Smaller Cam..Retard or Not?

[Ishiftem]

So I’m wondering, my cam is on the small side for the application and wondering if retarding it would be the right move.
Drag race only
480”
Operating range 4800-7000
4 speed 3900 pounds
Dyno 703 hp at 6800 and made over 680 at 6000
Solid roller installed at 111 ICL at dyno time.
@050:
Intake 254 Exhaust 260
Lift:
.660/.668
Timing @ .050 for cam installed at 108 ICL

Intake open 19 btdc close 55 abdc
Exhaust open 62 bbdc close 18 atdc

Lobe seperation 110

Should I leave it at 111 or put it at 108?

[F-BIRD'88]

I'd put it at 104 in CL to start in car drag testing. Opinions don't matter.

[mt-engines]

I'd put it at 104 in CL to start in car drag testing. Opinions don't matter.

Great advice!! For someone with no experience......

To the OP.. im my opinion of it is race only you are 20 degrees too small.. but whats the combo? If you are restricted on the heads..... adding a bunch of cam won't help a whole lot..

1/8th
1/4
Weight, gears, engine combo tire height etc.. tell us

[Tom68]

What heads and manifold ?

[Geoff2]

The only way to know for sure....is to try it. Are you ok for V to P clearance if you retard it?

[frnkeore]

If you move it from 111 ICL to 108 ICL, your advancing it 3°, 2° advanced from straight up.

Doing that should lower your peak rpm a little but, increase your mid range a little and maybe your average hp, in the rpm range you use.

Adding 20° to your duration, will raise your peak rpm by about 500 rpm, depending on how well your heads flow. If you want to stay in the same basic rpm range, I think 260 @ .050, with more lift, would be better. Keep it at 110 LSA and ICL at 106. Try +/- 2°, on ICL for best effect.

If you don't want to replace the cam, you could also get a higher rocker arm ratio and pick up some there. Again, the heads have to have the same or more flow, at the higher lift.

Some of it, will be in your gearing and how long and hard your engine pulls, in each gear so, average hp will help.

[ClassicComp]

Small cam for 480” but makes great power.
I’d run it as is and get some data.
Then make a change.
Imho

[cab0154]

what gearing, heads, intake, carb, compression, header size..... no way to give a recommendation without some idea of cross section. how hard are you willing to turn it? id be really curious to see how far down it is on power at 7k.

[Walter R. Malik]

If you want that RPM range, you need another cam.

Retarding yours may gain a couple hundred RPM.

[Ishiftem]

I have room to move it on V/P clearance. This is a 409 Chevy with factory heads. They flow in the 325-330 range at .700. A different cam is not an option at this point. Max rpm is 7k. I could push it to 7200 for a banzai run but after that the risk of breaking a cylinder with these blocks becomes a matter of when and not if. It has dual 750 afbs, 2” primaries 27” long with a merge style collector. Intake is a homemade piece. Gear is 4.57 with a 29.5 tire. 4 speed 3.14, 1.98, 1.34, and 1:1 if I recall. Moving the cam in the car is a pain. The engine has to come out and it isn’t easy. Here is a dyno sheet with it at 111. Runs good for what it is. I’m right at the 10.0s which it. I got some advice from Darin Morgan on the intake and heads I’m going to mess with.

IMG_0194.jpeg

[cab0154]

Dang, that thing really holds on to power. Any idea of the minimum cross section in those heads? Darin is the man. He can probably steer you in a direction on cam as well.

[mag2555]

So will changing things to help the motor make more power also help the car run more consistent?