Ironhead oil return for stroker

[11B40]

Originally Posted by RicThompson

Glad you mentioned tubing being inserted down from the top. The oil return hole is 3/16 which means hole must be drilled oversize to fit tube in. Why is it down from top when drilling from bottom would be much easier?

You can go to a modeling shop and buy tubing in many sizes. It is much thinner material. An exact fit can be reached this way. Using regular copper tube is putting in very thick material into the hole. The upper hole doesn't need to be absolutely sealed, as mentioned before, lots of splash is going in there anyway.

[OttoOtto]

If the upper hole is not completely sealed the oil will come in the cylinder above the oil ring which would cause motor to smoke right? Even if you flared the top end of the tubing after the oil flows down to the lowered hole isn't it possible for the oil to try to back up in the tube and if the tube isn't a tight fit going past the upper hole oil could get in the upper hole and above oil ring. I am getting ready to lower my holes and would prefer not to braze cast iron. I have done a few strokers years ago always brazed but always a chance of repercussions from all that heat even with preheating and such. I'm glad someone brought this up. I'm not experienced like a lot of you so I'm looking for a cleaner less crude way to lower the holes and plug the upper ones without failures. Thank You!

[OttoOtto]

Originally Posted by Iron Mike

I have seen both the epoxy and the brazing. seems the epoxy is much more commonplace nowadays. Also have seen the 3/16 tubing inserted down through the cyls.

Thanks to those that shared their past break in procedures.

2 years ago I let a machinist lower the oil holes for my Stroker, put tubes in then plugged upper hole with JB weld, woops motor started smoking out both cylinders, JB weld came out of one hole in each cylinder but stayed in two holes. All the other strokers I built I brazed the holes I don't like to braze them but I should have. Anyway maybe J-B Weld was the wrong thing to use maybe there's better epoxies out there but anyway just my one experience with epoxy. Thanks to everyone on this forum lots of good information

[MDT]

I have done the brass tubing, flared at the top, going into the case. I did not plug the cylinder holes. It worked fine.
Now I am running external returns It works also
If you need to plug the hole in your cylinder silver solder will work at a much lower temperature.

[RicThompson]

Originally Posted by Nitro57xl

It's done from the top because it's very hard to pick up the right angle from the bottom, also the original drilling varies ? If you drill from the bottom and you miss the intersection with the hole from the top you won't be happy?

Yesterday I grabbed an old cylinder off my shelf and using a 1/8 drill bit I drilled from the top all the way through the bottom. Now if I used a 1/4 drill bit and drilled from the bottom just past the oil return hole I could use a much shorter 3/16 tube from the bottom. Then drill my new lower return holes. I could even tap the bottom for a set screw to keep tube in place and stop oil instead of just relying on the base gasket. Thoughts?

[spacecoast]

Originally Posted by RicThompson

YI could even tap the bottom for a set screw to keep tube in place and stop oil. Thoughts?

Stop the oil from draining from the top? You'll be smoking in no time.

[RicThompson]

Originally Posted by spacecoast

Stop the oil from draining from the top? You'll be smoking in no time.

Apparently you missed the part about inserting shorter tube from bottom. The set screw would be in the cylinder base. Yes the whole idea is to have oil return from heads into crankcase.