330 Engine Studs

[treue]

Hi Guys:

The engine from my 67 330GT 2+2, SN 9129, is now totally disassembled and in boxes at my machinist's shop (Jim Lewis Racing Engines, Vian, OK). I paid a visit last week to view the status and plan our attack with Jim. Last summer, our FCA chapter visited Bob Smith's Coachworks in Gainsville, TX. Bob has quite an extensive shop and has a veritable museum of very rare cars in various states of restoration. I asked Bob about 330 engine stud replacement and he admonished all to replace every stud on the engine AND TimeSert the block. Jim Lewis had pulled all of my studs, stating that all but one backed right out without problem and was questioning Bob's emphasis on TimeSerting the block. I looked at the threads in my block and they all looked in excellent condition, including no bulge-out of the deck, next to the stud holes. It looks like TimeSerting the main bearing cap studs would be difficult because of the guide sleeves. Also, the TimeSerts would be considerably shorter than the engaged-thread-length of the original studs. I still plan on replacing all of the studs.

Does anyone have an opinion on the advisability of installing TimeSerts in a good 330 block?

Tom Treue

[fest]

FWIW

I am planning on NOT
removing, replacing, or 'inserting'
ANY Studs on my 400i Engine
(see other threads for details)
unless necessary

[tyang]

Hi Tom (Treue),

Bob Smith is probably considered one of the top Ferrari restorers in the U.S. and has a client list to prove it. He's very knowledgeable on Ferraris, and I don't doubt time-serting would be good insurance from blown head gaskets and worse failures, but you have to consider the probability of this happening. Will the engine be raced? How hard do you plan on driving it? How much do you have for this rebuild? No reputable mechanic can gaurentee a bullit proof engine without certain precautions, but not every engine needs to be assembled like this to be durable. It's a judgement call.

FWIW my 330 engine did not have any studs replaced.

Tom

[fest]

I am familiar with the Heli-Coil process
(having performed this during the Tranny outage)
and no doubt will be re-familarizing myself with the process
before this is over
but
I am unfamiliar with the term 'TimeSert'
I deduce that it is similar to Heli-Coil

what is the difference
(is TimeSert superior? if Y why?)

[tyang]

Hi Fest,

Helicoils use square wire to form the threads while timeserts use a one piece insert. It's supposed to be a stronger way to repair threads.

Tom

[treue]

Fest:

Try www.timesert.com. Bob Smith said Helicoils are for your lawn mower not your 250GTO.

Tom Treue

[Koll]

Boeing, Pratt & Whitney, Rolls-Royce, NASA, Harley-Davidson, BMW & Porsche specify HeliCoils where parent materials are weak. Boeing uses them very extensively. Although not Ferraris, these manufacturers are not to be dismissed as makers of "lawn mowers".

Unless the block is aluminum, then I'd have to see any reason why one would need any type of insert. There's the "bigger, meatier is better" school of thought, but unless you're a metalurgist and know all the reactions that occur with up to 4 different types of metals (block/head/stud/insert) that can be expected to be heat-cycled thousands of times then it's all just tough talk.

[treue]

Koll,

I don't believe Ferrari has EVER made an engine block or head from other than aluminum.

Note that I wrote, BOB SMITH (not me) said that Helicoils were for lawn mowers not your Ferrari. No one was totally dismissing the use of Helicoils. Bob's assertion is that TimeSerts are better because they are stronger and more physically stable. TimeSerts take four installation tools, so maybe the use of Helicoils by those august organizations you cited is partly driven by economic considerations. Also note that Tom (Yang) said that Bob is probably considered one of the top Ferrari restorers in the country and has the client list to prove it. I strongly agree with Tom's evaluation of Bob and add that Bob is not stupid. I agree with Bob that I do not want to go in there (the engine) again, so a little insurance is well spent. After spending six and seven figures on a car, Bob's clients spare no expense in doing the job right.

TimeSerts are available in stainless steel which would be significantly less reactive than carbon steel when used against aluminum. There's going to be a steel/aluminum interface with either TimeSerts, Helicoils or the existing direct application, so that is not a consideration.

My main concern is still: am I wasting my time putting any insert in my (what looks to be a perfectly) good 330 block?

Tom Treue
[/u]

[tyang]

Hi Tom,

If you don't mind spending a little more money and time, and want the extra insurance, go with the timeserts. Bob's clientel tend to leave no expense or proceedure spared, but it may not be necessary IMHO. If I had the unlimited funds like those owners, I would have probably spent a lot more money on my rebuild, but I'm just a regular guy with a regular checkbook!

Tom

[fest]

not to stir things up
but
I must mention that my engine
uses Heli-Coils from the Factory
(in what they deem to be high-stress / risk areas?)
and in fact, are listed in the parts manual

that said

I DO like the idea of a solid insert
(as opposed to a coil insert)
as the Heli-Coils I have installed
struck me as being kind of 'cheesy'

we design and assemble with aluminum enclosures where I work
and using Steel Inserts e.g. 'Pems' is the norm

[xs10shl]

One thing you may want to consider is just timeserting the cam cover studs. The threads in your head may be perfectly good now, but the next guy who does a valve adjustment may overtighten the cam cover nuts, and thus strip the stud threads on the aluminum head. It's easy to fall into this trap, especially when you're trying to stop a leaky cam cover using brute force. I'm guilty of this sin myself.

I've had 4 cam cover studs re-threadded with timeserts (only one was my fault, I swear!!) and they work excellent. However, I'm not planning on doing all of them unless they individually fail, and I'm forced to.

Just my 2 cents.

[Chris Coios]

A caution here. Keep in mind that everytime you machine out material from a head or a block, it is gone and you cannot put it back without welding, distortion, and machining again. Consider also the thickness or width of material that is holding the stud originally. For each condition, there must be enough wall thickness remaining to adequately hold the insert. The strength of the insert is going to depend on the stability of the aluminum remaining. You may have a nice strong new stud that will rip out if the aluminum left is thin, distorts or fails. I tend to leave well enough alone, but this preference. I am sure inserts are fine if you do it right.

A note about rocker arm tower studs on 250/275/330 V-12's. I have been told that the studs holding the rocker towers of single-cam motors are prone to stripping out if you overtighten them, even with the factory torque guide. I do not have the values in front of me, but I will look up the suggested lower torque that works fine, but prevents a headache.

Regarding corrosion of dissimilar materials, galvanic action is not only a function of the relative reactivityof the metals, but also the relative mass of the pieces joined. A small stainless insert in a large mass of aluminum will be generally ok, but a small aluminum piece in a large mass of stainless will disappear if the conditions of moisture, etc. are prime.

Chris

[Matt F]

I asked Bob about 330 engine stud replacement and he admonished all to replace every stud on the engine AND TimeSert the block. Jim Lewis had pulled all of my studs, stating that all but one backed right out without problem and was questioning Bob's emphasis on TimeSerting the block. I looked at the threads in my block and they all looked in excellent condition, including no bulge-out of the deck, next to the stud holes. It looks like TimeSerting the main bearing cap studs would be difficult because of the guide sleeves. Also, the TimeSerts would be considerably shorter than the engaged-thread-length of the original studs. I still plan on replacing all of the studs.

Hi Tom,

I think that inserting Time Serts into perfectly fine threads is a really bad idea, particularly if the inserts have a shorter length of thread. That pretty much defeats the purpose.

Clean the female threads with a tap, and use new studs.

If you want more information, refer to Carroll Smith's Nuts, Bolts and Fasteners and Plumbing Handbook.

--Matt

[fest]

on this I must concur-
removing Studs that are solidly planted
seems like overkill and may also be risky-
due to Galvanic reaction, they may really be in there

I also would be hesitant to remove material
in some areas, becase of the fine art of Ferrari's Foundry
there is just not a lot of 'meat' around some of those Studs

I may be facing removing some of the Studs on my Engine, actually
as I may have to do so to install the (one piece) Timing Chain
(details elsewhere)
I am not looking forward to this
as I do not want to disturb them
and fear they may be in quite tight
(as I mentioned)
and may get damaged when I try to remove them

speaking of safe Stud removal-
I favor the good ole fashion
2 'jam' Nuts technique
any body got a better idea?

(I know there are various Stud removal Tools
on the market, but the ones I've seen
all look like they would mangle
or at least damage the threads
in the process)

[David Booth]

Bob Smith's reputation certainly speaks for itself, but I must admit I fail to see the wisdom in adding an insert to a perfectly good block, in an area where some of the parent metal must be removed to do it, and especially since the grip length (how much of the stud's threaded end is in the insert) will be less than original. If the aluminum allloy of the block is prone to radial cracking around the stud hole, that's a different story. Matt's reference to Carroll Smith's book is well placed. Tons of great information in there, including the proper way to safety wire your fasteners.

I personally wouldn't use the jam-nut technique to remove a stud of any kind unless it was an emergency situation. Most of the major tool suppliers sell a roller-cam stud remover - mine's actually a set of three in different size ranges from USAG in Italy.