I've heard rumours that 92U prefix 3406's were available as both pre-cup and direct injection. Mine is apart on the shop floor and will need a complete rebuild. Just wondering what is all involved in converting the engine to direct injection? Mainly concerned about whether or not I'd have to replace the injection pump (too much $$$$).
Hope that Nige sees this or you might want to "Start a Conversation" with him about it. That said my money would be on needing a different pump or at least some serious changes to yours, Pumpguy may also be someone to check with.
The PC pump was used with DI but IIRC there is a change in timing. I'm thinking the pump drive gear was different for some reason. I did two PC to DI conversions over 35 years ago but it's been too long to remember everything.
I know they updated the timing advance once or twice. I believe mine is the newer style.
If it's out on the ground, I bet you can find a nice B model for the same money to convert yours.
I've thought about it but this is just for a play truck. Figured if I needed a new head and the conversion was pretty easy I'd go for it. If my head checks out ok I'll just keep it PC.
If it is for a play truck I would keep it PC for the cool sound factor.
They do have a sound all their own.
I can't find any information relating to this conversion. That doesn't mean to say it isn't possible, just that without the info in a "how to" Special Instruction makes it difficult unless you can find someone who's a) done it themselves and b) documented what they did.
I suppose if you could find a DI engine with a close application to yours and get the S/N off it and then compare the parts break down to the one for yours one could get a good idea of what major parts are different. That TMI Web site when it would work for me might have been some help.
When I look in SIS they do list PC and DI pistons, as well as DI and PC heads. Nothing on the injection pump breakdowns indicate PC or DI though. I may just need to sit down with an adult beverage and spend an afternoon digging into SIS to see if I can find anything.
I found this thread: http://forums.aths.org/Topic84741.aspx I hate to say but I wonder if some of the people offering advice on that thread are still in a condition to offer it 8 years later.
It might be worth joining that forum and posing the question there. Who know, you might hit pay dirt..?
I think the injection pump housing does not change but I'm not fully sure if the piston pumps change. I think the PC injection pump and the DI pump housings are the same. I'll see if I have time to look on SIS and see.