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Discussion Starter · #1 ·
I will be installing a 3.80 gear w/ 24" drag radials next time to track. With this set up i believe i will be pretty much topped out at end of the 1/4. I only have the stock heads and w/ the 3.55 gear rpms were 4621 w/ 25" tires. I used the calculators and it's showing 4947 w/ the same trap speed of 96.9(best speed) and 24" tires. trying to give myself some wiggly room and was wondering if there are any ways to increase rpm range w/o going into the heads or cam. I ran the calcuator at 100mph and it shows 5285 rpm's w/ 3.80 gear and 24" tires.
When i ran car i was shifting at 5200 tops and it did not feel it had any more.
 

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try a 2" open spacer under the carb & might need to jet up 1-2 numbers. if small carb, try a stub stack on carb top if one available for your carb. hard to say more without knowing your engine setup.

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S/ST 1818 S/P 1018 H/R 1564

<font size=-1>[ This Message was edited by: igo1090 on 6/27/06 12:00am ]</font>
 

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Discussion Starter · #3 ·
engine is .030 289, stock crank, rods and heads(1.78/1.45). 10:1 flat tops, Weiand single plane , holley 600 dp, tri-y's, mild race cam not sure spec's.
 

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that should be somewhat happy to over 5000 rpm. maybe running out of fuel? still have stock pump & 5/16 line? 600 dp good to 6000+. stock heads maybe 5000+. intake 6000+. point bounce? what ignition? if points, get electronic conversion kit or at least heavy duty accel points. if all is right, that combo should go 5000+ without any problems.
 

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Discussion Starter · #5 ·
I have stock dizzy w/ petronix. replacement pump and stock fuel lines. It does go 5000+ just barely...I'd like to get 5500 out of it. Would any ram air be good for add'l rpm's? I ask as i have the same AIS box that project 11.99 used but have not put it on yet, still have to relocated the
battery.
 

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Those stock 5/16 fuel lines are a killer... I noticed a significant difference with 3/8 lines.
 

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Discussion Starter · #7 ·
When you swithced over to the 5/16 lines was your car running
12's already. I'm only mid 14's now and wouldn't think the fuel line
upgrade would be needed til i get her faster....any thoughts??
 

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The valve springs may not be up to the task. Valve float will hurt power before it becomes audible.

People forget that the stock 289 heads made peak power on the 289 hipo at 6,000rpm. I doubt that you can't get 5,500 out of that 289 with the stock heads and the correct valve springs. Something else isn't right IMHO.

I still run the stock fuel lines on my '65 and shift at 6,000 at the track. I do run a Carter mechanical pump. Again, I doubt that the line is the problem unless it has a severe pinch somewhere (they all come with crummy bends).

I used to run a fuel filter in front of and after the mechanical pump. This did cause a problem when I tried to make a run shifting at 6,500. In third gear just before the shift at 6.5k it would stumble. Removed the filter before the pump and everything seems OK. The car slows down when shifted over 6k. I think the line may be maxed out there. Not at 5,200 though.

Have you played with the timing? What is the total advance?

Have you ever tried making a run shifting at 5,500? What about 5,400? I would try from 5k up to 5,500. However, I wouldn't start playing with siftpoints untill you feel you've got a handle on how to launch with the new tires. Get used to getting out of the hole with your current shift and let it go through the traps with the pedal to the floor. Also don't let up till a tad after you've past the finish.

I feel your combo should already have a couple hundred more rpm in it. When you gas pedal is to the floor does it completely open up you carb. You can have it floored and not have the carb at wide open throttle. Distributor could also be a problem if it's the old single points type.

Don't sweat it too much. You're gonna have fun with just the tires and gears!
 

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Hmmm, I was running the stock dizzy with pertronix too... and had no problem doing 6000 rpm.
My cam was bigger but you should still be able to hit 6000k.
Nate makes some great points... check the obvious things and then look for a restriction in the 5/16 line... is it a new tank?
What filters are you running... some of them really restrict flow (especially if they are dirty or clogged).
Also, check your timing with a digital gun if you can and see how she performs at different advances... I know mine woke right up at 38 total.
 

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Discussion Starter · #10 ·
I recurved the dizzy w/ the lighter springs and have 37 total all in by 2500rpm. I have not tried taking it over 5200 on track. Maybe it does have more and I'm being a wimp...i try to shift at what point feels good w/ the car and when i've watched the tach it has not been over 5200. Is it possible that maybe the engine will turn higher but not be gaining anything by doing so? I will check the fuel lines as well to see if there are any bad curves, I have a glass fuel filter w/ element that's pretty new. I have a fram airhog air filter as well that's new. I did confirm WOT before last race and actually had to cut out some of my carpet under the gas pedal so I know it's working well.
I have had someone else mention the valve springs possible not be enough. Is it possible to replace the valve springs w/o taking the heads off?
 

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Yes, it's possible to shift the engine at a higher rpm and not gain anything or go slower. If you mean crossing the finish at a higher rpm your mph will be higher all else being equal. Increase in mph can be seen as potential to cut time off of your e.t. (and will do that if the car and driver allow it). You can gain mph and have a slower e.t. based on things such as poor 60 ft./traction and bad shifting.

The mph is a good indication of how much power you are making. You've better used your power curve if you shift 200 rpm higher in gears one through three and end up crossing the line in fourth at a higher rpm/mph. Shifting lower could also cause you to cross the line at a higher rpm/mph. Keep going to the track to find out how your car in it's current tune wants to be driven. It's the most fun I've ever had "working" on my car.
 

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I ran into this problem years ago...when I still ran a 302 and gas. Switched from 4.56 gears to 4.86...car picked up ET but lost MPH and gained 250 RPM +/-. I leaned the fuel mixture a little and retarded the total advance back to 34 and got the MPH back...AND most importantly, it became more consistent (bracket car). From what I've seen...SBF engines are more consistent and run better on the lean side as opposed to the rich side. Everyone's stuff is different, but ours always liked to be a little lean (almost white plugs after a run).

Motor combo I have now doesn't care much if it's shifted at 7200 or 8500....If it spins or I get out of shape, I can let the RPM climb on up to about 8300 then shift, and it'll pick up about .02 ET. Sometimes its enough to make up a little loss at the starting line but more often it's not. As long as the 60' times are somewhat consistent, it will "zerox" timeslips. I once left the same dial in on the car for 4 weekends.

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<font size=-1>[ This Message was edited by: mavman on 6/27/06 10:18am ]</font>
 
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