1967 Calais - Differential

Started by John Baker #2259, August 26, 2007, 12:16:34 PM

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The Tassie Devil(le)

Quote from: Michael Stamps on August 30, 2007, 05:19:18 PM
Replace.

Stampie

PS - Boy that was a lot of reading for a one word answer.

I'm with Stampie.

Get rid of the clutter, and simply re-route the Vacuum Advance to Full Manifold Advance.

You WILL notice the difference.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

John Baker

Yes it was Stampie. Was not sure if my assumpitons were correct leading up to the question. Apparently they were (?).

Stay tuned (no pun intended). Should be fun. Can't wait to explore this new territory (for me anyway).

Regards,

John

The Tassie Devil(le)

I am sure that the reason that the Auto Makers went for the step-Vacuum was only to do with meeting the Pollution Requirements.

One method of overcoming the "non full Vacuum Advance" until trhe engine warmed up, ot got into top gear, was to simply earth out the wire that went to the Transmission that "told" the Vacuum Motor that the car was in top gear.

Many a Holden here got the wire "conveniently" caught between a couple of metal mating surfaces.   Looked factory and unchanged, but the performance was improved out of sight in the lower gears when cold.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Glen

Quote from: john baker on August 30, 2007, 03:47:49 PM
The vacuum advance in my car currently runs off of ported vacuum. It will advance the spark as the rpm load in the engine increases (vacuum will drop).

John


If I read your post correctly I think you have it backwards.  The vacuum advance increases the spark advance as the vacuum increases. 

As you probably know there are two flavors of vacuum for the vacuum advance, ported and manifold.  Manifold vacuum is directly off the manifold.  Ported comes off the carb just above the primary throttle plate.  With the throttle closed the vacuum advance get no vacuum while the manifold is at a high vacuum.  Cracking the throttle a little puts full or nearly full vacuum on the advance unit.  I’m not sure how the ported vacuum tracks with manifold as the throttle is open further. 

Glen
Glen Houlton CLC #727 
CLCMRC benefactor #104

John Baker

Thanks for vetting my thoughts Glen,

The remark highlighted from my post was gleaned from an article that I read (and perhaps did not interpret correctly). It seemed counter-intuitive to me at the time. That was one reason why I went into the detail that I did in the post to Stampie. I am an amateur among experts, but continue to learn as I go.
The subject matter expertise offered by you, Stampie, Porter, Geoff, Bruce, Chris and others on this site is superb and deeply appreciated by greenhorns such as myself.

I am chomping at the bit to make this tweak to my 1967 Calais. It has been a blast driving this car during its transformation from where it was three weeks ago.

Regards,

John