Flathead: Early fuel-pump pushrod bushing in a late flatty

Hi fellas,

So thanks to Bruce 'The Encyclopedia' Lancaster, I went ahead and bought the pushrod bushing for an early flatty and found that it does in fact fit inside the existing pushrod bushing in my 8ba... Sorta...

It's not exactly an 'Interference fit'... It goes in pretty easy for about the first 1/2" or so and I don't want to get it only sorta stuck by shoving it in any further without a plan to keep in in place.

So what would you recommend to keep the early bushing stuck inside the late one?

-JB Weld?
-Knurl the outside of the new bushing?
-???

I've never knurled anything before and I have my doubts that enough of a surface can be raised to make this fit snug. But I'm willing to try...

Also, do I need to worry about the oil passage in the late block?

Thanks...

 

I'm thinking I might be able to get the bushing down in there and peen-over the top of both bushings to make sure they won't come up and out...

I don't think it'll fall down but I'm not sure...

Best method?

Also, this is a basically complete motor. My plan was just to cut down the 8ba pushrod to the right length but Bruce suggested I try to use as many readily replaceable parts as possible. I think that's the best approach...

But I have to carefull with shavings etc...

 

aneewhun???

 

Red Loc-Tite if it fits that snug. Or the old timey way before Loc-Tite tin it with a thin film of solder.

 

So, would the solder just be to make the tight fit needed, or are you actually trying to create a bond? I could do this for sure...

I also took a 1/2" 20 die and 'threaded' the outside of the bushing which makes the fit a little more snug...

I just don't know how tight this thing has to be? What kind of force is going to be on it to drive it out of the hole?

I'm thinking that with the way it is now and with the heat cycling it'll be under, I doubt it'll go anywhere. But the soldering thing couldn't hurt.

Thanks!

 

Is this a together engine or a bare block??

 

Soldering is just a way to slightly increase the diameter. Being that it is very soft any excess will shave away.

 

Anything that requires some tapping with a hammer should be plenty strong...and solder is nice and soft if chips get loose in there.
Aso, if you clean well, anything you use can be supplemented with loctite.
I asked whether engine or bare block...issues might arise from chips or from too-tight a fit causing outer bushing to be driven down. Hence, more caution if assembled engine.
Pushrod should be an easy fit and move with essenially no resistance, so if any real effort is required to gettitin, you should be fine. I meant to check on this after I suggested nesting the bushings...but alas, I am still looking for the blasted spare bushing.

 

Thanks for checking in Bruce.

The situation sort of solved itself... I was test-fitting it when it got stuck... So it was drive it in or risk screwing it up trying to get it out. So I coated the exposed area with red loctite and drove it down. It was MUCH tighter than I thought it was going to be. I actually thought it wasn't going to go in.

So now it's in but the pushrod is a little tight with whight litium grease. It requires a little effort to get it in but once it's in, it moves up and down the little ammount it will have to without much effort. Do I need to hone it or anything? I certainly hope not because this is about the last thing I had to do before buttoning it all up and test firing it.

 

Use a 3/8 (I think) reamer coated in grease to catch the shavings...or just a 3/8 piece of rod or old pushrod with a groove cut into it. I reamed a tight one once, and found that the entire problem was in about the first hundredth of the bushing, caused by the driving-in. If this seems to be the case, a common tapered reamer will kill the problem.