cdaniel525

iTrader: (1)

I have a DUI on my 489 stroker making 537hp/594tq but am having a hesitation / bogging issue when getting on the throttle from idle while trying to come up on plane.... I am running a Speed Demon 850 carb that was on the motor when being dyno'd but has kind of had the bog all along...
I sent off a spare Holley 750cfm to Nickerson Performance to build up to my exact specs of the motor, cam, heads, etc.... BUT I want to make sure everything is on point with the ignition as well.

That said I am running a DUI distributor with initial timing of 12deg and total of 36... AFAIK, the distributor is all stock inside besides replacement cap/rotor...
One of the guys at Nickerson said to run the medium silver spring on one side, and the heavy gray spring on the opposite, and install the black heavy bushing. BUT these are MSD parts he is referring to... When I check into DUI it seems as if they dont sell the parts to adjust the timing curve but you need to send it back in to them.... Normally thatd be OK but I dont want to send it in with the beginning of the season coming.

Are the MSD HEI parts interchangeable with the DUI HEI so I can try out the combo they are recommending??

That said, does my symptoms point to a fuel or timing issue??

Thanks in advance....
Chris

picklenjim

Sounds more like a fuel issue to me.

cdaniel525

iTrader: (1)

That's what I was thinking... The boat will idle fine and once it is cruising, there is no lack of power or hesitation at all.
Just was thinking maybe timing advance issue but sounds more like accelerator pump or powerjet, no?

Baja Rooster

iTrader: (1)

It sounds like a lean spot in your carb tune. It's fine at idle under no load but stutters when tasked? I'm no expert on the matter but that's been my experience tuning motorcycles.

You have to send your distributer back to DUI for a change. I've only called them once about a different issue but a real person picked up the phone and was technically competent. I'd wait until you try the new carb first though.

Black Baja

iTrader: (2)

Do yourself a favor and buy a decent carb. Speed Demon=junk. Nickerson modified carb = bigger piece of junk. Buy a new Holley or a Quick Fuel and go boating. After you recover from the sore rectum you recieved from dealing with Nickerson get a decent ignition.

Griff

Sounds like the accelerator pump is bad, not properly adjusted or too small.

ezstriper

will run better with more base timing, but your issue is in the carb, also the 850 @ that power is iffy, 750-800 much better choice

cdaniel525

iTrader: (1)

Thanks for all the replies.... I'll ignore the timing for now as I know it's set properly and advance comes in good... I'll see what Nickerson carb acts like, and in mean time am going to try fine tuning the Speed Demon. If neither work out I'll be buying something new like Black Baja suggested....
Thanks again guys

sprink58

I sent my DUI's to them for a tune and had them back working flawlessly within a week.

cdaniel525

iTrader: (1)

What would you suggest for initial/base timing? What's usually best for total timing too thats still safe?