What to do to a 2056 with 2.0 DJet, Help get this motor worked out. Options

[Teknon]

Ok Motorheads,

Senerio:
New 2056, Slightly more aggressive than stock Isky VP-228 cam, ported 5pt heads with '74 2.0 D-Jetronics. Crane xr700 009 dizzy. Burch exhaust through SSI HX'ers

Question:
What would be some tricks and tips to make this engine more efficient. (IMG:style_emoticons/default/cool_shades.gif)

I thought of having the MPS adjusted for a 2056, read that somewhere. Would like to put an oil cooler in most likely.

What else would be things to concider. The engine is in boxes ready to assemble.

Please chime in

Joe D

[jk76.914]

I'm running an Isky 229 with D-Jet. Though there isn't much overlap (12 degrees at .050" lift, just like your VP228), I saw a significant reduction in vacuum at idle, though my idle was still pretty smooth and quiet. I experimented with advancing the timing at idle, and it improved significantly, which makes sense if overlap is indeed the issue. I'm in the process of modifying a spare distributor to reduce the total centrifugal advance, so I can run more advance at idle but not exceed 32 degrees (plus or minus) total at 3500 RPM. I'll know later this season.

The second thing I noticed was a lean miss at about 3000-3500 RPM at part throttle cruise. I "fixed" it by installing slightly higher flowing injectors, but I think the real solution (not proven yet!) is to tweak the MPS for richer running. Trouble is, I'm convincing myself that the problem is that the diaphram transitions off the part throttle stop too late, because if I open the throttle more (reducing the vacuum, and thereby starting the transition) the miss goes away. Unfortunately, this isn't one of the adjustments available. I hope to get a better handle on this this season as well.... There have been a number of posts from other folks having this problem as well......

I have no regrets in going with Isky.

Good luck with the engine... Jim

[Demick]

Trouble is, I'm convincing myself that the problem is that the diaphram transitions off the part throttle stop too late, because if I open the throttle more (reducing the vacuum, and thereby starting the transition) the miss goes away. Unfortunately, this isn't one of the adjustments available.

Jim

Actually, this is exactly one of the adjustments you can make to the MPS. The stock MPS has the diaphragm come off of the part-load stop at about 6 inHg. That adjustment is set with the so-called outer screw. You can set this to a larger value to get it to start the enrichment sooner. With my 2056, I experimented with this and ended up adjusting my MPS to come off of the part-load stop at 9 inHg for earlier enrichment just like you are talking about.

Here are some posts that you might find interesting:

part 1

part 2

Demick