Mikuni Jetting

[jmortensen]

Yes, I think those are a big air restriction. I tried to Google to find a dyno plot with and without screens but couldn't find one. The best I could come up with is this: http://porsche356registry.org/resources/tech-articles/troubleshooting-and-repair/371-velocity-stacks--for-looks-for-power-or-both.html

You could easily test my theory by pulling them off and seeing how it runs, but don't just sit in the driveway and rev it up. I bet it runs like crap with a load at higher rpms.

[lila725]

Thanks for the info. I think ill go with the ITGs and spend the money on a high performance oil pump instead. Steve ill keep you posted on the jetting when they get here.

[Travel'n Man]

Yes, I think those are a big air restriction. I tried to Google to find a dyno plot with and without screens but couldn't find one. The best I could come up with is this: http://porsche356registry.org/resources/tech-articles/troubleshooting-and-repair/371-velocity-stacks--for-looks-for-power-or-both.html

You could easily test my theory by pulling them off and seeing how it runs, but don't just sit in the driveway and rev it up. I bet it runs like crap with a load at higher rpms.

Jon -

The next time I dyno - I'll go with filters and without filters to find out if there is a restriction -

Edited November 22, 2011 by Travel'n Man

[lila725]

Steve, just keeping you updated, i turned my pilot screws 2 turns out from seat so that the idle on the meter was on the rich side. It has helped with the hesitation but it is still there. But it keeps me positive that the pump nozzzles will fix it or most of it at least. Will let you know. Traveln man if you see this id like to see those dyno results as well. This is interesting.

[steve91tt]

Sound like you are going in the right direction If you have a set of bigger pilot jets that may be worth a try as well. No experimenting for me right now as I'm in the process of pulling the engine but I'm looking forward to hearing more about what you find with the bigger pump jets.

[jmortensen]

If you have to run the pilots 2 turns out then you need bigger pilots. I was taught to run the pilots out 1.25 to 1.5 turns, and if it was lean, run a bigger pilot. A bigger pilot will help with the hesitation IME as well. I went down this road and found that squirting more fuel in with the acc pump made it worse after a point. I would put the pump linkage back to the middle setting and then focus on the pilots.

Smaller chokes will also help, but that will hurt top end, so you have to weigh the pros and cons. If you really want it gone, smaller chokes is probably the answer.

[Travel'n Man]

Steve, just keeping you updated, i turned my pilot screws 2 turns out from seat so that the idle on the meter was on the rich side. It has helped with the hesitation but it is still there. But it keeps me positive that the pump nozzzles will fix it or most of it at least. Will let you know. Traveln man if you see this id like to see those dyno results as well. This is interesting.

I will not get another dyno completed until Spring - FYI - it's too soon till the end of driving season at this point.

There is a formula you use to set up your triples - have you used that set up guideline? It is in the Mikuni manual - have you discussed your challenges with Todd at Wolf Creek Racing?

Edited November 23, 2011 by Travel'n Man

[lila725]

This is my plan. I will put the pump nozzles in, put the linkage back in the middle hole and i can afford to screw in the pilots a quarter turn as I now have them out 2 turns to compensate.

This will be my first real step. Ill see what happens and let you all know.

If nothing happens i will pin it as hard as i can into the nearest body of water and let the fish have a nice place to make a home, .

[lila725]

Gentlemen, my accel pumps have arrived, earlier then expected, (Thank you wolf creek racing). I have installed them and drove the car around, stop and go, shut down waited and restarted, highway on and off accel opened her up, down shifting, power shifting, cornering, drifting and any thing else I could think to do and it seems to be cured.

There was no hesitation on accel, even if i depressed the pedal super slow through its range it was smooth, it did go leaner on the AFR meter but that is to be expected but not enough to make a driveability issue. Maybe going slightly larger on the pilot jets and the AFR meter may not change at all, I will try it.

So as of now Im running 220 main air, 180 main fuel, 60 pump nozzles with rod set at top hole (Most fuel), 57.5 pilots, on 44s with a 3.0 stroker kit, e88 big valve head, nissan motorsports header, k&N air filters, isky cam 360/500 and it is running good.

I think I will go to ITG filters and go with 58.5 pilots and I should be going strong.

Thank you all for your help and support and your input. When I make those other changes I will let you know my results. Im going to go drive,

[lila725]

Hello again. I have now installed my itg filters and also went with bigger pilots (60 from 57.5) and the car is running great. The transition from the pilot system to the accel and main system is consistant and smooth and dosent drop past stoich and it idles great. Just keeping everyone informed.