Cam Selection Advice

[DNasty777]

Hello everyone, yet another cam selection advice thread!

I need some help with cam selection, as I'm not well versed in cam selection and I'm a little off the beaten path with this one. I'm open to anything out of the catalogs or custom grinds, basically any advice you'll feel like bestowing on me. The car is a '69 Valiant with a 360 Magnum hyd rollers, IMM 2.055 Speedmasters with Comp 914-16 springs, and 1.5:1 mancini rockers. Two choices of intake, airgap clone or super victor, both set up for port injection. Ram short tube headers into an ebay gt45 turbo. FTI 4000rpm stall converter, 3.73 gears, and 28" tires. I have enough fuel system for 700 crank hp, but I don't think the stock bottom end will hold up to that, so we'll save that for the forged rotating assembly.

Any other info I can give to help please let me know. Thanks!

 

[273]

Say your goal is about 600 hp, a 300 NA engine with about 15 psi of boost would get you there or a 400 hp NA with 7.5 psi of boost etc..

So you don't need much NA power to get decent boost output, so you could run a fairly mild cam to keep streetability especially if you plan on a lot of boost, but say your going for 5-10 psi of boost that's like 1.33 to 1.66 x NA power so say 425 hp x 1.33 to 1.66 = 565 to 705 hp.

Need more details about those heads but I imagine were talking 225 to 245 degree cam depending on NA, Boost amount (psi) and Boosted power goals.

 

[DNasty777]

Say your goal is about 600 hp, a 300 NA engine with about 15 psi of boost would get you there or a 400 hp NA with 7.5 psi of boost etc..

So you don't need much NA power to get decent boost output, so you could run a fairly mild cam to keep streetability especially if you plan on a lot of boost, but say your going for 5-10 psi of boost that's like 1.33 to 1.66 x NA power so say 425 hp x 1.33 to 1.66 = 565 to 705 hp.

Need more details about those heads but I imagine were talking 225 to 245 degree cam depending on NA, Boost amount (psi) and Boosted power goals.

Thanks for the input. Conservatively, I’ll likely start at 3-4psi as that’s the springs in the wastegates. I do have electronic boost control though and I doubt I’ll be able to control myself.

Here’s a flow test on these heads if that helps.

 

[273]

Thanks for the input. Conservatively, I’ll likely start at 3-4psi

That's about 1.25 x na = boosted hp, those heads are easily 500-550+ hp x 1.25 = 625 to 688 hp. You'd probably want to keep the cam on the milder side same with boost.

as that’s the springs in the wastegates. I do have electronic boost control though and I doubt I’ll be able to control myself.

Here’s a flow test on these heads if that helps.


View attachment 1716150047

 

[TT5.9mag]

How much would you guess your car weighs?

 

[RustyRatRod]

What is your assembled spring height? Those springs set up at 1.8 with 165 on the seat. Don't the Magnums set up like the LA at around 1.625?

 

[DNasty777]

How much would you guess your car weighs?

Hmmm, I’d have to guess 3000 wet with driver.

What is your assembled spring height? Those springs set up at 1.8 with 165 on the seat. Don't the Magnums set up like the LA at around 1.625?

I’d have to measure them to tell you or call IMM and ask if they have any data on these heads.

 

[DNasty777]

What is your assembled spring height? Those springs set up at 1.8 with 165 on the seat. Don't the Magnums set up like the LA at around 1.625?

I just went out to the garage with a caliper, looks like 1.8” best I could measure. Definitely looks like the spring seat was cut and it has some shims/locators at the bottom.

 

[TT5.9mag]

Hmmm, I’d have to guess 3000 wet with driver.

You didn’t specify street/strip or a percentage of the two so I kinda assumed 50/50. With your gear, weight, tire size, converter, and cubic inches, I’ll recommend a cam that’s an off the shelf grind and should be easy to get if Hughes has cores. You might could get them to grind it on a short snout (magnum core) if you’re using a magnum front cover. If not follow their recommended parts at the bottom. And I’d definitely Use the single plane intake.
Edited to add; and if your not married to those rockers, I’d like to see a 1.6 with your head flow numbers.

Hughes Engines

 

[RustyRatRod]

I just went out to the garage with a caliper, looks like 1.8” best I could measure. Definitely looks like the spring seat was cut and it has some shims/locators at the bottom.

If it's really 1.8 and you're using those springs, you know they have 165 on the seat at 1.8. So that's your camshaft's needs on the seat. It cannot have a ton of lift.

 

[DNasty777]

You didn’t specify street/strip or a percentage of the two so I kinda assumed 50/50. With your gear, weight, tire size, converter, and cubic inches, I’ll recommend a cam that’s an off the shelf grind and should be easy to get if Hughes has cores. You might could get them to grind it on a short snout (magnum core) if you’re using a magnum front cover. If not follow their recommended parts at the bottom. And I’d definitely Use the single plane intake.
Edited to add; and if your not married to those rockers, I’d like to see a 1.6 with your head flow numbers.

Hughes Engines

Awesome, thanks for the feedback! I’ll call Hughes tomorrow and see what they have to say. I’ll start looking for some 1.6 rockers too.

 

[DNasty777]

If it's really 1.8 and you're using those springs, you know they have 165 on the seat at 1.8. So that's your camshaft's needs on the seat. It cannot have a ton of lift.

A spring change isn’t out of the question, if needed.

 

[TT5.9mag]

Your first call should be to Brian at IMM. He’d probably be able to get you set up really well. He did the heads so see what he recommends.

 

[DNasty777]

Your first call should be to Brian at IMM. He’d probably be able to get you set up really well. He did the heads so see what he recommends.

Good idea, I’ll give him a call tomorrow.

 

[RustyRatRod]

Your first call should be to Brian at IMM. He’d probably be able to get you set up really well. He did the heads so see what he recommends.

I agree 100%. He may have had a camshaft in mind when he set the heads up.

 

[DNasty777]

I gave IMM a call this morning, had a good chat. The springs in the head now would work for a hydraulic roller cam but the pushrod holes needs to be opened up more. He gave me some pointers on how to do that but I may send them back to IMM to have them re-set up the heads. He also said the rockers are good to go at 1.5 but to thoroughly clean them and make sure to knock all the flash from the inside of the shafts.

 

[TT5.9mag]

Did he give you some guidance on cam specs?

 

[DNasty777]

Did he give you some guidance on cam specs?

No, I'm leaning towards sending them back to him and we can talk about that we he gets the heads as I'll probably end up having him change out the comp springs. Didn't want to take up too much of his time on the phone.