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TR6 Timing using a vacuum gauge

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bonzocfi

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Just bought a 74 1/2 TR6. 73,000 original miles. Pertronix ignition. Will connect the gauge to the ARV. As I rotate the distributor, what should I look for? A specific pressure, the highest pressure, steady pressure? Thanks for your help.
 
If you have a stock TR6 cam for that year AND if you are at sea level, you should find the sweet spot when the manifold vacuum is in the 17 to 20 in-Hg range. The idle speed will change as the timing is changing. Make idle adjustments at the carbs as necessary for 850-900 rpms.
As usual, clockwise rotation of the distributor advances the ignition.
When setting the ignition timing it's equally important to take note of the Vacuum Gauge needle's movement...Anything more than a quiver might be indicating a particular problem.
The various "SCENARIOS" are at the bottom of this link.
https://www.secondchancegarage.com/public/186.cfm
 
I forgot to mention that the retard unit had been replaced with the vacuum advance. Do I still need to disconnect the vacuum line at the distributor and plug it?
 
If you have the Advance module connected to the proper location on the carb, there will not be enough vacuum to activate the advance when the engine is idling, so the answer is 'no' you don't need to disconnect it and plug the nipple on the carb.
 
I am from Baton Rouge; I lived in Shreveport for a while, then moved to New Orleans, then Hammond for a long time before retiring and moving to Mississippi...It's pretty nice out here in the country.
 
Decided to check my rebuilt engine. Got 15" at 1,000 rpm idle. Advanced the timing and got 17". It has a little needle shake as I run the Goodparts S2 cam, and the valve timing is a bit advanced. It really runs great, zips to 4,000 rpm. Need to check the plugs next for mixture.

Perry
 
gbtr6 said:
Decided to check my rebuilt engine. Got 15" at 1,000 rpm idle. Advanced the timing and got 17". It has a little needle shake as I run the Goodparts S2 cam, and the valve timing is a bit advanced. It really runs great, zips to 4,000 rpm. Need to check the plugs next for mixture.

Perry
Click to expand...

Goodparts S2? I thought theirs were the GP2 or GP3 with Ted at TSI selling the S2?

I have the S2 in our GT6 and cannot get a vacuum reading nearly as high as yours. If you have a more or less smooth idle with 17" vacuum at 1000 then you have a healthy engine.
 
There was a TSI S2 cam in my 73 TR6 when I bought it from "TR6 BILL".
Because of the overlap the vacuum wasn't steady or high..Seems like I had 13ish at 1100 rpms.
Not that I couldn't idle slower thereby perhaps obtaining a slightly higher manifold vacuum but I went for smoother rather than lumpy idle.

I have put the vacuum gauge on a few engines with the milder GoodParts GP2 cam and they seemed to run good with 15 in-Hg when idling under 1000 rpm.
 
I remember emailing you about the S2 cam before I made my purchase. Like your experience, I remember a reading closer to 13" Hg. We have our idle set to somewhere between 900 and 1000. It idles well but with 13" Hg I never saw the need to hook up or use a vacuum gauge again.
 
You are correct, my mistake. It is the GP2. I imagine that has some overlap as well. It pulls strong and quick to 4,000-5,000. I love it.

Perry
 
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