Distributor Pickup coil problem

[John]

I have a souped up chevy 350 engine in my GT40 (no snide remarks please!)
It has a Isky gear drive cam which means the cam runs counter-clockwise. To compensate for the this backward motion, the distributor uses a reverse drive gear to make it run clockwise.

The problem is that this setup causes the distributor to grind down the pickup coil - the plate that signals the main coil rides on the surface of the pickup coil and wears it down and eventually shorts it out.

I've been stranded once because of this, and was almost stranded a second time by a damaged pickup coil.

Anybody have any suggestions on how to solve this problem!

John



:blank:

 

[Jac Mac]

Yep, in normal Chev dist land the rotation tends to push the dizzy shaft up, in your case the shaft tends to be pulled down, therefore the thust washer needs to be placed below the mech weights etc inside the dizzy and the end float controlled at that point, not down by the dizzy gear where I assume it still is.

 

[Jac Mac]

Should probably also mention that the camshaft endfloat thrust button now needs a fairly robust pad in the timing cover as the oil pump load now tends to push the cam forward out of the block instead of rearwards against the thrust face.

 

[John]

Yep, in normal Chev dist land the rotation tends to push the dizzy shaft up, in your case the shaft tends to be pulled down, therefore the thust washer needs to be placed below the mech weights etc inside the dizzy and the end float controlled at that point, not down by the dizzy gear where I assume it still is.

Jac Mac,

When you say "dizzy shaft", I assume you mean distributor shaft - is that correct?


As to the thust washer , what is that and where is it located? If you have a diagram or picture available, that would help!

Thanks, john

:thumbsup:

 

[John]

Jac Mac,

When you say "dizzy shaft", I assume you mean distributor shaft - is that correct?


As to the thust washer , what is that and where is it located? If you have a diagram or picture available, that would help!

Thanks, john

:thumbsup:

Jac Mac,

I've found out what thrush washers are - they sit just above the dist drive gear and control the motion of the shaft up and down. Do I remove these washers and place them on the surface of the pickup coil and then slide the dist shaft in? I have three washers now, do I need to move all three?

John

 

[Jac Mac]

Jac Mac,

I've found out what thrush washers are - they sit just above the dist drive gear and control the motion of the shaft up and down. Do I remove these washers and place them on the surface of the pickup coil and then slide the dist shaft in? I have three washers now, do I need to move all three?

John

Cant imagine the 'new' thrust washer having to sit on the pickup coil John, but right down in the inside of distributor housing as per the following drawing. Text in drawing should explain. Looks like you might have to enlarge it to around 200% to read easily.

BTW, ignore the post #3 above about the camshaft thrust on the front cover, I had a total brain fart while trying to mentally envisage that one, all is as per normal.

 

[John]

Jac Mac,

Thank you again for taking the time to help me - is there a phone number that I can call you at for more questions.

1. Do you know of a company that makes a chevy dist with the thrust washers already inside the distributor for a reverse drive gear?

2. Even if the thrust washers were located as you recommend, it seems to me that the reluctor would still grind on the surface of the pickup coil. When the dist uses a regular drive gear, I assume that the reluctor tends to float above the pickup coil avoiding contact under normal operation. However,for a reverse drive gear, the reluctor is going to ride on the surface of the pickup coil even though the thrust washer is absorbing the downword force. It seems to me that there's got to be a way to prevent the reluctor from riding on the surface of the pickup coil.

John

 

[Jac Mac]

Jac Mac,

Thank you again for taking the time to help me - is there a phone number that I can call you at for more questions.Sent you a PM, Im in NZ so phone right now or in 22 hrs time if you need to, but you might be better to enquire in USA

1. Do you know of a company that makes a chevy dist with the thrust washers already inside the distributor for a reverse drive gear?Chev used to, dont know if they still do, it had ball bearings to accomodate reverse thrust, check directly with Accel, Mallory or GM motorsport

2. Even if the thrust washers were located as you recommend, it seems to me that the reluctor would still grind on the surface of the pickup coil. When the dist uses a regular drive gear, I assume that the reluctor tends to float above the pickup coil avoiding contact under normal operation. However,for a reverse drive gear, the reluctor is going to ride on the surface of the pickup coil even though the thrust washer is absorbing the downword force. It seems to me that there's got to be a way to prevent the reluctor from riding on the surface of the pickup coil.If you have enough thrust washer thickness to keep the reluctor above coil I dont see how this could happen, it must have a shoulder on the shaft that limits its downward movement in the standard setup... if not the current distributor might require a collar that is pinned or fixed to the shaft for the 'new' thrust washer to act against.

John

I will send ph # & email address by pm in case you wish to send pic's of dismantled distributor.