engine and drivetrain Dcoe Tuning On New Engine -

[76dailydriver]

Felix, 

 

Just read your post and I feel your frustration. I had the same issue with my 40DCOE32 3 weeks ago. Chased everything from jetting to timing. I was too running a crane XR 700 optical wheel and a 037 mechanical distributor. My bosch red coil would get real toasty after 15-30 mins of running. And all the issue you are having I had.. 

Try this - 

While engine running try wiggling the optical wire that connects your xr700 to the optical sensor inside the distributor. If it misses or kills the engine. Bingo! you problem is the optical wiring assembly. If you still have your points/condenser setup. remove the xr700 optical wheel assembly and swap in the points and condenser. Properly gap it to .016 and fire her up. This solved the problem that you've described. Also check your coil. What coil are you running anyway? Hope this helps.

 

John

[felix_666]

Felix, 

 

Just read your post and I feel your frustration. I had the same issue with my 40DCOE32 3 weeks ago. Chased everything from jetting to timing. I was too running a crane XR 700 optical wheel and a 037 mechanical distributor. My bosch red coil would get real toasty after 15-30 mins of running. And all the issue you are having I had.. 

Try this - 

While engine running try wiggling the optical wire that connects your xr700 to the optical sensor inside the distributor. If it misses or kills the engine. Bingo! you problem is the optical wiring assembly. If you still have your points/condenser setup. remove the xr700 optical wheel assembly and swap in the points and condenser. Properly gap it to .016 and fire her up. This solved the problem that you've described. Also check your coil. What coil are you running anyway? Hope this helps.

 

John

 

 

I will try this. Last week I went over the ignition system with a fine brush, although everything is new, I wanted to double check, but given how well it starts up and runs till warm I'm assuming the crane is ok.

 

Coil is a Bosch Blue unit, I think it's got 3.4-3.6 ohms of internal resistance. I have a couple of others, but they are all pretty similar regarding internal resistance.

 

It seems to run well when cold (no load - so it might run like crap in the road) which makes me feel the ignition system is fine - my assumption is that an ignition problem should be consistent through operation.

 

Anyway, I'll jiggle the crane, something I haven't done.

[Hans]

And one other thing; check floats for leaks. Shake them and listen for sloshing. 

[76dailydriver]

I will try this. Last week I went over the ignition system with a fine brush, although everything is new, I wanted to double check, but given how well it starts up and runs till warm I'm assuming the crane is ok.

 

Coil is a Bosch Blue unit, I think it's got 3.4-3.6 ohms of internal resistance. I have a couple of others, but they are all pretty similar regarding internal resistance.

 

It seems to run well when cold (no load - so it might run like crap in the road) which makes me feel the ignition system is fine - my assumption is that an ignition problem should be consistent through operation.

 

Anyway, I'll jiggle the crane, something I haven't done.

My thoughts exactly with the ignition. Since she fires up when cold and revs up freely on idle. But when i start to put load or drive away. It sounded like jiffy popcorn being made and lack of power until 3500 rpm. COIL was toasty as heck. Replaced with a known working coil and did the same thing. I also noticed the tach bouncy. Surging from 2000 rpm then bouncing to 6000 rpm. Do you notice this, in yours, with the tach? So i started going over my 40s like a fine tooth comb. I dealt with mikunnis before with my AE86, so should be the same theory. And after all that, it was the optical wheel in the distributor. The wiring was grounding out/loosing connection during load (in gear) somehow. This was found by accidentally nudging the wiring during timing checks. I also don't think it will hurt to put on a good set of points/condenser back on to just trouble shoot and eliminate the ignition system as the culprit.

Also - brand new does not usually mean brand good.

[Hans]

I've seen a needle valve that was missing it's ball.

[Chris_B]

I have seen needle valve assemblies that were loose in the top (i,e., not screwed down all the way). They leaked gas profusely.

[felix_666]

UPDATE

A follow up for any suckers out there in a similar boat to me in the future.

The Crane trigger wasn't aligned correctly, which was installed at the beginning of the year and has caused all sorts of problems, like rich running due to insufficient time for the charge to be released and crazy timing according to adjustable gun.

Thanks to all those who helped along the way, I learnt heaps. Soon as I restarted the engine with the trigger correctly adjusted everything began to fall into place, idle mixture screws actually making a difference, nice idle at 800rpm and most importantly it pulls like a wounded bull with no hesitation or flat spots, although I'm pretty sure I have a bit of tuning to go as things are still pretty rich.

In summary, "90% of your carb problems are the ignition".

Videos to come.

Cheers.

Edited December 21, 2014 by felix_666

[76dailydriver]

Congrats! Glad we can all help and leading you in finding the gremlin.... Now go out there and drive and enjoy! Brrraaaaappp!

[felix_666]

A final update:

I took my car to the carb guy who rebuilt the carbs to begin with and he played around with the jetting, timing and the chokes and eventualy stuck it on the dyno.

Mains went down to 115

Chokes went down to 30

Everything else seemed good.

I wanted it to be ok on fuel and good down low, which it appears to be, but hard to know for sure when you haven't much comparison.

Good times.