The Stovebolt Site Forums The Shop Area The Electrical Bay comression check

Can anyone tell me how to use a pedal starter to turn over the engine so I can check compression while I just have a motor and frame. I want to make sure the guy that sold me the motor did not lie and that it is as good as he said before I start to put the sheet metal back on. Any and all ideas would be great.
Thanks
Brian

Brian,

I would pull the plugs, get a helper to operate the starter, and with the gauge stuffed in a hole (or screwed in) have the helper give it a stomp for about 6 revolutions or so and check your gauge. It sounds like there is no wiring yet, so just stomp away.

Remember you are looking for both adequate compression and little variation between cylinders. I would want at LEAST 95-100 psi for my high reading and a variation of not MORE than 10 lbs. These values would indicate a engine that would work, but wasn't new. Any large difference on any one cylinder would indicate a problem with that cylinder...enough rant, good luck. I just re-read...no cab! Push on little button on starter switch.

Stuart

If the lever that slides the starter shaft into the flywheel and contacts the starter button on the top of the starter is still there it should be fairly simple. With the sheetmetal on my 38 I simply use a long/heavy screwdriver to pry against the sheetmetal and force the starter shaft lever forward to engage the flywheel and starter button. I do that with one hand while holding the compression tester with the other. Since your sheetmetal is gone you should be able to rig something to pry against or simply push the lever forward with your hand. It doesn't require that much force.

Thanks for the info. If I understand right all I need is a good battery and a starter. No other wiring needed to get the starter to trun over. I am going to give it a shot today. I will let you guys know what happens. Thanks again for all the help.

Brian

Turns out my starter is probably bad. I have a new one on the way so until then I am just in sit and wait mode. Thanks again to everyone who had advice.
Brian

little horse,

Far be it for me to tell a person what he should do, but the starters are REAL simple, and very fun to take apart, repair and assemble then paint. It looks like a factory rebuild, except you did it yourself.

If you have a new one en route and they don't require a core, don't dump the old one, it has value.


Stuart

If your vehicle has been sitting for a long time it could be your starter switch. Very simple to pull the two screws & remove it to see if theres something (cobweb, dead bug) keeping the switch from making contact with the top of the starter.

Well I decided to take my starter apart clean it and give it another try. Sure enough it worked. I was able to get between 85 and about 110 psi on all but one. One came in a little lower closer to 70. Pretty good for a $50 235 out of a 56. I hope that 70 won't become a problem later.
Thanks again for all the advice.
Brian

I'm happy you got your starter working Brian. You should be concerned about the compression though. Every manual I've seen considers a difference of more than 10% between the cylinders as being out of tolerance. Even without the 70 PSI cylinder you show a need for further investigation to determine whether you need a valve job, ring job or both. Remember Murphy lives.

Since I have zero wiring other than the battery what would the minimun needed to get the motor running and see how it goes. I will look into the compression issues as well.
Thanks again

little horse,

I thought this had already been talked about above...I don't see it. I think all you need from an ignition standpoint would be a wire from the battery to the + side of the coil. You should run this through a switch so you have the ability to shut the truck off.

If just for a short while, a fully charged battery should run the rig without a charging system on line.

If your system is 12 volts, a run resistor in the primary coil circuit is needed, and probably a good idea even for a short run....or a coil with the secret goodie inside (internal resistor).

Not very many wires to hear the old beast purrrrr! Don't forget your throttle return spring.

Stuart