I'm having a 408 built for my 80 Vette, and would like to get a good cam recommendation.

SBC 400 2 bolt- bored 40 over, zero decked
KB forged 10.5:1 pistons
intake- either Weiand Team G or RPM Airgap (not decided yet)
210 race ported AFRs 65cc (not purchased yet)
scat cast crank/ 6.00 rods
1 7/8 Hooker header/sidepipes
Carb not selected yet- thinking Holley S/A 770
1.6 roller rockers
roller lifters- not selected yet
About a 2600 Stall- not purchased yet
TH 350

I'm looking for 500+ HP/TQ- mainly a cruiser, occasional track use.

I want a hydraulic roller cam- and I'm considering the Comp 286HR or lunati 60112, or maybe a custom grind. Any other suggestions?

I wouldn't mind hearing some intake and carb suggestions too.

Thanks for any advice you can provide.

 

Well....your biggest issue will be keeping it at 500HP. We did one for Auto Enthusiast magazine a while back based on the Dart SHP 400" shortblock along with out of the box Dart 200cc as cast heads. We used a custom solid roller 248/248 on a 109 LSA with .616/.577" lift (1.6/1.5's). It had 11.0 compression and made 540HP with a Dart dual plane and 555HP with a Team G single plane. Both used a 750 street HP Holley carb. It runs great on 93 octane in Houston heat with no detonation at all.

It peaked HP at 6100-6300 depending on intake and made 512 lb ft (Dual plane) and 520 lb ft with the single plane.

JIM

 

This looks like it might work well- anyone use Howards cams?

http://www.summitracing.com/parts/HRS-CL110265-12/

 

all the manufacturers of cams have a tech line I'd call 2 or 3 and have a cam spec'd for your app. its way better to have one made for your car.

 

bigger cam = less vacuum.
something to think about.

 

Comp 286HR Hydraulic Retro-fit Roller “Magnum” Camshaft
RPM Range: 2500-6000/6200
Duration @ .050” lift = In 230/232, Ex 230/232, Valve lift = In .560”, Ex .560”, Lobe sep 110

Lunati: Hydraulic roller tappet
Basic Operating RPM Range 1,600-5,600
Duration at 050 inch Lift 231 int./239 exh.
Advertised Duration 282 int./290 exh.
Valve Lift with Factory Rocker Arm Ratio 0.535 int./0.550 exh.
Lobe Separation (degrees) 110

Howards: Hydraulic roller tappet
Basic Operating RPM Range 2,400-6,000
Duration at 050 inch Lift 234 int./242 exh.
Advertised Duration 294 int./302 exh.
Valve Lift with Factory Rocker Arm Ratio 0.533 int./0.548 exh.
Lobe Separation (degrees) 112

I'm leaning towards the Howards- nice price w/ the cam and lifters. Do you think it's a good match for what I have?

 

I did that yesterday- spoke w/ Howards Cams. Told him what I had and he recomended the exact cam that I linked to before I told him which cam I was looking at. I was just hoping to get some input from some CFers with no "horse in the race".

 

Think you made the right decision for a street motor, with a little less overlap. Should work out perfectly for your application. Let us know when everythings together.

 

That's just it- I haven't made the decision yet. A couple of folks, on a different forum, have told me that I should not use a dual pattern cam and should go with a single pattern on a built 408. I hate making decisions without a *complete* understanding of all the variables.

 

then the engine will never be built! someone will always chime in about something, and worse yet they more often than not wont know what they are talking about. pluck a cam grinder and let them spec it. they know their job

 

Howards, Isky Shneider, etc.
Single vs split dont worry about it youd never notice the difference.
You got a head capapble of running up to 7k+ so keep that in mind.
If you ever thought it was too much a 195cc would be nice also.
Either way the car is gonna rip.
Prefer a Team G myself, they are within 5-10lbs tq til the upper end where the team G walks away from it. That 400 can move some air let her eat!!

 

simple explanation.... from what I've gleaned over the past few years.

Split pattern cams are useful to optimise air flow through the engine for specific head flow characteristics.

The engine acts like a pump: air has to move in to make the power, but it also has to move out.
Restriction on the exhaust stroke to remove the extra air sucked in costs power too.

Lets look at 2 heads in a hypothetical buildup.

Head A: Has intake port flow of 250 cfm @ 0.500" lift with exhaust port flow of 200cfm @ 0.500", the ratio is 80%.

Head B: Has intake port flow of 260 cfm @ 0.500" lift with exhaust port flow of 182 cfm. The ratio is 70%.

Although Head B has more intake flow at 0.5" lift, it has less exhaust port flow.

To improve the ratio of actual air movement in and out on this second head example, the cam grind could either have more duration or greater lift for the exhaust lobe.

Rather than using a single pattern cam with duration of 236 degrees and a lift of 0.5" on both intake and exhaust, the builder of engine using Head B might choose to use a split pattern cam with duration of 236 intake, 242 exhaust with maybe a bit more lift on exhaust too. 0.500 intake / 0.550 exhaust.

For someone to say 'Don't use a dual pattern cam" without knowing your complete build up and anticipated use is questionable.

The heads and the compression ratio will dictate the optimum choice of cam based on your anticipated application.


hope this helps.

 

I'm doing a build at the moment aiming for similar targets 550HP from 427SB. I have a Team G intake matched to 210cc port Heads. After talking to friends about cams I settled on Crane Cams 119691.
234/242 .548/.558 lift lsa 112
Most people agree that I will have reasonable idle with plenty of torque through the middle rev range. That Howards cam has similar specs.

 

Port that Team G it will respond well.

 

My engine builder, and a tech from AFR (Jeremy), recommend a more radical cam- around 248/254 at .50 lift. Iv'e done tons of research on this and it seems very few are running a cam this "hot" on a 406 or 408, and this concerns me a little.

I don't want to be undercammed (go big or go home, I always say), but I also don't want a cam that runs like crap on the street. Both my builder and the AFR tech said a 408 *needs* a cam like this for big power, and it will be fine on the street.

Here are the cams I'm now looking at:

Comp cam XR300HR- 248/254 @.50, 300/306 advertised, .562/.58 lift w/ 1.5s, 110 LSA.

Howards cam 113155-10, 247/255 @.50, 300/308 advertised. .6/.6 lift w/ 1.5s, 110 LSA.

I'm leaning towards the Howards, as I like the idea of being able to take advantage of the AFR's high flow with the increased lift. I ordered the AFR 8019 springs, good to .65 lift (I can still change back to stock springs as the heads won't ship for 2 weeks). According to my calculations, the Howards cam lift w/ 1.6 roller rockers will be .64.

Is such a high lift a concern? Why is no one else running such a high lift? I do plan to order the upgraded Howards lifters that can handle the spring pressure.

Is the extra lift worth the increased cost (upgraded lifters and springs will run me about $300 more than lifters and spring for under .6 lift.)

Any input is appreciated.

 

I have a 383 with a hydraulic roller cam spec at 242/240 @ 050, with 0.594 lift on both intake and exhaust, and an LSA of 112.
Motor doesn't come alive until at least 2500~3000 rpm.
The car didn't feel comfortable... even though I fitted a 5sp TKO-600, it was a bit jerky around town, and laboured below 1500 rpm.
I replaced the 3.36 ratio with a 3.73 diff and the whole attitude of the car changed. Now its an absolute joy to drive, either cruising the boulevard, roaring through the twisties in the hills, or blasting down the strip.

Big cams need low diff gears (higher numerically) to overcome the drop off in torque at lower rpm.

Now with a 400 cube motor, you will of course have more torque than a 383, but you may have to revise the torque converter stall speed.
What does the engine builder recommend for stall speed and diff gearing? I'd be thinking about 2800~3000.

Other issue with bigger duration cams is the lower vacuum produced.
This will affect your vacuum accessories... on the early vettes, the pop up lights cause some issues if there are any slight leaks. Get lazy eye syndrome, where lights take a while to come up, and often come up one at a time .... Power brakes can also be affected.
There are solutions of course, but they are the sorts of issues associated with bigger cams.

Oh, and one more thing.... big cams put a big grin on your face when you can pull strong well past 6000rpm.... but that of course also puts more stress and strain on the engine, and eventually on the wallet.

 

The 2600 stall was what I was considering when I was looking at a smaller cam. I now plan to go to around a 3000 stall, 9.5 inch converter, built by CF's own Pete K.

I was aware of the vacuum issue- I recently went through and replaced headlight vacuum components and I don't have any leaks that I know of. If I still don't have enough vacuum after the big cam is in, I plan to add a vacuum canister. If that doesn't work, an air pump.

I was really hoping to get away with the 3.07 gears, as changing the gears looks to be a huge expense.

 

I would run a smaller cam with 3.07 gears.Build for torque(a 400 will have plenty of that).You don't need to spin 7000rpm with a street motor.
You need a certain amount of compression and cam with a 210cc head or it will be lazy.Maybe a 195 head is a better choice for mainly a street cruiser(your words).
Build for as much low end and mid range torque as you can and the hp will be fine.You don't need to spin it over 5500-6000 rpm to achieve your goals.
A dual plane intake will idle better and have better part throttle response with your 3.07 rear.

 

With your gearing, automatic, intended use, compression ratio, heads, choicve of hydraulic rollrer and build specs I would go with the Comp 286 HR. You need to maintain DCR, vacuum, decent idle quality and with a hydraulic roller you want your torque peak at a lower RPM. Those bigger cams might give you more peak HP on the dyno but street manners, vacuum, idle quality and low and midrange power needed with your geraring will suffer. A 3000 RPM+ convertor is not the best choice on the street. With the 286HR you will end up with well over 500 HP that will run on pump fuel and pull all the way through your powerband with your gearing and setup. The 112 LSA will flatten the torque curve to help with your gear and trans. Overcamming with your gearing is a real bad idea.

 

Any thought on my question about the lift- (going from just under .6 lift to just under .65 lift will cost me about $300.00 for a spring upgrade and better lifters.) Is a .05 difference in lift going to be noticeable in terms of hp/tq? Or should I go w/ standard lifters and springs?