[crm318]

I just got my new heads on the engine with new 7/16 screw in studs. I can't use the crimp/Stover nuts on it because they will chew up the threads. I have a set of poly locks, but they don't thread down far enough and seat before any play is removed. My idea is to run a washer and a 7/16-20 nut on top of the rocker ball and then use the poly locks (have to use the washer because the nut seats again before play is removed). On my old heads with screw in studs, I used a Stover nut with poly locks and it was fine. The Stover has a recession in it and took up the slack. With this new set up, am I asking for trouble?

[b-man]

Either cut down the studs or buy some the correct length. The polylock screws need to be mostly inside the nut to properly lock them in place, what I see in that first picture is a recipe for failure.

I've had to shorten the studs on a couple of builds to get the polylock nuts to seat properly, not unusual.

[Schurkey]

What part number screw-in studs?

Are the pushrods the correct length? How do you know?

[400 Lemans]

http://www.ebay.com/itm/New-stock-le...0AAOSwxYxUrdp2

[NeighborsComplaint]

Had the same issue with mine. Prior owner had the same issue but his builder chose to rind retainer clearance into the rockers arms! Yikes.

I bought new studs, rockers and RAIV length pushrods. Tried both Pontiac and Chevy studs. Rocker arms still did not clear the retainers and the KoolNuts only engaged a thread or two with any of them.

I bought hardened, flat machined head bolt washers from Summit. Have run these for 15 years without an issue and geometry is on the money with them in place.

[gtofreek]

Agree, either the pushrods are too short, or the studs are way too long. What studs did you buy? You should only need the standard length BB Chevy studs, which I believe are around 1.7" from under the head of the hex, to the end of the top of the stud. Looks like you have studs that are about 1/2" too long, made for long valve BB Chevies, with stud girdles. Something is way wrong, and that will not work for long, like Bart said, recipe for disaster.

It would help to know what you're working on. If you have an old 389/421 and you put late model open chamber heads on with the 389/421 pushrods, that would explain your problem, as the 389/421 pushrods are considerably shorter than what the open chamber heads need.

[gtofreek]

Looking closer at the pics, it does look like you have 389/421 pushrods in it. It looks to me like the wear pattern on the pushrod from the pushrod guide, is way below the guide plates on these heads, which are obviously later model heads.

[crm318]

The heads are 1967 small chamber #15 with enlarged 2.11/1.77 one piece Ferrea valves. The studs are Pontiac studs with the larger 1/2" base for conversion to screw in. The engine is a 1971 400. The old heads are 1967 #16 big valve. It seems as if the stud isn't threaded deep enough. The pushrods were in the motor originally as were the #15 heads. I ran the 16s for 3 years and am now going back with the 15s.

https://m.summitracing.com/parts/arp-290-7201

[Big Mike]

Originally Posted by NeighborsComplaint

I bought hardened, flat machined head bolt washers from Summit. Have run these for 15 years without an issue and geometry is on the money with them in place.

This will work just fine. Soft washers like you have in the first photo is asking for trouble.

[crm318]

Here are the studs and pushrods.

[b-man]

I've used those ARP conversion studs before, the bottom threads needed to be cut down by about 1/8" before they would seat properly and clamp the guide plates down.

The top threads were excessively long as well, same as in your pictures, I had to cut them down a considerable amount for proper fit of the polylock nuts.

You have no other choice but to remove the studs and have them machined down to a useable length, the ARP conversion studs only come in one version. If they're not seating down like mine did at first you'll need to trim the bottom threads as well, anytime I've read about someone using those studs they had to do the exact same thing.

Your pushrod measures correct for the 1967-up engines with 14-degree valve angle heads, 9.145" was the length used on the common D-port engines. The 1966 and earlier engines (and some 1967) with 20-degree heads used 8.715" pushrods.

[gtofreek]

Those studs work better in the old closed chamber heads, but still needed the bottom threads cut down. These look to be seating fine, but have a long top thread. Pushrods look right length in these pics, compared to the other pics, and proper length for your heads, so I'd say you're good there.

[steve25]

You do not need anything more than standard grade 5 washers to space up the outer section of the poly lock , my question is if the stud is too long to clear the valve cover , as it's hard to judge from the photos.

Your push Rods may need to be longer than that with that Cam and or the valve job done to the heads, but if the heads where milled or if the block was decked it could make up for the Cam or valve job.

Either way or not the geometry should always be checked!

[JLMounce]

I had this issue using comp magnum rockers on my KRE heads. You could do it with spacers to prop up the poly lock outer, but then you run in to clearance issues with many valve cover types. For me I couldn't fit a 3" valve cover due to the wiper motor as well as the booster diaphram.

In my case, switching to a full roller rocker (HS 1.5) solved the issue and allowed me to fit the valvetrain under a standard height valve cover.

[grandam1979]

Looks like you have the nut under the poly lock you don't want that. Make sure you have the correct poly locks also.

[NeighborsComplaint]

Originally Posted by JLMounce

I had this issue using comp magnum rockers on my KRE heads. You could do it with spacers to prop up the poly lock outer, but then you run in to clearance issues with many valve cover types. For me I couldn't fit a 3" valve cover due to the wiper motor as well as the booster diaphram.

In my case, switching to a full roller rocker (HS 1.5) solved the issue and allowed me to fit the valvetrain under a standard height valve cover.

Yes, Comp Magnum Rockers are the culprit. I had to use the spacers in mine.

[surfsama]

I might have missed it but why not just replace those with proper studs?
Butler has 7/16 ARPs for $39.95.

http://butlerperformance.com/i-24452...-100-7101.html

[b-man]

Originally Posted by surfsama

I might have missed it but why not just replace those with proper studs?
Butler has 7/16 ARPs for $39.95.

http://butlerperformance.com/i-24452...-100-7101.html

Unfortunately the heads have been tapped 1/2-13 to use the ARP conversion studs. I've used them before but now I'll always install 7/16-14 Heli-Coil inserts so I have a choice of a wide variety of BBC rocker studs.

[crm318]

I ended up drilling out the crimped part of the old Stover nuts. I was then able to get the nut down with out chewing up the threads and i got the proper lash after that. I put the poly lock on top of the stover nuts. The BBC studs I have on my old heads start the thread at the same point on the stud, with the new studs being longer. I just needed the recession on the bottom of the Stover nut to take up the remaining slack. Basically, I am using my old set up, which worked fine before.

[Squidward]

Originally Posted by b-man

I've used those ARP conversion studs before, the bottom threads needed to be cut down by about 1/8" before they would seat properly and clamp the guide plates down.

Yes. I am running those studs now, and they required some chop-chop to fully seat the hex head.

I prefer the 290-7201's to doing the heli-coil. I have no idea why ARP makes the base thread that long. If it wasn't for having to chop off the 1/8" or so, the 1/2-13 base conversion studs would be a hands down winner.

Instead of chopping studs, just use a hardened washer under the poly nut, which raises up the nut and allows deeper penetration of the lock screw. I used these:
https://www.summitracing.com/parts/arp-200-8531

But since you are using poly lock on nut on ball, something is a little weird. Maybe get some longer poly locks.