87 90HP Overhaul time

[Distress_signal]

Starting an overhaul of this 90 hp. Removed the heads from the PH and noticed a lot of wobble in the pistons. I do know there is supposed to be some clearance between the piston and the cylinder wall. Just not sure how wuch. How much is to much. <br /><br />Distress

 

[Goodoleboy]

Re: 87 90HP Overhaul time

Hi disstressed!<br /><br />If your kat..can crawl in it..its way tu lose.<br /><br />But if you can only..jest bearley get uh .004 feller gage long side it!<br /><br />Welt it aint half bad!,,ittl still go fishin.<br /><br />Ps! an ole fellar tolt me won time...son.. theys only two reasons why your ideys aint excepted...wun is yar idey aint worthy of exception....the other won is.... Son...you aint salesman uhnuff to put yar idey across tu folks!<br /><br />Now thatill cause us chew our cud..fer uh while!

 

[Distress_signal]

Re: 87 90HP Overhaul time

Thanks For the info, Well, Kat tried to crawl in, got hung up. HUH. And .004 isn't too snug, Just a little loose. Probably about .006, Trying to determine what has to be done. Cylinders have already been cut .030 over. Does not seem to be any indication of cylinder wear. No ring at the top. Just curious as to whether the machine shop that done the work last cut the cylinders right! Hope so.<br /><br />Distress

 

[DHPMARINE]

Re: 87 90HP Overhaul time

distress,Haven't seen anything in your posts and answers that tell me why the overhaul is needed.Can anyone enlighten me?

 

[Distress_signal]

Re: 87 90HP Overhaul time

Well DHP, Several Months back, I had to replace all the main bearings in the engine. When I split the case to get to the center bearing, there was a small Star Washer laying in the back of one of the pistons. I removed the washer with hopes that nothing was wrong. Since then, the engine has seemed to slowly start loosing power. Done a compression check on the cylinders, and 2 of the 4 where less than 60 lbs. The other 2 where 120 and 118 Top 2 cylinders where reading in the 100's, lower 2 where around 60. Today I was on the lake running, and the engine shutdown on me ( did not lock up) buty then had a hard time restarting. So after the comp checks, Tore the engine down to see what was going on. Pistons seem to have a little more clearance to the cylinder walls than I am used to seeing. This is why the rebuild. Any help would be appreciated.<br /><br />Distress

 

[Solittle]

Re: 87 90HP Overhaul time

You could go to 0.040 max unless you resleve.

 

[Dhadley]

Re: 87 90HP Overhaul time

The next OS is .044 and .064.<br /><br />Dont worry about the "wobble" what do the cylinders measure?

 

[Distress_signal]

Re: 87 90HP Overhaul time

Have not measured the cylinders yet, have to borrow some tools froma friend. Will be sometime this week. The cylinders do not appear to be worn, they do not have a groove at the top. But that does not mean that they are not cut to big. Will find out soon. Will keep everyone informed.<br /><br />Distress

 

[Dhadley]

Re: 87 90HP Overhaul time

You need to have the pistons out to measure the cylinder correctly. We need to know the size at the bottom as well as the top.

 

[Distress_signal]

Re: 87 90HP Overhaul time

Ok, finally got some tools to do the measuring with, One good thing is, all cylinders measured within .0001 of each other. Measuring top to bottom across the cylinder at top was 3.532 Bottom of cylinder read the same. Reading all cylinders from left to right across cylinder. measured 3.530 The bottom of the cylinders measured same. The pistons are stamped .030 on the top. Measured those, and all the pistons seem to measure thick in the middle, and narrow on the ends (top and Bottom).Thickest measurement of each piston ranged from 3.520-3.525 Seems to me that there is a lot of wear on the pistons. Which leads me back to my original question. How much free play is allowed between the piston and the cylinder wall. From what I am seeing, Changing the pistons out is guaranteed. As well as having the cylinders re cut. This engine already has been sleeved, can sleeves be cut to next biger size?<br /><br />Distress

 

[Dhadley]

Re: 87 90HP Overhaul time

Technicaly speaking you are within spec although about 1/2 way thru the acceptable limit for wear (life). However, .005" difference in pistons is a lot so youre going to change pistons anyway. Since you are going to change pistons (the expensive part) it only makes sense to bore (cheapest part) the cylinders.

 

[Distress_signal]

Re: 87 90HP Overhaul time

Thanks Hadley, That is pretty much what I thought. Now, Name me a few places I can get Parts at a good price if possible.<br /><br />Distress.