Guys, I made it out to my local 1/8 mile track tonight only find my problem still not solve. Car is missing around 4500 and will not rev past 5k or so in third gear. I have added a new MSD coil and MSD dist but my problem won't go away. All of the other ignition parts are new and in good working order. I am pretty sure it is not a fuel issue because I still had 6psi as I cross the strip. Any suggestion? Help....I cannot get my new combination to run the number. Best pass tonight was 7.38 at 92 MPH. Thanks,
What do your plugs look like?Throw some jets at it and see if it picks up mph if it does keep jetting it up until it falls of then back it down to the last jet that picked up mph.Just because you have fuel pressure doesn't mean it's getting enough in the motor.You may want to try 7-7.5 psi.Does the car nose over or miss.We are going to need a little more info to help you better.
I will pull the plugs tomorrow if i get a chance. The car misses and noses over, more to the point it just won't pull in 3rd about 5K. I just upgraded the fuel system to include a sumped tank and CV mechanical pump( no pressure regulator) the JW sells in place of my malloy pump and 1/2 modified stock pick up w/ the same problems. Both systems used the same -8 fuel line from the tank to the fuel log. I am running two sizes up in the front from when it was dyno'd in simalar conditions and thought that fuel was not the issue.
I re-read your previous posts so I got rid of the extra stuff. I will agree with Kevin and say check your plugs at the end of a run. THey should look like new. Buicks long rods and race gas gives a real clean burn so if they are colored that you can see without looking down inside the plug, I would say your rich. Even if they look close to right, try going up OR down 2 jet sizes in the front and rear and see what it does. It would be nothing to pick up 2 tenths from changing the jets, even if you think its right. The clocks don't lie. What kind of mufflers are you running and how large on the exhaust pipe? Did you run the same mufflers on the dyno?
I am running 3" pipe w/ large case walker mufflers. The mufflers were not used on the dyno. I will move up 2 sizes in the rear and see if that picks up MPH. The last time out I pulled the plugs and they did/do look almost new after a pass. Thanks for the ideas.
Jim, What are you running for an ignition system these days? (As in box).. I see you have an MSD distrib and coil, but I am assuming your using the distrib to fire a CD box.. (like a 6AL) yes? Fuel related problems rarely cause misfires.. running out of fuel will generally just make the car lay over and die... if it's a hard "bang bang bang" then I would be looking at electrical stuff. JW
Just have to ask the obvious question, do you have jet extensions? If not do that first. I built a buick powered firebird that would bang out at the top of the gears. An old timer came over a said 'Boys you need jet extensions'. Sure enough problem solved. Are you coming to Temple?
Over-view.. This should help with those that don't know or remember the background of this problem. How is you GROUND and VOLTAGE to your MSD Box? Where is your battery grounded? Is there a ground strap going to the motor and body or is the battery grounded directly to the motor and body? Or do you run solid mounts? What plugs are you running and at what gap? Have you change the plugs since the dyno run? I'm looking to see if somehow "iron head/short reach plugs" were put in place of "Aluminum head/long reach plugs" if they were changed. Or if they haven't been changed, if one maybe has a cracked porcelain. o No: ***TIP*** take a spray bottle of water and spray it over the wires, plugs, coil, and cap to see if it you can get it to stumble showing a problem. If you lost 2 mph going from 26 to 34 degrees timing, I would try going down to 30 and run it again but it would be nice to find your gremlin/problem first. :rant:
Thanks for the replies. JW, it doesn't bang hard but noses over, stumbles, misses and just stops reving. The box is a 6AL. David, yep jet extensiion are installed. I won't be able to make it to Temple as I will be out of town working. Rick, thanks for digging up my story. I have the battery grounded to the pass. head and I have the factory ground strap from the firewall to the same head. I have not checked the voltage to the MSD box lately but I seem to remember that is was around 13v last time. I am running stock mounts that I modified to solid. The plugs are the same ones that it had in it at the dyno. They look new so I didn't change them. Thanks for the tip. I will try it when I get back in town. Thanks,
Jim, I had an MSD box that was fairly new do just what your talking about. Any chance the valves came in contact with the pistons? Been there done that too. May want to try a leakdown? jeff
Does this "problem" occur at the same RPM? You mentioned the MSD 6al box right? Did you try taking out, or putting in a higher rev limit "pill"?? I had this problem, like a 200 rpm difference lower than the "pill" says. Just a thought, I'm not sure if "nosing over" is the same as dumping cylinders hitting the rev. limiter. Gary G.
engine miss I had a chevy do that once and it had a busted valve spring. Would close the valve fine till rpm's came up. Just had to put in my two cents worth. Bernie Steffen
Jim: With a BB Buick turning 5 to 6000 RPM at full throttle, it is possible to run out of gas in the carburator while the guage at the regulator or fuel log reads 5 to 6 lbs. pressure. I have been there. I read an artical by Barry Grant Fuel Systems titled, "Fuel Starvation" Quote: " Test your fuel system by obtaining a 1-gallon gas-can. (do not use a moulded-plastic gas container, or marked super-jug, or antifreeze-jug as you will not get accurate readings). Open up the top of the tin-can and insert the two or four carburetor fuel lines from your regulator. switch on the system and carefully measure the time it takes to fill it. High 10 second cars will net to pump 1 gallon in 25 seconds or less. A 9 second car should fill the can in 20 seconds or less, 15 secons is all it takes for an 8 second car and under 12 seconds for 7 second vehicles. IMPORTANT NOTE: It's essential to observe two strict rules during the test. One, keep a fire extinguisher handy and two, do not carry out the test by yourself." I have their address as www.Barrygrant.com. Phone No. 706-864-8544. I don't know how to check it with a mechanical pump. Maybe someone else has some ideas there. Hope this will help. W.C. Taylor, "Superdog"
update Okay guys I made the following changes which seem to solve my 3rd gear pulling problem on my only full pass Friday before the rain. Installed a BG fuel pressure regulator, pressure set a 7 1/2 psi. Readjusted the floats Installed new plugs Installed new battery ground cable I also installed a tach recorder and notice that my flash stall is only 3700 rpm and that the motor only drops back 1k between each shift. Does 1k rpm drop between gears sound okay or is the converter to loose? He is my slip 60 1.63 330 4.704 moh 73.11 1/8 7.291 mph 93.48 Here is my second run where the heater by pass plug broke (rubber one on the timing cover, from the help section at Pep Boys) and shot water under my car. Yep I did take the timing cones out! What a ride. :eek2: 60 1.55 330 4.58 mph 72.77 1/8 7.35 mph 78.64 Any comments would be appreciated.
Jim, I dug up an old time slip to help you complete your second pass, just FYI. 60 1.546 330 4.572 1/8 7.145 mph 95.35 1000 9.384 1/4 11.29 mph 117.82 From U.S. 41 in 2002.
Last year my car was doing the same thing, was dead in high gear and popped out the exhaust. I had a Holley box on it. I borrowed a MSD 6 A box to try, the popping went away but it went from 11:30s/11:40s to 11:70s so I am still lost with mine. I wonder if those Berry Grant numbers are real or something he came up with to sell his stuff. Tom
does it break up when you(the motor) is sitting still? After the motor is up to temperture hold it at about 3000 RPMs for a second then rev past it. You may want to change to a hotter plug if it stumbles or breaks up.
Mine runs great with the holley box in 1st and 2nd gear, it seems the harder the motor has to work the worse the problem is, It pulls hard out of the hole, I have had a best of 1:48 60ft on a good track. I can nail the gas at 1200 rpm off the line and get real good 60fts but my reaction times suck that way. With the motor warm and running in park I can hold it at 1200 and nail it and it jumps right to 6000 smooth as silk if I let it. I can make major jet changes and it won't hardly change ET and MPH. I have a 1050 holley with no rear valve and extentions and 96 jets in the back and 86 with the valve in the front. The carb came with front and back valves and 84/84 jets. It is a real old carb that Holley no longer makes, I think it was the first dominator holley sold, based on the old Ford nascar carb. On the same day I can go to 84/94 jets or 88/98 jets and it will run the same. But after reading the above stuff I wonder if the single Holley regulator is some of the problem. I have 2 holley blue pumps and 1/2" line from back to front. I wonder at times if the notches in the rear float are deep enough for the extentions and not letting the float drop far enough. Tom
I've read that any time you make big jet changes, and see no results(mph) it's probably fuel delivery.
