Here's my problem. I have a 306 in my comet. Aluminum heads, 236 duration cam, 523 lift, 650 holley, victor jr. intake, headers, msd distributor/box/wires/coil.... yady yady yady. It seems like the car pulls quite well and I did get a 13.40 out of it. However, it seems to "lay down" from 3500-5500, when it really starts pulling super hard to about 6500. What could be causing this. I have my initial timing around 12 degrees and total timing at 36, all in at 2800. Oh ya I have a 3200 convertor with 4.11's. Just curious if the distributor could be hanging up or if I could have a problem with the msd box. I know for sure the car can be alot faster as very occassionally it kicks in right through the rpm band. But it has only done it a couple of times and MAN WHAT A DIFFERENCE!!!! Please help....all advise will be appreciated. I am willing to try almost anything already. Sean
I have had wheel spin and not known it. Car feels really slow if you don't know you are losing traction.
3500 to 5500 is the area of the cam that provides peak torque and Hp. I think you have tires slipping. Try a bigger tire. I doubt it is a carb problem as it is running good before and after the loss of acceleration. You should be getting the highest acceleration in the range that you feel it going down. I doubt that is an advace problem unless it is too much advance. You might want to take out a couple of degrees of advance in the distributor (use a thicker piece of hose on the advance limit post). You could just set the initial advance back but you will lose some of your initial jump off the line if you do that. If you are running street tires at 30 to 35 PSI try dropping the pressure in them to 25 psi and see if that helps. Do one change at a time and if it helps go on to the next change. If it doesn't do anything then set it back to what it was and then go on to the next. If you doo all of the changes at once you may not get as much gain as you could have.
Could be fuel pressure loss.(harder to keep em fed at higher RPMs')If it is fuel pressure,Its intermittent.Could be the pump giving up the ghost from time to time.Really dont think its a carb problem either.Listen to PaulS,one change at a time!! more than one and you could find yourself chasing your tail for days.Good luck.
I am wondering why you are all in on timing by 2800 when nothing in your combo comes on before 3k-3500. I am no guru on timing. I am just wondering.
Thanks for all your help guys. I will try and cover a few more things to eliminate some choices. I have tried to take some timing out and if it made any change I did not notice it. I have 28" street slicks, with 20lbs air, on the car so I don't think wheel spin is an issue however I won't rule it out either. I have the timing set up as per a local speed shop so I can only hope they know what they are talking about. Should I have my timing coming in a little later? I also thought it was funny to have it all in so soon, but am just taking advice from someone I thought knows. I am running a brand new holley blue pump (yah, that p.o.s. noisy thing) hoping that would have helped but it never. I run 6.5 lbs fuel pressure. I will try these things you have talked about and let you all know how I make out. Thanks again....Sean.
sounds like to me it's ether your distributor advance, or your carb. but i think if it was your carb it would be sloppy on take off then clear up.
I'm a proponent of having the timing come in ASAP (locking it out even). It sounds to me that you either need to play with the jetting or fuel pressure. I'd go up an an increment at a time (changing only one thing, either fuel or jets), then down to see if there are any changes. If you do it correctly, making a pass, shutting the engine off, then reading the plugs will tell you a lot about your engine under acceleration. Here's a good link on fuel delivery: LINK and here's one for READING SPARK PLUGS Good luck.
Man i appreciate all the help. Thanks for the tips. I will let you all know how I make out as long as the snow stays away long enough to get it done.
Okay, building on Rick's comments: You perform off idle and up top. Your bog is in the middle... Correct? Check your primary jets! Could be lean. Your accel pump and PV will handle the off idle, and the rear jets could cover up problems on the big end, so that leaves a hole right in the middle where your primary jets are the sole provider until the secondary system kicks in.
OR Your secondary system might be crashing in, as opposed to coming in smoothly. You don't say if you have a DP or VS Holley... If you have a DP, you might check to see if you have enough pump shot to bring in the secondary main circuit. If you have a VS, you might check your spring and see if you are opening the secondarys extrodanarily early or late. If they are opening early, you will bog in the middle. If they are opening late, you are running out of cfm in the middle and then picking it up and smoothing back out late. Just some thoughts. ONE CHANGE AT A TIME!!!
Just thought I would let ya know. It's a 650 double pumper, mechanical secondarys, 30cc primary pump, 50 cc secondary pump, jet extensions, anti slosh tubes and equalizer tube. running 72 primary jets and 76 secondary. I have played with the jetting and found this to be close to best. Today I was under the hood and found when I went to pull the coil wire off the msd coil it pulled the extension off the coil.( blaster 2). I found that the pieces that held it together inside are broken and the top could not be put back on snuggly. After a while I figured out a way to secure it and made sure I was getting proper connection inside. It seemed to make a little bit of a difference. Mostly I noticed the slight miss I had at highway speed is completely gone. Bonus. Next I will be replacing the msd distributor with the factory ford one just to see. I will keep you posted as to what happens. Thanks again.
