Roller rocker info

[FuzzFace2]

Thanks I was thinking a week or 2 ago what if on the 1.7 rockers. With a calculator I found I knew what the lift would be just did not know what it would do to the package I have now. I will give it a read when I have the time.
Thanks
Dave ----

[rustyfloors]

I bought these crane rockers for my 401!
http://store.summitracing.com/partde...5&autoview=sku
Are you saying they are the wrong ones? I'm going to buy the dogleg heads from Indy for $700 bucks the work is done! Do I need to get a different set of rockers or longer pushrods?

[FuzzFace2]

Rustyfloors
I don’t know about the Crane rockers 1 size fits all makes so you should check them when you go to install them, guess that goes for any thing!
Now with the Harland Sharp rockers I did have to use longer push rods, As the longer rods set the rocker where it needed to be on the valve tip
I can not tell you the size as they where used on another motor I did not put together but do know they where longer than the stock 74 360 push rods I had.
Dave ----

[fifesjeep]

The Shop milled about .250 from my stud boses... I need to get longer pushrods... I want to say when I checked .100 longer were too much and .050 was too little... Both were relatively close but, Once I put it on the road I'll decide on what length... (I'm using the Comp Cam Magnum one piece chrome moly push rods...

[rustyfloors]

I was going to check my pushrod length when I assemble the engine! The clearence at the bottom of the rocker is something I never gave any though to when I purchased my rockers! I guess I'll have to keep my fingers crossed that they will work! If not I'll save them for another project.

[82Waggy]

If you are using stock heads with no port work there is not much additional flow to be had over .400" lift. If you do a basic port clean up, match to the intake, good three angle valve job with 30deg intake seats, and run headers then there is a flow benefit up to about .500" lift. It takes considerable port work to get much additional flow out of AMC heads above .500 lift.

Probably the biggest performance benefit to running 1.7 rockers would be that of snapping the valve open quicker, but max lift should be balanced against the flow characteristics of your heads. If you open the valve too far for the flow potential of your heads you could see a loss of velocity and therefore a loss in performance.

The ultimate check would be to stick your heads on a flow bench and see what valve lift produces the best velocity, then choose a cam and rocker ratio that gets you there.

A down side to running higher ratio rockers is increased stress on the cam lobes, lifters, and pushrods, as the leverage to push open the valve is decreased. It is very possible that if your pushrod column strength is not improved you may see no improvement when going to higher ratio rockers. And of course higher lift requires stiffer springs and yet more valvetrain stress.

A true 1.6 ratio roller rocker with a quick lift cam lobe profile that takes advantage of AMC's large diameter lifters and stiff pushrods is not a bad way to go for durability and improved performance.

[fifesjeep]

I just read on another tread/site that AMC heads produce the most performance with around a .500 lift with minimal amount of work on the heads.. the major of the minor work would be done to the exhaust side basically smoothing and matching... Anything over the .500" you will have to start doing some "work" to the heads in-order for them to flow properly etc.. I'll look for the Web Site again... (This information is backed by flow bench numbers)... Pretty interesting.

[AMX69PHATTY]

I have a '69 343 block fitted with a 3.44 stroke 304/360 crank.
Reduced base circle cam by about .060 and heads milled about .055.
Valves are Stn Stl pieces a little longer than stock I think.
Had been assembled with CRANE silver cast Roller Rockers, Chev dimensions I guess.
To make the geometry come out right I had to use
longer push rods, 7.894, which are SBC +.100
and longer rocker studs, 1-15/16, Moroso #67820,
so the Poly locks had sufficient thread engagement.

Now I have bought the Harland Sharp 1.6 AMC Rockers.
To make the geometry come out correctly with them
I've had to go back to "standard" Studs, 1-3/4 long
and 7.700 long Pushrods, shorter than '69 stock at 7.748.
Could maybe go even shorter, but two problems arise,
The Rocker gets to close to the Stud Hex
and run out of threads on the 1-3/4 Studs with the Poly Locks.
Both sets of rockers are 1.6 ratio.

So there is definitely a difference in Rocker Geometry
when using SBC dimension rockers versus AMC (Ford) dimension rockers.

Probably no surprise to most folks here but I am,
and I have it all to owe to BullTear and this Forum.

Allow me to say THANKS to all the helpful folks here.

[46flattie]

I have a '69 343 block fitted with a 3.44 stroke 304/360 crank.

Now I have bought the Harland Sharp 1.6 AMC Rockers.
To make the geometry come out correctly with them
I've had to go back to "standard" Studs, 1-3/4 long
and 7.700 long Pushrods, shorter than '69 stock at 7.748.
Could maybe go even shorter, but two problems arise,
The Rocker gets to close to the Stud Hex
and run out of threads on the 1-3/4 Studs with the Poly Locks.
Both sets of rockers are 1.6 ratio.

So there is definitely a difference in Rocker Geometry
when using SBC dimension rockers versus AMC (Ford) dimension rockers.

Probably no surprise to most folks here but I am,
and I have it all to owe to BullTear and this Forum.

Allow me to say THANKS to all the helpful folks here.

Thank you for this post! I am too in the process of ditching Crane energizer AMC, Ford, Chevy rockers and installing Harland Sharp 1.6 rockers on my 401....just finished checking pushrod length....I also came up with 7.700 and also found that I would like to go slightly shorter, but have the same issue with rocker arm to stud clearance. I am running ARP studs which have the shortest hex. I suppose we could have machined the pedestals down more to improve this....I believe we took off something in the 0.280 range, will have to double check.

At any rate your set-up gives me some confidence in my measurement!

My valve stem pattern is damn close to being perfectly centered to being slightly outboard...