[vicgto]

Originally Posted by Cliff R

I've posted our experiences with those rockers many times. From the moment we put them in service (used several sets early on) they start to grind up the rollers where the pins go thru them.

On my own engine I had a few with as much as .018-.019" clearance by the time I figured out where all the metal on the magnetic drain plug was coming from.

Removed them from several other engines we had them in and same thing, found heavy wear at the pins.

I replaced mine with Crower Enduro rockers and no more issues.........

Cliff, I believe you had a similar set up to mine with the OF Hydraulic roller cam and Crower Solid roller lifters with lash at .006". I'm wondering if this combination is putting more load on the valvetrain due to insufficient clearance ramp, what are your thoughts?

I ended up going with 1.6 Crower Enduro rockers. I was planning on going with Harland Sharp but I did not want the additional lift from the HS 1.65 (which are closer to 1.7) as I currently only have about .060" retainer to guide clearance with the 1.65 PRW rocker. Also I I don't want to work the valve train any harder and I'm not sure that exta .020" -.025 valve lift would help my SD ported 295 KRE heads (Daves data sheet stops at .550" with 299 cfm and I'm not sure how much better they are above that).

I had an interesting conversation with Scott form Butler Performance who I ended up purchasing from. I don't know the accuracy of his statements but he said Crower, Harland Sharp, Scorpian and most other US made rockers are bigger than the advertised ratio (e.g. 1.65 is actually closer to 1.7). He said he was told by one of the manufactures this is done to overcome losses due to flexing of components during operation so you end up with advertised ratio, not sure how true it is but that's what he said. He also said the off shore stuff (e.g. PRW) are much closer to advertised ratio.

Anyway I hope I don't get anymore surprises with these rockers.

[djustice]

Originally Posted by vicgto

I had an interesting conversation with Scott form Butler Performance who I ended up purchasing from. I don't know the accuracy of his statements but he said Crower, Harland Sharp, Scorpian and most other US made rockers are bigger than the advertised ratio (e.g. 1.65 is actually closer to 1.7). He said he was told by one of the manufactures this is done to overcome losses due to flexing of components during operation so you end up with advertised ratio, not sure how true it is but that's what he said. He also said the off shore stuff (e.g. PRW) are much closer to advertised ratio.

Anyway I hope I don't get anymore surprises with these rockers.

Yes that is what i have heard too, David vizard and also Eric Weingartner has video's on this subject. Eric also demonstartes the overshoot on Ratio on one of his motors without spring pressure and with full spring pressure. and you can see what the actual ratio is. As for me i have been running Scorpion 1.5 ratio rockers for about 10 years now, first on a ramair 4 cam (edelbrock flat tappet) and now on a comp roller and no issues this far.

[PAUL K]

I disagree that rocker arms are intentionally made with a higher than advertised ratio to account for deflection or any other reason. It would screw a lot of conscientious builders if that were the case. As mentioned in an earlier post a set of 1.6 rockers were chosen because of minimal retainer to seal clearance. With the trend today of hi-lift cams being used in street cars you would have a lot of excessive guide wear, coil bind and smashed valve seals if rocker arms weren't correct ratio or usually a little less.

It's not as simple for the average fellow to check ratio as most would think. First the pushrod length needs to be optimized for each rocker arm because that will affect the net lift. Then one must decide whether to check with the valve spring in place or a test spring. A high RPM race engine will give up .030 or more lift checking this during the assembly if it's checked with a valve spring in place.

My guess is most of the "extra" ratio comes from second hand information that stems from the ratio not being checked properly by the originator of the rumor. I have checked many rocker arms for ratio and how far the rocker moves the pushrod towards or away from the rocker studs.... I do the later due to my dislike for grinding the head for pushrod clearance. I have found very few that have more ratio than advertised. I have found that some can be "tricked" to give more valve action by adjusting the pushrod length. But then one must decide between added valve open time or optimized geometry.

I have never seen a high end rocker shaft have anything but the advertised ratio. For many reason the shafts are dead nutz on, but if any rocker arm builder was going to add extra lift "for a reason" , the most logical being valvetrain deflection, one would think it would be the guys building rocker arms for a 9,000 rpm application using 1500 lbs. of spring pressure.

The only rocker arms I have found that consistantly check out higher than advertised is the Harland Sharp 1.65 and the Comp Cams 1.5 (which used to be advertised at 1.52) Pontiac rocker arms. I believe HS now makes four versions of the 1.65 and only one consistently measures close to 1.7. I asked Randy Sharpe directly about this and he had no idea as to why this is and wasn't aware of it. He said it definetly wasn't done for a specific reason, such as deflection. That might be why their newer 1.65 rockers measure closer to the advertised number.

FWIW


PS..... It'd be nice if a manufacturer would perfect an adjustable ratio rocker arm like Crane offered many years ago.