The Stovebolt Site Forums The Shop Area Engine Shop Basic Carb What Should I Do Question

So, to make a long story longer, I rebuilt a military 302, and a PO (ok, it was me) attempted to drill and cut out the block for a mechanical fuel pump. But, about half of the pump lever (right name?) sits on the camshaft. The hole was cut and tapped and is offset for the pump.

I made a 1/4” steel block off plate, and resigned myself to use an electric fuel pump.

The carbs I can use are a NOS Zenith single barrel for a 270, or a 2 barrel Stromberg. I have the intake to fit the 2 barrel.

What are the pros and cons to help me decide what direction to go?

And, I need advice on an electric fuel pump that would best fit the application.

Truck: 1950 GMC 1 ton. Dual axle, flat bed. 4.10 rear end 20” wheels. Local travel, not really highway travel.


Thank you.
Tom

The other idea I had was to modify the fuel pump and figure out a way to add width to the pump levers. But, I stop short because I do not want it to fail and drop down into the pan or gaum and obliterate the camshaft (word choice for dramatic affect). Thoughts about how to go about doing that?

Thoughts were to remove a lever from an old fuel pump and somehow permanently affix it to the fuel pump. Either drill and tap 2 screws, drill and use through bolts, or weld, or both. Don’t like the idea of small screws and bolts inside a block. And not sure if a weld would hold under stress and working condition.

Will leave the fuel pump question to others.

If you have the CORRECT size Stromberg 2-barrel with the correct 2-barrel intake manifold, a carburetor designed for a 302 would be preferable to one designed for a 270.

Stromberg made hundreds of different 2-barrel carburetors.

The Stromberg type WW has one design flaw that should be addressed. Stromberg used an aluminum throttle body on the type WW carburetors. The aluminum, over time, oxidizes, and "sandpapers" both itself and the throttle shaft where the throttle shaft goes through the throttle body.

Design fit was 0.004~0.006 inch.

Bushings, professionally installed, will cure the issue.

Once the throttle body issue is addressed, the WW is virtually bullet-proof.

Jon.

As usual carbking is in the know. As many know I'm a Rochester model "B" Nazi. I do work on big vintage Holly's but rarely now. but for my two cents worth the Stromberg is bullet proof for your application. I worked on one several years ago and installed good American made bronze bushings and a mixture of super glue and acetone in a fine fluid to slow the oxidation. Doc

Let me suggest another approach to your fuel pump problem. Plug the bolt holes in the block with short pieces of cut-off bolts or all thread, and reposition the holes to center the pump lever on the camshaft lobe. It might be necessary to drill and tap the existing holes for a bigger plug so you don't get overlapping threaded holes. Anchor the plugs with red Loctite or even braze them into place before you start drilling and tapping for new pump mounting bolt holes. Trying to make the pump fit an offset mounting point is going to end up with two modified pieces instead of just one.
Jerry

Yep...that would be the best long term solution...why didn’t I think of that....

1. What is a "military 302" ?
2. What fuel pump did this motor originally use?
3. Why is the original fuel pump not being used?

OK I googled it. Built for GMC 2 1/2 T 1952-1960. 6 cylinder. Had electric fuel pump. Civilian 302 had a mechanical fuel pump. All I can say now is I would never have thought to, or would I ever, make a hole in a block for a fuel pump. If I tried that and made a mistake, I would close it up, use the WW carb, use an electric fuel pump with 4-5 PSI and go back in the house.
I could not find 302 info. The 60-66 GMC 305 V6 uses a WW carb and the pump delivers 4-6 PSI.
Tom, I fear that after all the redo, you may still damage the cam or something. I don't like his whole idea, it's making me nervous. If I had to do this I would make a template from a civilian 302 that registered off of a couple other bolts on the block and then scribe on the Military block. But I don't think I would even do that.

Another option would be to tap them for pipe threads and use pipe plugs ground off flush. Then redrill and tap for the correct location. It probably wouldn't matter if you overlapped the threads then as they'd be TIGHT. Your original size bolts may be a pretty sloppy fit, although loctite stud locker will fill the clearance as suggested. Just about any straight tapped hole would have the same issue. They make locking pins for fixing block cracks that have interference fit, but that system is kind of expensive.

Using a taper tap for a bigger bolt, like a 1/2" or a 5/8", and not going all the way through to the straight-threaded part of the tap creates a wedge-fit thread, even without thread locker. That's just a "belt and suspenders" approach, where the Loctite just adds a little fudge factor. Run the bolt in until it gets tight, cut it off a little proud of the surface, and grind it flush.

When making holes in a block that weren't there from the factory, "measure twice- - - - -cut once!" That goes for doing anything else that didn't come that way from the factory, also!
Jerry

Like the apprentice carpenter said "I cut it twice and it's still too short"

The 302 used:

Holley AA-1 (2 barrel)
Holley 885-FFG (2 barrel)
Stromberg WW (2 barrel)
Zenith 63AW14 (1 barrel updraft)
Zenith 63AW12 (1 barrel updraft)

Jon.

It's good he has a WW. I used the 305 to get the PSI value for an electric FP he is contemplating. I have a WW on my 305 V6. Good carb as you say.
BTW Jon, there was a soft "fiber" "washer" almost like felt, that I put on the Acc Pump rod. I thought is was to seal the hole. I put it on the outside of carb, maybe it goes on the inside? Or where does it go? What is it?

Yeah, I debated making mention that the holes I drilled were offset. I opened myself up for criticism but in the end this isn’t fatal.

Correct - military 302’s used an electric pump.

I researched Stromberg WW’s and found a NOS one for the 302.

I figure, that I should post my successes and mistakes, for the next person who is willing to step out of the comfort zone with al ttle self deprecating humor to share the lesson

I enjoy the dialogue...it’s good for others to see what the experts say.

Bart - some went on the outside, some went on the inside, with a metal washer protecting the felt from the return spring.

Tom - the new old stock WW, will have a leather accelerator pump. Prior to use, dribble several drops of light machine oil (3 n 1, neetsfoot, etc...........I use Singer sewing machine oil, my wife is a quilter) down the pump sticking through the hole in the airhorn, and allow to sit for a few hours to penetrate the pump leather. That 65 year old leather pump, if treated with the oil, will outlast 25 of the new neopreme ones.

Jon.

Good to know, Jon. Yep, that’s my impression of the new neoprene too.