The Stovebolt Site Forums The Shop Area Engine Shop HEI installation problem

I am attempting to install a Langdon HEI in a 1954 235. After dropping the unit into the block, I notice a 1/4 inch gap between the shoulder of the dist shaft and the block. I am sure I am engaged in the oil pump drive. I am worried that when I tighten the clamp I will be binding the shaft in the block. Anyone else have this problem?
Also, the o-ring sits in the notched groove in the block, but nothing is holding it down. I don't want to proceed if something is wrong.

I don't have the Langdon HEI, but can you measure the length of the shaft and compare it to the original distributor? If it's too long, you should send it back.

The hei is about 1/8 inch longer than the old dis, measured from the shoulder of the dist to the bottom of the drive gear. The main difference is old dist floats in the block. The retaining bolt just keeps it from rotating. The clamp and bolt on the hei unit actually pushes the dist down into the block which I believe will bind the shaft.

The one I have fit just fine. Please be certain you have the oil pump drive engaged. Hate to ask this but you do know the shaft turns as you install it, yes? So the slot and the tab can look like they will align, but by the time that the pump is inserted it will have rotated. The o-ring? I recall a thin rubber washer but not an o-ring. Is this what you mean?

Found a note I'd written to myself about that measurement...try 4 7/8" from bottom of dist. mounting flange to tip of the oil pump tab. See if that's close or if that number was for something else.

I am sure I am in the slot. The shaft rotates 5 to 10 degrees C.C.. If I'm not in the slot the gap is about 1/2 inch.
I also measure 4 7/8", but it is not the tip that is hitting. The bottom of my dist drive gear, (which is 3 1/4" from the dist base) is hitting the machined flange down in the block,(which is only 3" deep). This is the reason for the 1/4" gap. This might be ok if the dist floated, but the bolt and clamp from the hei push the dist down in the block and I would think cause it to bind.

It will bind. I was going to ask if the driven gear is mounted correctly, but that's a wasted question. If it was upside down, I think it would make a difference of about 1 inch. I just stepped out and measured a block which is here and 3 inches to that flange is correct. Have you measured from the bottom of the gear to the mounting flange? Can you let us know what that measurement is?

Also, the measurement from the bottom of the gear (the toothed part) to the tip of the oil pump tab should be 2 1/8".

Here are a couple of measurements from a stock distributor which may help. From the tip of the oil pump tab to the lower toothed surface of the driven gear is 1 11/16" and the stock gear is 1 1/16 wide (in total).

I am 2 1/8" there also, but my problem is not with the tip. I am 1/4" too long from the bottom of the gear shoulder(not the teeth) and the bottom of the mounting base.

How about this?
Might there be a difference between a 1954 235 out of a car and a 1954 235 out of a truck?

I don't remember specifing when I ordered.

I dug up an HEI (not Tom Langdon's but another) I had modified from another Chevy 6 to fit the 235. It was removed running and cleaned up but the floating mount was not altered. You can see it and the measurements below. Total length from flange to tip...4 7/8", bottom of flange to bottom of toothed part of gear...2 3/4" and bottom of flange to very bottom of driven gear...3 3/16".

There might be, but I don't know about that. I remember pre-54 had a forged camshaft and used a different gear. the gear on the camshaft was a bit more narrow as I recall. Then in 1954 I think they went to a wider gear and that's what I'm assuming you have. The width of the gear on mine (a 1959) is about 5/8" as I recall.

But I don't believe Tom's site differentiates between car/truck engine. I'll go look and see what I can tell.

Well, they only sell one distributor. So logic says it's not them. The only option is a steel gear for pre 1954. Did you buy the distributor yourself? Has anyone replaced the oil pump?
There online pic shows a gasket/spacer and an Oring.
Here are my guesses:
1. You are NOT in the slot
2. Someone has been playing with the Langdon distributor
3. It's a home made "Langdon" copy
4. It's all together the wrong Dizzy
5. Most of these guesses will be wrong if you yourself actually ordered it from Langdon. Seems like if you did you would have called or emailed them.
6. I see your hobby is "gears" hmmmmm, did you play with this dizzy?

Two other thoughts: the width of the driven gear in both the stock distributor and the HEI distributor is 5/8". Is yours for some reason different? I can't imagine it would be, but probably need to know. Also are you certain the bottom of the gear is hitting the internal flange? Can you see down into the oil pump connection? Is there any way something...anything...could have dropped into that slot? Maybe if you could use a bamboo skewer to measure from the bottom of that slot to the top of the block where the distributor flange will sit?

Thanks for the responses. This forum is the best. I've been lurking for 3 years. Could not have built my truck with out it.


A 1/4" spacer and a gasket would do it. Bartamos, where can I find the pictures you are talking about?

Yes, but that would require some machine tools to make, and I'm not altogether convinced the distributor should be doing this. I think he was just referring to the pictures on Tom Langdon's web pages.

Before I made a 1/4 inch spacer I would do my best to determine the distance from the bottom of the oil pump shaft up to the mounting surface of the block...

It is a Langdon stovebolt mini HEI distributor purchased recently from Jim Carter. I am sure it has not been modified, but it appeared to be an open box. It came with an 1/8" thick o-ring, but did not come with a spacer or gasket.

Oh, I thought you bought it from Tom directly. That would have helped in this case, but you could call Tom and ask him, I suppose. I think it should had a flat round gasket, too. But that gasket is only about 1/16" thick or less. Here is a link to Tom's website:

http://www.langdonsstovebolt.com/store/online-catalog/#!/Stovebolt-Mini-HEI-for-GM-216-235-261-&-GMC/p/1222040/category=18665949

I can tell from the dirt line that my stock dist had a 1/8" gap between the block and the shoulder on the dist, but it didn't matter because it had an internal o-ring and the retaining bolt did not push the dist down. It just kept it from rotating.

l'll check with Langdon tomorrow about this gap I have.


Thanks again for all the good ideas.

Problem solved. After talking to Tom to determine I had the correct dist. We determined that the problem was inside my block. I was then able to take a socket and extension and careful not to hit the drive gear, I drove the machined bearing surface down into the block until I had the 3 3/16" depth that I needed. After that the distributor slipped right in.

Thanks again for all the help and ideas.

Someone explain to me what kind of "machined bearing surface" can be driven down and why it was where it was, whatever "it" is?

That's interesting but confusing at the same time. The oil pump mount is the only thing down there but the hole the oil pump shaft mounts into is the same diameter as the distributor shaft, so it would not have kept the distributor from sliding down in any case. (the oil pump is held in place with a screw and a lock nut) So, the only thing that would keep the distributor from going in would be the oil pump shaft (where the distributor tab slides in). Curious, but glad it is solved.

Something being unsaid possibly? "A machined surface" does not describe the situation.

Glad you fixed your issue! Geez, and I thought I had it bad that I had to diagnose a bad ignition module in mine!

I feel the problem is just starting with this project.
If driving the pump down to give the correct dimension for the distributor, that means the pump is not secured correctly with the lock bolt.
This means any torque applied to the pump is taken up by the engine supply tube. I would keep a close eye on the oil pressure on this engine.

.............or something was forced to give......... or bent or broken or sheared or crimped or.........I have a hunch we don't yet have the full story, may be too embarrassing. I know the feeling.

Drop the oil pan- - - - -NOW! If you did manage to drive the pump housing lower in the block, you have done serious damage to something. A couple of hours' labor time and an oil pan gasket is a lot less expensive than a wrecked engine.
Jerry

Yes, that is the plan. I don't want to take any chances with this good running motor.

Thanks again for all the info.

I pulled the pan this morning and found that when the setscrew holding the pump was screwed in and tightened they missed hole. This left the oil pump high in the block . The old dist was OK with this, but the new one wasn't. So, thank goodness nothing was broke.

Very glad you checked and fixed this.
Good job!