cat 15 compression

that sounds awfully low--have you tried any additives to free up the rings?

No not yet was going to try oil but it seamed low so i was looking for a base line before wasting any more time

I have had several 15s that had that kind of compression that I brought back to life. Don't think in terms of modern compression numbers. I have never seen an actual new compression number but my guess is that it would be between 40 and 50.

Get everything correct from the magneto to the carburetor and start cranking. Every pop and snort you get will help free up the rings. I think you have a good chance to get her running. Keep us posted.

those are a fairly low compression engine, not sure how you are cranking it but cranking speed can affect compression numbers slightly. is the inlet manifold clear? sometimes you can get a mouse nest in it or other blockage that can affect compression. if it has been sitting for a long time, as others have said the rings could be stuck causing low numbers as well. don't give up. there are many old engines out there that are worn out and still run ok. you could put a few squirts of oil in each cylinder, to see a wet compression test but that may give you a false high number as well.

with good spark, and proper air to fuel ratios, the engine should start even with the compression numbers you have indicated. especially if the compression is even across all cylinders. if you had one cylinder that was drastically low you may have an issue.

my first pickup was a 1978 ford with a propane converted 390 in it. the 390 was built for propane with high top pistons, and shaved heads. the valves wer so burnt out that it only had 75 lbs compression on three cylinders, the other 5 cylinders had between 30 and 40 pounds compression. i drove that truck for two years like that. when i finally pulled it apart to fix it, it struggled to make 25 lbs compression on the 5 cylinders. that old truck ran wihtout a miss, but was really underpowered. a new set of heads and a bit more lumpy cam and it was off to the races.

I believe the correct procedure for a Compression test is "wet" not "dry".
As Jason states, lots of times they rattle loose after they are pull started and worked till hot.
My 22 which is totally worn out, you could spin it with 2 fingers on the crank.
We push started it, ran it, then loaded it for trip home. I was able to crank start it to drive off the trailer. Took it out in the field and worked it till it was blowing out the radiator. Now it has compression enough to start fairly easy though it does have a lot of blow by. I run high detergent oil in it to wash the crap out. I pulled the cover off from the bottom of the oil pan and scraped 3/4" of crud out.
Just saying!

Thanks guys for confirming my susspions that more r.p.m.would probably get her started the mag was rebuilt by marks magneto the carb rebuilt and gas tank flushed out.
What was throwing me of was i took a compression test on my cat 22 and it 50 to 60 lbs cranks up on 3rd crank so i was comparing the two.
I will get ready and try to drag her down the street in the next coule of weeks will keep you informed.
Again thanks for your support.
Dan

thanks guys took your advice got her all ready fuel etc. rigged up chain and pulled it about 40 feet in 2nd gear with Bobcat and she started right up.Ran it till had good temp. ran it back and forte steered left and right no problems not bad after 15 year rest. Have a problem with water pump packing nut adj. did not stop leak need to know where to get packing ? for it also on the track rollers where to get grease ftg. attachment. After sitting about an hour hand cranked 9 times and she popped right off it is a beautiful thing. thanks again

thanks guys took your advice got her all ready fuel etc. rigged up chain and pulled it about 40 feet in 2nd gear with Bobcat and she started right up.Ran it till had good temp. ran it back and forte steered left and right no problems not bad after 15 year rest. Have a problem with water pump packing nut adj. did not stop leak need to know where to get packing ? for it also on the track rollers where to get grease ftg. attachment. After sitting about an hour hand cranked 9 times and she popped right off it is a beautiful thing. thanks again