Has anyone tried running different ratio rockers on the IN & EX? It can be done just what are the effects? Wondering have enough to put 1.54's on EX or IN. Will one set-up be better for torque?

I would vote for using the higher ratio on the intakes.

(1) easier to drop total backpressure (piping and muffler choice) than to increase intake flow

(2) exhaust flow is "pressurized" by nature

 
 Steve Metzger       Tucson, Arizona

We used higher ratios on the intake when we wanted more lift and duration on a race car. Make sure your valves are not to close to the pistons.

Gary Ryan San Antonio.TX.

Running 1:43 to 1 rockerarms on one set of valves and 1:54 to 1 rockerarms on the other set of valves is a way to change not only effective valve lift, but also valve opening and closing time (valve open duration).



You also end up with the equivalent of a dual pattern camshaft in that the valve open duration and lift for the intake valve (measured at the valve) is not the same as the valve open duration and lift for the exhaust valve (measured at the valve).



IF you had a camshaft that seemed like it was a little too much or too little for your engine application, changing rockerarm ratio is a means to slightly adjust total lift at the valve and valve open duration measured at the valve.



Within limits, you can slightly adjust valve lash setting larger or smaller to adjust ultimate lift at the valve and valve open duration event measured at the valve.



From what I've read, Les Ritchey was a master at tuning engines for optimum performance employing techniques such as what you've brought up to make vehicles he worked on perform better than others comparably equipped at the drag strip. I'm going back to the early '60s and the heyday of y-blocks with this reference. Rest his soul... he was an out-of-the-box thinking Ford man akin to Karol Miller!

NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

We all normaly go with higher  lift rockes to get more performanc but following this logic you could tame down a cam that was too radical buy using lower lift rockers.

I am wanting torque.  I built this combo as a streeter.  292+0.040, mild cam, 8.9ish:1 comp, headers with 2.5" pipes to 2.5"flowmaster copies and still holley 2 barrel.  Running 1.43 rockers now but have 8 good 1.54's.  Wondering if them on intake will add or deminish low end torque.  Maybe EX who knows just wondering.

When I switch from stock 1.54 to 1.6, I couldn't feel any difference. I'm sure something would show up on the dyno or maybe when racing but for the street I doubt you'll notice anything.

Since you have them and it will cost only time, experiment, see what happens.


Lawrenceville, GA

the bast way to improve low end power would be to try advancing the initial timing. You'll probably have to limit the total advance. You aren't trying to run with the old "loadamatic' distributor are you? 

Frank/Rebop

Bristol, In ( by Elkhart) 

Cut your exhaust pipe size down. Also wondering if a 390 or 465 Holley might be better as the primaries maybe smaller than your 2 bbl ??



"Came too close to dying to stop living now!"

After mulling what you've said, Scott, I'm thinking that you're looking for better low end 'pull' off-idle and/or better throttle response.



- Gary and Slumlord are right... higher valve lift is generally associated with increased performance

- Charlie's right though, too... you'll never feel the change going from 1:43 ratio rockers to 1:54s



With 298 cubic inches, almost 9:1 compression, non-restricted exhaust... you shouldn't be having a problem with off-idle performance or throttle response unless the camshaft is something with excessive overlap for street use. Your engine should be making plenty of torque and horsepower.



- Frank is likely asking the right question. What distributor are you using? Does it have a centrifugal advance mechanism? A distributor ignition advance issue will KILL engine performance.

- Talk Wrench is also asking a good question. What Holley 2 barrel carburetor are you using?



Other thoughts...

- what kind of vacuum gauge reading are you getting at idle speed?

- what gearing do you have in the rear end?



Looking forward to your responses so that we can resolve the problem. Little stuff can create big problems... Murphy's Law


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York