I got a vacuum gage and car runs a steady 17" on a warm 72' 350 100% original engine. This site says its normal. scenario 1.
http://www.secondchancegarage.com/public/186.cfm


but the gage dial I got is on the border of late timing/normal. Should I advance the timing a little to put it in the green zone? OR is 17 good and if it ain't broke don't fix it.

 

What is your timing set to and what distributor is in there?

 

Welp, Cm says each V is 4*. It is right on the 4th V to the left so 16*? It's the OEM distributor.

 

That's a bit high for a stock points engine.

 

Important thing , the needle is steady like you said.

17" is a little low. It should be more like 20".

If you're not experiencing any problems to relate to the reading, Its not a big deal, might just be the guages accuracy or a vacum leak.

By all means try more timing. You can always change it back.

A vacum guage is just another tool in your arsenal. Take many readings, and use an average combined with other findings you record. In other words, keep a record.

 

If you're not experiencing any problems to relate to the reading.

Seems like I'm felling a slight stumble occasionally. This is what prompted me to buy the gage to measure vacuum.


By all means try more timing.

Meaning increasing or backing down some?


BTW I didn't pull vacuum hose on distributor and plug like the CM says to do when adjusting the timing. Not sure if I should do that just to check vacuum and timing at idle.

 

Timing needs to be set with vacuum advance disconnected and plugged. Have you adjusted your air/fuel mixture screws to see if you can get it a bit higher. I agree with the others although a bit low the main thing is that its steady.

 

BTW, where do you get a tach and dwell meter nowadays? NAPA acted like I was speaking Chinese when I was asking about one to tune car. I had to tell them no I'm not your parts supplier.

 

You can get one used at the usual places, I believe Sears still sells one also.

 

Sears, Ebay or try another parts store.

I have an older Sun multi unit. Volts,ohms,dwell, tach with inductive pick up. Very handy.

https://classicoldsmobile.com/forums...omendaton.html

 

Harbor Freight


Sears