This question might sound dumb but does vacuum become less over length? i want to put a gauge in the vette and in my super beetle. i guess this is geared more towards my bug than anything. In any case i hooked up a gauge to the port on the carb of the bug below the butterfly and it kept moving about 1 - 2 Hg, but stayed around 22. does this sound like ignition or valves?

If anyone has a Vacuum Gauge on their vette please post some pics

 

you might find this handy

http://www.users.bigpond.com/ergoff/vac1.htm

 

Don't know how familiar you are with bugs, but they had a bad habit of burning the #3 valves because the internal oil cooler blocked the flow of air to that cylinder for cooling. VW recommended wider valve lash settings for that cylinder to offset this.

The trick fix was to relocate the oil cooler to another spot in the shroud or outside of it to eliminate that problem and set all the valves the same. Along with adding a real oil filter to the engine, they would easily last 200,000 miles or more.
Kits used to be available for both many moons ago.

As for the fluctuating vacuum reading, it may be a sign that a valve is starting to leak a little.
If you don't trust a long length of vacuum hose, just splice a length of the right size steel brake tubing for a long run.
I run vacuum gauges in all my vehicles. A valuable tool.

 

Barry, awesome. that helped me a bunch many thanks. and noonie thanks for the extra info, any help is, well...helpful! thanks! i did end up doing a valve adjustment and found it was all valves being a little on the tight side, fixed it and vacuum nearly held perfectly steady at like 23 or 24. time to check the vette tomorrow and see what its at. now if my cam has a slight lope to it, will this cause vacuum to bounce around at idle or should it still be steady?

 

ack! i have issues with the vette that im not sure how to fix...yet. i found a few mistakes i need to correct along the way. 1. To plug both ports on the front of the carb i used a single piece of hose to connect the two ports (edelbrock carb). this im guessing would not give you the best vacuum or idle because your basically creating a "leak", right? please correct me if im wrong. Hmm, i guess thats only one mistake so far heh. well so far i have set the INITIAL timing to 12*, and put some heavy springs on it to find total. my TOTAL came out to around 35*, but only at 1000 RPM?!?! is my tach wrong? it sounds like 1000 rpm, i have a dial gun and it all lined up at 0 on the balancer when the gun was at 35. should i put really heavy springs on?

my REAL question is why my Vacuum on the motor only reads around a disappointing 14 - 16, and it will keep bouncing down 1 or up 1 every so often. Idle is set to around 750 RPM.i read that info on that site Barry and it says maybe the ignition system is to blame. Now i did make my own wires and im wondering if maybe there is a faulty connection on a wire causing a miss somewhere.

 

this might sound like a dumb question, but when should the centrifugal advance from the distributor start to kick in? 1000 RPM, 1250 RPM, 1500 RPM?? im getting something like 14 degrees advance @ 1000 RPM, just from the springs. im not sure why im getting so much so soon on heavy springs, if i put any heavier springs on there im not going to be ALL IN until like 4500 or higher. what am i doing wrong?

 

bump.

should i be in the Performance section with this?

 

first, try heavier springs in the distributor to see if you can raise the point that the timing is coming all in at. you can mix and match the springs, they don't both need to be the same. if you find that replacing both springs with heavier ones bring you in too late try swapping just one to a heavier spring and leaving the other one what it is, etc. it's a lot of trial and error.

the vacuum that your motor produces will depend on different factors of how your motor is configured including what cam you have in it. On my '65 with the 30-30 factory cam, which is a pretty radical cam and probably the most radical cam put in by the factory for a street motor, I only get around 11-13" of vacuum at 900rpm idle speed. That's typical for that cam.
depending on your motor and cam 16-18" of vacuum may be perfectly normal.

your centrifugal advance should start approx a couple hundred RPM's above your idle speed. Example, again on my '65 the normal idle speed is 850-900rpm and base initial timing is 12º at idle. My curve starts at around 1000-1100rpm when the centrifugal advance starts to kick in.
I'd wouldn't worry so much ar exactly what point your centrifugal starts as much as that it doesn't kick in yet at idle speed and that you have it all in somewhere between 2800-3000rpm.
To set up the distributor for a perfect "curve' which involves at what exact point it starts to kick in, what the advance is at certain rpm's as it increases speed, etc up to the "all in" point would require having the distributor set up on a Sun distributor machine.