Vacuum problem driving me NUTS!!!!!!!!
Ok 87 dodge daytona pacifica. Log t1 car about unmolested as unmolested gets outside of a replacement engine by the dealer about 5 to 6 year ago. It is a jasper engine as well. So not a junkyard non known motor. Everything is stock. So I got the car about a week ago and the stock gauge(which I know is usually off) was reading about 12 to 14. So I decided for sh*ts and grins to hook up my vacuum pump just to find out. Well stock gauge is accurate. So I do my modified vacuum harness that I do to all of these cars considering that it still had the factory harness. Didn't help. Think I gained and inch. So I was like ok came timing is off. So lined everything up and it is spot on. Moved it a tooth advanced didn't seem to help. Maybe gained a little. Catalyctic was rattling so removed that and still no gain.
So moral of this story is
Cam timing dead nuts on
Vacuum lines replaced and good
Cat out with test pipe in now
No blowby or burning of oil. Maybe 10,000 on engine
I'm at a loss
Re: Vacuum problem driving me NUTS!!!!!!!!
Ignition timing is going to have the biggest effect on idle vacuum, is it "right"? Maybe try moving it around a little to see what happens there.
Is the cal stock/correct for the car?
I expect you tapped the actual intake to take your readings, so restrictions shouldn't be an issue...
BTW, what does the FSM call out for "normal" vacuum? Seems like I recall having readings like this on most of my cars, so it may not be an issue... or my cars have the same problem!;)
Mike
Re: Vacuum problem driving me NUTS!!!!!!!!
Yeah, around 14-15 in of vacuum (different altitudes). Mine would break up at high rpms (valve float) but that could have just been crappy valve springs or something. Otherwise it ran fine.
Have you done a leakdown/compression test?
Brake booster hold vacuum?
you said it was a slider cam, but were the lobes or followers worn?
Re: Vacuum problem driving me NUTS!!!!!!!!
My experience with running rollers on a slider cam is the cam timing was very advanced. I retarted the cam 1 tooth and it ran fine.
Thanks
Randy
Quote:
Originally Posted by
shackwrrr
Slider cam, roller followers. Mine had bad vacuum when I did that.
Re: Vacuum problem driving me NUTS!!!!!!!!
Quote:
Originally Posted by
85boostbox
I did screw around with ignition timing with the distributor. But not with a light just seeing if I could get vacuum higher. And I did unplug the coolant temp sensor. It did help a little but nothing drastic. I know when I drop it into drive it drop down to 8 to 10. On a hard decel I get 22. Car runs fine though. Logic module AFAIK is original. No codes btw.
What I was curious about and I would have to confirm is what cam is in it. Isn't there a difference in degrees as far as slider vs roller? That is the only thing I could possibly come up with. And it is a 782 head on it as well so the head is correct for the cal.
Paul
I would get an actual timing light on there before making any further changes. A stab in the dark with timing is no way to start off hunting a problem with low vac at idle IMO.
Re: Vacuum problem driving me NUTS!!!!!!!!
At least you don't have a rudder in your pants, that would really be drivin your nuts!!!:D
Definitely compression check to make sure they aren't all low. Pinch off each vacuum line and see if the readings come up. Could be something you can't hear or missed during spraying for leaks. Could be leaking under the dash and might not be able to hear it.
Re: Vacuum problem driving me NUTS!!!!!!!!
Rip that slider out and install a 88 T1 or 88 TBI cam and roller's. Will be a whole diffrent car trust me. Shouldnt be that hard to track down. Just remember that you cant use 89+ cams because it will throw the cam timing out of wack. When I swapped a 88 T1 cam into my 86 NY it became a whole different car.
Re: Vacuum problem driving me NUTS!!!!!!!!
Quote:
Originally Posted by
85boostbox
Well did a compression test... 90 to 100 across the board and it dropped quickly??? So squirted some oil down the cylinders and shot up to 125. Still dropped quickly though.
So sounds like rings or could it be my valve seats. Dunno.
Yeah, that's not good at all. Have you triple checked the cam timing recently?