Dizzy curve

-
Slantsix64

Slantsix64

Well-Known Member
Joined
May 11, 2014
Messages
3,775
Reaction score
1,749
Location
Los Angeles
Hey guys i got a question stock 225 with 3.23 gears in a 1965 valiant wagon im working on the dizzy curve. i know the heavier wagon will effect the curve and spring type. my question is with the heavier wagon i would want a slower curve correct? im all in at 2800rpm and she pings not too much, if i retard the timing the car starts like **** so im guess the curve is coming in too soon?
 
First measure what's there from the lowest rpm. (Vacuum hose plugged)

This is the 225 timing specs from the '67 Plym Manual when initial is set to 5*.
'65 might be a little different but this one will get you in the ballpark to start.
A super quick 'all in' is fine with drag race only, no vacuum advance, points ignition. Other than that, take a cue from the factory. The engineeers and techs didn't just pull these advances out of thin air.
Plot where the timing is with your distributor.
upload_2020-6-26_18-41-18.png
 
I don't know but I wish to Christ some of you would stop calling them "carbies" and "dizzies." And then there's "tranny..................."
 
I ran a "Slanty" :lol: for 10 years in my '68. It liked the initial timing set at 21* with the vacuum advance disconnected while setting it and the advance plate welded and filed to limit the total initial & mechanical advance to 32*.

It ran the best with the vacuum advance hooked up to manifold vacuum, so that at idle the timing was in the mid 30's. As soon as the throttle was opened, the vacuum dropped back to the initial and mechanical totals until mid to higher rpm, which eliminated gas knock, gave incredible low end torque and improved the mileage a bit.

I tried tuning it like the factory recommended, which was based mainly on reducing the NOx emissions, while providing acceptable operation, but the drivability and performance suffered.

The method I used above was based on the Four Seconds Flat literature and numerous variations of that tuning theory to find what the motor liked best.
 
Update fixed the issue! after i verified TDC i found that i needed to adjust the bottom bracket to get my correct initial timing, then she pinged less but still could faintly hear took some timing out of the distributor 14 initial and 16 centrifugal gave me a dead 30 degrees with out V-can runs alot better!
 
Slantsix64 said:
Update fixed the issue! after i verified TDC i found that i needed to adjust the bottom bracket to get my correct initial timing, then she pinged less but still could faintly hear took some timing out of the distributor 14 initial and 16 centrifugal gave me a dead 30 degrees with out V-can runs alot better!
Click to expand...

Do your own experiment of running the vacuum advance to manifold and then ported vacuum, and see which one works better for you. When using the manifold vacuum, the timing falls back off as the throttle is opened, but it will still increase torque and low rpm power. You may have to turn the idle sown with it hooked to manifold, but I think you will find increased off idle driveability.

At some point, check to see if you have any vacuum leaks at the intake and consider installing a wideband in the exhaust to help dial in your carb. Also, check and make sure your exhaust butterfly valve is not stuck too.
 
You must log in or register to reply here.
-

Back
Top