Dolmar 421 base gasket thickness

[ColdStihl]

I measured squish at 0.027" (@ 4 points, std dev 0.001"). What is the base gasket thickness to help me determine if a delete would be prudent. While I don't have a comp gauge, the compression on this saw feels quite high as is.

On this note, for you saw builders out there who have worked with this saw, do you feel that dropping the jug down would be a risky proposition given that the squish is pretty small with the gasket?

Thank you.

 

[Poleman]

I find most Do;mars have VERY thick base gaskets and you have to careful deleating them as tolerances get to tight. How did you arrive at your measurement? Did you pull jug to measure if so couldn't you measure the base gasket...or did I miss something???

BTW, I have never ventured into this particular saw just going from working with 510, 5105's, 6400-7900's.

 

[ColdStihl]

I find most Do;mars have VERY thick base gaskets and you have to careful deleating them as tolerances get to tight. How did you arrive at your measurement? Did you pull jug to measure if so couldn't you measure the base gasket...or did I miss something???

BTW, I have never ventured into this particular saw just going from working with 510, 5105's, 6400-7900's.

Did not pull the jug. I used thin electrical solder through the spark plug hole and used a digital Mitutoyo dial caliper to measure the flattened solder. I took readings in four locations opposite of each other. I measured the sides along the axis of the wrist pin twice each and all readings were identical.

My initial thinking was that if the gasket was less than 0.010", I might be okay. Any more than that and I would most likely run into trouble.

 

[Poleman]

You might physically look and see if you can get an idea if you pull the muffler....sometimes a corner is sticking out to get a measurement. I'm thinking you may have to make a gasket to get to where you'd like to be in squish.

 

[ColdStihl]

With the muffler pulled, I see the gasket sticking out around the edges. Too tight in there to measure and eyeballing won't cut it, of course.

I do have a ring compressor kit, so pulling the jug is not out of the question. The saw is almost new, but I'm not sure if the gasket will be stuck or salvageable. This is pretty much why I started the thread. If someone knew the thickness off-hand, I'd be able to determine if deleting the gasket is feasible. I may have the jug machined (0.007") while keeping the OEM gasket. I'm still in the information collection phase.

 

[Poleman]

That might be the solution. I find Dolmar gaskets to be quite thick in there smaller saw that I have had a chance to work on. Usually in the area of .035-.038 with a rubberized outer coating and metal in the middle....at least thats on the 5105's. If your gaskets thick like that you could figure what you need to take out and use thinner material to get you at .020 or slightly less.

You could get a measurement by not totally taking off the jug....take the 4 bolts out and raise it until you can get a caliper on the gasket.

 

[ColdStihl]

I will take that into consideration. Thank you!

 

[fordf150]

base gasket is .018

 

[ColdStihl]

Uff da! That is pretty thick. Thanks for the info!

base gasket is .018

 

[Poleman]

Got me thinking maybe I've been inhaling to much saw fumes so I had to measure.......

Here's what I found.
5105


510

Found this interesting since we're on the subject.

 

[ColdStihl]

Thanks for the pics! This should be good reference material for others wanting this information.

 

[blsnelling]

There's only one way to find out. Pull the gasket and re-check.

 

[ColdStihl]

Brad, do you find that the gasket on newer saws are reusable/removable? The answer may be obvious based on your advice.