heres the combo;
406
Dart IE 230s flow 290-195 @ .650
13-1 CR
super vic and 950HP
1 3/4 headers
th400 with 5000 stall 4 .56 gears 29" tires
3700lbs /w driver
I have a comp solid roler now thats 268-271@.050 with 630 lift on 107LSA 104ICL
It runs 11.5 at 115 in 4000DA. I really think theres a better cam out there...any sugestions?

What ratio rocker? Does it cross around 6500rpm now? Is 4000DA your typical air or is that worst case scenario?

1.52 ratio now with .019 lash. Yes it crosses at 6500-6600 now. From june to September its 4000'+ ..May it can go to -40 same with October.

Its running out of fuel whats the 60' 330, 660?

60' is 1.56-1.58 no 330' 660' is 7.27-7.30 at 92 MPH

Is this a truck or am I thinking of someone else? I don't want to sound like I'm picking on your combo, I'm not, but it's down on power about 50-70hp even after corrected for weather. If this is a truck that would explain some of the lack of mph tho.

My FIRST thought is to shorten the intake up about 6dg and put some more lift in it either by changing the rockers or going to a bigger lobe. Look for something with lift in the .690 range with duration ~ 262/272 on 108.

Is this a truck or am I thinking of someone else? I don't want to sound like I'm picking on your combo, I'm not, but it's down on power about 50-70hp even after corrected for weather. If this is a truck that would explain some of the lack of mph tho.

My FIRST thought is to shorten the intake up about 6dg and put some more lift in it either by changing the rockers or going to a bigger lobe. Look for something with lift in the .690 range with duration ~ 262/272 on 108.

I agree. A little shorter cam should help, but your combo isn't that far off now though -- seems odd it doesn't run faster as it is now.

In the nasty hot weather here in MI I am running 11.2's with decent traction (but not dead hooking). 11:1 383 with 248*/254* on a 108* LSA, 3.73 gears, 4k converter, 3580# race weight. IMO You should be .5 faster in good air, and a couple tenths faster even at 4000 DA.

Your 60' times are what I'd expect, but your 1/8 MPH is way off IMO. For a reference point, I am typically running 95-96 MPH at the 1/8th mark on an 7.24 sec 1/8th, 11.2 sec 1/4 pass.

Have you watched fuel pressure throughout a run yet? what about jetting? Maybe some chassis dyno time and a wideband O2 sensor would help before making a cam change. I don't think you'll pick up .5 with a cam change.

Just my opinion.

yes its in my 67 pick up...I think I will book some dyno time. My carb builder says I need more jet. They are at 87 squared now. Fuel pressure is good. Thanks for the hep guys

but it's down on power about 50-70hp even after corrected for weather.
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My thoughts exactly...its frustraiting

Just a thought Jim, but are you showing any signs of poor ring seal?

Jim,

I think John is right on in his cam suggestion. That being said it should still run better as it is.

Is the 13:1 measured or calculated? How much cranking compression?

With a 230 cc intake port and your cam you should be making peak power up around 6800-7000 RPM. Have you tried shifting it higher? How much tuning have you done? What is your fuel pressure at the end of a run? How much timing are you running? What kind of fuel are you running?

The exhaust port on your heads looks really weak if you are running an exhaust system.

Looks like the converter may be slipping in the 11-12% range depending on tire growth.

No blow by....very little smoke at full load. It has about 90 passes on it and is actually faster now than b4. Im going to freshen at the end of the season and the roller help was for when I freshen. The new engine will be run on the dyno...just so I know what Im dealing with. I built this one expecting 500+HP. Its only about 450 or so.

Jim,

I think John is right on in his cam suggestion. That being said it should still run better as it is.

Is the 13:1 measured or calculated? How much cranking compression?

With a 230 cc intake port and your cam you should be making peak power up around 6800-7000 RPM. Have you tried shifting it higher? How much tuning have you done? What is your fuel pressure at the end of a run? How much timing are you running? What kind of fuel are you running?

The exhaust port on your heads looks really weak if you are running an exhaust system.

Are you crossing the 1/8th at 6500-6600 RPM??? If so, you have some converter problems. ~29% slippage.

The CR right now is a measured 12.5-1(the 13-1 is for next season) It kinda flattens out above 6800 rpm. Its a new custom TPC carb and I havent tunned it at all yet. The fuel pressure is 6.5 at the end of the pass. I run 3" flowmaster delta 40s right off of the collectors. Its 1/4 mile so the converter is pretty effiecent. I built it for the ability to go 7500rpm. splayed block 4340 crank and 6" H beam rods. Wiseco forged pistons. It ran 11.8 with the cam installed str8 up with open headers...I advanced the cam and picked up 3 tenths and 4 mph(lost 100lbs off of the nose too)...but now im running with mufflers

Im running 112 race fuel.

I have to agree along the lines of what John said. I believe it's slightly overcammed myself. And with the flow #'s you gave, your Exh/Int ratio at .650 lift is only 67%. If it's similiar to this throughout the curve, I would suggest a 8 to 10 degree split on the intake to exhaust duration, ie, 256/264 @ .050 to maybe 260/268 max. You could also try different ratio rockers 1.5 and 1.6 on either intake or exhaust. And, by the way crane makes a 1.7 for a SBC but that may be to aggressive for some roller lobes..IMO of course.

By the way, my combo's peak torque is at 4400 rpm and peak hp at 5800. My cam; 230/238 is puny as compred to what your running, thats one reason I believe 268/271 is abit much!

Off the topic slightly - What is the actual elevation of the track that you run on? Are there day's where the DA might be even higher than 4000? If so, is the new combination going to have a little more wind in it ( 14 or 15 to 1 comp. ratio)? I'm just curious what high altitude racers do with their combos. when running normally aspirated.

T-man

the elevation is only 600 feet...the average sumer temp is 110 with a barometer of maybe 28.10. The new engine will have a minimum of 13-1. Depending on head configuration/chamber size will determine piston.(dome or flat top). These heads have a 53cc chamber. Im looking for another set. Theres a set of 867 pontiacs(nascar knock offs) I can get cheap with matched manifold. I'm waiting to see the flow results.

Your engine combo, converter, rear gear, and car weight all say Lunati 501D1LUN, which is 302/310 at .020, 271/279 at .050, .640"/.640" gross valve lift, and 106° LSA. However, with such low air density because of the heat, which makes the engine act as if it were at high altitude, you'd be better off with a 501C9LUN, which is 294/302 at .020, 263/271 at .050, still .640"/.640" gross valve lift, and 106° LSA. A 1.6 on the intake helps, and I install them between 99° to 102° ATDC on the intake. You need a fuel system that can pump a gallon of gas in 25 secs or less, or you may run the float bowls dry....
If your Comp Cam is the 304-5/310-6, at .200 it is 183/185. My cam is 184/193 at .200. At .020", the 501C8 is 294/302, 8° to 10° shorter than the Comp, and bigger above .200". Because of the way I design, the 294° intake opens the valve as if it were a 288° symetrical cam, and this causes very high intake port velocities. You also get the power stroke of a 296° cam on the exhaust.
Both these 2 design factors greatly increase the torque output of the engine, at ALL RPMS!
The 302 has set a number of NHRA records, starting back in May of 1980....

UDHarold

BTW, be sure to ask for a small base circle cam.....