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.