Type 4 distributor shims

[SGKent]

Tom Wilson in his book gives an obscure measurement on page 119. It is the up-down freeplay in the distributor drive gear. He lists it as .020 to .050 on both T1 and T4 engines. I can remember shimming T1 engines but I had not seen this on T4 because the design of the washer is different. To my knowledge there are not different thicknesses available. With one shim I get .060 freeplay and with 2 I get .010 freeplay. Does anyone know if this measurement is critical on a T4 bus engine or can T1 type shims be used on top of the T4 shim to tighten it up? Besides the Wilson book I have some ticking in this area but always blamed the excessive cam endplay and runout in the camgear for it - however the sound has always been at the base of the distributor. It is NOS and the spring is there.

I checked the drive gear, bracket, aluminum thrust area the bearing rides on for wear. Nothing is worn enough to feel with a fingernail. The old washer is thicker by .002 than a new one. The teeth on the drive gear are showing shiny almost dead center so the gear appears to be running about the right height.

I found an old post on T4rum by Scott at German Supply commenting on this subject as well as Jake but there was no definitive solution in that thread. 103mm was given as the distance from the top to the thrust area on an EA case but on my GD it is 109mm and in no way are we ever going to be able to make 103mm work as that is about 1/4 inch and we are only out .010 from the stock spec per Wilson.

Anyone know about this and solutions if it is an issue. I was thinking that one could add T1 shims but that might not be a good idea.
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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[nathansnathan]

I remember (?) it saying in the wilson book that type 4 only gets 1 shim?

[nathansnathan]

yep there it is on page 119

http://books.google.com/books?id=bdG4s_di9bAC&...mp;f=false

type 4 only gets 1 shim, it says. It says better to have too much than too little.

Funny, this site says exactly the opposite! -I think they are confusing flywheel endplay, though. I'd trust the tom wilson book

http://www.wolfgangint.com/Parts/Distributor+Drive+Shims/Type+4/

[SGKent]

yes but he also says it can use more than 1 shim and the freeplay should be .020 to .050. This seems to be one of those you can't get there from here situations if type 4 shims are the only option as one would need to have .0074 freeplay minimum before they could run 2 shims unless the type 1 style can be used in addendum to the type 1 shims. I guess I could have .030 machined off the bottom of the Dist or Dist clamp as it is flush. Unless some one else has a better idea or frankly I really wonder if this is even an important measurement.
_________________
"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[nathansnathan]

at lower right ther, it really seems to say that there should be only 1. The way a type 4 shim is, all the 'divots', I don't think you can stack them? I've never seen a type 1 so don't know if it's just like a flat shim -

http://www.aircooledtechnology.com/store/product.php?productid=16204&cat=306&page=1

"Try to find this new part anywhere else"
Seems to imply that these are pretty hard to come by , especially in different sizes as it seems to say in the wilson book - I think that's what he's saying, there are different thickness type 4 shims to be had?

[SGKent]

the type 1 are flat shims similar to what is inside the distributor.
_________________
"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[nathansnathan]

seems to me, without any other options, either a .025 type 1 shim and the type 4 shim would put you right in the middle, or just ride with the .060 with just the 1 type 4. ..just my thinking there, no experience actually trying this - mine always came in in spec.

[SGKent]

[keifernet]

Type 1 shims won't work... the type 1 drive shaft is different diameter and the shims are much larger diameter as well.

The type 4 drive is a smaller size where it fits in the case and has a unique washer. IIRC there are some hardened steel thin shims out there from places like Mc Master-Carr or other supplier you can use to set it up if your sloppy.

[SGKent]

Thank you. Looked there after your suggestion and didn't see exactly what was needed so out came the mill file, a strong magnet, the ginder, 350, 1200 and 2000 grit paper. We took material off each side of the spare washer so now we have a choice of .020 clearance using 2 shims or .055" using one.

I am thinking that .055 is probably safer than .020. I might have the top of the bracket machined to lower the dist to .040 - .045" , which is a descent margin of error in both directions.

I wish I could find this spec somewhere else. The Orange factory manual shows a single washer. I don't doubt Tom Wilson, just don't know where that spec came from.
_________________
"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[orwell84]

I revived your thread because I am doing exactly the same hand-wringing over this obscure measurement. My endplay with 1 shim is a little more than yours was, maybe like .070, but I am using a 050 distributor. The gear shows wear right in the middle, like yours.

I was just wondering how you ended up resolving this problem and how it worked out. Also, do you know of a source for these shims or can something else be substituted.

I have never had any distributor-related or timing issues.

Thanks for the help.

[SGKent]

I went with one shim and did not double up. I used a new shim. The consensus from T4 engine builders is that the Bentley numbers are for a T1 engine. On a T4 it is what it is and one lives with it.
_________________
"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[orwell84]

So just to clarify;

I think you mean to say Tpm Wilson's book. AFAIK no one else lists end play specs for a Type 4 distributor, not my Bently, Haynes or Tom Muir.

So do you think I am safe just putting the old shim back in place and continuing my build?

It doesn't seem that distributor cam end play specs for the type 4.

Thanks again for the help.

[SGKent]

it could be Wilson. I know it was in a book somewhere and I am not in a place I can look at them. Just look at the shim and see how worn it is. New ones are available.
_________________
"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin