I have heard that also, A friend who has a Skyhawk with a 350 buick motor in it couldn't get it to run like he thought it should so he had the fuel system redone with a sump installed on the stock tank and big lines and so on, with the same carb setup it went from almost to lean to way rich. I have a good system eccept where it pulls out of the tank. I have 2 blue pumps, one pulling out of the stock pickup and the other on a second pickup soldered in next to the stock one. After seeing how much it helped my friends car I am going to put on a sump and bigger inlets to the pumps. I also think I am going to put a regulator on each bowl or just get a bigger regulator and stay with one. Maybe there is nothing wrong with my Holley ignition, maybe it is popping from a lean condition. Tom
If you ever took apart a Holley regulator then you would wonder how you ever got enough fuel to your carb. I would definitely upgrade the regulator and go from there. On the converter, 1000k drop beteween shifts sounds good but you could probably use a little more flash rpm. 4200 would get things moving a little quicker. A transbrake would solve it. :Brow: They can cut apart your converter and shim the stator a little to help it flash a little more off a foot brake if you want to go through the trouble of taking out the converter. It my even help to loosen it up. I'd get a few more runs on it now that you have the fuel you need to see where your et and mph settles out at. Your getting closer. Get your trap rpm so you can calculate you converter slip. I'm sure it is pretty tight but and exact figure can help with a converter adjustment if you decide to make one. A little nitrous is perfect fix for a tight converter. :Brow: Have you tried changing the jets now that you have enough fuel?
Rick, Thanks for all of the input. I hope to get out tonight and I will record the RPM at the traps. What is the formula to calculate % of slip? I have been thinking about changing out the 700 for a 400 and talked w/ Neil Chance about the converter w/ combination. They thought they couldn't get more than 4k stall w/o the converter being to loose at the top end. 4k is okay but I know the motor would really like a little more. I wonder if the 400 would be a little quicker??? However if I went with a tranbrake he would have the perfect set up but I am not ready to go to a full manual valve body. I still like having a little street car left. No jet changes yet as I only got 1 1/2 pass last weekend before the rain.
A transbrake th400 is still plenty streetable in my opinion. I drove 2 455 Buicks around with manual valvebodies and my buddies 87 SS with a th350. They drive and shift great. You just have to do it manually. It helps that manual setups don't drag the motor like a standard stock valve body in first gear and if your driving around easy with 3.73's or better you can get by with just using 2nd and 3rd. How easy is that?? I would think a th400 would pick up your et over the 700. You have a overdrive right? Its heavier and that 3.08 first is great for multiplying power but I wouldn't be surprised if that 3.08 is too much for a drag car. It is better to use a 2.48 first gear and flash the converter harder, hold the flash rpm a little long, and use the converter torque multiplication to get the car moving thru the 60ft. I have seen a math calculator on the net but I won't have enough time on the internet to find it and post it. Hopefully someone else will bail me out. I'm suppose to be moving and will be "out" for a bit, I think.....
Click on to TCI racing and they have a section called racing calculators.This is a handy bunch of formulas check it out. :beer
Just thought I give a quick update on my car. Last Friday I made the following pass :3gears: 60' 1.55 1/8 7.07 @ 94 mph While I still have several issues to sort out but I want to thank everyone for all the help. Hopefully with a couple more adjusts and working on the tune I can hit my goal. Regards,
Problem still eludes me Well I guess I cannot locate my problem that I fixed w/ my last set of changes to the fuel system. The car at BG just surger/sputter starting at the top of 2nd and all the way in third. On the first pass it would not rev past 5k, the other 2 would rev to 6k. Timing and jet changes had no effect on et or mph (6 sizes in total). Fuel gauge showed 6 psi each time the car hit 3rd to the lights. Does anyone have any additional thoughts that I have yet to try? FYI - this is the first 1/4 pass I have made w/ this motor. Racing mostly 1/8 mile. Here is one of my slips 60 1.6 330 4.67 1/8 7.24 mph 94.14 1/4 11.50 mph 114.5 Thanks
no cam change and it was degreed in. around 106 if memory serges me. I still think it has to fuel but the car holds fuel pressure and the carb is the same one it had on it at the dyno. At this point I am pretty lost.....
Where is the pressure reading being taken from? Maybe you have six pounds where you gage is but not at the carburator? The fuel pump has to over take the graverty (spelling) of the acceration of the car (you are doing a 1.55 second 60 foot time). What most racers will do is plum the regulator in front of the carberator in some way and then let graverty (spelling) carry the fuel to the carburator.
Fuel pressure was 6 PSI at the traps. Fuel pressure is taken at the fuel log and the regulator is attached to the log.
Enough with the Fuel... Pull the valve covers and check over all the valve spring real good. Especially the intake. Get your hands on a Moroso spring tester if you can. You said you had a solid cam not a hydraulic, right? How much lift?
Rick, I will check the springs tonight. Valve lift is right at .600. I believe this is the same gremlin that I have been chasing ever since I install the new motor. Thanks,
Fuel system After going through everything on the car again and talking w/ product engineering (fuel system folks) and the Reher-Morrison crew (which are a bunch of great guys) I have come to the conclusion that my fuel system cannot supply the volume needed. So it is time for a new fuel system. Product engineering has a nice solution but it will cost me around 1k to do it. Does anyone have any thoughts on a new fuel system to supply my 625hp, 3800 pound lark that won't cost so much? I have the following currently on the car or available. 1 BG 2 port regulator 1 Mallory return style regulator Sumped factory tank -8 line from the tank to the front of the car TSP billet pump Thanks for any input!
To me that doesn't sound right. Did you check the springs like Rick mentioned? With my old 462ci that ran low 10's, I fed the 1050 dominator, and the nitrous unit with a Holley "blue" with the upgrade spring, 7 psi to the carb. and about 6 to the unit. I didn't have a sumped tank but a stock one with a 1/2 inch pick up and 1/2 in fuel line to the Holley regulator, no return, and -6 to both bowls of the dominator. Never a fuel problem, and the car weighed in around 3700lbs with me in it. What about a timing mark/balancer issue? Have you followed that "thread"? My friend had a similar problem with his Olds, ended up being the cam was not degreed in correctly. I know there's some test of a fuel system, so many seconds to fill a gallon, but can't remember all the details. Good luck. Gary G.
Gary, Yea I visually check the springs as I don't have access to a spring tester. The motor has maybe 500 miles on it w/ 20 or so 1/8mile passes so I am willing to bet that the springs are okay. The cam was degreed in correctly. I have been following the balancer thread and will check my Romac again but I believe it is correct. I have been chasing the same problem since I installed this motor and the way it surges in 3rd and seems lazy all leads to fuel. Yes, I might be wrong but I am at wits end w/ this car. At BG I could only hit 114mph...something is just not right!
I have been having the same problem with mine for 2 years. I was always thinking a ignition problem but now I am also stating to thing some kind of fuel problem. I have someone who will run my Holley ignition box on a dyno motor for me to see once and for all if it is OK or not. I did not make any major changes to the car to bring it on eccept to go faster with tuning. I have the BHJ balancer on mine and I know it was real close when new but I am sure going to check it again after the problems others have. The reason I am thinking fuel problem is I can make huge jet changes and it won't change the way the car runs, I would think that going from 84/94 jets to 88/98 in one jump and it runs the same is not right. I have run 86/96 for years in this carb before the problems started. Tom
I'll keep thinking.....Do you have access to a chassis dyno?? My friend with the Olds took his to one after alot of frustration, it was very helpful, money well spent. Pretty sure the ROMAC balancer is good, that's what I had, it checked out good. Have you tried a different carb? What ignition do you have?I'm sure this info. was already posted, just didn't look back. I'd hate to see you spend 1K on the fuel system, what you have should be plenty. I think the chassis dyno was about $70 or $100, I'd look into spending that first. Please keep us informed. What about the tank sump?? Could it be getting empty during acceleration? Could you try something else temporarily?? I'm just trying to see the difference between the car and the dyno, maybe make a list of them, then go thru each one. Gary G.
Gary, Thanks. I do have access to a chassis dyno and I have been thinking about doing it. However, I am not sure if the dyno will pick up on the fuel problem as the car is static. Ignition system is all MSD and has been changed out because of this problem. I just installed a new dominator this week, instead of the custom 4150, so we will see if that helps. Hopefully this weekend. I am just worried that the mechanical pump just cannot suck enough fuel going down the track no matter how many gallons it can pump on a dyno.
Tom, I have the same trouble. It seems it will run the same no matter what jets are in the carb. At this point I am still think fuel. Good luck!
