Issue 2 - if you replaced the vacuum advance, and it still does not move, did you check to see if the plates in the distributor move? If not, definitely a problem.

Issue 3 - political problem (garbage gas).

http://www.thecarburetorshop.com/Troubleshooting.htm#Hardstartcold

Jon.

I'm assuming a Rochester carb is being used. Correct carb to spacer gasket? Please do not assume anything here...look at the vacuum passages, compare to your gasket and understand you may have to cut a notch or punch a hole in the gasket you're using to get vacuum running as designed. If it runs for 20 minutes and dies, I'd wonder if the gas cap isn't vented or if there is some obstruction in the fuel line (or the connection inside the tank) where crud is hampering the flow of fuel. A float adj issue wouldn't have it running that long. Remove gas cap and see what happens. As for buying a "rebuilt" Rochester from any auto parts store, good luck. There is almost a perfect likelihood anything you get will be at best a hodge-podge of assorted but not correct nor matching parts.

Further answers: new carb, I can physically move the distributor Like the vacuum advance does (I will double check!)

Rochester B is being used, no issues with truck dieing once running. I plan on checking the gasket below carb when we replace the carb (linkage is wrong from manufacturing).

My thought with float is that could cause stumbling when gas applied, and low fuel in bowl on start up. I can slowly increase throttle, but can’t apply quickly or it stalls.

Ok, so this isn't a new carburetor but a rebuilt one that is new to the gentleman who owns the truck. That could be problem number one. And it runs without stopping after it starts but stumbles and won't pump fuel into the manifold to make it start. First off, I would be highly suspect of any Rochester B or BC carburetor bought through any flaps. They all get their mdse from commercial or independent rebuilders. If you are curious about how these rebuilders work, please call CarbKing and ask him. The story isn't pretty. If you want to see what I discovered in opening 5 of these up a couple of years ago (and posted here), please read that stuff again. There was nothing that would make you want to buy anything but an NOS Rochester. That is if a Rochester is indeed what you want to use. Personally I'll say I tried hard to be as objective and positive minded as I could be about them, but with the fuel we get today, I agree 100% with Jon...hire a 15 year old to stand on the running board and pour fuel into the manifold from a leaking boot.

Here is what I'd suggest doing: get a carburetor rebuilding kit from Jon (CarbKing). The Rochester you have may be a mongrel (I would bet large that it is), but he'll be able to send what you need. Check everything in the carburetor...not just the float level, but the power piston, all the vacuum tubes, whether passages are open, what kind of accelerator pump the "rebuilder" used, etc, etc. Also see what size jet was used (could be any size at all). Stumbling can also be caused by no choke and an engine which hasn't warmed up yet...although in San Antonio, it ought to warm up enough pretty quickly. Please let me know if you need rebuilding specs. As for the vacuum advance, I'd remove the line from the carb and suck on it while watching. You ought to be able to make the dist plate move without too much effort. If that isn't happening, something is wrong either with the advance, the way it connects to the distributor or...the carburetor. Since I have no earthly idea who worked on the Rochester, there isn't any way to know if they even checked the vacuum passages. I've seen them rusted completely shut and I know Jon has also.

Jon,

You confirmed my thoughts. I have Previously read carbking’s info and talked to him a few times. Since this isn’t my truck, I can only assist and make suggestions. I just need confirmation that I wasn’t thinking incorrectly. I fully acknowledge and don’t trust a flaps carburetor.

Thanks,

Chris

ndkid275, I love the model "B" but I have worked on them for over 58 years. They are simple and yet touchy regarding being exactly put together. carbking and Jon G are informative and very professional so follow their advice. I rebuild these as a hobby and for the locals. If the linkage is wrong a novice or some person that could care less assembled it. I think I'm the only guy in the U.S. that has an original nos in the box. Keep it safely stored, good luck. Doc

I have a second Rochester B that I could rebuild for him. Hotrod Lincoln schooled me last time! I’m not saying I’m even on the same playing field by all means, but maybe I could get him on the road.

Chris

Chris I sold every bit of the Rochester B & BC stuff I had (some I'd owned since 1963) or I'd have been happy to send some your way. Good luck with it. I have a NOS Carter, but it is for the 216. I also have a Carter 3211s (Auto choke, made for the 1957 and newer 235), however I haven't had time to go through that one yet.

From the Book of "Its Never The Carburetor", check everything else but the carburetor first.
My first bet is that the gasket doesn't have a hole where it belongs, given that the vacuum reading is low and the vacuum advance doesn't do anything.
My second bet is that the coil is heating up at the 20 minute mark and is crapping out. Once the coil cools off, a marginal coil will make a spark again.Check for spark at a spark plug as soon as it dies.

Chris, is there a paper gasket, a phenolic spacer, or both beneath the carb?

Carl,

It does not “die”, we turn it off and it won’t start again unless we squirt fuel into the carb, then it runs normal again until we turn it off again. We have spark, fuel filter is full, fuel pump works fine after it starts. I never took off the carb. It needs to be replaced due to linkage issues. My money is still on the carb. I’m rebuilding one this week to see. Figured I would check it at that time.

Chris

Well of course its the carb. Its always the carb.
Sounds like you covered everything else.

Thanks, just making sure I didn’t miss anything!

I think everyone is right on with the carb. However, if that doesn't remedy the situation, I did have a similar problem on a car once (6 volt system and carbs were probably marginal), the starter turned over too slow. I had to replace it and it started fine after that. But it could easily having only a mitigating factor due to the carb situation.
don

DONSZ,

There are other issues that we need to sort out. Example: Dash lights come on when you turn on the key, not to mention figuring out where the draw is coming from that is draining the battery. I’m just trying to help get him on the road, then we can work on different issues as we go.

Chris

On the Rochester, here are a few things to look for...and a few surprises I found when looking inside the 5 I used for the study:
A. Parts of the airhorn. 1 the float, 2 the main jet, 3 the power valve...this one had been stripped and had an o-ring installed in an attempt to make it seal (which pretty well made sure it wouldn't work right any longer, 4 the main well housing assembly, 5 the power piston, 6 a vacuum tube (could have been knocked off by the rebuilder, 7 crossbar / air bleed, 8 idle fuel passage, 9 vent hole
B. If the pump isn't shooting fuel in the manifold, please pay attention to 1 and 2 in the second image. Also the passage leading into the bore for the fuel. And be certain the correct pump type was used.
C. Make certain all these little holes are clean and open (3rd image)
D. You may have this vacuum hole scheme. Your gasket may cover one of them. (4th image)
E. At this point your fuel inlet diameter could be any size at all. It is all a matter of chance and it matters what size it is. Carter specified the inlet size in all their carburetors. If Rochester ever did that, I could never find the data. Too large? You risk flooding. Take a look at what I found (5th image).
Good luck. Please let us know if you have questions.

One other thing. Make certain the main well tube is present. These get knocked off and Mr. Sleepy Rebuilder doesn't care a bit about that. But your carburetor certainly does. Here's what I found in one (image 1) and my repair of it (image 2).

And please check to be certain the power piston vacuum port is still present. These get knocked off or broken off by Mr. Genius Rebuilder and while he doesn't care, if your air horn (and float bowl) are warped (which is almost a guarantee), your power piston won't receive enough vacuum and will leave your power valve constantly open (which will make this poor thing run about twice too rich). Here's how I repaired one which was missing the port completely...

Thanks Jon!

Jon THANK YOU! The best I have ever seen. Copied it for my Rochester book, as you know I'm a Model "B" Nazi. Also thank you for using 5 different carbs. Over the years the mix and match of all B's, BC's and BV's have interchangeable parts with the two castings and steel throttle plate. One needs to be a pro due to this 70+ years of swapping around. It would be great if I could PM you some time. I have enough parts to make up ten at any given time. I try to match type to the year it is going on. Is there a manual that shows what type goes on what year? All these years I have just been winging it. Ed

"Is there a manual that shows what type goes on what year? All these years I have just been winging it. Ed"

This is a huge file so be patient. https://www.carburetor-parts.com/assets/manuals/Rochester%20Service%20Manual.pdf

...and one from drdoug and another that I stumbled on a while back.

Of course there is always the The Old Car Manual Project.

Phillip

Thanks Doc,
Sure...please feel free to PM me or contact me via email ([email protected]). There were other images on the Rochester B and BC, but you can't see them any longer since Photobucket went broke, sort of imploded and did away with everyone's images. I still have them, and have been meaning to post on Google photo but have yet to get around to it. I did move the straightening images to Google, so you can still see those. Rochester data isn't always easy to find.