It has been fun watching 200TW tire development and the tire wars that have resulted. An awful like the DOT Race tire wars that eventually gave us the purple crack that everyone wants, everyone needs but only a few can truly afford. Does seem like 200TW tire develop is moving faster though. I can remember when these 200TW tires were actually cheap even in jumbo sizes. Not any more.....

Seems to me that the solution is a spec tire rule and also limits on the number of tires a team/racer can use during a weekend. Because no matter what, a faster tire will always be in our future and new tires are always faster than old ones. Even when the definition of "old" is just a few hours of use.

 

Runoffs Prep in full swing. Because of the running issues I had in the last two races, I decided to address each sub system that could be be at fault separately and go each one completely.

For the electrical system, I replaced the switch panel that I had been using for Ignition, fuel pumps and the start button. My concern is that the ignition switch could be failing internally so it was going to be replaced anyway, I decided on a completely new switch panel from Moroso because it has the advantage of being fused and adds two more circuits. Then I replaced the master switch because it is old. The old master switch will be added to the spares drawer in the trailer

For the fuel system I started at the carb and work my way back to the fuel cell.

On the carb, I checked the float, float level and the needle and seat. I also looked for any debris, general grundginess and the condition of the float. The carb turned out to be super clean inside and the float didn't have any gas in it. However, the float was a couple of MM to high so I adjusted it after I installed a new needle and seat. I am using a .330" glass ball needle and seat but I also have a new .300" standard style weber needle and seat to install if I need to. I also checked to make sure the throttle blades are opening fully and cataloged the jets to make sure every thing is correct. Finally I fitted the 44MM and 45MM chokes to the carb body to get them ready for dyno testing later this month.

At the fuel cell, I decided to just replace everything. So new Carter 4070 fuel pumps, inline filters and new fuel cell foam. All of these parts have some time on them and it is cheap insurance to have all new stuff. I have had fuel pumps kick my *** in the past and have seen fast cars crippled by fuel cell foam clogging up the works. I am also checking all fittings from front to back.

On the ignition I am building new spark plug wires out of a Taylor Spiro Pro V8 set, installing new plugs, checking grounds for shielded wires and inspecting all connections. I will also look at the cap and rotor and inspect magnetic pickup wiring in the distributor. I replaced the analog MSD 6A with a Digital 6A earlier so I think that part is good.

I have the car scheduled for some dyno time at JPM on the 17th. Will be hopping to verify that the running issues are resolved and get a baseline with the 42MM chokes. Then see if we can get anything with 44 or 45MM chokes. I was going to do a test day at a track but decided that I would be in better hands at JPM. I want this bitch fixed!

 

good call! for one of the 25's we did, we had the master switch go bad, and the symptom was a dead battery.

 

Be careful with preventative maintenance...you can create your own failures with a "known good part". We lost about 12 hours of racing a week ago due to 1: A new defective Holley fuel mat and 2: Loose ignitor ground wire caused by removing ignitors to inspect and clean contacts. Good thing you are going to the dyno first.

 

Yeah there is risk but the car already has an issue somewhere so I have to poke around to find it. So far no huge smoking guns have been found. Part of me wants it be stay broke so it shows up on the dyno. We will see.

In 2017 the car was running pretty good and was just chasing a drive line vibration. So I took the drive shaft to a local shop to have it checked/balanced. They ended up bending the shaft and screwing up the balance. They did paint it though. Anyway that started a cascade of issues that ended with me doing a trans R&R to get at the flywheel.

Anyway, as my wife reminds me when I am thrashing about trying to get my car running right...."racing is fun."

 

I think I lost count last weekend how many times I said "this is the fun part?"

 

Been a long-time lurker on this thread and love it. I just wanted to chime in to ask where you've been getting the bigger needle valves - I can only ever find the standard Weber ones. Thanks!

 

I bought it here: https://www.cbperformance.com/product-p/7349.htm

 

Thanks for the link. Do y'all see any fuel dripping from the mains at idle with the 3.3 installed?

 

Not that I have ever noticed or looked for. I would think that an issue like that would be related to float level and fuel pressure. The glass ball style needle and seat is supposed to be more fuel pressure tolerant/indifferent so that is why I use them. I used the same style needle and seat in the Niki I used to race with.

Fuel pressure, using a Holley low pressure regulator, is set at an indicated 3psi. Note that gauges can be inaccurate so my actual fuel pressure may or may not be 3psi but that is what the gauge says and that is where I keep it set.

I set the float level based on the closed height of the glass ball needle and seat less the thickness of the top cover gasket. Which is a little different than the 24mm weber spec I have seen on Pierce Manifolds. So I set the adjustment tool to something like 24.6mm and then bent the tab on the float so that it is 5.5mm proud of the carb body when the carb is upside down.

Instructions from Pierce Manifold: https://www.piercemanifolds.com/category_s/316.htm. I have most of the weber float tools (don't have 98015.500) listed in the instructions which makes this an easy but tedious process.

Overall I have had no issues with the way the carb performed in the past. In fact I set it up back in 2015 and other than a couple of jet changes for altitude, have not looked at it again until just a month ago. Which is admittedly too long not to look inside a carb on a race car. If this were a Niki, that kind of lacksadaisical approach would be deemed criminal. Any who, what I found was a float level that is 1-3mm high which I corrected when I installed a new needle and seat.

 

i set the float on mine by making it as high as possible without dripping at idle. a race car can tolerate a drip here and there. it kind of doesn't matter where the float is, as long as you set it and leave it, how high the fuel is on the jet stacks effects how they work

 

picked up the CSF 8066 model from Summit. Very similar in size to the OEM cooler. Will probably fab a shroud like Carl did. I install this one about 3” higher and split the lines on the crossmember tube.

 

You're not going to mount it bosozoku style like CSF advertises?

 

Negative.

 

Party Pooper! Would be the talk of the paddock in Indy!

 

Anxiously awaiting results of the dyno time.....

 

Maybe watch it on a future JPM youtube episode?

 

Kind of doubt that would happen, allot of cars get dyno'd there. If you were wondering, the cars he talks about on the videos are twice as impressive in person.

Update.....

I believe I found the SMOKING GUN. My list of Ignition Inspection and updates included spending time looking at the distributor. It is kind of a trick piece put together by the 2nd owner of the car. Anyway the plate the holds the magnetic pickups was loose. As in the screws that retain it came out and were stuck to the magnetic pickups. So the magnetic pickups were kind of floating around and only retained by a vacuum advance arm. I had looked at that stuff before, mostly to check the wiring on the Leading Pickup so I am not sure how I missed this. But I did. I put the screws back in tight for now. I will add some blue loctite next. My education continues.

On the fuel side, the cell has new foam, filters and pumps. With the new stuff in place, fuel pressure was about a psi higher than before at the regulator so apparently the old pumps were a little soft.

As for the rest of the ignition, I made up some new wires, installed new plugs and made it all neat and tidy. I found these Edelbrock wire separators and like them better than ones I used to make out of zip ties. https://www.summitracing.com/parts/edl-22799

Hope to get on the dyno soon once we can get this scheduled.

 

i've been meaning to write a little thing about ignition problems, but lack of anything quantifiable has been the problem...

there are three problems, and there are different fixes for each, so it makes it doubly hard to say that x or y is the way to go, it depends.

the first, and best known, its RFI/EMI, Radio Frequency Interference. its kind of when the firing of the ignition creates signals that interfere with other things. generally you'd hear it as a buzz over the radio, and it can mess with EFI stuff too. typical solution, is to put a grounded sheath over the plug wire. very common in the airplane world, the metal car has some natural shielding, but the plane (and old Corvettes) do not

Number 2, and the big engine killer is Inductive Cross fire. This is when the magnetic field of one plug wire can fire an adjacent wire. its a huge problem. hard to diagnose, but basically in a v8 its like randomly advancing the timing 90 degrees for one cylinder, so the symptom is that the crank is on the ground, or the #8 rod broke again. there are two fixes, either keep the wires apart, OR cross adjacent in the firing order wires at 90 degrees. the cross cancels the magnetic field. if you notice the stock Mazda routing they actually do cross the wires.

Third. This one is tricky, but we can call it spark leakage. this is more of a turbo car problem, but when power goes up, combustion pressure goes up, and then ignition power also needs to go up. the trouble is that at some point its easier for the electricity to go somewhere other than the spark plug. this is bad.

so pay attention to the routing of the wires! it can really matter a lot.

picture is the Revolution FD wire set, they are insulated and shielded (FD is setup so the wires are all far from each other). these wires, cold plugs and the right clearances in the engine and they run stupid power

 

j9fd3s I can attest to spark leakage. Many moons ago I had an issue with the car miss firing at specific places around Heartland Park. The car would sputter and then shoot fire ***** out of the muffler when it caught. Corner workers thought it was cool.

I went through the normal stuff - carb, electrical connections, grounds, thinking about buying a new car, etc. Then a friend of mine found it - the rear plug wires were coming in contact with the steering box. New wires were installed, I covered the bottom 6 inches of the wires with some heat wrap (that brown stuff I put on everything) and it was solved.

For my new wires, I used Taylor Spiral Pro resister wires with 45 degree boots. Those boots keep the wires closer to the engine. Then I covered the leading and trailing wires on the rear rotor with the brown fire sleeve to prevent leakage on the dipstick boss. Also kept the wires short and loomed them so they can't move around much and touch each other.

As far as using shielded wires - yep had to do that for the trigger wire going to the MSD and the Coil wire coming out of the MSD or the tach goes nuts.

 

Easiest way to fix spark leakage / confusion / jumping, is to throw away about 4hp and set leading and trailing to the same timing

 

Question for you on the fuel pump/pumps. Can you you tell me what the benefit of dual Carters is? I'm assuming they are running in series? Does this up the GPH without effecting max psi? Why not run a single Holley red or blue pump? I saw a few FB race cars this past weekend (Portland rotary reunion) running the same set up but never got the chance to ask any of them why...

We've been running a Holley red fuel pump for ten years or so but we recently developed what seems to be a fuel problem. Our defective fuel mat was only part of the problem. Now the car fuel starves over 7k rpm for extended period. For example it will take off from a standstill and pull hard through 1st and 2nd gear but at the top of third it starts to loose power and AFRs go to 20 then as you shift into 4th it gets worse and sticks around 6k and wont go any faster... Running at a track day last Friday it was much worse only going to 5k. It will free rev without problem. We changed the mains from 205 all the way up to 235 and that gave us improvements up to where we are now along with replacing the fuel pump (to a Holley blue) and new pressure regulator. We've also cleaned the carb out many times in the last week. Next step I'm thinking is bigger main jets and smaller bleed jets for more fuel up top. Float level has been checked and verified also. Oh...I'm also planning on going from a 2.0 needle valve to a 3.0...

Any advice would be appreciated...

 

Using Carter pumps vs Holleys is a learned trait. Charlie Clark had allot of issues long ago making dual holleys work on his D Production/GT3 Corvair. Carters never failed him so I followed his lead. Holleys are probably fine but my cell is set up for the Carters so it is easier to stay with them.

The fuel pumps on my car are plumbed in parallel. The fuel cell I am using has dual pickups and each pump is connected to a fuel pickup located in the rear corner of the cell. The output from each pump flow through a fuel filter and a one way valve to a 3 way fuel distribution block. From the distribution block I run -8 to the regulator and carb. The one way valves are there to keep the pumps pushing past each other when fuel levels get low or if a pump starts to fail.

Pumps are model HP470

 

imo, you might do a volume test, it sounds like the carb is just running out of fuel up top.

 

That's what it feels like as well. With the old pump and the new pump testing from the fuel line that attaches to the carb it'll fill a standard water bottle in a matter of seconds. We're now running -6 an line as that seems about the same diameter as the stock metal fuel line and 3/8 rubber hose that we've been using for the last ten years. Is that maybe actually too small diameter and keep enough volume of fuel?