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Thinking of doing the unthinkable... *Rotor to cap gap. Normal?*

Thanks fordum. Fwiw, I can advance the timing to the point where it starts to run worse with no increase I'm vacuum. The timing on the tbi motor is supposed to be 0*. To get mine to even run as good as it is I have been running around 6*. Back it off and it gets worse. And yes I do set the timing with the tss wire disconnected.
 
So, I have formulated a plan. It's as stupid as it is awesome. Ok, stick with me. I'm going to swap the cam. With one from the junk yard!... Yep. I have determined that the quickest/cheapest/easiest thing for ME to do in this retarded situation is just to go to the junk yard and pull a cam/lifter setup out of a random tbi truck. I will go ahead and keep track of which lifters came from what spot and put them back in accordingly, but that's about as far as my care-o-meter goes for this particular stupid project. So, I'm going to begin tear down of the burb tomorrow and go get a junkyard cam next week. This ****s gunna be epic. Oh and don't worry, I know that this is not only a very bad idea but will also make no difference in the way it runs. But It's better then sitting around doing nothing damit!
 
cam swap and match the lifters like that back in same spot is 100% correct.

done it before no problems. :waytogo:

i just used big cardboard sheet and marked frt/back & dr/pass sides. cut holes to pop all lifters in to and away i went no problems n reinstall job.
 
i have the same exact problem with my 87 1 ton, and have no clue what it is either. my buddy has a durango that did the same thing though, and it ended up being his battery tweaking out( strange i know) but i havent tried putting a different one in mine yet to see if it works
 
some year dodges were vary picky to cca spec on battery to computer problems. seen it 2x in my years as a mechanic and heard lots of other guys also same thing.
 
Forgot to add that the first thing I'm going to do is pressure test the intake and make sure It's not cracked and therefore creating a vacuum leak.
 
better unload the valves that will be open .

and better to try and pull a vac than pressure since thats what it is trying to do under normal loads.
 
See if you can't rig up a smoke machine. That not only show up cracks, bad gaskets, and whathaveyou, but shows where they are too.
 
y5mgisi said:
Thanks fordum. Fwiw, I can advance the timing to the point where it starts to run worse with no increase I'm vacuum. The timing on the tbi motor is supposed to be 0*. To get mine to even run as good as it is I have been running around 6*. Back it off and it gets worse. And yes I do set the timing with the tss wire disconnected.
Click to expand...
At 0 my motor ran like crap and it was also a fresh rebuild. My motor liked timing advance so that is what I gave it and it runs great.
 
The reason everyone is loosing cams as the years go by is most all oil off the shelf does not have near enough zinc and phosphorus for flat tappet cams.

Every new car for about a decade has roller cams and don't need it and it causes pollution. Last car to leave Detroit with flat tappet cam was a 2006 Jeep 4.0l engine and it required special oil or void warranty.

Amsoil makes a synthetic oil with zinc and phousforus or look for Brad Penn racing oil. I think Comp Cams also makes oil for flat tappet cams.
 
better unload the valves that will be open .

and better to try and pull a vac than pressure since thats what it is trying to do under normal loads.
Click to expand...

Im going to pull the manifold off and seal it off and check it on the bench. And yea, i will use vacuum instead of pressure.

See if you can't rig up a smoke machine. That not only show up cracks, bad gaskets, and whathaveyou, but shows where they are too.
Click to expand...

I messed around with this idea for a while and couldnt really come up with any good ideas. I was able to use cigarette smoke to find a leak in the throttle body though.


At 0 my motor ran like crap and it was also a fresh rebuild. My motor liked timing advance so that is what I gave it and it runs great.
Click to expand...

I have tried advancing it so far that it starts to run even worse. At no point between 0* and however far advance that must have been around 30* or so i would guess did it run any better.


The reason everyone is loosing cams as the years go by is most all oil off the shelf does not have near enough zinc and phosphorus for flat tappet cams.

Every new car for about a decade has roller cams and don't need it and it causes pollution. Last car to leave Detroit with flat tappet cam was a 2006 Jeep 4.0l engine and it required special oil or void warranty.

Amsoil makes a synthetic oil with zinc and phousforus or look for Brad Penn racing oil. I think Comp Cams also makes oil for flat tappet cams.
Click to expand...

I dont think my cam has gone bad. I just think its the wrong cam. Whether it was miss boxed, miss ground, or just not right for my motor, i just think that its not working with the TBI.
 
did you check the degree on it? If not before you pull it check it. It may be as simple as an offset key.

What is the vacuum at idle?
 
No i havent checked the degree yet. I dont know if it will be worth the trouble or not? Vacuum is low. Thats why it runs so bad is the map is reading low vacuum and the computer is compensating for it. If i pull a proper vacuum on the map sensor the truck runs perfect.
 
May I suggest checking the cylinder pressure next? If you have high cylinder pressure (160-ish), and low vacuum, then it's not the motor itself, it would be a vacuum leak or similar.

If you have low cylinder pressure, it could be cam timing, too much overlap, etc.

Best wishes to you in finding the problem.
 
Sounds like low cylinder pressure, so you won't be able to build much vacuum.

It's a pain, but it may be the cam timing, or cam design, thats the problem. But it doesn't sound like a vacuum leak.
 
Sorry for the extra post, but you might want to look at the timiing gears, and without pulling the cam, advance the cam 4 degrees.

4 degrees advance could gain you 20#'s of cylinder pressure, and about 4" of vacuum.
 
Quite alright! Feel free to add as much as you would like! I do believe that my problem is in the cam. I have thought about advancing the cam, but i could never get a for sure answer on whether or not it would in fact increase the vacuum. I guess my main concern with advancing the cam is running into valve-piston clearance issues. I dont know if i would or not, but that would be my worry. For what its worth on the compression numbers, they are the same now as they were back in 2007. If i were to advance the cam, how would be best to go about it? Is an offset crank key best?
 
On another note, can i get by with just loosening up the oil pan to get the timing cover in and out? Or do i need to drop it all the way?
 
You could loosen the front of the oil pan, and get the timing cover off. I have not used an offset key, I bought an inexpensive timing gear set with a 4 degree advance / retard feature (brand unknown).

You will not have any valve / piston clearance issues, but before firing it up, take another compression test to see what increase it made.,

The few times I've advanced the cam when cylinder pressure was low (not bad rings), it was usually worth 20+ #'s of cylinder pressure, sharper throttle response, and idle vacuum would go from 10-12", to around 14-16". Tuning was much easier both carbed and tbi.
 
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