1988 Johnson 70hp inspection

[airshot]

Prop guy says block must be at a certain temp to bore correctly.

Any details you have would be muchly appreciated.

Matt

I never heard that, and mine turned out ok. Remember, your inky removing a tiny amount of the dia....015 up to .030. Heavy cuts might make a difference.

 

[airshot]

Bored a couple of cylinder jugs on a lathe w/4 jaw chuck, but no engine blocks.

A block would take forever to set up properly on that Bridgeport. Much better off using a mill designed specifically for engine work.

Very true, but sometimes you use what you have. I worked in a die shop at that time, we had all kinds I of setup fixtures...at home in a garage....yep would be a challenge !

 

[saltchuckmatt]

I never heard that, and mine turned out ok. Remember, your inky removing a tiny amount of the dia....015 up to .030. Heavy cuts might make a difference.

Yeah, he said he thought they had to go into a freezer. Obviously they shrink and expand based apon temp. If anyone knows if that's true please speak up.

Right now I have two 30 hp and a 70 jphnsons that have low compression in some of the cylinders...usually here in Seattle its off to the scrap yard.

 

[tphoyt]

If you have access to the mill practice on a junk block and see how things go.

 

[saltchuckmatt]

If you have access to the mill practice on a junk block and see how things go.

In my area, these are junk blocks!

 

[tphoyt]

I guess you have nothing to lose. That’s the kinda of project that would be on the top of my list just to have fun and see how it came out.
When I was a kid I got TH350 transmission from the junk yard and rebuilt just to see if I could.
I didn’t have any parts left over so I think it would have been fine but never did try out.