JimH Posted July 7, 2005 Posted July 7, 2005 Have a non running briggs model 23D that I need to know how much compression I should have for a normal running engine. The readings I get are between 40 and 45 lbs. per sq. inch. I suspect these reading's are on the low side. What are your thoughts?
D-17_Dave Posted July 7, 2005 Posted July 7, 2005 On a dry hand stated engine, this sounds normal. Try pooring a tablespoon of light oil down the plug hole and useing a starter on it for a controlled starting speed. I'd guese it should come up at least 40psi.
ReedS Posted July 7, 2005 Posted July 7, 2005 Briggs manual says only to spin engine counterclockwise by hand, if it bounces back when it hits the compression stroke compression is adequate. Not very scientific by todays standards. A valve problem will usually result in no compression (stuck or burned). Most ring problems are mostly of an oil control problem, in fact when really bad the oil will almost help seal the cylinder, of course at that point you'll have a great mosquito fogger at no extra charge!
ka9bxg Posted July 7, 2005 Posted July 7, 2005 Hey was'nt that a option for those tractors.Why waist all that extra money for a fogger when you just put a smoker engine in your tractors. Oh I think I have a few of those now.Oil is cheep compared to new pistons and rings,
HubbardRA Posted July 8, 2005 Posted July 8, 2005 Most of the older engines had "easy spin". This is a small bump located on the camshaft that opens a valve slightly and relieves a significant portion of the compression when the engine is turning slowly. This will make your reading show much lower than it really is when the engine is running. The bump on the camshaft is insignificant when the engine is running at speeds above 1000 rpm. I know. I filed the compression release bump off my 243431 when I first started tractor pulling. This makes it very difficult for the starter-generator to turn the engine past compression. I either need a new belt with high tension, or I have to turn it backwards to compression, then hit the starter, to give it two revolutions to get up to speed before hitting compression. Starts great, if you can get it past compression. It also has some great low end torque. Hard to kill that engine.
dlcentral Posted July 8, 2005 Posted July 8, 2005 So true on compression,these engs didnt have much.ratio is like 5.5 to 1.the reverse hand crank test works best to check comp. possibly the valve clearances on both or one of the valves is zero thats been my experience with them,they do pound down with time,And I think using racing gas in them its useless it dosent do anything unless comp ratio is above 9:1,then you need slower burn/racing gas so it dosent pre-ignite, imo of course,, our pullers all use old 87 octane with no probs at all,comp pressure on ours is around 100 lbs BUT thats modifing head,special valve job, etc.
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