DUI Distributor issue

8122pbrainard wrote: Orlando76 wrote: Guessing the distributor wasn't seated all the way which I would grill your mechanic over, then find a new mechanic..

Gary S wrote: I think that's pretty harsh especially if DUI determined that the gear mounting was questionable. .

The "harshness" was directed to whoever installed the distributor not noticing it wasn't seated and not to DUI's gear placement possible mistake

Gary,
There wouldn't be any wear on the gear since they are straight cut bevels.

May be too late too ask but how much is slightly higher?

Just curious because Ford has some pretty tight tolerances on the distance from the bottom of the seating flange to the bottom of the gear, see the link below

dist gear installation

Sounds like a DUI screwup on the original shaft

KenO[/QUOTE]

KenO, not sure how much higher ~1/16" to 1/8" at max... I did not get a good enough picture, that "Ford Racing" guide had some good info, thanks. I have not called DUI yet to give them a constructive debrief. I'm so dang happy that my boat works. I put on the new 3 blade Acme 540 and i ran it up to almost WOT. 44 mph (not GPS certified) @ ~ 3900-4000 RPM. The only hitch is that there is a new "whine" when the boat is engaged in forward. It does not happen in reverse. The alignment still looks ok. I pulled it out of the water and ran it, and no whine... no binding, all sounds and looks ok. Again, so thankful to no longer be "boat-free"

So, I replaced the Pro Tec with a DUI in a 454. When I dropped it in place, it is not possible to tell how much of the shaft is engaged. If it bottoms out, you can tell ...... but engaging 1/4 inch vs 3/8 inch vs 1/2 inch.... how would you know? Maybe mine isn't engaged enough...I wouldn't know. I have never heard of anyone measuring the distance prior to install. Is that done? How can you tell during install since you don't see anything and it would "feel" the same. Stupid question from a simple guy.............

Keno-

His directions are exactly what I did and what I am referring to. You can assess too much engagement (bottoming out) but it is not possible - by the means in that description - to assess too little engagement.

Hard to throw anyone under the prop if you can't assess marginal engagement. Using the old dizzy shaft setup would be the only practical way I would see to compare placement... and that assumes proper initial setup. Are there fancy ways to assess marginal engagement, Pete?

KENO wrote: Air206 wrote: Keno- His directions are exactly what I did and what I am referring to. You can assess too much engagement (bottoming out) but it is not possible - by the means in that description - to assess too little engagement. Hard to throw anyone under the prop if you can't assess marginal engagement. Using the old dizzy shaft setup would be the only practical way I would see to compare placement... and that assumes proper initial setup. Are there fancy ways to assess marginal engagement, Pete? If you go back to page 1 of this thread you can see how I checked a 351 engagement that came out the same as what the broken DUI had (about 1/4 to 5/16 of an inch). This particular engine has been running for 40 years with this distributor so the engagement must be OK.. It would be taking the same basic measurements on a Chevy and doing some math. I think it would be a little harder to get all the measurements on a Chevy but it can be done.

That's exactly what I am saying - The "checking upon installation process" doesn't assess minimal engagement only bottoming out. The only way to do it is to measure the old dizzy and hope the setup doesn't change (intake manifold change, etc.). In your write up, you give measurements and use the term "about".
The DUI install discussion says to seat and wiggle to assess 100ths of inch wiggle. That's my point.... "wiggling to assess 100ths of an inch" is best guess process given what's known. It isn't a process that separates the "hack", as Pete calls, them from the Engine Gurus.

It worked for me with a Ford distributor.

I was curious what I had for engagement since I hadn't really thought about it before this thread and I'll guess neither had you. Now I know. what mine is.

I didn't have any "instructions" on how to do this, just thought about it logically and started measuring things.

The "about" was rounding off a few thousandth's at the most to get the concept across and keep things easy to read.

You can take measurements of the new distributor just as easily as you can the old one and figure out how much engagement you have when you know how deep in the engine the top of the oil pump shaft is.

You can have faith that DUI or any other outfit did it right or you can measure.

You probably did a quick comparison of the new and old before installation right?

Air206 wrote: Yup - Found out I had the wrong gear rotation! Like I said - Simple guy...... LOL!

I remember that.

Good write up you did about it back then

From another simple guy

PS When I should have been getting my beauty rest last night I think I thought of a simple way of checking the engagement depth on a Chevy but I'd rather try it first to see if it actually works.

Air206 wrote:

Stealing Steves picture for a minute Pete are you saying for example,that if the gear is running half engaged that the forces on those teeth are not increased? If they are not then why not cut the gears in half to cut friction losses?

8122pbrainard wrote: Gary S wrote: But if not fully seated the gears would be running out farther on their tips instead of the full width of the teeth? The pressures would have to be that much greater The OD shoulders on the main shank of the distributor body that are in the block maintain the proper gear engagement depth no matter how far the distributor is inserted into the block.

Pete

Could you put this into some language that can actually be understood and makes sense too?

I did a little looking at Chevy distributor shafts and oil pump intermediate shafts today and from my "simple" measurements there is about 4/10 of an inch of engagement when the distributor shaft is bottomed out in the oil pump shaft

Since all the installation instructions tell how to make sure it's not bottomed out and say nothing about engagement, it's probably because you have plenty of engagement and you use shims where the distributor sits on the manifold to reduce engagement if you're bottoming out in the oil pump shaft.

The location of the mounting pin hole in the distributor shaft makes it pretty much impossible to screw up the gear mounting because you can't really drill a new hole anywhere.

You can't mount the gear too high and you can't mount the gear too low either

The first picture shows the distributor shaft with the gear off and you can see the mounting hole. You can't redrill a hole closer to the distributor body or you'll be drilling thru the gear to put a pin in it. There's no room to drill closer to the oil pump end without breaking off the tang at the end of the shaft. And you can't go 90 degrees without drilling into the tang also. You also can't drill the hole in the gear at a different height and have it fit and mate with the existing hole in the shaft.

The second picture shows how much engagement there is when bottomed out against each other. (The piece of wire is just sneaking in to do a little photobombing)

I didn't take a picture of the distributor itself with the gear on it but there are a million or so on the internet to look at.

So........lot of words to explain at least to myself why nobody seems to worry about lack of engagement on a Chevy distributor.

Gary S wrote: Pete I'm not talking about it not meshing correctly. I thought we were discussing the distributor not being fully seated. If it's not fully seated and say only half of each gear were meshing would not the forces on those gear teeth be that much greater?

Gary,
I searched for a picture that would explain it better than I can in words but didn't find any so, I'll try again. The technical description of the distributor gearing is a crossed helical gear set. These gears have straight cut gears so when they mesh, there's only a single point contact. This single point contact can be anywhere on the gear face.so depth of engagement of one gear to the other can be anywhere on that face. IE: the point contact doesn't need to be centered on the face.

Where's the new member who's the gear engineer for Chrysler? Maybe he could explain it better than I can?