Group Buy on 1.73 rockers

Just curious why people aren't looking at 1.8 rockers? If you have a stock or mild cam you could actually end up with a performance benefit rather than just some "bling bling" under the valve covers. :confused:
 
Yo Sparky - tell us more about the benefits of 1.8 rockers for stock cams, before we place our orders.
Thanks,Jim.
 
Simple, if you have a stock cam and want to get a little more lift out of it, .447" stock lift becomes .465".

Perhaps you have some ported heads and a mild cam like the Comp Cams one that lifts .491" then presto, it's .513". Just remember that .520" is max lift on stock guides.

Not much, but it's a little and I think it helps. Bolt on 1.8's (not no-namers here, Harland Sharps same as Morana sells) run about $240 in a group buy. I'm sure Paul could set that up as well.

In theory roller rockers alone are supposed to help performance, but at low lift and light spring pressures it's gotta be minimal.

Just my $.02.
 
Dave makes a good point, one which came up briefly during the last group buy. The reason for NOT using the 1.8s is due to how much it throws off the valvetrain geometry. As Jeff said, it puts a lot of stress on the valvetrain as well. The 1.73s are a tried and proven upgrade over the stock stamped rockers which is why they are the only ones being offered for this group buy. The performance benefits of the 1.73s have already been spoken of in the previous threads. I have received many emails and PMs about these, yet Jeff is the only one who has paid so far. Just a few days ago, it looked like 6 people would be a walk in the park. Pony up guys, the clocks a tickin.

Paul
 
I was not trying to throw cold water on anyone's purchase plans, I just thought I'd suggest that there are viable alternatives. However I find this statement somewhat disturbing.

it puts a lot of stress on the valvetrain as well.

I feel that is a complete wives tale. I'd like to see some documentation or calculations to support that assertion. Anytime you increase valve lift, increase spring pressure, or increase rate of lift you are increasing the stress on the valve train, but how much of an increase in stress does .020" make on the valve train? I challenge that it is minimal and most likely offset by the reduced weight of the aluminum rocker. It is my opinion that the 1.8 rocker does not affect valve train any more than a slightly higher lift cam would.

As for geometry issues, I was concerned about this as well. However I have recieved more than one qualified opinion upon inspection of the contact area, that the Harland Sharp rockers do a great job of keeping things where they need to be. The same can not be said about all 1.8 rockers (most of which were designed for other applications anyway and have been "borrowed" for our use).

That's all. Personally I just think that 1.73 roller rockers are a waste of money on a stockish cam. Oops. Did I say that? :rolleyes: :D
 
i think i'm going with a .548 lift cam so i wasn't thinking in terms of "stockish". It was recommended to me by a trusted source to go with 1.73 rockers instead of the 1.80 rockers. :)

Jeff
 
Even the 1.73 will change the geometry slightly. If your having the heads done have your machinist offset the mounting location of the rockers on the pedestal a little to correct the geometry for the new rockers.

The 1.80s are to long to correct in this fashion. Besides if you look at the high lift flows of even the most extreme heads the flow gains at higher lifts are not significant.

I'm convinced that the 1.73s are fine even with the most exteme head/cam combinations.
 
Sparky , I didn't miss your point.

And I look forward to see you at the SC Shootout,in my rearveiw mirror.:cool:


Thats because I plan to park in front of you:D
 
Here comes that fire engine again...

As being one that has used rollers for more years than I will admit to, I will have to agree with what Dave has said. The "Sharp" rollers are by far some of the better ones out there. The upgrade to the 1.80 ratio will not hurt your setup, it will only help you. The biggest thing that you MUST keep in line is the valve train geometry. This is very important, or you will have trouble.. We have just gone thru this with something that we were building. If you are using push rods that are not the stock lengh, you had better do some homework or bring a basket to the track with you. We found that if you roll that rocker too far it will start to bind and either your studs start to pull out, or you start to bend those push rods. Both of these are not good and both will cost you lots of $$$$. One more thing to keep in mind and no one talks about it is "spring bind" this is when the spring is compressed too far and it becomes one solid peice of metal. When this happens it is good by engine,hello empty pocket book. If someone wants to pick my brain on this feel free to and I will try to help out....Rich
 
Ok being we are talking about bolt down rockers..Its very important to get the proper rocker. Otherwise valvetrain geometry will be off. Not all 1.73 rockers are created equal as in the same dimensions. Some people dont realize that. We can shim them but that will only do so much to correct a problem. Being noone makes..And I say noone makes a direct made for SC rocker....Its a metter of experimentation..Regardless of brand or quality..Take a 1.73 rocker for several vehicles and you will notice various degrees of differences between them...SO basically the 1.73 we are using are for a differnt application but just happen to allow us proper valvetrain geometry..Arnt we lucky..However I have seen people with the 1.8 rockers..Yes Moranas that just wernt giving proper wear pattern indicating geometry was off. I;m sure we can find a source..And perhaps shimming them and getting a different pushrod to make up teh difference would have worked..But who knows..Anyway on my v8 ford with a basically stock motor going from a 1.6-1.73 rocker netted me 12 rwhp
 
Damon, thankyou, that is exactly my point. You indicate that increasing rocker ratio got you some HP on your 5.0. That is what I was suggesting for us going from 1.73 to 1.8. Keeping the stock 1.73 is not going to give much hp if any especially at stock valve lifts.

And, yes I am off my rockers.
 
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