Crankshaft end play- Just how critical is it?

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Flathead Builder

Member
I'm rebuilding/restoring a 1972 Briggs 3HP, Model 80202 "Koolbore" engine. It is important to note that this engine is NOT a race engine or otherwise any type of "performance" upgrade or build. This engine will never see anything over about 4,000 RPM. I checked the crank endplay and it is .013". For this engine, Briggs specs say .002-.008" for crank endplay.
My question to you all- At .005" over the maximum, just how big a deal is this? Any anticipated damage to the engine if I run it this way?

I know that I can install one of those thin Briggs thrust washers (they are about .020" thick) to reduce endplay, buy then I will then have to add one (or more) of the thinner (.005" or .009") side cover gaskets to bring it back into the required .002" to .008" range.
Before anyone suggests just installing a thinner side cover gasket to begin with, the Briggs manual states that on this engine you should not use any side cover gasket less than the "standard" one which is .015"
I would welcome and appreciate your comments...
Thank you,
Michael
 
It will be fine. What would be good though is to pull the locating pins from the side cover and then sand the gasket surface on a flat plate at least until it looks to be flat again. That would make your gasket seal better and reduce a little of the endplay.
 
Thank you for the reply. Actually, I have been using the technique you suggested for years to flatten the sidecover so that they seal better, w/o leaks. I use a piece of 1/4" glass with a sheet of 400 grit wet or dry sandpaper taped to it. No need to "pull the locating pins" as they are fixed into the block, not the sidecover, in the engines I have seen.
Michael
 
You can just running a thinner sidecover gasket without worries.
Since it is not for sanctioned racing (ie no sealants allowed) just use a quality sealant on the sump cover (with or without the gasket) since you've already got it flat.
Unless you have a LOT of blow-by (or not enough ventilation), there's not enough pressure in the crankcase to blow out even the thin paper gasket.


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In order too do the block .
The pins need removed .
Flathead Builder said:
Thank you for the reply. Actually, I have been using the technique you suggested for years to flatten the sidecover so that they seal better, w/o leaks. I use a piece of 1/4" glass with a sheet of 400 grit wet or dry sandpaper taped to it. No need to "pull the locating pins" as they are fixed into the block, not the sidecover, in the engines I have seen.
Michael
Click to expand...
in order to do the Block , the pins need too come out .
 
Many thanks to all that have replied- much appreciated. That being said, back to the reason for my original question...
With the engine as I have described, if I do nothing and left the (excessive?) end gap where it is- Is it a big deal or otherwise any cause for concern?
Michael
 
The predator type engines have shims available to slip over the nose of the crank. Maybe Briggs does too.
 
End play doesn't stay where you set it. .002" is rediculous, .008" is bare minimum, nothing wrong with .015". If it were .017" I'd be concerned. I shoot for .012".
 
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