Mini sprint dyno and\or tuning question

McInturff Racing · 5/23/11, 11:21 PM

I just switched from compacts to mini sprints this year and the learning curve has been a bit steep and I'm hoping you fine folks can give me some direction. Right now I am having an issue with a HUGE flat spot in the middle of my rev range on my '02 R6 on modified Odum carbs. Carbs were just cleaned, adjusted and balanced by Odum, I am running the 3# fuel pressure that he told me to run (float jets were drilled out and replaced by a screw in type that runs 3# as opposed to his usual 5#), new plugs, new alcohol resistant fuel pump rated at 130 GPH, new fuel pressure regulator, clean filters. Fuel system is set up as a deadhead. The engine does this under load and at idle, but once I get past it the engine runs great. I'm not sure what adjustments I should be trying to make to eliminate this or if I should just bite the bullet and have my engine dynoed. The only problem I have with the idea of a dyno test is that I do not know anywhere near me that is set up to do a mini (I'm in Troy, Ohio half an hour north of Dayton). Any suggestions to help steer me in the right direction would be greatly appreciated!

DAD · 5/24/11, 12:52 AM

mid range is controlled by slide needles. sounds lean to me try raising needles higher with either slots in needles or shim washers.

DAD · 5/26/11, 8:56 AM

I know how you are feeling right now. Thest things seem 360 degrees out from every thing you have experienced before. Go on line and google "factory pro" this old guy has a compleate guide on how to adj your carbs. We have a dyno now and it has helped a lot in tuning however before the dyno we used an old country rd. A dyno is nothing more than a road with a modest hill in it. that adds the resistance you want. What you would do is place your car in the gear you will be racing in probably second or third aproach the hill at the speed you line up a race in and when you get to the hill floor it, and note what areas or good and what areas are not so good go back to factory pro and read, make adjustments then do it again.
good luck
DAD If you have any questions give me a call 502-778-6833

TQ29m · 5/26/11, 9:39 AM

Quote:

Originally Posted by McInturff Racing

I just switched from compacts to mini sprints this year and the learning curve has been a bit steep and I'm hoping you fine folks can give me some direction. Right now I am having an issue with a HUGE flat spot in the middle of my rev range on my '02 R6 on modified Odum carbs. Carbs were just cleaned, adjusted and balanced by Odum, I am running the 3# fuel pressure that he told me to run (float jets were drilled out and replaced by a screw in type that runs 3# as opposed to his usual 5#), new plugs, new alcohol resistant fuel pump rated at 130 GPH, new fuel pressure regulator, clean filters. Fuel system is set up as a deadhead. The engine does this under load and at idle, but once I get past it the engine runs great. I'm not sure what adjustments I should be trying to make to eliminate this or if I should just bite the bullet and have my engine dynoed. The only problem I have with the idea of a dyno test is that I do not know anywhere near me that is set up to do a mini (I'm in Troy, Ohio half an hour north of Dayton). Any suggestions to help steer me in the right direction would be greatly appreciated!

I may get you into more trouble, than you're already in, but there are a few things about your set up that bother me. With that much of a fuel pump, I doubt the regulator will do any good, I've had it with reg's, first thing I'd do would be either buy a pill holder bypass, or make one, but you need to regulate the fuel some other way, I've seen all kinds of methods used, but you'll need to run a -6 line back to the tank, and put your bypass in there, just before it enters the tank. My first one, I just drilled the fitting, so a pill would slide in, and then had to fish it out, but it was an improvement. My initial adjustment was to turn on the pump, with the bypass hose in a gallon jug, and chg things till I got 3/4 of a gal a minute, and that was all I needed, I've seen setups, where they had a hose clamp on the hose, and just "trim" it out, till it ran right, but a pill holder is handy, Kinsler's QC is too, but, it can be as simple as a hose clamp on the return line. I'd get rid of the regulator, I've never seen one that would work at that low of pressure, everytime, and, I've never seen a "dead head" system that worked right everytime, plus, it draws down your battery, and heats the pump. Good luck! There is a place in Indy, that for a hundred an hr, will help you tune it, if that's the last resort. Bob

DAD · 5/26/11, 5:21 PM

I would go to jegs buy an old mallory regulator and a 15psi fuel gauge then you dont even need a return line.

TQ29m · 5/26/11, 7:16 PM

I wouldn't! Bob

TQ29m · 5/26/11, 7:39 PM

My dyno! I'm the one with the ball cap on, I guess backwards by today's standards, but I still wear it that way! Bob!

TQ29m · 5/27/11, 10:16 AM

Pardon me, coming thru! Bob!

5/26/11, 7:16 PM	#6 Re: Mini sprint dyno and\or tuning question
TQ29m Senior Member Join Date: Aug 2008 Posts: 6,559	I wouldn't! Bob __________________ "Being old, isn't half as much fun, as getting there"! Ole Robert I!

5/27/11, 10:16 AM	#8 Re: Mini sprint dyno and\or tuning question
TQ29m Senior Member Join Date: Aug 2008 Posts: 6,559	Pardon me, coming thru! Bob! __________________ "Being old, isn't half as much fun, as getting there"! Ole Robert I!

5/23/11, 11:21 PM	#1 Mini sprint dyno and\or tuning question
McInturff Racing Member Join Date: May 2011 Posts: 114	I just switched from compacts to mini sprints this year and the learning curve has been a bit steep and I'm hoping you fine folks can give me some direction. Right now I am having an issue with a HUGE flat spot in the middle of my rev range on my '02 R6 on modified Odum carbs. Carbs were just cleaned, adjusted and balanced by Odum, I am running the 3# fuel pressure that he told me to run (float jets were drilled out and replaced by a screw in type that runs 3# as opposed to his usual 5#), new plugs, new alcohol resistant fuel pump rated at 130 GPH, new fuel pressure regulator, clean filters. Fuel system is set up as a deadhead. The engine does this under load and at idle, but once I get past it the engine runs great. I'm not sure what adjustments I should be trying to make to eliminate this or if I should just bite the bullet and have my engine dynoed. The only problem I have with the idea of a dyno test is that I do not know anywhere near me that is set up to do a mini (I'm in Troy, Ohio half an hour north of Dayton). Any suggestions to help steer me in the right direction would be greatly appreciated!

5/24/11, 12:52 AM	#2 Re: Mini sprint dyno and\or tuning question
DAD Senior Member Join Date: Aug 2009 Posts: 5,957	mid range is controlled by slide needles. sounds lean to me try raising needles higher with either slots in needles or shim washers.

5/26/11, 8:56 AM	#3 Re: Mini sprint dyno and\or tuning question
DAD Senior Member Join Date: Aug 2009 Posts: 5,957	I know how you are feeling right now. Thest things seem 360 degrees out from every thing you have experienced before. Go on line and google "factory pro" this old guy has a compleate guide on how to adj your carbs. We have a dyno now and it has helped a lot in tuning however before the dyno we used an old country rd. A dyno is nothing more than a road with a modest hill in it. that adds the resistance you want. What you would do is place your car in the gear you will be racing in probably second or third aproach the hill at the speed you line up a race in and when you get to the hill floor it, and note what areas or good and what areas are not so good go back to factory pro and read, make adjustments then do it again. good luck DAD If you have any questions give me a call 502-778-6833

5/26/11, 5:21 PM	#5 Re: Mini sprint dyno and\or tuning question
DAD Senior Member Join Date: Aug 2009 Posts: 5,957	I would go to jegs buy an old mallory regulator and a 15psi fuel gauge then you dont even need a return line.