The Stovebolt Site Forums The Shop Area Engine Shop Hesitation and power problems

Trying to get my '53 Chev 3/4-ton running properly. It had been sitting for about 5 years. Drained the gas and replaced it. Starts, but has little power and lots of hesitation during acceleration. I pulled the plugs and all have heavy carbon deposits, although it brushed right off. Checked point gap and it is set at 16. Tried to check timing, but need a better timing light to do it. Engine had been overheating, so put in an electric cooling fan and that stopped the heating problem. Vacuum advance seems to be functioning properly. So, aside from checking the timing with a better light, what would be the most logical cause of severe hesitation and no power plus the carboned plugs? This is a 235 and it was rebuilt about 7 years ago and never has run right.

Check the power valve piston in the carburetor. It's probably stuck in the down position which is bypassing the main jet with a severely over-rich mixture. All the symptoms you're describing are characteristic of a VERY rich mixture. Rochesters are notorious for sticky power valve vacuum pistons.
Jerry

I forgot to mention that I was having a problem with the accelerator linkage binding and it was causing the engine to rev very high when it got warm. I've corrected that today, but would high rpm revving cause the carboned plugs? also, probably doesn't make much difference, but the carb is a Carter 1 bbl.

Judging by how long you've told me the engine sat your gonna have carb issues. Go through and clean the carb out. The hesitation through the rpm rang can be either vacuum leaks or lean fuel mixture, or even your spark is not advancing properly or timing way to retarded. Clean the carb, throw in a new set of plugs, make sure the distributor cap and plug wires are in good condition, make sure you've got fuel pressure as well and that your fuel line and filter aren't dirty cause if they are that will cause poor operation as well. You say it hasn't ran right since it was rebuilt? Then there's a ton of other factors that could come into play, but for now...check the carb, check your ignition(plugs, wires,coil, ect) and adjust your timing to 8-10 degrees advanced without vacuum, and make sure you have good fuel going through the system.

Thanks for the tips. Much appreciated.

Just finished rebuilding my "B" last night and the power piston is the one thing I'm not quite satisfied with.

The large part of the piston moves in its bore pretty well. The travel against the little check ball in the well housing is what I'm not sure about. If I move the piston against it's spring all the way...the small end tends to hang on the housing rather than float freely back against the check ball and small spring. But, I might be moving it farther than what occurs in "real life." As long as the small end stays somewhat engaged against the ball...and doesn't completely leave the housing...things move OK.

That's probably a terrible explanation....but if anyone can interpret, do I need to remedy that?

Okay, I think I've fixed the hesitation problem. Cleaned the spark plugs (they weren't all that old) and gapped them at .040. The timing was off a little and I got that adjusted. My engine has a Carter 1 bbl 2100S carb. I know from what I've been able to find here that they are "easy" to disassemble. However, I've not done that before, so can someone walk me through it or put me in touch with a link where I can get some step by step information and not screw this up? My shop manual for the '53 does not show a 2100S carb. Any help would be appreciated. I test drove the truck after adjusting the timing and it was much better, but it died on me as I got home and didn't want to start at first, so I'm pretty sure there is an issue with the carb since it sat so long with 5+ year old gas in it. The shop manual said to turn the idle screw all the way in and then back it out 1-3/4 turns. I did that, but am wondering if following those directions were appropriate for a 2100S carb as well, or did doing that cause this new problem with it dying and not wanting to start again after the engine was warm? Thanks in advance for any guidance.

You have to modify the heat insulator block when using a carter 2100s. There is a vacuum port at the base of the carb. If you do not make a "channel" in the insulator block, that vacuum port is blocked and you will have drivability issues. There "channels" in the block for the Rochester B but they do not line up for a Carter.

John G

Ok I'll check that out. Thanks for the heads up.

Rick, if you think it will help, I'll upload/post a link to pictures of my Carter YF 2100S disassembly and cleaning I did a couple months ago. My carb's still as clean as it'd get, and it's still disassembled. I guess I'm letting it air out some.

Just take your carb apart and keep the parts grouped together as you remove them. Maybe use sandwich bags or something to store them in. I used lacquer thinner & a rifle cleaning brush to scrub it clean.

John, thanks for posting the adaptation information. I have never heard about that & need to check into it.

Brad

Edited to include those YF2100S disassembly pictures.

This modification is not necessary if one uses the Carter mounting gasket instead of the Rochester. The Carter gasket is slotted for the vacuum port.

Jon.

That is correct. I do not know how many people have installed a carter and used the wrong base gasket or did not modify the heat block, get frustrated with the performance of the crater and put the B back on.

John G

Hey thanks for the photos! I think they will be of help. Much appreciated.

The gasket issue reminded me of another question. My carburetor has the thick black insulator block, but it also has a thin gasket both above and below the insulator. Is this a proper installation?

No problem---Here's a previous thread with good info if you haven't seen it.

And, a link from Kurt & (DADS50 also has some) in the same thread on Carter YF service procedure. I printed this off as a guide.

Brad

I was doing a little work on the '53 yesterday and checked the heat riser only to find out the spring was missing. Fortunately I had a new one in my collection of parts, so got that fixed. Not sure what happened to the old one, but it wasn't broken -- it was just plain not there. Just curious -- what does a missing spring do to performance?

Once the engine is warmed up, the spring is out of the picture as far as performance is concerned, as long as the heat riser is in the warmed up position. The counter weight is what puts the heat riser in the warmed up position. The bi-metallic spring holds the heat riser in the cold position until heat works on the spring, allowing the counter weight to move the heat riser into the warmed up position.
Carl

Got it. I never noticed any difference after I installed the spring, so just curious. Thanks.