Is vacuum at idle any kind of an indicator as to wether the engine is healthy? I'm looking at a few rx-7's and one the guys said he hasn't had the compression checked since few dealers/shops have the tool it takes, but it's 14-16Hg at idle? I'm just trying to ask the right ?'s so I don't get burned. Thanks, Mark

 

a healthy motor pulls probably 15-17 on average. A little low isn't necessarily bad, what you wanna look out for is if it doesn't hold vacuum or idle, a lot of fluctuation can indicate low compression.

 

Is there any kind of guage like at Home Depot. that's cheap that I could buy? And which line do I hook into too?

 

You can buy a $20 boost/vacuum gauge from any decent auto parts store. Get about 8 feet of vacuum tubing (5/32" works fine). Attach one end to the gauge and the other to the unused nipple on the upper intake extension. It will have a black cap on it and is located on the passenger side.

Now you can check the idle vacuum AND boost during a test drive. I'm sure accuracy isn't super high, but it's within a couple inches Hg or 1-2 psi.

 

You can also buy a compression tester at any auto parts stores, and test it yourself. Search the forum on how to do the test. It's quite easy.