The Stovebolt Site Forums The Shop Area Engine Shop mini hei

I'd like to hear opinions on the mini hei. Specifically, is the fact that the distributor shaft smaller a problem? It seems to me that the shaft needs to be the correct size ~0.49 otherwise, the oil pump won't support the side load of the gears. This would also seem to be a problem with the large hei as the lower part of the shaft has a wobble joint. How about pressing a bushing onto the disty shaft of the mini hei to bring the diameter up to 0.49?

Bringing this back to the top...

I know one problem with the so called mini Hei's if used in a 235/261 or GMC inline.The Hei has a flange on the distributer similar to the 230-292 6's or the small block V-8. When the Hei with this flange is bolted down,the shaft may force down the oil pump drive resulting in chewing up the pump or at worst a pump siezure.Since the original distributer is clamped in place by a semi floating affair,the accuracy of the surface machining of the distributer pad wasn't critical.
I suggest anyone planning to install a mini Hei in an old block,carefully check the to make sure the dist. isn't slammed down on the oil pump and the driven gear meshes properly with the cam drive gear.This is info the guy who makes these units doesn't seem to hand out, when modify an engine with non stock components, check all clearances
On the later 230-292 engines,the above isn't a problem

When you say "mini HEI", are you talking about Langdon's distributors?
Have you already purchased it, that you know the shaft is smaller?
I pulled a internal-coil HEI out of a 250 that had a lower end diameter of .4666". The shoulder was just up inside the bottom of the gear and below the roll pin and I did not notice it. The bearing was nice and tight so I just dropped it into my engine(292). It wobbled around like crazy. The oil pump tang was sliding back and forth on the pump slot every half revolution.
That one was in a Olds or Buick with a 250.
Don't use it.
I have only seen one of those. I pulled it out of a '75 Nova and it had the external coil. I'm not sure that it is factory. I think it's an after-market rebuild and that is how they repaired a damaged shaft. I don't like the looks of it, so I'll probably never use that shaft.
I used the housing and another shaft and created the problem Tony mentioned. I placed a couple shims between the gear and the bottom of the housing to take up what I thought was excesive play. I left about .004". Unfortunately, with the shaft tang in the pump, the housing was about .010" plus the gasket above the block with the clamp tightened. Not good.

The wobble joint was a factory fix.GM was getting warranty claims for worn distributer shaft bearings,the holes bored in the blocks for the distributer weren't true.It was easier for GM to modify the distributer shaft than bore the holes properly in the first place.This story was told to me my Langdon,maybe true, maybe not.
I used to sell modified large cap HEI's for use in 235/261 or GMC's,all that I saw had the wobble shaft.I have no experience using the HEI in the L series engines, but in the old 6's,the wobble shaft didn't cause a problem I was aware of.
Back to what Jason asked about shaft diameter;I believe the mini Hei being sold is originally from the non computer 2.8 V-6.

I bought the mini hei from a salvage yard. It is from a 1983 S10 with a 2.8L. Cheap and plentiful. I paid $35. I wanted to adapt it to a reo 331 truck engine. In that application, the gear is on the oil pump making it easier to adapt an alternative distributor.

The shaft diameter on the mini hei is 0.426 vs. the original gmc/chevy diameter of 0.490. It appears to me that the stock disty gear is located at the top by the disty and at the bottom in the oil pump. Does it need to be supported at the bottom? In the stock floating arrrangement, probably. But what if the disty is clamped in place and not allowed to move. If not allowed to move, will this be enough lateral support? Is this how Langdon's mini hei is getting away with a smaller diameter shaft?

What about the large hei with the wobble joint? Will removing the flange at the top also allow the disty to move away from the cam gear resulting in poor engagement?

Jason,on all GM older 6's the cam gear is designed to pull the distributer shaft downward,so the retaining clamp only needs to prevent roatation.I beleive the later 6's are the same also,not sure about 2.8's
I've been told Langdon fits a reworked V-8 shaft into the 6 cylinder HEI and a a 6 cylinder inline gear,the 235 and Later 6's use the same gear.
It appears the side thrust on the dist shaft is controlled by the distbuter body,not the oil pump.

I can't buy that story. If it were true, the point dist in the first 250-292 blocks would have had the same problem. The problem you described using the HEI in the 235 block might actually be solved using the wobble joint. I still don't like the looks of the thing and I think it would cause accelerated wear on the bottom dist bushing.
My book shows the 2.8 dist with two different kinds of pickups. One uses a Hall-Effect pickup and the other the more conventional GM style magnetic pickup. Not having a 2.8 dist here to look at, would it be possible to use the large body, .490" shaft and pickup in the 2.8 housing?

I'm not sure it is working. The small shaft dia has been discussed here before. One guy with a 235 lost the pump, dist gear and cam from what I believed was caused by the small shaft.
If your REO engine doesn't use a gear on the dist shaft it does sound like it would be OK. A bushing like you mentioned in your first post sounds even better.
I'm going to take a look at the 2.8 HEI housing. The Corvair flat six and the L6 use the same point dist housing. The only difference is the Corvair has a much longer shaft. The Corvair shaft in the 2.8 housing might be the HEI I've been looking for.

Tony
I think the side thrust is controlled by both bushings and that is what caused Chiphead's problem. I know for sure that the smaller, lower end of the shaft on mine caused the dist to wobble with the clamp fully tightened. In case you're wondering, I checked the shaft and it was true.