which Mityvac?
Thread Starter
Instructor
Joined: Mar 2003
Posts: 240
Likes: 3
From: Mt. Prospect Il
which Mityvac?
In all the threads obout timing, the Mityvac keeps comming up.
Which Mityvac is the one to get?
part # 07000?
part # 04010?
http://www.mityvac.com/kits.html
Thanks.
Which Mityvac is the one to get?
part # 07000?
part # 04010?
http://www.mityvac.com/kits.html
Thanks.
Drifting
Joined: Mar 2005
Posts: 1,300
Likes: 0
From: Iowa
Get the 4000 kit. The die cast pump is much better and resistant to more fluids than the plastic body pump. Also, the 4000 kit includes the accessories you need for typical automotive applications and comes in a decent case.
I've had both the plastic version and now the die cast. The plastic one lasted a few years, but I've had the die cast now for at least 15 years.
I've had both the plastic version and now the die cast. The plastic one lasted a few years, but I've had the die cast now for at least 15 years.
Burning Brakes
Joined: Mar 2004
Posts: 1,108
Likes: 4
From: Plano Texas
I agree with rgs. The die-cast kit is the way to go. I have found the MityVac invaluable as a tuning aid, a brake bleeder, and vacuum canister checker. I've used it to check vac advance canisters, heater door canisters and carb ports. Pretty cool tool!!!! 
Two thumbs up!!
Two thumbs up!!
Thread Starter
Instructor
Joined: Mar 2003
Posts: 240
Likes: 3
From: Mt. Prospect Il
Got the 4000 kit, read the manual, still don't know what to do!
327/350 4spd
Please bear with me, I know in principle what I want to do, but not in application.
I would like to check the vacume while the engine is running and compare the results to the manual's diagnosis chart. Where do I hook it up?
I would also like to test the vacume advance can, how do I hook it up?
327/350 4spd
Please bear with me, I know in principle what I want to do, but not in application.
I would like to check the vacume while the engine is running and compare the results to the manual's diagnosis chart. Where do I hook it up?
I would also like to test the vacume advance can, how do I hook it up?
Drifting
Joined: Mar 2005
Posts: 1,300
Likes: 0
From: Iowa
Start with the vacuum advance line from the carburetor to the distributor advance can. Someone can correct me if I'm wrong, but I believe your application ports manifold vacuum to the advance can.
you can use the gauge on the pump, or an external gauge directly to this line. Just pull it off the advance can and plug the gauge in it's place. During your tests of manifold vacuum, you will not have the vacuum advance working, but this will not hurt anything.
For testing the advance can, plug the line you pulled off (otherwise the mixture leans out), and attach a hose, in your kit, from the pump to the can. Use a timing light to verify timing, and slowly pump up the advance can. You can map out the vacuum/advance ratio by watching the increased advance while pumping and watching the applied vacuum.
I'd recommend using a dial back timing light since the timing pointer doesn't have enough range for this test.
you can use the gauge on the pump, or an external gauge directly to this line. Just pull it off the advance can and plug the gauge in it's place. During your tests of manifold vacuum, you will not have the vacuum advance working, but this will not hurt anything.
For testing the advance can, plug the line you pulled off (otherwise the mixture leans out), and attach a hose, in your kit, from the pump to the can. Use a timing light to verify timing, and slowly pump up the advance can. You can map out the vacuum/advance ratio by watching the increased advance while pumping and watching the applied vacuum.
I'd recommend using a dial back timing light since the timing pointer doesn't have enough range for this test.
Race Director
Joined: May 2000
Posts: 12,712
Likes: 2,271
Originally Posted by rgs
During your tests of manifold vacuum, you will not have the vacuum advance working, but this will not hurt anything.
No, no, no! Disabling the vacuum advance alters the engine speed, manifold vacuum, and mixture.
To check normal idle manifold vacuum you get a 1/8" tee and a couple of feet of 1/8" vacuum tubing from a parts store. Tee the vacuum gage into the vacuum advance signal line.
When you check the vacuum advance against spec, it's a good idea to tie up the centrifugal with a rubber band. As you add vacuum revs will increase and you want to make sure the engine doesn't speed up enough to deploy it, otherwise your data will be contaminated.
Duke
Drifting
Joined: Mar 2005
Posts: 1,300
Likes: 0
From: Iowa
I agree that disabling the vacuum advance will alter engine speed, etc. I should have been more explicit in my discription. Yes, using the T is a better way, but for a quick test I just manipulate the idle/throttle to map out intake vacuum. As long as the rpm is held to the desired value, the vacuum created with or without the additional advance is not affected.
I also agree with keeping the mechanical advance out of the equation when checking vacuum advance. Instead of taking all of the time to take the cap/rotor off to disable it, I just ensure that I keep the rpm below where the mechanical advance kicks in.
Too many things that we do without thinking about it!
I also agree with keeping the mechanical advance out of the equation when checking vacuum advance. Instead of taking all of the time to take the cap/rotor off to disable it, I just ensure that I keep the rpm below where the mechanical advance kicks in.
Too many things that we do without thinking about it!
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