Cam Question 455
 

A question for the cam gurus out there. After reading through the forums I have decided on the 60919 cam, Rhodes with 1.65 rockers combo. Is there any advantage/disadvantage to this combo compared to just having a cam with the increased lift built in with 1.5 rockers? What is easier on the valve train? Some on here are saying that you don't need the Rhodes lifters with the 60919 cam. Without the Rhodes lifters does it cause the low end to suffer?

You haven’t posted up enough info.

What compression will the motor have?

What heads will it have?

Will they be ported?

What intake manifold will be used?

Will exhaust manifolds or headers be used?

What rear gearing does the vehicle have?

My apologies
 

It will be a .30 over 455 with out of the box KRE 85 cc heads. It should be close to 10.5 to 1 compression. I have a Butler CNC ported 1972 455 HO intake that I need a built Qjet for. I have headers but I may use the 2.5 manifolds. The car has the original 3.31 gears. I am just looking for a nice hot street car.

Higher lift cam or higher-lift ratio rockers?

https://forums.maxperformanceinc.com...d.php?t=716247

Go onto the internet and you will get all kinds of opinions.....

https://www.hotrodders.com/threads/c...r-lift.542767/

https://www.speedtalk.com/forum/viewtopic.php?t=3662

And many more on the subject.



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When I run these what a call “standard issue “numbers on your 4.180” bore motor you will need to mill the heads to 79CCs to get a 10.45 compression.

Piston valve notch 6 CCs
Head gasket volume 9.7 CCs
Deck clearance ( .019” ) 5.4 CCs.
CC total = 100.1

Or do a combination mill the heads and deck the block .

To end up with a 10.5 to 1 compression you will need a total of 99.64 CCs above the top of the piston.

If your going to run exh manifolds I would only put 1.65 rockers on the exh side.

I have a nitraded 60919 cam for sale as well as cam saver lifters if you’re interested.

Not the same intended combo here, but this for interest....

4.185 x 4.25"/ 467 cubic inches
Non Ported KRE D-port heads, 85cc chambers
1.65 roller rockers
Crower 60919 hydraulic flat tappet cam
Edelbrock RPM intake / Q-jet by Ruggles
Doug's headers

543.9 ft.lbs. torque at 3600 rpm
560.7 ft.lbs. torque at 4500 rpm (peak)
502.4 HP at a very manageable 5300 rpm (peak)

"By 1969 standards the 60919 would be considered a somewhat aggressive lobe, by today's standards it would be slow, however sometimes a combination will favor a lazy lobe."
Paul K


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Rhoad’s lifters really should not be needed on that combo with a current 60919 unless for some reason you wanted a more smooth idle and maximum grunt force right off of idle. Driving manors would be no issue at all with regular lifters. Original 3.31 gears sound like an a 12 bolt car with a 4 speed or a non A/C automatic. I would not expect any issue with low end power with that much compression in a 455.


On a Pontiac using a HFT cam with .842” diameter lifters of the same size duration as a RA4 type cam the 1.5 rocker arm cam combo will not be able to not have the same lift as a RA 4 cam with 1.65 rockers, the contact point of the lobe at the lifter will be off the edge of the lifter face. I am not sure what the maximum lift is for a 231* @.050” HFT cam is with a .842” lifter without making the lifter bigger, but it is likely a little less than .516 lift. The cam tunnel size also impacts the ideal rocker ratio, a bigger cam tunnel is able to run more lift than the smaller cam tunnel and more easily run larger ratio rockers.

More or less to compare the options equally the 1.65 rocker cam would need to have less lift. The bigger rocker ratio wins the debate most of the time before the debate even starts.

Thank you gentlemen for the great feedback!

I’ve run that combo quite a bit. I’ve gone from regular lifters to rhoads and the rhoads definitely help with brake vacuum and making a little smoother idle. It also depends on how much lash you run. On my last two engine teardowns I’ve had lifter/ cam wear. Not wiped out but not what you want to see either. I finally decided to go HR and currently am doing so. Like was said it’s not necessary to run the rhoads but I bet you’d prefer them if you ever did a back to back comparison. I’ve got a 2012 version of the 60919 in the garage. It has 304/316 advertised.

Use Crower Cam Saver lifters. I am running the 60919 with them.

The lifter diameter controls the max velocity.As stated if the velocity is to high the lobe runs off of the lifter face. A .842" diameter will take about 0.00765 max. This shows the lobe profiles that will produce the same valve lift profiles one needs a 1.65: and the other needs a 1.5:1. The other shows the velocity in crankshaft degrees which needs to be doubled for values at the cam. You can see the RAIV lobe for 1.5:1 is almost 0.008.

Stan