Im sure glad there isn't a "post a thread" limit on camaros.net, cause I've worn out my welcome...

I am in the midst of installing Aluminum Pro Topline heads to my stock decked 327. I ordered my heads assembled with the K2 kit, meaning 1.46" OD spring, 1.8" installed height, +.1" valve length.

With 1 remaining head on my motor (see thread: Reuse Head Gaskets)I did a geometry mockup with my Comp 1.52 Pro Magnum Rockers and a Pushrod length checker. I soon realized The screwiness:

The retainer comes in contact with the rocker (right where the neck starts to radius downwards). There is no way that "minor machining" of the rocker arm could clear things up. There is major interference. Besides, machining voids the warranty.

I then extended the pushrod length checker until the rocker tip touched the valve and cleared the retainer. However, the pushrod was so long that The roller tip was resting on the outside edge of the valve stem, and there was no more thread left on the Rocker Stud because the arm sat so high. :eek: The pushrod was 8.1" when it first touched the valve graemlins/sad.gif

I began to brainstorm and guessed maybe the Salesperson sent me heads with the K3 kit (1.9" installed height and 1.54 OD spring, +.2 valve length and a fatty spring rate to boot).

What is your best solution? Am I a candidate for valve lash caps? Remove a spring and check installed height? Measure to make sure the valve length is +.1 and not +.2? Thanks a lot, sorry to keep rambling, but I wanted to make sure I didnt forget anything. This is my first rebuild, and I'm already burnt out. graemlins/angry.gif

[ 08-13-2003, 08:56 PM: Message edited by: sik68 ]

forgive me, but i'm not quite clear on your sequence of events. so if you get the valve in question on it's base circle, put the checking p rod in, then throw the rocker arm on, it hits immediately, or at some point through the cycle of the valve opening/closing? i'm running pro topline 220's with isky 1.550 springs, and comp pro magnum 1.6 arms, and indeed when i throw th rockers on, they are real close to making contact with the spring, at the trunion of the rocker. but once they are all the way on and sitting on the pushrod and valvestem, clearances are all good. remember as the valve opens, it moves away from the rocker/stud, increasing clearance. and as for the valvestem, it should sit up above the retainer, since as you say, they are supposed to be .1 longer (mine are), unless the locks are the type that increase your installed height, thus moving the retainer up the valve stem. there should be ample clearance here with proper retainer installation. and as for your pushrod, mine ended up being 8.0's after checking them. so i'm not totally clear i guess, maybe throw a bit more info at me and i'll try to help, those heads should set up similar to mine. hope that helps

Sik,

A couple ideas that may help. First off you are running guideplates under the screw in studs aren't you? If not the rocker will sit too low and you'll probably not have enough thread at the top of the rocker especially if you're using GM factory rocker studs (they are much shorter than any of manufacturer). I believe the Toplines are all machined for studs with guideplates, it makes a difference how much material is milled off the head if you're using plates or not.

Second try a set of ARP studs if you are running anything else. They're the longest stud, the strongest and will give you more adjustment at the top end and could solve you problem. Dorman, ARP, Summit and GM are all very different in regards to overall length, the number of threads, the thickness of the hex base, the radius at the hex base and can give you fits by adding to other geometry problems that may already exist.

Something still doesn't sound quite right about the pushrod lenght though. I ran +.100 on my .007 decked 331 with a composite gasket and had no problems. I'd make sure they didn't use longer valves and I think you're right in checking the installed heights again.

sy1, i must have beat you by seconds. good point about the stud length. my heads set up fine with my 7/16 screw in studs from my previous heads, but while driving the car about a month later, i broke a stud. knowing that i used manley studs, and they were 7/16, needless to say i was worried. especially when i knew my geometry was spot on. what i found was the .1 longer valves and likely just general geometry changes from my old heads to the pro's, left very little stud left in contact with the meat of my poly lock, which allowed likely a bunch of flexing, and a broken stud. i just went with a set of arp big block type 7/16 studs that have a longer top, and bottom as well. i slightly shimmed the bottom up out of the intake ports (only about .030), and that left a ton of threads for the poly lock. i've been running it for a year like this now, and all is good. so, i doubt this is causing your geometry woes, but by all means take a look at this before your done graemlins/thumbsup.gif

Good point on the big block studs. I'll try to remember that one. On the flexing in the past I've deliberately reduced the amount of material that I've milled from the stud bosses to set the studs higher and thus the rockers lower on the studs. That's when I began experimenting with all the manufacturers screw in studs to see who had the stud threaded the furtherest down the shaft. There's a world of difference between manufacturers, I was surprised at what I found.

I am suprised you are having any trouble with those Comp rockers. They should clear 1.46" springs no sweat - that is the root of your problem IMO. Once you get the proper springs or rockers check again and I bet your stud length will be fine.

You can measure the springs with a machine ruler. Measure height from the bottom of the retainer to the spring pocket. Measure the width straight across the center of the spring.

ps. you can/should measure with the spring installed

Here's the latest:
To clear things up, 68rs406 I did mean that when everything was settled down and the rocker was actually in place, there was interference.
My mockup was indeed done with the supplied guideplates and 7/16" studs, and "EO-IC" was followed.

I took my head down to the machinist to have him measure the spring diameter. He measured the spring itself, not the retainer diameter. He measured 1.54", not even close to 1.46".

Also, to acheive "proper" geometry (roller tip on inner third of valve stem, and minimal clearance between retainer and rocker base) I would need a .082 lash cap (based on feeler gauge), along with a longer pushrod.

Im in serious doubt that the supplier of my heads sent me the correct spring kit, so I am probably going to take the final step and have the springs (dual springs) removed and measure the installed height, as well as the length of the valve itself.

Eric: Im suprised too by the comp rockers not clearing the supposed 1.46" springs. We'll see.

Thanks to all, if there is any more advice/similar situations I'd like to hear it...otherwise I'll keep this thread alive with my updates.

sik, yeah, it does sound like you should start checking that things are as they should be, something doesn't sound right. (i wish i was there to physically see them, that makes it much easier to diagnose). who assembled the heads, pro topline or another distributor? with those rockers and .1 longer valves, clearance should not be an issue. maybe they did some monkeying around with the installed height, like i mentioned previously, and now the retainer is so high on the valve stem, it's creating an interference. at any rate, that does suck, but once you get it straightened out it will all be worth it, don't get discouraged. i'll be interested to hear what it turns out to be, good luck graemlins/thumbsup.gif

http://www.mercurycapri.com/technical/engine/cam/vtg.html

sik, (Name ?????????)
I don't like to say anything negative without actually seeing parts but....I have seen several problems with the Pro Topline heads not being machined properly. You should see if you can find a different set of heads to compare some measurements with. The studs may be in the wrong place, or at the wrong angle.

sounds like enlargign the spring seats might help
good luck!
Eric

sorry,enlarging!
it's late

Update:

I had an engine builder take measurements of my heads.

He came back with the following:
1.88" installed height
215# seat pressure :eek:
1.54" OD spring


This is a far cry from the ordered:
1.8" installed height
135# seat pressure
1.46" OD spring

Just an update for those interested in my situation.

SO MUCH FOR A "BOLT ON" :mad:


BillK, I know that knowledge is the best weapon against bad choices...but I didn't want to read that :(

those sound like solid roller springs to me. you definately need to contact the place they came from, thats just not right. but, i'm still amazed that you have interference, since thats about the same spring i have. Billk, is the issue you speak of something you've seen on a few occasions? the guy i got my heads through (a buddy, that is a machinist and a hi performance engine builder, btw) has done a few sets of the pro heads, including mine, with very good results. however, it is interesting you mention that. he told me about one set he did on a motor he built (he used them after good results from mine), that upon assembling, noticed one head had slightly less clearance between the stud and spring, kinda similar to what sik is describing, only these were big roller springs (which unfortunately sounds like what he got), and the difference was slight, they still had clearance, just one head had about .010 less. thats why i asked about if it was after they were seated or not, because his clearance issue was only noticed as the rocker was slid into place, as the trunion slid by the retainer, where clearance is tightest. this is odd, but it sounds like both sik's heads are having issues, that would really be odd. hopefully this isn't some machining anomaly thats going to show up in pro's heads now, i know mine were great. so sik, maybe try taking some measurements to see if the studs are closer to the spring on one head, or if anything else is amiss. this would explain the interference, but from the sounds of things, there are quite possibly some issues with how your heads were set up to begin with, obviously in seat pressure at least. so thats probably the first thing to get straightened out. good luck, i sure love my pro heads, hopefully you get your issues figured out. and remember, there really is no "simple bolt on" once you start to modify things, :( sad but true. again, good luck and keep us posted graemlins/thumbsup.gif