A Flat cam or not!!!

[BUICKTR]

I'm having problems with my car. I'm already very frustrated with it. I have a fresh rebuild with billet caps and put a 218/218 flat tappet comp cam with comp lifters all were new. My car lost vaccuum from 14 in down to around 10 in. Car doesn't want to stay on. While its running the motor shakes. I check the rockers and the shaft they seemed good, check each header with a water sprayer. Sprayed each header and water evaporated from each one very fast. So I have some idea that each cylinder is working. I also check all hoses, vaccuum lines, put new spark plugs, new o2 sensor. My question is how can you tell when you have a flat cam. What to look for to get an idea.

 

[Russ Merritt]

Tear the valve covers off and turn over by hand and watch. Simple yet effective. If the motor is running that bad should be easy to see which valves aren't opening as much. Is the vaccum gauge bouncing or steady? I just had this same problem on a guys car, 10# of vaccum shi%$# idle. He had his engine rebuilt by a circle track race shop and they put a 218/218 comp cam in a STOCK gn. Had Red A make us a chip and it was much better

 

[BUICKTR]

Russ Merritt

So the car you were speaking off did have a bad cam? It sounds like the same problem. My vaccuum bounces at first then after a couple of minutes it at a steady 10 in of vaccuum. It always had around 14 in vaccuum. This happened after a good full throttle blast on the hwy. I stayed on it for about a 1/4 mile.

 

[Russ Merritt]

It does not have a bad cam! "the car is fine" must be something else, did it push a hose off somewhere, check for vaccum leaks first. You could also do a compression check, watch the needle while you do it, I found another car with a bad exhaust lobe #3 cyl. and the needle movement was differant than the rest. With that cam you had 14" of vaccum?

 

[BUICKTR]

I did have 14 in of vaccuum all the time. My cam is advance 4 degrees. It spools up great. I havent tried to spool again because of this problem. I first thought electrical problem maybe coil pack or bad spark plug wire, but I don't think that would affect vaccuum. Would egr vaccuum hose have anything to do with this problem?

 

[Russ Merritt]

The gasket under the EGR would!

 

[BUICKTR]

Thanks, I'll take a look at it.