(Login jbrad71) Member from IP address 220.127.116.11
I went to set the lifter preload on my new engine and some of the pushrods are popping out (pushing toward the top) of the hyd. lifter cup after a revolution or two. Not all push rods are doing this. I used a pushrod length checker to get the proper pushrod length. They ended up being 8.150". I thought that was quite short compared to stock 8.40, but I did have .025 taken off the block to square things up. The heads are CC 4V's that I got rebuilt from a guy for $400. He said they were "Race Prepped". I had one head CCed at 65cc, so I know that the heads weren't cut, but they were modified for screw in rocker studs and some material taken out of the exhaust port. Could the machinist have messed up cutting down for the screw in studs that would be causing the pushrods to not seat correctly?
Also, the heads had 3/8 guide plates on it when I got them and I just switched to 5/16 plates to match my pushrods. Would this cause issues too? I measured the plates and the new plates are only .008" thicker. (.106 vs. .098).
These $400 race ready heads have already cost me new guide plates, new studs to fit Harland sharp RR, new springs to fit my camshaft, labor to CC the heads and custom pushrods. I've spent about $1200 so far and now I think the head machine work could be messed up.
How are you setting the preload? Maybe the lifters aren't all the way on the base circle of the camshaft. I've done the same thing when adjusting valves on my solid lifter engine. What worked best for me was using the tdc 270 180 90 marks on my balancer and just following the firing order. I couldn't make anything else work consistently but I've never messed with the hydraulic stuff. Also had to use different length pushrods on intake and exhaust sides because of previous valve jobs, installing hardened seats on exhaust and non-stock length valves. Ended up with 8.350 and 8.150. I know the old cast iron heads take require a lot of attention and money, but they make horsepower!
With that short of a pushrod it is posible that the rocker arm is bottomed out on the rocker stud. Look at the bottom of the rocker arms to see if any material is scraped off the rocker. Also check to see if there is space between the pushrod and the guide plate near the valve spring to see if maybe the pushrod is bottoming out on the guide plate. You need to check these things out by turning the engine over and watching the pushrod throughout its travel.
I'm running brand new Comp Cams 5/16" guide plates and the push rod is making full contact with it during the entire engine rotation. The lack of movement is binding the pushrod into the rocker arm cup and its sticking as the lifter is moving back down. I checked the 3/8 guide plates that I just took off and they are quite a bit different and are probably Manley. The bend on the Comps are also about .175" further away from the rocker stud making it more likely to bind up.
I'm sending the Comp plates back and getting the Manely 42163-8.
I could have avoided all this crap if I could have found a set of 3/8", 8.150" Long, restricted pushrods. O'well!
I cant imagine why Comp would make these guide plates if they dont even work correctly. Geeeee!!!
Thanks for all the replies!
This message has been edited by jbrad71 from IP address 18.104.22.168 on Jul 17, 2012 7:28 PM
Amazon Dot Com has them for $636 USD any day of the year
July 17 2012, 10:04 PM
An internet shopper should be able to find them for $600 USD +/- $50. I've seen them as low as $550 USD, but I did a quick search and couldn't find that price tonight.
There's also businesses selling them for $1300 USD ... which is double Amazon's price. I can get T&D Machine rockers for less than $1300! T&D rockers are my personal favorites. I know you've used them too.
(1) Stock stamped steel rockers fastened to standard pedestal with 5/16 cap screw (not adjustable)
(2) Ford Racing bolt-down roller rockers fastened to standard pedestal with 5/16 cap screw (not adjustable)
(3) Yella Terra YT6015 ADJUSTABLE roller rockers fastened to standard pedestal with 5/16 cap screw
I received the Manley 42163 guide plates today and they have a lot more room for the pushrod. The slot is .14 deeper than the Comps. The hole for the rocker stud is also a little larger which should allow for a more precise alignment of the rockers over the top of the valve stems. I'll report back tomorrow with an update.
I would have had these installed today, but I need a thin wall 11/16" socket like someone on this site mentioned before. I"ll have to order one since my local Sears didnt have one. It will cost about $12.
A six point, 3/8 drive Craftsman deepwell socket usually works without modification. Sometimes it is necessary to split the Manley guideplates apart to get the rocker tips to line up on the end of the valves. A 12 point socket is thicker and usually has to be modified. Torque studs to 70 ft. lbs. and they usually won't move. Make sure you don't over or under tighten the studs.
A 7/16" cap screw passes through the rocker arm fulcrum and its saddle and clamps them together and to the machined pedestals. The fulcrum and saddle are steel parts about 3/4" or 7/8" in diameter. They form a very rigid "T" shaped structure for the rocker arm to pivot on. The 7/16" cap screw holds the assembly together and clamps it to the head, but flexing forces are resisted by these large diameter steel parts. This structure has a rigid fixed position and functions like an individual shaft mount. Lash adjustment is accomplished via a push rod cup style adjuster.