View Full Version : engine vacuum

10-16-2014, 09:20 PM
I just fired up my 3.8 sc that I install in a 1978 Jeep CJ. The engine was brand new not rebuilt and never fired until today oct 15.
Two issues. the timing appears to be retarded.
Do you have to have the tool to set the Cam sensor or can you rotate the cam sensor and set the timing at 10 BFTDC or do you need to align the cam sensor when number 1 is at 26 deg after tdc like the manual says
The engine acts like retarded timing when it is trying to start but once running it is ok.

Second issue
I can't get any boost. I used 3 in silicone elbows on the tubing to and from the inner cooler( stock unit). When I rev up the engine the elbows collapse and the engine boost gauge shows 30 inches of vacuum,- no boost. If I disconnect the tube on the outlet of the supercharger I get hot air at startup?

Please help
David Wilson

10-18-2014, 08:30 AM
I have never had to adjust/set the cam sensor so I am no help on that.
Remember that to set base timing you do need to pull the jumper plug which is near the DIS on top of the A/C compressor, the manual covers this, my memory is rusty on that, again, I have never adjusted base timing, it has always just been correct for me.
On the air circuit, you can use your hand to close the bypass valve which is near the back of the blower, this should create positive pressure in the intercooler loop, usually people have trouble with vac leaks in this system.
by actuating this lever you should atleast see a big difference from vac to some pressure.

10-21-2014, 09:20 AM
Our engines are the only ones out there that run vacuum throught the intercooler circuit, according to Dave Dalke. I ran into the same problem with the collapsing elbows. If you used a kit for a turbo car that is the problem. I lined my elbows with a matching 90* aluminum elbow. I am having the silcone elbows replaced. The elbows should go back to round when you rev the engine because that removes the vacuum.