should I swap cams

[grumpyvette]

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hey grumpy? here is my friends combo,
406 sbc
AFR 195 heads
little under 11:1 compression
RPM intake
Holley 950HP
SFT 247/255 @50 525/540 106lsa
1 3/4 headers

He was wondering what RPM would the horsepower and torque peak at.
He is putting this in a 66 chevy II mini tubbed with cal-trac springs & bars.
Going to run a 28x10.5 slick with a TH350. He is going to order a 8" ATI to match the motor. Car weights @3100 with him in it.

Just an update, friend got car together. The compression ratio ended up being 10.6:1, he went with a 4.33 gears, it weighs 3120 race ready with him in the car and 5 gallons of fuel. Has had the car out twice shift light set at 6300 and running 93 octane.
60ft - 1.435
1/8th - 6.721
MPH - 100.36
1/4 - 10.644
MPH - 122.65
it is turning 6700/6800 at the strip.The car is running much better than my friend thought it would and of course now he wants to go even faster. He is thinking about a cam swap over the winter. Talking about leaving everything else the same and just changing cams.
He is looking at two cams:
251/259 @50 530/551 106lsa
255/263 @50 540/556 106lsa .

computer wild guess at current combo

computer wild guess at current combo, with swap to new cam and darton intake

looking over the combo I think the 251/259 @50 530/551 106lsa cam would provide some gains but that about maximizes the head flow on a 406 with that intake , that seems like a really good combo, but if I was swapping cams to the larger cam Id at least try this intake, to see if a bit more flow helps

http://www.summitracing.com/parts/HLY-300-110/ with the larger cam, the combo would kill a bit of low rpm torque but it should provide a bit more upper rpm breathing.
Ive generally found that once you get over about 250 duration on , a tight 105-108 lsa a 406 with that 11:1 compression the 195cc heads show a benefit from the darton intake

 

[Indycars]

hey grumpy? here is my friends combo,
247/255 @50 525/540 106lsa

251/259 @50 530/551 106lsa


looking over the combo I think the 251/259 @50 530/551 106lsa cam would provide some gains but that about maximizes the head flow on a 406 with that intake ,

With 4 degrees more duration and .005/.011 more lift, would it not come down to how aggressive the lift curve was??? Especially if the flow is restricted at the higher RPM, because of the heads and intake manifold.

 

[grumpyvette]

your correct to a point, but from the info ,the cams , are very similar,flat tappet solid lifter cams ,his current cams 247/255 @50 525/540 106lsa
but in this case its the intake swap thats going to potential make the biggest improvement not the slightly longer duration cam, in this case.
the cars obviously set up well and making good hp and running mid tens the heads are a bit small, but over all thats a really nice combo thats not going to see huge improvement without much larger heads, and a killer solid ROLLER CAM
many guys fail to differentiate between a true race combo and a hot street/strip combo, when selecting parts, hes built a really nice effective street strip combo, then installed a torque converter stall that moves the combo into the weekend race car category, but theres a huge difference, its obviously still an effective combo but its a bit of a mis- match, and just as obviously the budget restrictions we all must deal with had a significant influence on the parts selected. your not going to like driving a 4000rpm- 5000rpm stall converter on the street, and he could really use a much larger set of heads and a solid roller cam on a strip combo, posiably even a tunnel ram or at least a 250 nitrous plate, it the cars a bracket car where hes mostly concerned with low times, but let me point out I,ve been that route several times, and its TRULY a BOTTOMLESS MONEY PIT theres always something that you can do to gain a few hundreds or tenths in the 1/4 mile or a few more mph, it just costs more money, money that can make your car faster, or parts that can make the car lighter or get better traction, etc.