Turning an engine on a pallet w/the starter? [Archive] - Chevelle Tech

: Turning an engine on a pallet w/the starter?

Apr 8th, 06, 7:04 PM
Okay my fellow enthusiasts, I must admit to all of you who don't already know, that electrical tech stuff intimidates me, and is my absolute weak point amongst automotive topics. So it's for that reason that I need to ask you the following, which I suspect will be easy stuff for some of you guys. If you don't care to read all of the details nor the reasons for my question, then just scroll down and read the rest of the words in this post of mine that are below the two happy faces.... and if you're curious about some of the reasons and details, then feel free to read the words of this entire post.....

I want to turn over the BBC crate engine I've purchased using the starter motor that I've already mounted on it. I want to do this before installing the engine in the car, in order to satisfy this carnut curiosity I have concerning exactly what PSI reading a compression test will yield for this engine.

In case you're curious about my reasons, let me explain that although a compression tester is most commonly used to detect the possibility of worn piston rings, or valve seals, that isn't the reason for my desire to perform this test on this engine since it's a brand new motor.

I've just read an extremely informative and intriguing article written by David Vizard (this guy knows his stuff!!!)given to me by Steve, which among other things, explains how and why a compression test reading can be used for evaluating if the compression ratio of an engine is ideal for the camshaft and valve timing that's used therein. Before anyone argues, please note that I'm very aware of the fact that a compression tester cannot be used to determine the static compression ratio of an engine, and that isn't what David Vizard is stating in the article. But since I'm not intending for this thread to be about David Vizards article, if you wish to hear more about my choice to use a compression tester for this evaluation, then click on this link to read his article, and it will explain. http://popularhotrodding.com/enginem...power_squeeze/ (http://popularhotrodding.com/enginem...power_squeeze/)

If you don't want to read the whole article, then just scroll down to the part that's titled "Dynamic CR" since that's what can be determined by the use of a compression tester, and also read the short section titled "Compression Pressure" which is right after that. It speaks of the ideal PSI readings being between 180 and 210 for the best combination of power and avoiding detonation/pinging for an engine that's run on 93 octane pump gasoline alone (which will be what my BBC engine will be run on).

HAPPY FACES>>> http://forums.hotrod.com/ubbthreads/images/graemlins/smile.gif http://forums.hotrod.com/ubbthreads/images/graemlins/smile.gif

Anyway, I need to know exactly how to jump the starter and solenoid in order to turn the engine over with the starter, in order to perform a compression test, before I put the engine in the car. I did this once before with a Cadillac engine, but it was so long ago, that I don't remember which of the starter terminals to use.

Obviously the positive battery cable get's hooked to the big terminal which is located on the starter motor itself, but that leaves the two small terminals on the solenoid sarter solenoid, one of them being the "S" terminal (short for "switch") which I know is for merely kicking out the pinion gear to mesh it with the teeth on the ring gear of the flex plate/flywheel. But how do I run a jump in order to turn the starter , and therefore turn the engine over for the compression test that I wish to do?? I know that I can simply use a screwdriver for this, or I can use a handheld button that has terminal clips that's made specially for bumping the engine with the starter, but which terminals do I need to run the jump from, and to ????

Apr 8th, 06, 7:08 PM
All you have to do is make sure the big lug has 12V and the engine is grounded well, then apply 12V to the "S" terminal and watch out.

Apr 8th, 06, 7:10 PM
Connect the (+) battery cable to the large terminal on the solenoid, and of course the negative cable to the block. Put 12V (+) to the "S" terminal of the solenoid. This will pull in the solenoid (and the pinion gear) and turn on the starter motor.

Apr 8th, 06, 7:14 PM
Thanks guys!! Ya know, someone just reminded me of the fact that this test might not be accurate with a cold engine, and I honestly was completely overlooking that. so maybe I'll have to wait until I get the engine in the car, and I'm then able to run it in order to get it to operating temperature before performing a compression test. Again, thanks for the info.

Apr 8th, 06, 7:17 PM
Unless this is a roller-cam engine, I wouldn't be doing a compression test BEFORE breaking in the cam 'n' lifters...

Apr 8th, 06, 7:23 PM
Unless this is a roller-cam engine, I wouldn't be doing a compression test BEFORE breaking in the cam 'n' lifters...Very good point my friend, and thankyou for looking out for me. However, it is in fact a roller cam in this engine, and the engine has also been run and broken-in on the Dyno by the engine builder before it was delivered to me. I do appreciate your reply though. :thumbsup:

Apr 8th, 06, 8:18 PM
I was about to warn you that you probably won't get an accurate reading until you have it broken in, since the rings wouldn't be seated, but then I read your last post.

al carson
Apr 8th, 06, 9:36 PM
I remember my good friend did the TEST??. He put gas to it and Jesus H Christ he thought something was wrong-seems that he was pouring gas down the carb-what a hell of a ride he experienced-he was standing over the carb-
BACK FIRE-he walked a little funny for sometime-oh well-humans are stupid.