Cam Thoughts

[middleagecrisis]

I have two cam choices for the 360 that I have been trying to find the time to finish putting together for quite some time. I was originally going to use the solid FT cam for a second engine build, but realistically I may never get around to that option. I have a set of ported J-heads (2.02/1.60) and the cam choice really centers around max head flow and the cam lift numbers. I thought I remember hearing ported production heads usually have minimal flow improvements above .500 lift. I asked a question about these two cams in another post ( 360 Cam Opinion), but didn't factor in the head flow question. Hence my new questions. My drivetrain and engine build can support either cam choice (trust me on this) and I'm going to use the parts I already have bought. My options:
1. Oregon Cam hydraulic (FT) Regrind #1176: 230/236 (.050 duration), .490 Lift (1.5 rockers), 110 LS, 106 IC.
2. Hughes Cam solid (FT): 246/250 (.050 duration), .576/.588 (1.5 rockers), 108 LS, 104 IC NOTE: Already checked PV clearance (with checker springs) and closest clearance was .100 (Intake), .080 (Exhaust) with 10 degrees sweep on either side of TDC.
3. To further muddy the water: Running solid (FT) lifters on cam #1. Any advantage, besides eliminating lifter leak down concerns?
Both lifter sets have been refaced. Drivability associated with the bigger cam isn't an issue, but if I can't effectively utilize the extra ~.090 lift then I won't have to hassle with changing out the valve springs after initial cam break-in.

 

[Swingn’71]

It looks as though you answered your own question. You didn’t mention compression numbers, but if it isn’t “up there” as in 11:00 to 1 or better that Hugh’s cam is out. Not sure about solids on the Oregon cam but if it’s a go that would be my choice. Swingn’

 

[Cuda416]

It's not necessarily about max flow, rather matching the cam to the flow profile. Do have the info from the porter as in what the flow bench numbers are?

 

[middleagecrisis]

It's not necessarily about max flow, rather matching the cam to the flow profile. Do have the info from the porter as in what the flow bench numbers are?

I'm the porter and I didn't use a flow bench, never have. The basic reason for my question, when does a factory head that's been mildly ported run out of steam and the extra cam lift doesn't pay off. Example, if I lose 30 cfm going from .500 to .550 is that when the .550 cam lift becomes a detriment to horsepower gains, and I should use no more than .500 cam lift, or does the head just become less efficient? I can find CFM numbers (avg) on basic factory port jobs, but how does that translate to valve lift benefits. What I do when I port a set of heads: Bowl area cleaned up and radiused (guides & port transition areas). Intake port matched to standard 360 gasket to remove flow restrictions and pushrod "bump". Exhaust port smoothed out and contoured, especially in the roof area. Used this basic concept on probably a dozen heads I've done and never been disappointed.

 

[Cuda416]

I'm the porter and I didn't use a flow bench, never have. Bowl area cleaned up and radiused (guides & port transition areas). Intake port matched to standard 360 gasket to remove flow restrictions and pushrod "bump". Exhaust port smoothed out and contoured, especially in the roof area. Used this basic concept on probably a dozen heads I've done and never been disappointed.

The suggestion isn't about the quality or effectiveness of your work, rather having the numbers to match your cam and heads. if you don't have those numbers, it's by guess and by golly as my father would say.

 

[TT5.9mag]

And you left out likely the most important part of the equation. How will the vehicle primarily be used?

 

[middleagecrisis]

The suggestion isn't about the quality or effectiveness of your work, rather having the numbers to match your cam and heads. if you don't have those numbers, it's by guess and by golly as my father would say.

I edited my original response, please reread.

 

[273]

Seems like you want to go with the bigger cam, as long you got the cr, gears, stall etc.. to go with it I don't see no reason not to and if it's too much cam, you can always swap in the milder cam later.

 

[Cuda416]

I edited my original response, please reread.

My understanding is you want the valve open as long as possible so even if your flow takes a dump at 550, keeping the higher lift cam, keeps the valve open longer a 500 so I think that's a win. If I'm wrong I'm sure I'll get chastised.

On the other hand, pushing the lift too high for your valve train, forces your upper rpm lower to avoid instabilities which will kill the top end.

So, again, in my opinion, which is worth much less than others around here, is that to make a good choice, you need to know the numbers.

 

[middleagecrisis]

And you left out likely the most important part of the equation. How will the vehicle primarily be used?

NOT a daily driver, go look at the thread link I posted at the beginning of this post. I want the quickest acceleration possible with my given parts. If I had a race track nearby, I would say 80% race 20% street. Loud, obnoxious idle doesn't scare me, those things are encouraged, lol. I'm not concerned that I can get 20 mpg and drive for 300 miles at a time.

 

[TT5.9mag]

NOT a daily driver, go look at the thread link I posted at the beginning of this post. I want the quickest acceleration possible with my given parts. If I had a race track nearby, I would say 80% race 20% street. Loud, obnoxious idle doesn't scare me, those things are encouraged, lol. I'm not concerned that I can get 20 mpg and drive for 300 miles at a time.

The Oregon regrind is a compromise lobe. It’s slow. There is no chance id use it over the Hughes cam for an 80/20 race/street 360 with ported heads. But to take full advantage of it, you’ll obviously want some compression and some converter.

 

[273]

I'm the porter and I didn't use a flow bench, never have. The basic reason for my question, when does a factory head that's been mildly ported run out of steam and the extra cam lift doesn't pay off. Example, if I lose 30 cfm going from .500 to .550 is that when the .550 cam lift becomes a detriment to horsepower gains, and I should use no more than .500 cam lift, or does the head just become less efficient? I can find CFM numbers (avg) on basic factory port jobs, but how does that translate to valve lift benefits. What I do when I port a set of heads: Bowl area cleaned up and radiused (guides & port transition areas). Intake port matched to standard 360 gasket to remove flow restrictions and pushrod "bump". Exhaust port smoothed out and contoured, especially in the roof area. Used this basic concept on probably a dozen heads I've done and never been disappointed.

At Peak lift the valve only spends a small fraction of the time there, it about getting the most average flow, so lifts that go above peak port flow tend to give more average time where the port flows best say .400-.500" lifts

 

[Demonx2]

I run a Bullet SFT cam in my 408. 251/255@.050, ~.560"lift. 10.5 CR. Sounds nastier than it is as the car only runs 11.0's.

Since strokers eat duration, your 246/250 Hughes cam should be similar in a 360. But it's obviously a faster ramp as the lift is higher. But the smiles a cam like that will put on your face makes the choice obvious to me. Note that I run an 8" torque converter that stalls at 5000 rpm. My car is highly streetable and does so often!

 

[middleagecrisis]

I run a Bullet SFT cam in my 408. 251/255@.050, ~.560"lift. 10.5 CR. Sounds nastier than it is as the car only runs 11.0's.

Since strokers eat duration, your 246/250 Hughes cam should be similar in a 360. But it's obviously a faster ramp as the lift is higher. But the smiles a cam like that will put on your face makes the choice obvious to me. Note that I run an 8" torque converter that stalls at 5000 rpm. My car is highly streetable and does so often!

I have a 727/9.5" converter and 4.11 gears. Converter stall might be a little lower than optimum, but should still work. Hughes says:
Use: Street/strip. High rise dual plane or small single plane. Head porting and oversize valves.
Idle: Noticable
Converter: 3400 rpm +
Rear gear: 3.70 +
Thanks for the feedback!

 

[Newbomb Turk]

I'm the porter and I didn't use a flow bench, never have. The basic reason for my question, when does a factory head that's been mildly ported run out of steam and the extra cam lift doesn't pay off. Example, if I lose 30 cfm going from .500 to .550 is that when the .550 cam lift becomes a detriment to horsepower gains, and I should use no more than .500 cam lift, or does the head just become less efficient? I can find CFM numbers (avg) on basic factory port jobs, but how does that translate to valve lift benefits. What I do when I port a set of heads: Bowl area cleaned up and radiused (guides & port transition areas). Intake port matched to standard 360 gasket to remove flow restrictions and pushrod "bump". Exhaust port smoothed out and contoured, especially in the roof area. Used this basic concept on probably a dozen heads I've done and never been disappointed.

If you had a flow bench and you tested with it you’d know that just because the flow breaks over at XX test pressure without an intake manifold on it doesnt mean it will break over with the intake manifold on it.

Also, how do we know that XX test pressure is what the port “sees” during the whole lift cycle? It doesn’t. The pressure drop across the port changes with lift, piston motion and header tuning.

I don’t get too excited about the break over at XX test pressure without testing at other test pressures. And with the intake on it.

FWIW, if the valve job isnt garbage and the port isnt jacked up you can see a single plane intake make the flow curve flatten out and not dip down. With a tunnel ram you can see the flow curve move up before it flattens out.

Then you can play with test pressures to see what the port does at different pressures and watch the trends.

 

[Bewy]

You have answered your own question. Use cam #2.

 

[PRH]

If the engine has adequate CR for the Hughes cam, I’d expect it to crush the Hyd cam.