RB Cam Performing Right?

[Road Grabber]

I have:

440 bored .040 over
Stock stroke
Trickflow 240 heads
1.6 Harland sharp roller rockers
Hydraulic roller lifters
MSD ready to run distributor
10.5 to 1 notched pistons
Cast iron manifolds
Six pack carbs with aluminum intake

A Howard’s .530 lift cam that I was told should give me 500-525 hp?

A Preliminary dyno test 450? Hp 490 torque?
during the 10th dyno test it was discovered that there were a number of bent 5/16 pushrods. The thought is that 3/8 thicker wall pushrods should have been used and will solve this issue.

I’m disappointed in the dyno numbers and as much as I would hate spending more money was thinking about different cam for better performance. I know cast manifolds are not a great choice but I have been told by an experienced person 525 hp is a reasonable expectation with manifolds.

Am I wrong in thinking this cam should have resulted in better performance? Would bent pushrods have a large impact on performance?

If decided- Has anyone used a proven cam that will give great performance yet be able to be used on the street? These heads have been used with .600 lift cam but I’m not sure how a cam like that would work with a street driver. I like power but don’t want to deal with red light stop and go problems.

Any suggestions or thoughts?

 

[Aron Gleason]

What I've been told by the guys at trick flow is their .600 lift cam is very streetable cause of the smaller duration @.050.

 

[Dave6T4]

Possible valve spring bind. .530" lift, with 1.6 ratio rockers could be more than your springs can handle.

 

[Road Grabber]

What I've been told by the guys at trick flow is their .600 lift cam is very streetable cause of the smaller duration @.050.

Interesting thanks

 

[Road Grabber]

Possible valve spring bind. .530" lift, with 1.6 ratio rockers could be more than your springs can handle.

Builder said that was checked. Thank you

 

[gtxdana]

Impossible to read the cam card, but those numbers might be in the ballpark with stock manifolds depending on the cam. The duration numbers at .050" would be much more informative than just the lift.

 

[Road Grabber]

 

[BSB67]

Was it dynoed with the exhaust manifolds on it?

I think something else is not right. Pushrods don't just bend on a hydraulic cam. Find and fix that first.

 

[69Bee]

You just said TrickFlow 240 heads but didn't specify so I grabbed a roller cam head and chose steel retainers. The other head with the Tn retainers could have the same specs, I didn't check. You also didn't mention how the cam was installed, retarded/advanced, or how much advance was ground into the cam to begin with.

Intake Valve Diameter (in.): 2.190 in.
Exhaust Valve Diameter (in.): 1.760 in.
Maximum Valve Lift (in.): 0.680 in.
Installed Height (in.): 1.900 in.
Seat Pressure at Installed Height (lbs.): 175 lbs.

1) A Howard’s .530 lift cam that I was told should give me 500-525 hp?
The 0.530" Lift spec by howard's is for 1.5 rocker ratio. With the 1.6 rockers, you are at:
Intake: 0.347"*1.6=0.555" Lift
Exhaust: 0.353"*1.6=0.565" Lift
You are well inside the coil bind window; 1.900" IH - 0.565" Lift - 1.190" CB HT = 0.145"

2) A Preliminary dyno test 450? Hp 490 torque?
In my opinion and experience, with an intake valve of 2.190" will let a lot of air in, but you are being restricted by the 1.76" exhaust valve not to mention the stock manifolds

3) during the 10th dyno test it was discovered that there were a number of bent 5/16 pushrods. The thought is that 3/8 thicker wall pushrods should have been used and will solve this issue.
The valve springs are huge. At the installed height of 1.900", you have a closed valve seat pressure of 175"lbs. It is no wonder the 5/16 push rods didn't bend enough and get spit out. Use a 3/8" 0.080" wall (or more) pushrod to handle that seat pressure

 

[lewtot184]

Heads are better than the intake manifold. I wouldn't use that cam with cast manifolds. Those rockers will add somewhere between .030"-.045" lift at the valve. push rod geometry problems? A simple test would be to test with headers. There is something negative to dynoing vacuum secondary 6pak carbs.

 

[Road Grabber]

You just said TrickFlow 240 heads but didn't specify so I grabbed a roller cam head and chose steel retainers. The other head with the Tn retainers could have the same specs, I didn't check. You also didn't mention how the cam was installed, retarded/advanced, or how much advance was ground into the cam to begin with.

Intake Valve Diameter (in.): 2.190 in.
Exhaust Valve Diameter (in.): 1.760 in.
Maximum Valve Lift (in.): 0.680 in.
Installed Height (in.): 1.900 in.
Seat Pressure at Installed Height (lbs.): 175 lbs.

1) A Howard’s .530 lift cam that I was told should give me 500-525 hp?
The 0.530" Lift spec by howard's is for 1.5 rocker ratio. With the 1.6 rockers, you are at:
Intake: 0.347"*1.6=0.555" Lift
Exhaust: 0.353"*1.6=0.565" Lift
You are well inside the coil bind window; 1.900" IH - 0.565" Lift - 1.190" CB HT = 0.145"

2) A Preliminary dyno test 450? Hp 490 torque?
In my opinion and experience, with an intake valve of 2.190" will let a lot of air in, but you are being restricted by the 1.76" exhaust valve not to mention the stock manifolds

3) during the 10th dyno test it was discovered that there were a number of bent 5/16 pushrods. The thought is that 3/8 thicker wall pushrods should have been used and will solve this issue.
The valve springs are huge. At the installed height of 1.900", you have a closed valve seat pressure of 175"lbs. It is no wonder the 5/16 push rods didn't bend enough and get spit out. Use a 3/8" 0.080" wall (or more) pushrod to handle that seat pressure

The cam was not advanced or regarded. I was told he did use the intake lobe? to degree the cam in.
One set of pushrods were bent so bad the lifters jumped out. The engine was immediately shut down and he told me the oil filter was checked for damage and it was clear with no metal.
I can see that the pushrods were not strong enough. There had been no mention of this detail when using these heads.

I mentioned 525 hp with manifolds because Just Mopar Joe gave that estimate. He does quite a few dyno tests on different motor builds.

The motor will have the heads removed just to make sure pushrods have the clearance needed for the block and heads. The block was decked.

I figured if I wasn’t going to be happy with 450 after all this work now is the time to make a change. I also didn’t get 15 manifold vacuum like Howard’s said I would.

First I was hoping to get some feedback on this cam performance.

Thanks for the effort and response.

 

[Road Grabber]

Heads are better than the intake manifold. I wouldn't use that cam with cast manifolds. Those rockers will add somewhere between .030"-.045" lift at the valve. push rod geometry problems? A simple test would be to test with headers. There is something negative to dynoing vacuum secondary 6pak carbs.

He had headers. I will ask him for a test with headers. Thanks

 

[ksurfer2]

Your numbers may not be as far off as you think. Below is the dyno sheet when I had a my 440 rebuilt with a 493 stroker kit. This was with Edelbrock aluminum heads and an aluminum 6bbl intake and 10.5:1 compression. It has been a few years since this was built so I do not remember which heads were used or what the cam specs were. The dyno pull was using headers, but I ran HP manifolds in the car. The power was plenty to roast the tires at will in my 69 RR.

 

[gtxrt]

check how much preload you have and how many threads do you see on the bottom of the rocker arm adjusting screw before you order new push rods. the spring pressure is overkill especially with that slow ramp cam. wonder what open spring pressure is at.

 

[Road Grabber]

The stock 440 has 490 torque and that was the disappointing result. A lot of expense and time for stock torque results.
I guess the cam is more of a retro muscle car cam but that’s not the impression I was given by Howard’s.

 

[6872n73]

I also didn’t get 15 manifold vacuum like Howard’s said I would

What vacuum reading did you get? Before the bent pushrod?

 

[BSB67]

He had headers. I will ask him for a test with headers. Thanks

So, based on this statement, I assume he dyno tested with the exhaust manifolds, correct?

So if we’re assuming everything is alright, then it should make 500 hp. 525 hp would be a bit on the high of what I would expect, IMO.

The cam is not what I would use, but I do not see it as a bad choice either. I don’t think it’s the reason you’re not making 500 hp.

If the springs are truly 175# on the seat, that seems high for what your cam profile needs. If the lifters are collapsing due to pressure, that could suck a bunch of power.

FWIW, my iron head 440 with 0.455” lift MP cam with a six pack made about 440 hp.

 

[dvw]

The 108 LCA is not ideal for manifolds. But with the valve train not happy power numbers are a crap shoot. Start there first.
Doug

 

[BSB67]

..I also didn’t get 15 manifold vacuum like Howard’s said I would.

Hard to make any judgement without knowing the corresponding RPM.

That said, I would not expect a cam with that seat timing and overlap to have 15” vacuum at typical stock-ish idle rpm.

 

[BSB67]

The 108 LCA is not ideal for manifolds.

?
112 LSA,
108 ICL