87_LG4

So I recently installed new rocker arm studs from Comp. Installation was a breeze and the finished work looks good. I then proceeded to install the valves and springs followed buy the push rods. Finally the turn came to install the rockers, upon which I noticed there was a large gap between the rocker and the rest of the valve train, as you can see in these pictures:




As a result of the new studs having a raised hex shaped base for screw in application, its effective length is shorter than the stock press-in ones had. Apart from the studs, springs and cam the rest of the valve train components are stock. Now, obviously I can't run the engine like this, so my question is this: do I need new rocker arms with a shorter base (if that exists) or longer push rods? Which would be the best/easiest? Any specific specific suggestions?

Thank you

87IROC-DAN61

Hello 87_LG4!!

Just a question........aren't the bases for the studs supposed to be turned down, when you install screw in studs????

I don't see that in your pictures........if they were turned down, then you would have the same effective length......?????

Educate me!!!!

87_LG4

That is a very good question. To be honest, I have no clue. There were no instructions included with either the stud set or the press in stud removal kit. So I did this the way I thought it was supposed to be done. If the way you say is how it's supposed to be done then I am royally f-ed, cause I used loctite on those studs, and not the forgiving kind Any one else care to shed some light on how it's supposed to be done?

87_LG4

Maybe I'm not that f-ed after all. I managed to remove the screw in studs without any damage. I guess shear luck would have it that I test fitted the rockers at all. Originally I didn't plan to assemble the rest of the valve train till I got my new rocker arm nuts (next week). So if I hadn't test fitted them, discovered that they didn't fit and post for help, the loctite would have set for sure, and I would never have been able to remove them without destroying them.

So now then, if the correct way is to turn down the bases, how would I best go about doing so, and how far down would they need to be turned?

305sbc

iTrader: (3)

The stud bosses have to be machined down quite a bit in order to run the studs with the hex base. It won't work any other way.

There are some straight studs available from engine supply companies like Pioneer, but I never use those.

91interceptorZ

iTrader: (3)

well the nut is going to take up some room no matter what. Are these even compatible with stock rockers?? they may not be. You may have to go to a roller rocker and yes you should measure your pushrod length with a length checker (looks like a pushrod, but adjustable with measurements), and order the correct length, that's if you go to rollers though. The stamp stock rockers are probably supposed to run where the nut is on the stud. I'm not sure if they are installed incorrectly. looks like they might be right, the concave part faces up on mine as well, the flat part of the stud does face towards head. You are supposed to shave some material off the stud boss (where it screws into head) to make up the difference for the nut being on there, I believe.

87IROC-DAN61

Hello 87_LG4!!

The best advice that I could give you about turning down the stud bosses, is to call up your local automotive machine shop/engine builder, and ask them!! However, I'm sure that someone on these forums with the correct answer will eventually come along, and tell you!!



I'll have a look in my "library" of automotive books, and see what I can find!!

87IROC-DAN61

Hello 87_LG4!!

Stud bosses are to be milled down 3/8 inch!! *

* Note: Not a confirmed number, but I have seen it on the net!!

Summit apparently has a cutter for this job!!



I'll keep looking!!

87_LG4

In this article (on page 2) they mill the base socket down 0.332" to accommodate a pushrod guide plate as well. Not sure however which studs they are using, but they look a lot like mine. I'm not sure what the numbers are for the stock studs, but if anyone has them is should be possible to calculate something when we know that my new studs have an effective stud length of 1.750” and a length of .680”. Anyone good at math?

Thanks

87_LG4

Never mind. 0.680" were the base threads, and 1.750" is the entire length. I'm heading out to my local machine shop soon. Wish me luck!

87IROC-DAN61

Hello 87_LG4!!

Good luck!!!

I hope it's not too much $$$$$!!!

87IROC-DAN61

Hello 87_LG4!!

I found this in a HP Books, called "How to HOTROD Small-block CHEVYS" on page 113 it states "have the stud bosses milled 0.250 inch for Chevrolet production studs without guide plates; 0.320 inch for production studs and guide plates; or 0.410 inch for Mr. Gasket studs without guide plates."



At least you now have the specs!!

87_LG4

Thanks Iroc-Dan! Let's hope the machine guy gets it right. I already dropped off the heads to get machined. Can you believe they estimated the job to cost $300!!! If it weren't for the fact that I've already put a serious amount of time in porting and such I would have scrapped the heads and used the money to buy some aftermarket ones. I'm committed to this build, but there's no way I'd do it again. If this engine dies on me it's "Hello crate 350"!

But thanks anyways!

87IROC-DAN61

Hello 87_LG4!!



It's only money..........it goes into the bank account every two weeks!!

87_LG4

Yeah, I know, but I was hoping that I could have use those bucks to start upgrading my breaks, suspension, rims or save them for gas money (here in Norway gas prices are almost $8 a gallon, pay checks come out once a month).

87IROC-DAN61

Hello 87_LG4!!

Use only half of the monthly pay cheque, keep the other half for 15 days, "presto", two pay cheques per month!!



Sometimes money isn't very well spent, but then you wouldn't learn stuff either!!!

$300.00 lesson = lifetime of knowledge!!

I guess your other upgrades will just be a bit further down the road!!

Gas at $8.00 a gallon, is that Imperial, or American???

4.54L/Imperial gallon vs 3.78L/American gallon!!

87_LG4

That is US Gallon. 3.78 liters per gallon, 1 USD = 6.06 NOK. 1 liter petrol is circa 13 NOK, So about $2.25 per liter * 3,78 = $8.5 actually. Go figure.

87IROC-DAN61

Hello 87_LG4!!

It's $1.02 per liter here in Chilliwack BC, for Regular 87 octane!!

I don't use that in my IROC, just in the wife's Chevy TrailBlazer!!

IIRC, it's $1.22 per liter for Premium 94 octane!!

I was living in Lahr Germany from 1989 to 1991, and a couple of times I bought fuel without the "military" gas coupons..........it was really expensive, I can't remember the exact price, but it was really expensive, took a big chunk out of 100 DM!!!

87_LG4

I feel sick to my stomach.. Since I had already threaded the stud holes on the drivers side head, the guys at the machine shop said they couldn't use the regular tool that uses a guide stud in fear of damaging the threads. So it took them another hour to complete the job. Grand total: $400!!! For two and a half hours of work! And they didn't even have the professional courtesy to clean the parts afterwards.

87IROC-DAN61

Hello 87_LG4!!

Are the heads at least usable now?????



$400.00 and they better guarantee their work!!!



P.S. Have you got a picture of the completed work????

87_LG4

I can only assume they are usable now. They should be, but I haven't gotten as far as assembly yet. I'm still finishing up my port work on the passenger side head. I took a few pictures just a few seconds ago. Looks undeniably good, so let's hope they function as good as they look.

87IROC-DAN61

Hello 87_LG4!!

How much were they milled down??? Are you using guide plates??

I ask this because of the spec's that I gave you!!!

You don't want anymore surprises!!!

87_LG4

I actually don't have the exact number, but they assured me the rocker arm would be able to sit as it should on the stud. They milled them down to match the old press in studs, so if all went as planned they should be able to install correctly now. I'm not using guide plates. And I appreciate you taking time to dig up those number for me, but they had already started working on them when I got the specs from you. And you're right, I definitely don't want any more surprises now, but since they assured me they would work I'll make them redo it free of charge if it doesn't.

87IROC-DAN61

Hello 87_LG4!!

If they milled them down too far, then you can use the guide plates, sort of a free gift from them to you!!!

One last thing, there is a question of rocker arm geometry, and if you have a problem with it, the answer is different length push rods!!!

Basically it goes like this: If the rocker arm is not even on both sides, (valve and push rod) different length push rods are then required to compensate.

I don't think your going to have a problem, but keep that in mind!!

I'll check this out myself, and let you know what I find!!

JakeJr

Someone please clue me in on this. I've never come across a situation where the stud bosses had to be milled just to install screw in studs.

I had the press in studs removed from my early 86 Vette heads and ARP screw in studs installed and the boss heights weren't touched.

What's going on here anyway?

Jake

87_LG4

The new rocker arm studs I use have a raised hex shaped base to allow wrench screw in application. Did yours have that as well?
If not then I suppose it could be that your rocker arms didn't have to be installed as far down on the stud as mine do, like if you had longer valve stems and push rods. Do you remember how much clearance there was between the bottom of your rocker and the stud base?

JakeJr

When I re-built the 86 Vette engine I had at the time and went with a ZZ9 cam, I knew the press-in studs would begin to pull out over time. So I put the heads in the shop to have the normal stuff done: a valve job done, surfacing, new guides and tap the stud bosses for screw-in studs. I went with ARP hex head studs like those shown in your photos.

I put the engine back together using Comp's 1.6 Pro Magnums and 7.200" hardened pushrods and guide plates. Valves were stock 86 Vette valves. All this was in 2002, but IIRC the springs were set up at 1.800" installed height.

When I saw what the shop charged you I was shocked!

Who came up with this machining down the stud bossess as the best fix anyway? What was the thinking?

Seems like there's a cheaper, easier way to accomplish the same thing. Like going with roller rockers ($222 for Scorpion 1.6s) and perhaps longer pushrods (if needed) and pick up 15 or so HP in the process. That, instead of having to pull/re-install the heads, pay $400!!! for the machine work yet get no HP increase after all that.

Jake

87_LG4

The thinking behind milling the stud bosses came mostly from this article, but I do agree with you on the price, shocking to say the least. On the brighter side though, pulling and reinstalling the heads wasn't really a problem as only the one head had been installed, and only as a mock up to see if it all still fitted. I sure am glad I did that before I had properly installed them both.

87IROC-DAN61

Hello JakeJr!!

How early was your 1986 vette??? The L98 came with aluminum cylinder heads mid 1986, and should have already had screw in studs!!

Yes, some studs can be installed with no stud boss milling, however, 87_LG4's stud bosses had to be milled, using the studs that he had!!

87IROC-DAN61

Hello Again JakeJr!!

If you read the whole thread here, you'll see how the stud boss milling became the fix!!

87_LG4's price went up after the shop found out that one head already had the stud bosses tapped, and couldn't use their "regular tool" to do the job, therefore the shop sees another pile of money, to fix this problem!!

Also, his shop is in Norway, what is the comparable rate of labour, your town $85/hour, his town $120/hour, for the same job!!!!

$400.00 is alot of money, no doubt, but it might be like comparing apples to oranges, and doesn't become a deal breaker!!

Buying more parts, and having them shipped to Norway, might be more expensive than just fixing the immediate problem!!!

JakeJr

You seem to be very defensive about my questioning this. Lots of "?" and "!" marks. I'm wondering why that is. I'm merely asking "why" and for supporting evidence.

"If you read the whole thread here . . ." If you're assuming I didn't read the entire thread that wouldn't be correct, because I did. My core question is why milling down the stud bossess became the recommended path to take.

Apparently, from what OP posted, he didn't realize he had a "problem" until he tried installing the rocker arms. This was after he has tapped one head's stud bosses. Then it became an question of how to correct his "problem". From that, the recommendation was to have the stud bosses milled.

My question is why was milling the recommended way? Where's the science supporting that recommendation? I'd iike to read it.

Also, in drilling down to the core question in search of an answer, it would be best to eliminate costs, where he lives, what tools the machine shop has or doesn't have and, instead, concentrate solely on why milling was recommended in the first place.

In other words, why was milling the recommended way to address his "problem" as opposed to other possible cures? Seems extreme to me, but the jury's still out until I learn more.

My 86 came with iron heads with press-in studs. That's why I distinguished them by using the word "early" as opposed to the "late" heads which were aluminum.

The studs I installed were the same as his - perhaps a different brand - and had the same hex head. It just seems strange to me that his only option was to have the bosses milled, especially when contrasted with what I had to do.

In all my years (65 of 'em) I've never come across milling down the stud bosses as a requirement when installing screw in studs so - since I DO have this questioning mind - it peaked my interest. Made me want to know more about the science leading to that recommendation.

Could be/maybe I'm missing something; I just don't see it yet. I plan to do some research on this.

Jake

87IROC-DAN61

Hello JakeJr!!

The !!, and ?? are to stress the point!! Like this!!

My post was not trying to be defensive, nor offensive, but rather just making the point!!

I assumed that you didn't read the whole thread, because if you did, you would have seen the progression as to the option of milling the stud bosses!!

The only option that he was presented with, and confirmed by another poster, and by two articles, one by the OP, and one by me, was the milling of the stud bosses!!

Your option came after the work had already been done, therefore your option wasn't even considered!!

It's up to the individual to ultimately make the choice, as it's his money!!

I would not have presented the option of milling the stud bosses, if I had not seen it done with my own eyes, and I have two SBC cylinder heads in my garage done this way!!

As for your vette heads, time has a way of clouding memories, and that's why I asked "How early is your 1986 vette???"

Bottom line is, there is sometimes more than one way to acheive the end result, and you do learn something new everyday!!

Check my reference to the HP Book, you can find it at most book stores/automotive shops, this is where my quotable figures came from!!



We have both learned from this thread, you from my recommendation, and I, from your past experience, now everyone will have benefitted from this!!



Old school method = mine, new school method = yours?????

JakeJr

Researching results. I went through my 86 FSM and my 96 FSM but found no mention of the stud milling procedure. I didn't expect to find anything in the 96 book, but the 86 had possibilities. Then I checked my "Small Block Chevy Performance Volume Two: 1982 and Later" book, but still zippo.

Then I checked "Max Chevy" magazine on-line site and wondered why I hadn't come across that mag before. Then I read that it's an on-line magazine, which explained why I hadn't. I read the article and I now see how that milling procedure became a recommendation. Someone came up with that procedure and others bought into it.

Now, I've got about a hundred pounds of other different magazines, accumulated over the years, but I'm not about to go through all of them. Not just to see if there's any mention of the milling recommendation. Too much work for too little reward.

I'm confident that had mention been made in any one of them, I would recall it, especially considering how many times I've used them as a reference.

Over the years I've seen a few other (how can I characterize them) unorthodox methods being recommended, both in posts and in magazines. What I'm going to do is to put this milling method into the same category. Besides, the milling mod has already been done by OP and I don't see any benefit in continuing to beat on this.

Jake

87IROC-DAN61

Hello JakeJr!!

If you google "milling stud bosses" you'll come up with a whole bunch of info on it, you might even be lucky enough to get the HP Book, page 113 that I quoted to 87_LG4, as I just did!!



I wouldn't put this method in the unorthodox bin just yet, do a little more research like I mentioned above, and you just might buy into it too!!



I agree with you, that there is no need to continue to beat this to death, there just happens to be a couple of ways to "skin the cat", so to speak!!

87IROC-DAN61

Hello 87_LG4!!

Did you mock up one of your cylinder heads to see if everything was good???



Send a picture, if you can!!!

87_LG4

All this quarreling makes me feel like a child whose parents are fighting for custody



Mocked up, bolted up ,torqued up... All done! (except I'm still waiting for my new rocker arm nuts, hope I get them today) Other than that, worked like a charm
Thank you all for your help, couldn't have done it without you

87IROC-DAN61

Hello 87_LG4!!

Looks good!!!

It wasn't really fighting, more like a little bit of wedding night jitters, you know, scared of the unknown!!

I was doing some searching on the "net", and I found a couple of posts in another automotive forum, where this guy paid $800.00 US for the same work that you had done to your heads, looks like you got a bargain!!

By the way, for the thanks!!

On a last note, help is what we are all here for, whether giving or receiving!!

Keep us posted, once you get the engine running!!!

305sbc

iTrader: (3)

Looks good.
Those hex-base studs with the big radius on top are designed to have extra strength and to hold down guide-plates for the push rods.
It is standard procedure for a head machinist to machine several thousandths off the stud boss area to install these and allow room for guide-plates. The procedure has been a common standard since the time of Smokey Yunick.

It's a very simple operation to machine and tap the holes, and only costs between $50 and $100 where I am.
That $400 was outrageous for that. If I had known I would have given you a link to the straight type studs, so I regret that.
http://www.scpraceparts.com/3-8-sbc-...kt-no-hex.html

The effective length on these is about 0.300" shorter due to the lack of the hex head and radius area. Yeah, $14 per set.
I mentioned that they were out there, but I really never use them. I always use guide-plates in any build, so hex is a must for me.

I feel bad about neglecting to give you better advice, but here's the thing. The purpose of the screw-in studs is for strength to prevent pull-out and deflection. The straight screw-in studs only addresses the pull-out problem. I'm sure they would've worked for you though.

JakeJr

Naw, we're not really "quarreling", not from my point of view anyway. Just something I'd never come across before and it seemed to me to be an extreme method to solve such a minor clearance issue. My thinking centered around "There has to be a easier, less expensive way".

Since I'm a member of and visit 8 or more different Forums every day, I frequently come across unorthodox recommendations to address minor issues. When I do, I ask for the supporting evidence and, quite often, I'm directed to a site or magazine article supporting the procedure.

Yet when I do an independent search I usually find a much simpler, less expensive way to accomplish the same task (someone mentioned "cat"). As examples are the complicated and labor intensive methods some advocate to determine the correct pushrod length; adjusting lifter preload, check valve stem to guide clearance, etc., etc.

I have to admit that, although I've built more engines over the years than I can count, I've never built one with iron heads, switched to screw-in studs AND maintained the stock ball and sled rocker arms. Iron heads with press-in studs aren't what we usually come across these days or for more than 20 years for that matter.

When I did my 86 with iron heads and switched to screw-in studs I didn't re-use stock rockers. So the difference could be due to the additional clearance the RRs gave that didn't call for machining the bosses. I've often seen hex-less (is that a word?) screw-in studs but never had cause to use them. I agree, though, that using those would have been a far simpler and much less expensive method to address the problem.

Basically, I was blind-sided by the milling recommendation. Initially, my gut told me that the recommended procedure was over the top (too labor intensive/too expensive) and is why I asked for supporting evidence. That's what I do when I come across questionable recommendations and, in fact, is the same thing others do to me when I post something that's unfamiliar to them. That's one reason I maintain such a large reference library, so I can site my source. Others, like Shoebox and Agent86, have created websites to post their references. I just never got around to doing that though.

Best thing is that should this issue come up again on this or another Forum, I'll know to recommend, as a possible cure, the use of hex-less studs or studs with reduced height hexes.

Jake

87IROC-DAN61

Hello JakeJr!!