View single post by DeDub
 Posted: 05-03-2007 03:29 am
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DeDub



Joined: 04-10-2005
Location: Sebastopol, CA, California USA
Posts: 27
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I'm taking off on a thread from a year and a half ago on the DellO 40 vs 45 forum (last used a year and a half ago) and posting here because I think my need better fits this forum subject line AND this forum has seen more recent activity.  We'll see who is still monitoring this forum (besides you of course, Greg).

My car: a 74 era mutt made up of at least 3 bodies, now titled 19377 with a mutt of a motor with an unknown history.  But it's sound, good even compression and hasn't smoked noticeably after sitting for several years.  It was purportedly good when parked.  I had 104/107 cams and towers from another motor, put those on instead along with a new set of DellO 45s from JHPS.  They came set up as follows:

37mm chokes
160 mains
7772.8 emulsion tubes
230 main correction jet
62 idle jet
7850.9 idle jet holder
50  pump jet
95  cold start jet
7482.3 cold start emulsion tube

I mention the above because I think I have a fuel problem rather than ignition.

I first ran the car briefly as soon as I put on the DellOs; they didn't have air cleaners or even velocity stacks on them yet so the car ran poorly and was very balky.  Then I got around to putting on the stacks and went for a first drive but still without the air cleaners.  It ran amazingly well for not having balanced carbs; even and strong with only a hint of hesitation once in a while.  I'd read that DellOs must have the stacks on to run right.  But as I drove it, it would occasionally stumble on mid throttle, erratically, increasingly as I came home.  Yesterday I put on K&Ns and went for a drive that started well but it increasingly would bog down mid throttle as if it was running out of gas.  EIt worsened and eventually I could barely drive and only got home the last bit in first gear.  It would idle but would only run with the slightest crack of the throttle; any more and it would act like it was out of gas and die.  Since then, I've checked the fuel pump; it had plenty of pressure and flows plenty of volume (though I didn't try flow under a few pounds of pressure).  I checked and blew out all lines; they were completely clear.  Went for a drive, no change.  I pulled the tops of the DellOs to look for fuel level (it looked fine), water (none), and debris (none).  Went for a drive, no change.  I decided maybe it was ignition so I put a Pertronix I had lying around on a spare distributor and installed and timed it.  No change.  Pulled the plugs and regapped them to 40 thousandths, no change.  I swapped out the coil for one off a parts car, no change.  It's already got new wires and cap so that's the whole ignition system.  By now, I'm starting to get a bit testy.

Data points:  It always starts right up.  It runs better when cold and becomes more undriveable as it warms up.  When I hit the throttle part way, it initially very briefly surges, then completely bogs down and will die if I don't let off the throttle.  BUT, once I couldn't quite get home and sat on the side of the road for a minute with the motor idling, and it was then better enough to get me the last few feet home.  It acts as if the fuel pump can't keep up but there's definitely pressure in the fuel line at the carbs and will hold that pressure for a few minutes after I turn off the key.  It also acts like as if it might be heat related.  It's not a vacuum in the fuel tank problem.  I'm not losing coolant and the car doesn't run hot.

At this point, I'm looking for a fresh perspective. What am I missing?

David,
quietly, so far, going nuts in Sebastopol