1.7 Rockers ... why so rare?

I noticed BB Sharp 1.7 rockers used in Hot rod's "Mild Mauler" build. There is no sign of them in Harland Sharp's store. Nothing in Summit either.

Why aren't they strongly demanded for Big Blocks? I know some possible excuses...

My heads dont flow better above 0.50":
That might be true for a 906. A typical aftermarket head sees cfm increases up to 0.75" and dyno improvements up to 0.80" lift

I would just get a bigger cam (lobe):
You'll be forced to take unwanted duration. Your hp peak will end up beyond 6500. Low end torque would suffer greatly.

I would just switch to a solid roller:
It helps, but why settle when brand x has the best of both -- low duration achieved through solid roller AND 1.7

I'll have lube issues:
Project 505 and Mild Mauler resolved lube issues

Shafts can't go that high and I don't want to pay someone to machine my heads to a pedestal:
Mild Mauler did it without machine work. Mopar shafts should be an advantage, not disadvantage. If demand was strong enough, I'm sure the aftermarket would iron out glitches.

Call Harland Sharp and ask to talk to Randy. They can and will make you what you need. 440-238-3260. Good-luck

Do you WANT or NEED 1.7s? Or are you simply making an observation?

They're available, but not from every rocker manufacturer, and not necessarily as a shelf-stock part.

Love my 1.75 rockers. Have friends that run 1.9 rockers.

If you read through the Trick Flow head thread you'll see that swapping to a higher rocker ratio isn't always a magical experience.

More than anything else pushrod clearance becomes an issue--heck a 3/8ths on some heads with a 1.5 makes you grind--1.6 ratio can drive you crazy grinding in a "delicate area" with risk of blistering or punching through
we use a lot of 1.7 and bigger on SBC circle track engines but it is just not needed on the Mops IMO what the heck will a magic 1.7 do that a well planned out 1.5 won't? IMO not that much and for sure hardly worth the extra effort
I know that if you are aiming to win a contest on the dyno when every single HP counts well then maybe but who needs a street strip engine on a 50 year old car that is that "scienced out"

^^^^^^^^This^^^^^^^^^^

There isn't enough room to get the push rod close enough to the shaft and you can't make it much longer on the other end.

I know those 1.7 rockers are made, or can be made but when I was doing my W-5 deal I spent over an hour on the phone with Wayne Jesel with him talking me down off the 1.7. He would build them but didn't think there would be a pinch of [censored] difference and also said I would probably never get the geometry correct without some welding and moving.



Sometimes it just ain't worth it.

I've done a lot of testing in this area but I don't have any exact wisdom to share. You can easily get 1.70 rockers if that is what you want. T&D sells them and so does Harland. If you are willing to machine your heads then you can get Jesel rockers in ratios up to at least 1.85 which is what I have on my Indy EZ heads.

The real question is what are you trying to do and do you need more rocker arm ratio in order to achieve that. When NASCAR engine builders were told they had to use flat tappet cams then they figured out that a ton of rocker arm was the solution to their need for lots of velocity at the valve. That doesn't mean that the average bracket motor needs either a bunch of lift or a bunch of valve velocity.

If you wander thru the Super Stock pits at any NHRA race and talk to engine builders you'll find out that a lot of them use rocker ratio to solve the problem but not always.

If you haven't read my article in Car Craft go find it and read it. I spent a bunch of time and money testing different rocker arm ratios on my 470 low deck. Zero power increase. We don't know why exactly but I suspect it is because the heads are already close to sonic choke so the extra valve velocity and lift were wasted. I could figure it out with more testing but even I have limits on the amount of time and money I'll spend on a project!

Yea! Gimme a 1.5 ratio and a 5/16ths pushrod so I don't even have to look!!! Toss them in and roll!! I have to tell the truth--Since the Sidewinder head has come along and..it needs a serious grind to get 3/8ths to clear I have gone to a smith Brothers 5/16ths pushrod against all conventional wisdom and guess what?? engines make same ole HP--run great NO issues with even solid roller street cams and...I never ever have to grind or even think about something rubbing--no big on a roller but can be death to lobes on flats so...why not?? and...they are cheaper
Smith Brothers can tell you FOR SURE what diameter at what length with what open pressure will work--They KNOW
Yea run a 7/16ths and tell me you got if all figured out and yea..tell me about the Spintron you saw--I will tell you I Love me some 5/1ths and 1.5 ratio
I have seen on the dyno that a .120 wall vs. an .080 helps a teeny bit at above 8000 on some SBC's but we don't turn that and we ain't a SBC now are we?? I call it Trick weight savings!!!

Here is a set of Harland 1.7 intake and 1.5 on the exhaust. In theory this should be a very good setup but it didn't pick up any power over a 1.5/1.5 set on this engine.

http://www.hotrod.com/articles/trying-find-extra-power-rocker-arm-testing/

I have gone to a smith Brothers 5/16ths pushrod against all conventional wisdom and guess what??

Its the mopar world on the no go 5/16, 3/8 or its WRONG, the chevy guys have done it forever, smiths 5/16x.116 have worked flawlessly in everything and if you notice it seems they make alot of the middle of the road heads to use 5/16 rods.

I swapped out the Smith Bros 3/8x.088 wall (I paid for .120 wall 3/8 originally ) pushrods after one folded up and broke into two pieces during a dyno pull on my old bracket 526 C.I. 440 block. I had to have the lifter bushing repair after one of the pushrods gouge a groove in it when that lifter pop out at 5600 RPM and broke the tie bar on the Crower Ultra roller lifters and gouge the cam lobe
I bought a set of Manton 3/8x.120 wall Series three pushrods and went back to the dyno for more testing after fixing everything on that motor, I made several pulls to make sure the motor was happy with the old Smith Bros. pushrods (they did replace the two bad ones with new .088 wall for free but not the broken lifters) and would repeat on the power and torque. I then swap the pushrods with no other changes and the motor made 8 HP more at 300 RPM higher peak HP RPM than with the 3/8x.088 smith Bros.
Getting the correct parts needed for the most power is essential to success on motors
My new bracket motor has the Jesel pair shaft chrome moly rocker arms on it with Manton 7/16x.145 wall pushrods in it

Cab, on that build you reference to, what did you come up with the reason it ate a pushrod at only 5600?

SBC pushrod diameter vs. 440 pushrod diameter = apples vs. oranges.

Arguing pushrod size........kidding right? Pushrod size and wall thickness is dictated by the spring pressure you run. It's that simple.

Shouldn't length be considered too when determining diameter and wall thickness?

YEP

What makes you think the pushrod failed first?

I ask because in 1988 I was breaking rockers so fast it would make your head spin. It would kill a PR, eat the lifter and tear down a lobe. Everyone said it was the pushrods. So I bought double taper pushrods. Now I had broken rockers and lifters. So I changes from the MP ductile rockers to Crane gold. Now I only had broken rollers.

It was the roller that was failing the entire time. Because of that, there a two cam companies I will never ever use again.

You call Smith Bros and they ask length? pressure open? Power adders? then they tell you what wall thickness AT THAT length will work --Monte is correct--that is all there is to it
I am guessing Cab found 8 more HP because the rings were seating?? No snub to Cab I think he knows his stuff and I could be way off so...no harm meant just asking
I know longer push rods like on an Indy head etc is the length where yea maybe that 5/16ths is not the way to go AT THAT LENGTH
I get that

Mainly wanting to know the WHY Mopar fans are not standing at the gates with pitchforks and torches, demanding 1.7! I can see 1.6 for people wanting a bit lower spring rates.

Previous owner of my engine bought a nice, brand new 1.5 rocker. At first I wondered why. Then I noticed the whole community is pretty relaxed about the catalogs not having it.

I read Andy's article. It's a real eye opener.

But didn't you pick up a lot of hp in the other engine, going from 0.66 to 0.80? I thought that lift level put you over 800 hp and caused the block to crack.

It required a custom cam with awesome lobes to do it, but in this build, 0.75" lift level was chosen, resulting in 750 hp. Yeah, his ratio is 1.6 IIRC, but lift is worth noting.

http://www.hotrod.com/articles/how-to-get-755hp-from-your-wedge-mopar/

Wouldn't a NASCAR team cry foul and exit entirely if they were required to use 1.5 while competitors kept 2.0 ratios? If we tested a bunch of engines, wouldn't higher lift produce outstanding gains in many, if not most, configurations?

What are some things that can cause peak hp at 0.67" ? Just speculating:
Trick Heads claim to flow on par with ported E. Victor heads, but do they flow more like unported Eddy RPM heads? Were valve springs mislabeled or defective, resulting in float/instability that caps hp? Is duration curtailing effective CR? Is there something about the runners or cam that do not lack cfm on the bench, but do curtail velocity in practice? I don't know what happened in your test. You've given me something to think about.

In the meantime, imagine everyone demanding 1.7. Vendors get tired of broken part complaints and devise bulletproof systems. Everyone switches over. Armed with the knowledge that 0.67 is best, you request a lobe of just 0.39". Your 1.7 rockers get you to 0.67. Now you ask the cam grinder to drop the duration down. The rocker ratio adds a small margin of duration, but let's say overall it's a 15 degree drop in duration. Low rpm torque goes up. Driveability goes up. Valves close sooner so more CR is retained. People with dual plane intakes can ditch them in favor of single planes. Peak hp happens at a lower RPM, making dicey high RPM unnecessary. Low duration usually means less overlap, which means fewer hydrocarbons, if you're into that. And when it comes to forced induction, duration must be low.

But the article spells it out in black and white. I'll consider myself warned.


Thanks

Personally I would always rather have ratio than lobe, but it's tough with stock type setups

BINGO!!

I've been dyno testing motors since 1990.
I have done the rocker swap waaaaayy too many times to remember....... And in the last 10-12 years it's usually at the customers request, in an attempt to unlock some magic.
I don't know what people "think" they're going to find, but from what I've seen, particularly when it comes to bb mopars with std architecture heads, as long as the valve is open far enough at peak piston velocity so that there isn't a big pressure drop across the intake valve at that point, then getting the valve open even faster and farther will yield little to no gain.
There are some general exceptions to this, but that's usually how it plays out on the running motor.
On one occasion..... On a combination that was pretty air flow limited...... Where I was as sure as I could be that going from a 1.5 to 1.6 on the intake rocker was going to show a nice improvement....... I was wrong by 180deg.
The motor lost 15hp by adding the 1.6's.
Messed around with lash, jetting, timing...... All to no avail.
Put the 1.5's back on....... Power came right back.

That's the most extreme example of the rockers really not helping, but I have seen the higher ratio make less power on a number of occasions.

As it is with just about every other aspect of engine building, there are very few things that "always" make more power, on every combination.

If the cam is close to being right it makes
very little change.. on the exhaust side I
havent ever seen a change on a lot of engines..
I tried a rocker change a few times and only on
my W-9 405ci did it change the output(intake rockers)
but that cam was way off..it needed another .150 lift
than what I had but I wimped out thinking I would be
changing springs often

I have Hughes 1.7's on my 511. No clearance issues with 3/8" Manton push rods.

My reasoning for using them was/is:

1) Most Mopar guys told me not to do so.

2) My cam grinder recommended it.

3) Larger base circle cam, etc.

4) Offset lifter / stability load control.

5) I wanted to have room to grow towards .800 lift, which of course everyone also advised against.

This engine lived for lots of NA dyno pulls and 3 soft nitrous pulls that made around 950 hp and 900 ft lbs at shutting it off at 6k RPM. NA the engine made peak around 7100 with a QF 1050-AN 4150 carb/400-2 intake/Hughes CNC MW Victors @ 11.2CR.

I'm almost done with the GF5R install so hopefully the rest of the chassis work will be done by spring so we can wring it out in April or May.

My next 511 will also get 1.7's. The current deal will help decide if we stay with a shaft rocker or go gold chainer and bust out the $1800 Jesel/T&D route. I also notice that Scorpion has a set of 440 -1 shaft rockers out for about $1200 IIRC?


ps my engines all have screen in the valley for extra parts if the engine decides it doesn't need them any more lol.

Jeremiah....... Did you ever check the net loaded rocker ratio with the full spring load?

Dwayne, do you mean checking for lift at the retainer with everything assembled to run? I'm still learning the lingo over here lol. We did check it and it was pretty close IIRC, I'll have to dig in my notes.

I do the screen in the intake valley also..
all my engines have it.. on my first W-2 the
rockers were labeled wrong.. they were B engine
rockers so with the geometry all wrong I had lash
caps on it.. glad I did.. it spit lash caps off on
a regular basis which ended up in the valley.. the
screen kept my spare parts up there and didnt hurt
anything.. back then I thought these things were
made correctly but I sure did learn otherwise..
even when I got the right rockers

The pushrod that broke in two (can't remember now if it was a intake or exhaust on # 1 cylinder, sorry)had a defect in the metal that you could see real easy with the naked eye, when it broke it got caught up between the block and the pushrod beside it bending it in the middle but not making it fall out
As far as HP gain and the increase in the peak RPM gain the motor had quite a bit of testing on it before the pushrod failure, the rings where seated. I had broke that pushrod on the local Studka dyno in Madras(2500 ft.) in the morning wasting the rest of the day ) and decided to take it to a new(two yrs. old )version of the DTS engine dyno in Klamath Falls, OR(4300Ft. altitude) I did several pulls to get a semi accurate base line on the engine on that dyno to make sure it was healthy and not hurt elsewhere before swapping the pushrods. The main reason for me switching to the DTS dyno in Klamath was Dan, rest in peace, insisting that the dyno in Madras was a real happy dyno, he was correct. That motor lost exactly 100 HP from Madras to Klamath Falls I took the motor back to Madras later and we, the new owner and operator of the dyno, calibrated with his motor on the dyno and it lost exactly 100 HP from making pulls before we calibrated it to the next pull thirty minutes later
My real irritant was that I had ordered and paid for the 3/8x.120 wall pushrods for this motor knowing it had 300 lbs. on the seats and 780 lbs. opened and I got 3/8x.083 wall
I guess(and hope) that there was a foul up in quality control on that set in production, I hope it wasn't intentionally done that way

Yes, lift at the valve with full spring load and zero lash, divided by the actual lobe lift.
I realize this is actually checking the "system" net ratio, since there is deflection of other components besides the rockers, but IMO, unless the pushrods are seriously undersized the majority of the deflection will be in the rocker.

Just curious how rigid those rockers are, and whether any additional ratio was "built in" so the net loaded ratio was close to what they are supposed to be.
Some brands seem to have this, some don't.

Not trying to stir anything up, but if your invoice showed they sent you .120 wall, and the one that failed was .083 wall....... I can't imagine they wouldn't have taken them back and replaced the full set with what you paid for.

Still doesn't help with the failure on the dyno though.

Fixed it for ya!

From what I've measured, Hughes doesn't (and I know HS and Crane do/did). The way my .600"-offset Hughes 1.6s are setup, the actual ratio using CHECKING springs, not the actual springs, was 1.58, and the standard-offset 1.5s came in right at 1.50.

One of the things I have on my task list is to check again w/ the 240-closed / 600-open springs installed. So, it would also be interesting to see what their 1.7 (advertised) measured, too.

What brand of rocker did you find that didn't have any additional ratio built into it? I bought some Norris rockers in 1999 and I had a full set of cranes and and MP ductile iron rockers. The Norris were 1.6 the others 1.5.

I was checking things out and with checker springs the Norris rockers had a ratio of about 1.68 so lift was above what it should have been. I don't remember the other numbers but they were also all greater than advertised.


Couldn't get Norris on the phone so I called Jesel and somehow got Wayne on the phone. From that point on I always check P/V with the springs I'm going to run. The flex is amazing.


BTW, all the rockers had the exact correct ratio when loaded with the springs I as running. What was stunning was once you get over about 130-140 on the seat, the flex is done.

Yes, on my 514 with MW ports I made more power every time I added lift. I ended up with 1.85 ratio rocker arms on that engine. But as others have pointed out, what works with MW heads doesn't necessarily work with std port heads. In the case of my 470 engine we evidently already had the valve open far enough with the 1.50 ratio rocker arms that the engine didn't care about the extra lift.

I'm going to put the 270cc heads on this engine when they come out and then I'll redo the rocker arm test and I expect to see a power difference. I think the MW head will use the extra lift.

I tried to respond and this web site dumped it Pierre at Smith Bros. didn't offer to replace them after I pointed out that I had paid for the .120 wall and he wasn't going to replace the two bad ones until one of the shop supervisors came in and looked at both of them and told Pierre to replace them both for no charge.
Needles to say I normally buy Manton now at a better price and get what I order and pay for
Smith Bros. was here in Bend back then, they moved to Redmond, OR (23 miles further north now) several years back. I started buying pushrods from the original owner back in the late 1960s when they where in West Covina, CA, that guy was a real jerk His Son was a lot better to deal with His Son moved the business up here to Bend a long time before I moved here in 2005 and I think he sold it to the current owners in that time frame, 2004 to 2006

Sounds fun, I'll roll the engine over this weekend once all of the welding is done and chips vac's up. I'll try to get some pics of the valve train and dial indicator so we can check my work.

One of the many stories that have convinced me that screen in the valley is cool right there.

My comp solid roller has .432/.436 lobes, theoretically with my T&D 1.7's and zero lash the lift should be .734/.741". With .018" lash my lift at the retainers was .711/.719", with the lash added back it's .729/.737".

With checking springs or full spring pressure?

I still use Smith Bros, but if I had/have an experience like that I'd have switched too.

Full spring pressure.

BTW this is a Indy headed small block.

That's really really good if it's a 59deg block.

The worst case I've seen with aftermarket rockers was on some TA heads that had HS rockers on them. The rocker stands had been milled off, and they had the blocks around the shafts, along with the offset shafts(iirc) like W2 heads.
Going off memory, they were about 1.46 on the exhaust, 1.45 on the offset rocker intakes...... With checking springs.
With 500lbs open spring pressure they were down around 1.43-1.44.

On the BB ones I've checked, using rockers with the std offset, both Crane and HS seem to have about .5 added ratio built in when checking with soft springs(depending on exactly where you have the adjuster set).
The HS seem so have less deflection and are usually still higher than the advertised ratio even with 600lbs+ open pressure.
I had a set of HS 1.6's on some SR heads...... Checked about 1.67 with soft springs, were still 1.62-1.63 with 700lbs open pressure.

It's a 59*. I mentioned it to Brett in one of our phone conversations and he seemed to think maybe T&D put more ratio in them to offset the losses.

They would have pretty much had to.
You get loss from the pushrods and lifters not being in line with each other.