Finally got some dyno numbers wanted some input.

69Rcode_Mach1 · Mar 1, 2010

Hey guys I finally got the Mach on the dyno. Some minor issues but I will be posting up the sheet as soon as they email it to me, their printer wasn't working. So it put down 337rwhp can't remember tq off the top of my head I did it before I put it away for the winter. The thing was running very rich. I believe it was at 11:1 air/fuel ratio, and shooting some smoke out the tailpipes. I am getting ready to take her on the road and probably do some more pulls in the next little bit as the weather gets better here. The guy at the dyno said to expect a nice bump once it gets tuned up correctly. The ignition kept dropping out past 6000 rpms as well so that is another thing I am going to be addressing since all I have is an MSD 6AL box, a new MSD distributor is in the plans. Given the combo the car should pull up to 7000rpms. Pulled the carb apart today to rejet and wanted some ideas. It had 72s in the primaries, and 81s in the secondaries. What ideal ratio should I be shooting for I have heard around 14.7 or so, the guy at the dyno said 13 seemed low for a naturally aspirated engine, what do some of you guys recommend I drop the jets to? It is a mighty demon 750 carb.

blown65 · Mar 1, 2010

12.5-13.0 is what I'd shoot for n/a. As far as ignition breaking up, some of that is probably due to being at 11-1 a/f. Lean it out some and maybe tighten up your plug gap.

14.7 a/f is your target cruise air fuel ratio.

I run a 6al an 8300 rpm so I doubt that's your issue at 6k.

brianj5600 · Mar 1, 2010

1.7 rockers on a cam ground for 1.6? Hydraulic roller are not known for stability and your cam sounds like it is aggressive enough that the springs can not control the valve train with the extra ratio. That is my guess.

69Rcode_Mach1 · Mar 2, 2010

Those lift figures in my sig are calculated with the 1.7 roller rockers they would be lower with the 1.6 ratio. I talked to lunati and edelbrock when I was putting the combo together, those valve springs should be able to withstand that cam. As far as the ignition goes, blown65 are you running a stock dizzy? I am running the 6AL box, blaster 2 coil, late style cap, with the FRPP 9mm wires. Still points though, and yes I did change the distributor gear to match the roller cam. This cam is not a retrofit either I used vertical link lifters so as to keep the high ramp rates of a roller cam.

blown65 · Mar 2, 2010

69Rcode_Mach1 said:
Those lift figures in my sig are calculated with the 1.7 roller rockers they would be lower with the 1.6 ratio. I talked to lunati and edelbrock when I was putting the combo together, those valve springs should be able to withstand that cam. As far as the ignition goes, blown65 are you running a stock dizzy? I am running the 6AL box, blaster 2 coil, late style cap, with the FRPP 9mm wires. Still points though, and yes I did change the distributor gear to match the roller cam. This cam is not a retrofit either I used vertical link lifters so as to keep the high ramp rates of a roller cam.

oh, no I'm running a MSD dist.

69Rcode_Mach1 · Mar 3, 2010

How do you like your ignition setup? Which dizzy did you end up going with? Sorry it's taking so long to get the sheet, my buddy lost the number to the place and is trying to find it, it's a little ways away so I don't want to drive in.

blown65 · Mar 3, 2010

69Rcode_Mach1 said:
How do you like your ignition setup? Which dizzy did you end up going with? Sorry it's taking so long to get the sheet, my buddy lost the number to the place and is trying to find it, it's a little ways away so I don't want to drive in.

It like it, was getting a misfire around 8300-8400. Put a MSD digital 7 in this yr for more spark. Since I run Q16 it takes more spark since your adding even more fuel than just your regular race gas. Have not had a chance to run it yet with the new box/coil though. Also putting new valve springs in to cover that part.

Not sure on the dist, I'd have to go look. Its just a magnetic pickup vaccum advance dist, that is actually locked out at 34 degrees. I run no advance at all on my setup. 34 at idle and 34 at 8300.

69Rcode_Mach1 · Mar 4, 2010

Oh wow! I am not quite that extreme on the timing. I am still waiting for my guy to send me the sheet he said I should get it by Monday cause he doesn't know when the guy who did it will be in. I just want to get this thing dialed in and running right for this summer season so I can focus on the front suspension and braking system. The guy recommended dropping the jets from 72 to 70 on the primary and from 81 to 76 on the secondary. He is going to let me bring it in in a couple weeks and let me do some pulls $10 a pop and no tie down fees or rental fees to fine tune it. He wants to see what we can get the car to pull.

68RCodeConv · Mar 4, 2010

Hydraulic rollers tend to start floating right around 6000 because the valve train is so heavy and you can't run as much spring pressure with them as a solid roller. As a general rule of thumb if you want to rev beyond that you should go with a solid roller.

I also don't like the fact that you are running points. Ford used dual point distributors to deal with higher rpms.

57fairlane · Mar 4, 2010

68RCodeConv said:
Hydraulic rollers tend to start floating right around 6000 because the valve train is so heavy and you can't run as much spring pressure with them as a solid roller. As a general rule of thumb if you want to rev beyond that you should go with a solid roller.

kind of . . .

you do realize that guys have to run hydraulic rollers in NMRA real street right?

check that class out if you still think this way about HRs.

10secgoal · Mar 4, 2010

Yeah but what they do is way out there. They run a ton pressure and run the cups down to like .009 of preload left. So it's a solid lifter, but hyd for the rules. And they let the valves bounce on the seats, and count on it. Not quite what he wants lol. I've seen link bars lifter come apart at 6700. Pops the clips right out of them

Think Brian is right though. You should be able to light of 11-1 afr N/A no problem. If it's breaking up, it's somewhere else.

rbohm · Mar 4, 2010

i would go with 68's in the primary and 77's in the secondary. that should get you to around 13:1 a/f ratio.

brianj5600 · Mar 5, 2010

If it still has a stock points distributer, that could be a problem. Did the WB show lean when it broke up at 6000? If it was misfiring it lets a lot of O2 into the exhaust and should show on the WB. It seems like valve float would still burn the fuel and O2 and have less effect on WB readings. Might be something to run by the dyno operator.

Finally got some dyno numbers wanted some input.

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