Engine runs very bad

tomkline

tomkline

Junior Member
I have an engine that seems like it isn't getting enough fuel. Installed rebuilt carb, same problem. Retorqued head, no difference.
Retorqued manifolds, some change but still not good. Checked compression, all cylinders at 55+. Checked flat of intake/exhaust manifold mounting surface, intake may be 1/16 below flat edge. Any adjustments made at carb had very little effect. No cracks seen between intake and exhuast ports. What am I missing? Anymore suggestions.
 
And of course make sure you have adequate fuel flowing to that rebuilt carb. Could be an upstream obstruction, such as junk in the tank, etc.
 
tomkline said:
I have an engine that seems like it isn't getting enough fuel.
Click to expand...
OK so what are the symptoms? lack of power? misfiring? overheating? reluctant starting? or what?
also check carb/manifold and manifold/engine gaskets for leaks.
 
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I believe you need to fix the manifold, you stated you retorqued it and there was some change, then you also said that it was 1/16 out of alignment, It needs to be machined together with the exhaust manifold.
 
Are you getting spark to all the cylinders? Use a screwdiver to ground out each plug one at a time if no change is heard when grounding the plug out then that cylider is not firing.
 
First things first. I'm with Brian. If you're trying to say that the manifold surfaces are 1/16" out of alignment, then that needs to be fixed first. When bolting both manifolds together [ no gasket goes between them] and laying a straight edge over them if a .010" or greater/larger feeler strip can be fit/slid under the straight edge, then, they need to machined.
 
tomkline, if vacuum leaks are a suspect, buy a cheep, ($2.99) Harbor Freight stethescope, remove the probe & use just the open hose to check for vacuum/exhaust leaks. It'll scream like a BANSHEE when you find a vacuum leak! Used with just the hose, the stethescope is great for localizing noises that transmit everywhere when using the probe. Example: just 1 ticking valve can be localized by passing the hose alongside, (not touching) the engine side cover. WARNING never stick the hose on a vacuum fitting, it'll "suck" your EARBALLS OUT!! Bill W.
 
Thanks for all the help. I put manifolds back on and torqued. engine started but still have a little backfire when accelerating. I have an idea it may be a valve that may not be seating properly. I did check the points, set at 18, checked gap of rotor, set at 25. The carburator did respond to adjustments. Also tried a different coil. Should the spark be blue or orange?
 
leaky ex valves can sometimes be diagnosed by placing a hand close to the tail pipe if a valve is leaking or sticking it will momentarily suck your hand up on the pipe. intake leaks will pop out the carb. a vacuum gauge can tell the same thing.
 
Sounds like you are getting lots of advice. If the timing is correct the next obvious problem is fuel supply. Pull the fuel line from the carb and place the end in a coffee can or something to catch the flow and open the valve see if you get good flow. If it is restricted the car will run poorly.
 
It looks like the ones that suggested it is the intake manifold leaking win.
A friend, that is a county fleet mechanic showed me a trick. Spray some ether around the intake. It showed up right away. It sure looks like it is tight against the gasket. Thanks again to all who chimed it with suggestions.
 
Had manifolds machined flat, installed, runs great. Now am able to adjust carb. Thanks again for everyone suggestions.
 
Humble opinion:

A Model A whisper is someone who learns to talk to his Model A & listens attentively to exactly what his Model A is saying.

The minute you tightened the manifold, your Model A was whispering something to you as the rpms increased; but you did not listen!

In whispering to your Model A, if your wife sneaks up & catches you talking to your Model A, there is a canned answer to tell her that I learned years ago from an Uncle I heard talking to himself while we were working as carpenters:

For example:

If your wife catches you talking to your Model A, just respond & tell her: "I enjoy talking to an intelligent person, & I enjoy listening to a smart man talk!"

Your wife might think you are crazy, but at least in whispering & listening attentively to your Model A, you will have a far better chance to get your Model A running better!

Hope this helps!
LOL
 
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