Stroke .....? power curve....?

[KAGE]

SBC, 3.335 stroke, we have a ci limit of 366, steel block, run on no bigger the 1/4 mile tracks, most are little 'bull rings'. 16 deg brodix heads 15.5-1 comp, will we make any more top end power and how much more? going from a 4.145 bore to a 4.2 bore with a 3.280 stroke? We are using 6.2 rods now, what if we went to a 6.280 rod with the shorter stroke? Most tracks are black slick at the end of the night but start with good drive.
All top quality internals are used, currently turning 8400 rpm max, what we have now is working realy good, but having trouble making too much power off the turns at the end of the night. Wanting to make more usable power up top and not pull so hard off the turn, due to the short tracks and tight turns, the cars don't carry alot of momentum, so traction is hard to come by.
We also only use a 2.150 int valve, will going to a 2.180 pick up the top end?

[dirt2]

Kage
If the setup is good & you know for sure you have to much
power that is causeing the problem off the corner try retarding
the cam a couple of degrees to soften it up. This will also add
to the upper end power some. Tighten the valve lash a couple
of thousands & see what it will do. If these two things do no
give the results you need you may need to change the cam.

dirt2

[parrot69777]

Even though I've done it in the past....backing the cam timing will affect it all the time and not just when the track turns slick.....when you need the power when the track is good...your car will still be lazy.

Sounds to me like maybe your losing tail percentage by burning off fuel and by the end of the race it's killing your rear grip.

[soonersublime]

Easiest thing to do here is get a slick track carb by willy's w/ adjustable vacuum secondaries.

[connor]

Are you running msd box if so hook up two and have the second one retard timing.Then you have best of both worlds good when tacky and a little lazy when dry slick.

[KAGE]

Thanks guys for the help, the cam is alittle too big to begin with. I have seen one comptitor have a dial that I assume is hooked up to his MSD box that swings both ways, addvance and retade for his ignition?
What cam specs should put me in the ball park?

[hpontap]

Sounds like you are looking for an expensive cure for a traction issue. If the cam is too big with this short stroke, long rods then you should have killed off some bottom end as it is. Depending on the cam, this combo should be easy to drive in the slick. I would first look at the driver then the chassis to find the problem. I think you have the cure already. The throttle pedal. Good Luck

[KAGE]

We were thinking of going the other way and putting more gear in it, turn it a little harder to try and control the wheel spin that way? Any thoughts?
We don't run on an oper budget and really don't want to wear the engine out any quicker with more rpm's then we need to.
The pedal is going to be adjusted so its got more travel to the floor and some stronger springs on the carb.
What cam specs would need to be run in this setup? I know it has a 4/7 swap comp roller cam?

[4bangerhotrod]

with a higher gear it kills power and helps keep from spinning but when the car breaks traction the tires spin much faster and its harder to regain traction. with a lower gear once you break traction you can ease off the pedal a little and the tires slow down much faster and traction is regained much faster. as the track slows down we change gear to keep it in the same rpm range. this seems to work better for us and I know everyone in our series does the same thing. the only thing I would change is have a adjustable pedal and throttle rod an adjust to get max pedal movement before WOT. when we used to race weekly tracks I used to think the same thing until we did some testing with this and the stop watch def tells the difference