Technical /SBC cam profile with Rocker Ratio

Anyone with real world experience running big cams in their rods/customs know how rocket ratio affected their cam’s profile.

Some even numbers for debate:
4000lb vehicle
SOHC SBC 350 Advertised Duration: Intake 279=282 Exhaust 291-292
Valve Lift .460 & 485 with 1.50 rockers
Gross cam lift 3.07 &3.23 with 1.50 rockers
Vs
1.60-1.61 Rockers:
Gross cam lift @ 329 & 346
Valve Lift @ .493 & .520

64cc heads (461s) or 1.94s/2.02s
1 5/8 - 1 3/4 headers

Aluminum dual plane intake
Big carb 650-800 ( 750 ) cfm

Anyone running something similar to these numbers have anectodes/ advice?
Street ability? What was your power curve? Did you find 1.60 Rockers too much? If your camshafts profile was different what were its specs? Duration, lift, and how did the change with your increased rockers?
Thanks

 

A bit much a a cam for those heads.
Stick to 1.5 ratio. A lot of wasted motion with the bigger ratio.

You are asking questions that have no starting point..!
Yes, 1.6 ratio rockers can and do help, BUT with heads and manifolds that can "utilize" the lift and duration. Just having those cam values don't mean much if the rest of the "combination" isn't up to the task.

What does "streetability" mean ?
You elected to not really mention the car..!?
Manual or automatic trans.? Manual, gear ratio ? Auto. trans., converter ?
Rear axle ratio ? 2.50 or 5.13's ?
Tire diameter ? 27" or 35" ?

Again...stick with the 1.5 ratio.
Do you know how to verify your push rod length ? Should be done.

Mike

 

SOHC SBC..... I'd love to see pictures of that one.....

 

Street ability is idle capability.... can it idle or is it a strip set up only.
1.60-1.61 are the rockers equipped with the 461s. That’s how they came for 400$ cad.
TH350 no lock up
2600 stall TQ converter
Tires 26.1”
3.08 but that is irrelevant as it will be dialed in as necessary

Push rods were not included on the heads but I may re use stock 441 rods.
The model is irrelevant as this is a technical question
But it weighs 4000lbs

 

The cam is specs are what I’m trying to get at.
The vehicle is a 4000lbs monster wot will always bring the rpm way up whether it’s light to light, strip or highway use.
Again refer to the given specs as talking point
650=800 cfm carb (750 4160 or vacuum secondary)

 

Sorry for the amount of replies but what do you mean the cam is a bit much for those heads? Are these just numbers that are much or is this experience talking?

 

1.60 will not fit without slotting the pushrod holes,will the rocker with the increase lift clear the valve guide,what is the LSA of the cam,what is the cam grinder say.

 

LSA = 116 degrees & Intake C/L =112 degrees
Solid lifters

 

I am not sure what I am supposed to look at in the pictures,whose cam is it?Are they screw in studs are they stock ports?

 

There is no cam in the picture. Cam brand doesn’t matter you have all the specs, I’m looking for real world experience or anecdotes. The rockers lock with a nut the ports appear to be stock.

 

What pistons are in it,Flat top or popup,are you going to degree in the cam?

 

Those heads don't flow that good. The cam grinder can tell you what he thinks,those are not all the cam info,just whats on the card. If those are stock rocker studs they are 3/8 pressed in studs and you are looking for trouble with studs pulling out of the heads.

 

I am not sure, I am currently under the impression they are fat top and notched however as you see the 461s are not on the block. It is currently a 70 block with 441 heads, 79 L48 intake, 83 Holley 4160 and headers. It is unknown if the cylinders are bored over and if the current cam is anything but an RV cam.

 

The 461 heads don’t flow well?
1.60 is not stock ratio and the valves, springs, nuts look brand new. Seats are not recessed.
Thank you for the anecdote.

 

Not enough info to pick out a cam or to know much about the engine.

 

Chevy 441 Iron CHP 155/62 1.94/1.50
-
No Pipe 76 55/45 110/80 160/112 194/127 201/136 203/139
Chevy 461 Iron 161/63 2.02/1.60 64 - - - - 216/137 -

 

Flow data on the heads

 

At this time I’d like to reiterate:

The posed question and ask have any members ran above stock rocker ratios on their sbc? How did it run what where the gains, was the posed camshaft profile similar to yours? How did they differ? Where was your power etc.

 

I think what people are trying to get across is the rocker ratio wont mean squat if the heads wont flow. A big cam and 1.6 rockers wont help a poor flowing head.

Sent from my SM-G977U using The H.A.M.B. mobile app

 

please label the numbers better sdluck.

I am aware of how the 461s flow. The Canadian made ones actually flowed better than the American ones and were/maybe still are highly sought after for circle track events requiring stock engines. What is iron 161?
461s are 1.94” intake and 1.50” exhaust valve heads. There chambers are 64 cc + or - 1 or 2 depending on the casting quality, like any head.
Is the 216 the intake runner?
Is this copied from Stan Weiss flow chart at http://users.erols.com/srweiss/tablehdc.htm

 

Thank you

Thank you

 

These are the ratio that cam on the heads at purchase so I’m wondering now is this going to create an issue? Or give me gains? Howard’s Cams 1.50 full rollers are close to 460$ Cad so I’d like to use these for now if the aren’t going to drop my power.

 

Again I’m not sure what you guys run but the 461s are miles ahead of the 441s in terms of compression and flow plus any machine shop will tell you going above 216 intake runners drops off low end torque.
Unless someone here has some awesome heads kicking around that flow great at low rpm mid and high these are the heads I have lol.

 

They don't make an SOHC small block chevy and if they did it would not have rockers

That said if I want my valves to come open farther I buy a cam with more lift. I personally prefer a lower lift and a longer duration. But it is a preference of mine and has no bearing on the discussion.

Yes you will find the benefits of more lift with longer ration rockers but your valves being open more does not always give you the desired effect. There is a lot more to going fast that more valve lift.

 

1.6's will work just fine as long as you don't coil bind the springs, run the retainer into the valve guide, or hit the valves with a piston.

 

It will take a lot of money to bring theses heads usable,do they have harden seats for unleaded fuel,they need the slot opened up for 1.6 rockers, screw in 7/16 rocker studs seats for good valve springs. or just put in a small streetable cam

 

Also, don't assume stock length pushrods will work (for any combination that you screw together).

 

exactly. ^^^^^ my 355 has longer then stock pushrods. Granted I am not running stock heads but they do have a CARB number. LOL

Th only engine that runs stock length pushrods is an engine put together with stock parts. Anything else the pushrod length needs to be checked to make damned sure that you maintain good valve grain geometry.

Pay attention to @DDDenny here is has been playing cars a long time.

 

Is the Carb number a stamp # on the rockers?
Otherwise how did you calculate push rod diameter and length necessary?
Thank you Denny