350 diesel: Pencil Vs. Poppet I.P.
I am beginning to plan for my next diesel conversion. It will be a square body GM wagon from the 80s (preferably a Custom Cruiser or Caprice Estate), and I am in possession of a Goodwrench 350 Diesel DX block engine with only 38,000 miles on it. The car it was installed into was badly rear-ended, and as a result it was totaled. I got to hear it run before I pulled it, and I got it for $75. I know that there are people who hate this engine, but I am not one of them. I drove one for 5 years starting in my Sophomore year of High School; it was my grandfather's car, and he gave it to me with a bad transmission and said if I fixed it, the car was mine. It was a 1980 Olds 98 with a POS THM-200C transmission. I replaced it with a THM-350C and drove this car 80,000 miles with that engine. The engine was a Goodwrench engine (it went in at only 18,000 miles). The car had rolled the odometer twice when I got it (nearly 200,000 miles on the engine, despite the transmission being replaced 4 times before I got it) and I put another 80,000 on it, and I was a leadfooted teenager that whooped on it every day. I got a kick out of getting over a week out of $10.00 of fuel, despite driving it like the "General Lee" and single-handedly controlling the mosquito population in Delaware County PA (where I grew up). I am saving my other 6.2L diesel for my F-150 if and when my 300 six gives up. The Olds diesel will drop right in to anything that has a 307 Olds engine with virtually no fuss, and this is another reason I am intent on using this engine. So if you want to drop negative comments about the engine instead of answering my question, I would politely ask that you refrain from discussing this topic. I will give this engine a full once over and put it back together with quality parts and ARP bolts if it is in suitably decent condition. My question is for those of you with more knowledge than I about the DB-2 injection pump, particularly as it pertains to the 350 Olds diesel in pencil and poppet injector forms. (If you think my I.P. idea is stupid and leave a negative but constructive comment about it that is different, because I am looking for that particular feedback).
As we 350 diesel fans have heard many times before, the pencil engines tend to be peppier. Many have ascribed that to the I.P. not necessarily the injector. However, the poppet engines use a mechanical light load pump, and the pencil engines use speed advance. The two pumps are known to not be interchangeable. Part of that I believe is the pressure equalizer circuit in the hydraulic head of the poppet I.P. What if the hydraulic head for a poppet pump were transplanted into the body of a speed advance pencil style pump? This would provide the correct hydraulic circuitry for the poppet injectors, while affording the superior performance of the pencil I.P. and the better performing speed advance setup. I came to this idea after reading my GM Product Service Training book "The 5.7 Liter Diesel Engine" yet again. I spent a great deal of time reading and re-reading the section on the DB2 pump, and suddenly the idea was there. What do you guys think?
tomtaylor: 6.2 to 350dx swap
Thomas:
Your project sounds very interesting to me. I have a similar project in mind. I was curious if you started on this project and/or finished, and what kind of results you've seen. What type of injectors does your 350DX have? I'd be really interested in how you made out. I have 2 Goodwrench engines; one with pencil injectors, the other with poppet injectors. I would like to put one in a C20 2wd. Any information appreciated.
[Not sure if I'm posting this right--new to the site.]
It's good to hear you can get good mpg with 3 speed transmissions. I wonder what kind of rear-end ratios you're dealing with.
I have a 700-R4 [and adapter plate] and a TH350C with a diesel low-stall TC, that I could use.
