Hey i run a super 4 car in oregon.  I am having a really hard time tuning my carb.  The motor is a very decent motor.  Its a 5.7 long rod with a nice head and rotating assmbly. with just over 200 hp.  the carb is a holley 500.  Track size is 3/8 high banked.  The car runs great out untill i am at full throttle then it starts to miss all the way through the RPM's.  I am wondering what jets? PV? cam? i should use or try to get me closer
thanks
skip  

Skip.... Dave here out of Las Vegas, NV. Been building Pro-4 engines a number of years for Secord Motorsports. Your problem sounds as though you might be suffering 'pull-over' through the squirter (common on 4-cylinders) or you're way lean. If it's a 2300 Ford, 68-72 main jets should get you close if the rest of the carb is up to snuff.Check your power valve and make sure it's OK. The power valve channel restriction is too large in the 500, if it's stock. Ignition OK? Run about 2-3 hard laps in practice, clip the engine coming off the track, and see what the plugs look like.

Dave  

Hello Dave!! Todd here! I agree with Dave. You may try to eliminate the PV and go up a jet or two. The pull over is the common problem with these. Try a vent whistle, available at a decent performance parts house to raise the vent up. Are you running roseburg? Todd LaBronte Intermountain Pro-4 Tour Director  

I’m Joe from jbv-heads.com. I’ll be racing with you guys next year. I know Wayne #64. Dave #84 sent me this site. While lean can happen from fuel pressure or small jets with large holes behind the power valve letting too much fuel in during the transition period and then too lean when left with the jets. It’s 99% chance of pull over. It falls into 2 styles. Vibration and vacuum. With the builds at SOS I’m guessing, an EFI intake, lobe seperation of 108 or more, may be retarded a little, tuned header, Holley carb, Rick’s car and it’s vacuum pullover. Other than Ricks car, these other items make for prime candidates for vacuum pullover. I’m working with a gentleman from Maine on a patented cure for it now. On vacuum pullover it is caused by the vacuum pulses that 4 cylinders create with their 180 degree crank. We want these pulses as they are what we use for inertial supercharging. They just can be made so powerful in a 4 cylinder with the tuned length 11.5 inches on the EFI that we over power the acceleration circuit on the Holley.  There are a lot of band aids for the problem and Sleepy does have one that can help pure stocks, super 4s can go lean and burn a valve or piston quickly though. The most common cure is the siphon bleed that now is included with the Dorton 350. A .020 to .030 hole is drilled into the acceleration circuit elbow on the metering block. I have also seen it put just below the squirter on the main body into the vent tube area. This breaks the siphon effect from the vacuum created at the tip of the squirter. Next anti siphon squirters do move the rpm range up and can sometimes move it out of the rpm range we use. Use one in the .025 range or modify a normal one in the .018 range. The modifications is to remove the bump or head above the squirter outlet and redrill the .018 hole as it will close on you. The anti-siphon is from the spread bore Holleys. And last is a Rochester metering spring cut to size and place between the squirter free weight and the squirter holding screw. This is an adjust to fit, and does take most multiple tries. At the upper levels we must maintain this circuit where pure stocks can shut it off after ¾ throttle. These are about the only items I can give you here. There are more but I don’t want to take the responsibility for a burned engine and a good knowledge of Holleys is needed. If you need more go to my store above and fill out the contact form. This should help you. Good luck,

Joe  

Hi Skip. We ran into the same problem down were in the Southwest pro-4's. The most inexpensive cure is the custom cut-to-fit spring on tje squiter check ball. You should not try this if the check ball is the torpedo type. You can also try and find a anti-syphon squiter. But you need to look for a decent Holley Carb. outlet store. Hope this helps.
Rick Ammerman
Director Southwest Pro-4's  

Gentlemen, I just got registered on this new site, Thanks 84Dave for the heads up. I am looking forward to the info I can get and give. I too am running a super 4 dirt car in Oregon next year. So I will probably run into some of this stuff..HI Joe (JVB).. dr6.  

Back to you Skip72 and your problem. Generallly speaking, at least on the 4-cylinders I've looked at, you can see 'pullover' right in the shop. Warm the engine and slowly bring it up to about 4000-4500 while looking down the carb throat with a good light. You may see fuel being pulled out of the pump squirter. If that's all or even part of the problem, there are 2-4 decent fixes. You also can drill a .025" 'kill bleed' at the pump channel in the metering block. Any good performance carb shop should know what a kill bleed is. And you might try the Archives right here on Circle Track. There was an article in the March 2003 Circle Track entitled 'Holley's Two-Barrel Tunable Metering Block'.There is a picture of what the article calls an 'anti-siphon air bleed',which I call a 'kill bleed'. You don't have to install the fancy jet as the article shows but can simply drill a .020"-.025" hole that will bleed off the siphon action as Joe spelled out. The metering block that the CT article spells out is a sweet piece for a 500 Holley. I think it's about $120 'good-guy' price but well worth it if you know how to really 'tweak' a carb.

Dave  

Dave, Danny hi. Rick, Todd, I haven't met you guys yet. I have a question though. I have clients and some new ones that are coming in that run your series. Do either of you plan any major rules changes? Experimentation and testing will be starting next month and I am paid for success. It's nice to understand any new expected changes or concerns the governing bodies have. Sorry for the off the subject question but I know the owner and the car above. Skip is the chassis builder and does the best Dirt Pro 4 chassis on the west coast I've seen. Dave and Danny both have my email and I think phone if you want to talk.

Joe  

The Intermountain Pro-4 group(asphalt only), led by Todd Labronte, has talked about going to the F-45 Hoosier on the right side of the car. A bit more life out of the right-side tires. I suspect the Southwest Pro-4 group(asphalt only), led by Rick Ammermann, may follow suit if that happens because IP4 and SW4 race together frequently. The only unknown may be, can Hoosier provide the ~3" stagger at the rear with the F-35 on the left side and the F-45 on the right. Other than that, I personally know of no other rules changes, particularly as applies to the engine area. Todd and Rick may have a different answer?

Dave  

I haven't been able to find Ricks rules anywhere. I can find where they race together but no rules. Are they the same rule? Thanks,

Joe  

Hi Joe. The rules for the swpro4s and the ip4cs groups are the same, and will be the same for the 2007 season. If your interested you can go to www.swpro4s.com or www.ip4cs.com and get the rules packages there. We did make some 4valve engine rule changes that are not yet posted. Please call me at 951-538-6435. I promise to get back to you if I don't answer. See you at the races. Rick Ammerman  
Director SWPRO4S  

Hey there Joe and Dave good to see you guys on here.  

having someone holding a timing light hooked to either one spark plug wire or the coil wire will freeze frame the fuel flow from either the accelerator shooter or the booster venturi's