Well in my quest to get my car running, I've hit a snag.. I'm having rocker to retainer clearance issues. My valvetrain consists of the following:

Harland Sharp 1.6 ratio Roller Rockers
Comp 987-16 valve springs (1.437")
Comp Nitrous HP NX284h-13 Camshaft
Comp Stock Length Pushrods
Dart Pro1 215cc Aluminum Heads.

I know that you are supposed to have .050" clearance here, but isn't this at max lift??? (when the valve is totally open).. When the valve is closed is when the rocker is very very close to the retainer. It looks like it might actually be making contact! The harland sharp roller rockers are supposed to be clearanced for a spring up to 1.450" and mine are under this.... What's the deal??? All input would be greatly appreciated...

 

This isn't really unusual. Most racers grind additional clearance into the bottom of the rocker arm in the area closest to the retainer. The problem is made worse by flexing of the rocker stud. I run a stud girdle to minimize the interference but high spring pressures and high rpm combine to make it something that has to be watched.

 

Hey brotha...bad news.

I have a 1.6 set of Harlan Sharp's and a 1.6 set of Crane Gold Billets...Both don't fit my retainers. I resorted to finally buying the cheaper priced but stronger and better fitting Comp Cam Pro Magnum roller rockers...They clear A LOT better.

So I sold both sets to cover the cost of the new ones luckily.

Yes your springs are under 1.45 but are your retainers? I have a set of titanium 1.455" retainers on top of my comp 1.436" 986-16 springs. That was the issue to begin with. Goodluck! Believe me I tried everything, I almost did something stupid like going to a much longer stud and pushrod combo to move the rocker body upwards for more clearance. THAT's a bad idea, glad I didn't do it. Ya got biggie springs, ya need biggie rocker arms now. BTW...I'm running the cam which is a step smaller than yours. Same Nitrous HP lineup though but it's only the 274 grind, I'll step up to what you have if this one doesn't do well Goodluck!

 

Hey guys, thanks for the info.. I'm glad it's not just stupidity on my part.. :P I've resorted to ordering a set of roller rockers that are clearanced for springs up to 1.550", and I've also resorted back to 1.5 ratios because of pushrod length issues. If I do decide to jump back up to 1.6's, I've got another project car I can use the 1.5's on.... I never even thought about the retainers being bigger... doh!!!! Should I definitely run a stud girdle too??? My springs are Comp part number 987-16 and have 130lbs open pressure. I've pulled the inner springs to break in the cam though.. Thanks!!!

 

I'm assuming that the open spring pressure figure (130#) you included is a typo? Is that the closed pressure figure? According to my data sheet, that spring should be good for around 400# when you use 1.5 rockers on that cam grind.

I have a stud girdle on my motor because the open spring pressure is in the neighborhood of 600#. I've had no problems running up to 400# of open spring pressure without a girdle in a strip-only application although I'd certainly consider using 7/16" diameter studs in any situation much beyond stock.

I don't think spring pressure during cam break-in is a big problem if you're using a roller cam.

I have a set of the Comp Cams Chromemoly Pro Magnum roller rockers that I've had to clearance in order to keep from contacting the retainer on 1.55 diameter springs. But then, they have a ratio of 1:8 on the intake valves and 1:6 on the exhausts. Everytime I pull the rockers off there are a couple that need to be ground a little. It is my belief that the combination of very high spring pressures, high rocker ratios, aluminum head castings, and 8000 rpm is pushing the limit of a stud mounted rocker system. A pedestal mount such as Jesel, Comp Cams, T&D, or Crane is probably not too far in the future.

Good luck.

 

Yeah, derrrrrrrrrr typo........ that's 130 closed, 325 open......... lol..
I'm using a Hydraulic cam....

 

Hey guys

I am so glad I ran across this thread. I was planning on ordering some Harland 1.65 rocker and never even thought about this issue. I am running 987 springs and 740 steel retainers on machined LT1 heads. Anyone know if they will fit? or whats the diameter of the 740 retainer is?

Thxs
Jeff D.

 

According to my Comp Cams catalog, part# 740 (10 degree, Super Lock Retainer) has an outside diameter of 1.400".

 

thxs for the info.

Jeff D.