Hat nozzle type and starting issue

[Dunc the Funk]

Hiya
Our motor has been difficult to start, it always fires after priming but will often die either immediately or while you are feeding it on the bottle. Once on the pump it runs fine.
Inspecting it recently I noticed that the hat nozzles are the non-ported type. Would having the single hole ported type help with starting?

[Draw 3D]

I think you mean aerated nozzles and if I remember correctly, they mostly work when you let up from wide open throttle.

It sounds to me that not enough fuel is being used during priming. When I start my car by myself, I give it a 2-3 seconds of squirting into the hat and even then it may start then die immediately and I have to re-squirt.

If someone is helping by doing the priming, have them give the 2-3 second squirt then dribble the fuel in right in front of the hat blades, they can stop when the motor rpm evens out.

[Dunc the Funk]

I'm the one that does the priming, I give it a good squirt, driver cranks it til it puffs then I signal to put ignition on, it always fires but often cuts while I am trying to feed it. We did borrow a pump-up spray bottle from another team for the last two runs we did & that seems easier as you can keep spraying the butterflies much easier.

I wonder if the hole in our priming bottle is too big? When it was cold at the end of last season we were priming with gas & if it didn't go in a couple of tries the plugs would be fouled.

Also, do people sometimes use a feeler gauge size clip to hold the butterflies open a little further til it fires? I'm sure I've seen that done on Youtube.

[Draw 3D]

Is the motor self-starting or do you use an external starter? I take it that it self-starting so my comments below are based on that, my car is also self-starting.

When it starts and runs, does it run rich? I so then yes, too much fuel and unless you totally flooded the motor, it should start and run but it will be rich. When my mag was going out, it would start but run like crap; rich, popping flames and sounding like crap but it did start.

That first puff is what you squirted in so the motor is just about out of fuel so you need to dribble the fuel in as the motor is being cranked over. A self-starting car doesn't really spin the motor fast enough on the first go to prime the fuel pump, that's why you need to dribble the fuel in while spinning to get the motor running to prime the pump.

And as for the clip to hold butterfly's more open, what is your gap now and what have you set the barrel valve leak down to? If you need to increase the gap to start it then you need redo the whole leak down setting, I've never seen that being done.

[dreracecar]

You did not mention the type of fuel in the primer bottle?

[Dunc the Funk]

Thanks for replies.
Car has onboard starter & it cranks just fine.
It's not currently rich at idle. I've adjusted air & fuel it so it idles about 1500rpm & it's fairly lean, it surges a bit but responds to the throttle well.
As I'm sure you know, butterfly clearance & barrel valve leakdown are great for setting a baseline but once it's running then it's best to tune it.
The butterflies are currently at 8 thou, I just checked. This is fairly tight because the injector is too big for the application (buzzard).
We used to prime with gas but went to 50% gas, 50% methanol this year. Have also started it on 100% methanol this summer.
As for using a clip to increase butterfly opening, it was Matsuda Racing though I can't find the vid that clearly shows what he does.
If it gets established on the bottle then it only takes a few seconds for the pump to pull the fuel through, but it often quits before this happens (it goes crank crank - on - Raah! phlut, crank crank - on - Raah! phlut). It often spits back a bit when it quits.
As our tank breather is mounted above the level of the shutoff valve, at the next meeting I am going to remove the line from the shutoff & top the tank off with a small funnel at the breather fitting until fuel comes out of the shutoff. Then I know the pump is full of fuel which will be better than having it running dry & trying to suck as the tank is quite low.
So no-one thinks the hat nozzle type makes a difference at startup? I heard they were supposed to give better atomisation?

[dreracecar]

Better amo when running down the track, but not much a player at the start when low pressure is involved.  Cheap Gas has a low flashpoint and runs off of vapor, alc burns as a liquid and needs volume and you could be running out of prime, Block starters turn over slower then say a blower starter so your pump speed is low, running gas as a prime will help with this. With a blower, all the fuel is pushed forward to the front, and the alc is not getting to the back cyl's, gas as a vapor will get sucked back to the rear during rotation. If the motor is warm already then a mix or straight alc can be used, But "I" don't want to carry 2 bottles of prime with me to the line and just have the one with gas. This is what works for me and the way I run my car

[dreracecar]

Alc is a sloppy fuel , it can be a tad rich at Idle and not affect anything,  I have never changed my BV leak in 20 years(and run a jet range of 100 to 155), because it only effects idle and coming off idle at the hit. as long as it does not lean backfire and comes up off idle clean when the throttle is whacked, you are good to go. My fear with playing with it is that I would go the wrong way, so "I" just leave it alone

[Draw 3D]

The best way to troubleshoot is to film your starting process as you actually are starting then post it on here so we can see.


As for starter cranking it just fine, if it's not spinning the motor at a minimum of 1000 rpm, the pump will take some time to prime.

[BK]

I think you answered your question in your first post.
" It runs fine when its on the pump."
Sounds like the fuel is bleeding back to the tank and takes a while to fill the lines.
I think theres a check valve you can put at the tank outlet that would leave most of the system full.
As far as aerated nozzles or not. Solid bodies in a blower manifold. Aerated in the hat and for normally aspirated. It shouldnt make a difference for starting but once running solid bodies in the hat or manifold will allow vacuum to draw fuel into the engine making tuning difficult. If you have aerated in a blower manifold you will have boost leaking out of the holes.

[Dunc the Funk]

Regarding the starting problem, we got a Wurth pump-up spray bottle on the recommendation of lots of other teams in our class. It's easier to maintain a constant stream of fuel directly at the butterfly crack. Even then it it's surprising how much fuel we needed. The other teams were using gasoline so went to that. 5 secs full pressure spray direct on the rotors, 3 secs in each outer hole too, crank it, ignition on then absolutley p*** it on the crack & away it went, problem solved. Phew. Best run of the weekend (of only 3) with 26 degrees timing we went 8.35 @ 155, driver shut off before the line as it was drifting toward the mirrors. Now we just got to figure out why we are losing traction mid-track which caused the other two runs to be aborted.

[Dunc the Funk]

So...next meeting could not start it at all until we borrowed another racer's spare pump. Fired right up but tune now crazy rich, our pump must have been gradually wearing out. Seems to only need a tiny bit of prime now. Thinking of swapping the buzzard for a bugcatcher I have to see if idle tuning is easier. Could do with underdriving the blower til we get the chassis sorted too.

[Dunc the Funk]

At the next meeting, even with the new pump, it was hard to fire a few times. Same symptoms, fired up quickly but then quit after a few seconds. Then last week we tried to test run it, would not start at all.
I have finally been able to determine the area of the problem, it's to do with the ignition system & probably related to battery voltage.
I tried firing it in my garage on just the bottle, same issue. Then I replaced the MSD 10-plus with an MSD 7 powered from a seperate battery. It fired right up & ran as long as I fed it. Result!
Of course, the driver starts jumping to conclusions, it's the 10-plus, we need a new one, we need a mag.
So I wired the 10 back in with seperate battery. Started & ran on the bottle easily.
So it's definitely either an issue with the wiring eg ignition switch intermittent or it's the battery voltage dipping disabling the ignition.
I can deal with it now I know what's going on, I have a background in electronics.