Okay, just finished up on this truck I've been working on for about 3 weeks. This motor ran better than any other 81 diesel I had driven
previously. My father had one brand new in 81(plus we had a few in our constr company), I had two different rabbits in college with same motor. When I found this one I couldn't believe how much snappier it seemed than any other I had experience with.
Just got it back in running shape after sitting in a garage since 93. After I changed the belt and fixed the cam so everything was a TDC I timed it back at 94. Starts with absolutely no hesitation, no smoke, seems to run as expected but it doesn't have the snap it had before. Now, I believe before the ip pump cold start was not going all the way back to the stop and the TDC on the crank was about 1/4" past true TDC when I had the cam lock in.
Should I mess with it or put a little more lift to it?
If the cold start lever was not going back to the stop that would be like driving around with the cold start lever out a bit right? Well once the engine gets going on its own that amount of advance isn't going to change how it drives. The change in timing that is associated with the use of the cold lever is for when.... The engine is cold, or more like not running. It manually advances the plunger toward advance but quickly is changed with the pressure coming in when the engine is running.
Snappy engine is gone you say? Timed at 94 mm you say? And now you are pretty sure that the initial timing had the TDC in a better more correct place? I am thinking that the way the engine was set up before you were just running more advance than you are now. You do know that some stickers on the fender well mention that the IP can go to 1.05? for performance purposes only. Not so much for air quality. And it might rattle a bit more during running.
Run it for a bit as it is and then bump the timing a tad and see what that does to change it. If you like the change run it and bump again a bit later. If better keep if not better go back to where it was. This is what we all do and why our neighbors wonder about our sanity. Every weekend the hood is up on that car. Doesn't it run like my 2015? I never have trouble with it.
Keep playing with your timing like orcoaster suggested. There is a sweet spot for your engine you just need to find it. As long as your mechanical timing is bang on just keep playing with the pump. Id suggest installing an exhaust gas temp gauge and playing with the boost and fuel a bit once you get the timing right. Its very easy to get a good boost of power with these things for the cost of a gauge and a boost controller 😉 without hurting reliability.
1.05 is about the most people suggest so don't be afraid to increase it a bit more.
One of the biggest reasons we constantly "play with the timing" is that as the pumps wear, and they all do so at different rates the actual timing we get from measuring a number is different. So even if you timed your pump with a 1.05 measure and I did the same we might very well be firing off at different degrees of advance. That is why I love my set up that measures the flywheel mark and the instant the fire is in the hole. That way I can be the same no matter what pump I put on there.
That equipment was not cheap, even if I did buy it very used from a shop closing it out on Craigslist. The meter came with the cord to the flywheel buggered up so that was the first thing I needed to correct and then I finally got the proper insert for the VW glow plug hole for the optical feed. So now I can be at TDC, 3 degrees BTDC or clear to 12 degrees BTDC in short order.
It is all done in real time with the engine running too. Once you get the parts installed. Then you need to shut it down and remove some adapters and such. But still super easy and no diesel leaking out the back of the pump.
If the cold start lever was not going back to the stop that would be like driving around with the cold start lever out a bit right? Well once the engine gets going on its own that amount of advance isn't going to change how it drives. The change in timing that is associated with the use of the cold lever is for when.... The engine is cold, or more like not running. It manually advances the plunger toward advance but quickly is changed with the pressure coming in when the engine is running.
Snappy engine is gone you say? Timed at 94 mm you say? And now you are pretty sure that the initial timing had the TDC in a better more correct place? I am thinking that the way the engine was set up before you were just running more advance than you are now. You do know that some stickers on the fender well mention that the IP can go to 1.05? for performance purposes only. Not so much for air quality. And it might rattle a bit more during running.
Run it for a bit as it is and then bump the timing a tad and see what that does to change it. If you like the change run it and bump again a bit later. If better keep if not better go back to where it was. This is what we all do and why our neighbors wonder about our sanity. Every weekend the hood is up on that car. Doesn't it run like my 2015? I never have trouble with it.
Yes, I'll do just that. Not sure how much I'll be running it as it may have to go. Too many things happening right now and no time to mess with it. I had high hopes to keep it and fix her up a little at a time but time is the issue. I still need to get new rubber on and tranny fluid changed before registration and driving. After that I have headliner, carpet, driver seat and a paint job.
Also, no turbo on this car...although it would help.
