I have been chasing a problem for some time now when I hit about 6000 rpm I have a bad miss. I have changed cams and had the heads checked thinking at first it might be a bent valve. I am leaning towards it being fuel supplly. I am running a edelbrock mechanical pump with a holley reg. at 8psi. But I just ran some race fuel in it and it ran great. the carb is a Quick fuel 1050cfm annular with 30cc in front and 50cc in back with 86 jets up front and 90 jets in the back. I changed plug wires coil plugs etc. I am thinking of going to a holley black electric with a bypass reg. I just wanted to see if I was on the right track.Where I live ther is not alot of us v- drive guys around.
sounds like a lean pop to me. what size are the pickups in your gas tanks? that was a problem for me until I had my new tanks built with 3/8" pickups. no more problems for me. I think you are on the right track, definitely sounds like a supply issue.
Omega
[QUOTE=bbc540]I have been chasing a problem for some time now when I hit about 6000 rpm I have a bad miss. I have changed cams and had the heads checked thinking at first it might be a bent valve. I am leaning towards it being fuel supplly. I am running a edelbrock mechanical pump with a holley reg. at 8psi. But I just ran some race fuel in it and it ran great. the carb is a Quick fuel 1050cfm annular with 30cc in front and 50cc in back with 86 jets up front and 90 jets in the back. I changed plug wires coil plugs etc. I am thinking of going to a holley black electric with a bypass reg. I just wanted to see if I was on the right track.Where I live ther is not alot of us v- drive guys around.[/QUOTE
I'm not an expert but from my drag racing days high RPM missing sometimes was valve spring float. Have you changed the springs lately? Checked them? Just a thought.
fuel system check - what size lines and did you check for vacume leaks ? Manifold /carb ? i had the same thing - went to a larger acc pump and bingo it solved my problem
I have been chasing a problem for some time now when I hit about 6000 rpm I have a bad miss. I have changed cams and had the heads checked thinking at first it might be a bent valve. I am leaning towards it being fuel supplly. I am running a edelbrock mechanical pump with a holley reg. at 8psi. But I just ran some race fuel in it and it ran great. the carb is a Quick fuel 1050cfm annular with 30cc in front and 50cc in back with 86 jets up front and 90 jets in the back. I changed plug wires coil plugs etc. I am thinking of going to a holley black electric with a bypass reg. I just wanted to see if I was on the right track.Where I live ther is not alot of us v- drive guys around.
That mechanical pump is more than adequate for your carb. Assuming your ignition is up to par, I'll lay odds that it's the regulator, those Holley regs are way too restrictive, go to a bypass after the carb is fed. Also make sure your lines are big enough!..
Lucky, I don't know where your problem was,(RPM wise) but the accelerator pump has absolutly nothing to do with high end operation. bbc540, where is it popping? intake or exhaust? An exhaust pop at peak rpm is an indication you're unable to burn all the fuel you're suppling in the chamber, and the unburnt fuel explodes in the header. Any pop in the intake at high rpms is an indication of 1) lean condition, fuel lean enough to bang as soon as it sees the hot chamber, and the intake valve is still open. 2) a lazy exhaust valve, caused by loose lash,bent pushrod, lobe going away,(what springs are you using) and leaving hot gasses in the chamber. The acc pump ONLY works you through the transistion of closed butterflys to WOT by supplying additional fuel until the vacuum pulls fuel through the main jets. Have you checked float levels? What ignition system, and what condition is it in?? Although a weak spark will usually pop more than one cylinder..................MP
yes your right money pit - mine was not at high rpm -
when I pulled the heads off I changed the springs out with a new set of comp. I think they were 930,s but they were what comp recomended for the 306 solid cam. I have checked the pushrods and valve adjustment and the ignition is a mallory electronic and that was one of my thoughts also so I changed the coil and pickup. the last time I ran it it started about 5000 rpm then I drained the gas and added 116 race gas and the popping stopped but when I went back to 93 here it is again.the motor is a 10.1 540??
Try backing down the lead a bit, maybe you're detonating!..
Sounds lean to me. What were the stock jets in the carb? Are you running power valves? 86 jets up front sound a little small for a 1050 unless you are running power valves.
Keep in mind that Racing fuel will act richer then pump gas due to the fact that it burns considerably cooler. Pump gas EGT's will run 150-200 degrees hotter then racing fuel.
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