MAC 1-40 Cylinder pressure?

[crane]

Got a 1-40 that pulls 122psi cold on three pulls. warm the saw up and it drops to 111psi. Saw has sat a longtime before I found it and just finnishing a clean up. Does this sound right??? Thought I"d be higher when the cylinder warmed up. Could I gain psi once the saw gets a few tanks of fuel thru it??
Just wondering.....

 

[PES+]

Check your head gasket and check the head for warpage

 

[crane]

Check your head gasket and check the head for warpage

wasn't planning to go that far.....saw runs like a top now and afraid I won't find another gasket to replace this one if it's damaged during diassembly. What should that saw put out for compression? Looking through the spark plug hole, seems that there's plenty of cross hatch left on the cylinder walls, could the clyinder be damaged running it at low compression?

 

[PES+]

Then just tighten the head bolts and leave it be.

You can make a thinner gasket as the stock gaskets left miles of room in the combustion chamber at TDC.

In the old days we used to steal all the aluminum ashtrays from Burger king and roll them flat and cut them for head gaskets.

 

[046]

check your compression gauge... does it have a shrader valve at tip?

Got a 1-40 that pulls 122psi cold on three pulls. warm the saw up and it drops to 111psi. Saw has sat a longtime before I found it and just finnishing a clean up. Does this sound right??? Thought I"d be higher when the cylinder warmed up. Could I gain psi once the saw gets a few tanks of fuel thru it??
Just wondering.....

 

[PES+]

How long is your hose?....

 

[PES+]

OK.put the test gauge down

And back away slowly........

Now realize something.......there is NO PSI spec for those macs......all relative in the repair manuals.......if it is lower hot than cold...you are most likely losing compression due to a leaky head gasket seal.

The cast iron liner grows slower than the aluminum piston so it should raise some when warmed.

The troubleshooting spec for the 1-40, 1-50, 1-60 is no less than 90 PSI they do not list any other specs due to various configurations for varied fuel octane ratings and elevations. (The actual manual describes just pulling it over and feeling for the compression rebound only if suspect do you use the gauge)

There were several different thickness head gaskets to be used for the different condtions.

 

[crane]

check your compression gauge... does it have a shrader valve at tip?

yes it does. The tester is brand new and I checked that the schrader valve was tightened correctly......When I started this, figured I'd get in the neiborhood of 150psi.....Am I out to luch on this??

 

[crane]

And back away slowly........



Ya caught me Doc, Got a case of saw fever! LOL


Is the head gasket metal?, or can you make your own with gasket maker? Are there tolerances in the head that I should be aware of?? If so, where's a good place to start. Been doing some searches here with some results.

 

[crane]

Looking at PARRISW's pressure/vac set up. Looks like that could come in handy to check what/where any leak down I have may be.

PSE+ - Ashtrays at Burger King???? Now that's going back a ways :hmm3grin2orange:

 

[heimannm]

Compression?

You know that the 1-40 is not exactly a new saw? If it has enough compression to start and run it is probably good enough. Try tightening the head bolts, and if you decide you really need a new head gasket call Bob Johnson (607 638 9297) and he can probably fix you up with a new one.

I was using my 1-46 this past weekend to cut some firewood, thought it would be fun to use a classic saw again. Even my 621 Jonsered is lighter and faster (and only 56 cc) but it was nice to be reminded why I have the newer saws.

Mark

 

[crane]

......I was using my 1-46 this past weekend to cut some firewood, thought it would be fun to use a classic saw again.

Just asking questions to get a better feel for that ole saw. I'm with you,like to run a classic every once in a while. You get a feel for what the "Old Timers" went through. I'm one of those guys that if I own it I want to know it inside and out..... This site is the best for that....HANDS DOWN

 

[pioneerguy600]

I agree wholeheartedly ;I run a couple of different vintage saws each weekend to keep in touch with days gone by and to remind myself of how far modern saws have advanced since 1948. Pioneerguy600