LT5 Head Gaskets

[A26B]

I posted the following as a response on another thread under Parts for Sale and Wanted, but thought it should also be here, so It's copied below.


I don't like publishing info until a project is 100% complete, but in the case of head gaskets and the concern for future availability, I'm going to go ahead & fill you in on the status.

I have placed the order for the tooling.

Gaskets will be made in the same LH & RH configuration as the OEM gaskets

Gasket material will be graphite exterior with a steel core sandwiched in the center. The design & material is virtually identical to the current offerings by Victor & FelPro for premium head gaskets.

Before any gaskets are offered for sale, they will be tested for 2 days continual running on an engine dyno, making 50+ power pulls, and thermal cycling from high operating to ambient temp.

Availability? as soon as possible, 4~6 mo estimate. None will be produced in quantity until engine testing is completed.

The OEM material, Astadur, is now old technology, it's expensive and virtually unavailable. Event if it was readily available, the tooling cost would be exhorbitant as specialized tooling is required to make the cuts smooth.

The compressed thickness will be abt 0.005" thinner than the OEM. I've measured the fire ring height on over 80 cylinder sleeves. The variance is very tight, 0.041", +- 0.0005". Net fire ring clearance below the head with the OEM gasket is very close to 0.020", ample room for clearance with the new gasket. If anything, the new gasket and the associated reduction in fire ring/cyl head clearance could result in a cleaner burn. Another very slight change would be a minimal increase in compression. None of these changes are expected to have any noticable effect.

There you have it.

[Pete]

Jerry,why tool up for 2 different gaskets just do the RH wouldn't it be a liittle easier/cheaper?
Hope all goes well.
Pete

[A26B]

Jerry,why tool up for 2 different gaskets just do the RH wouldn't it be a liittle easier/cheaper?
Hope all goes well.
Pete

I thought about it Pete, but not everyone who wants a set of head gaskets will know about the procedure to make the RH work on the left hand side and will be skeptical of a replacement gasket that is a "one size fits all." I decided not to have to explain special procedures, especially to owners in other countries who aren't fluent in english.

Would be a little cheaper, but in the long haul, not enough to possibly be perceived as "half-azz", even though it's not. Straight forward replacement, LH & RH, seems the best way to inspire customer understanding and product confidence.

[todesengel]

any possibility of having a multi layer steel gasket mfg'd, for close deck purposes Jerry?

I thought about it Pete, but not everyone who wants a set of head gaskets will know about the procedure to make the RH work on the left hand side and will be skeptical of a replacement gasket that is a "one size fits all." I decided not to have to explain special procedures, especially to owners in other countries who aren't fluent in english.

Would be a little cheaper, but in the long haul, not enough to possibly be perceived as "half-azz", even though it's not. Straight forward replacement, LH & RH, seems the best way to inspire customer understanding and product confidence.

[A26B]

any possibility of having a multi layer steel gasket mfg'd, for close deck purposes Jerry?

Not by me. I've looked into it extensively with Cometic. VERY expensive proposition. LT5 is already a limited market & closed deck LT5's.....you can count on 1 hand.

[jonszr1]

jerry you are awsome, bill b. looked at some of your gaskets that i had the other day and said they are first class all the way . that you for caring about our cars like you do . we are all so very lucky :cheers:

[A26B]

UPDATE, 30Jun10:

Tooling is finished & 2 sets of gaskets for inspection & testing are being shipped.
If they pass the fitment test & visual inspection, then a set will be installed in an engine for 2 days of engine dyno running & subsequent tear-down for inspection.

[bdw18_123]

Awesome, Jerry! :thumbsup:

[tomtom72]

jerry you are awsome, bill b. looked at some of your gaskets that i had the other day and said they are first class all the way . that you for caring about our cars like you do . we are all so very lucky :cheers:

:notworthy:worship: I agree, thanks Jerry!:cheers:

[HAWAIIZR-1]

Is there any new developments to availability of head gaskets?

http://www.cometic.com/news-details.aspx?id=56

[A26B]

Craig,
I have installed a set of my new head gaskets in a spare engine for verification. Fitment is perfect.

I have scheduled an appointment for 2 days of dyno testing Sep 20th and subsequent tear-down to verify integrity.

If the test results are as expected, I will authorize production Sep 23rd and place them on the website for sale.

Insofar as the Cometic MLS gaskets are concerned, I corresponded several times with Cometic. The reason I did not choose to proceed with the MLS gasket is because I was told that the MLS gasket WILL leak if flatness exceeds 0.002". I fully recognize the precision of the LT5 engine, but 0.002" is not much when you consider 4 independent cylinder sleeves, that all gasket decks have to be level to that tolerance AND at the same time, level to the block deck.

To even inspect it would be a chore. Add the need to seal all coolant & oil return passages and the fact that many engines are built with aftermarket cylinder sleeves, the expense involved if leaks occur......... well, I just decided against it.

[LGAFF]

Jerry how much would it cost me to "test" these on my 90?

[tpepmeie]

Craig,
I have installed a set of my new head gaskets in a spare engine for verification. Fitment is perfect.

I have scheduled an appointment for 2 days of dyno testing Sep 20th and subsequent tear-down to verify integrity.

Jerry,
Is this a 350 LT5? Engine dyno or chassis?

One more question... what is the compressed thickness on these?

Great to have you in this hobby, Jerry.

Todd

[A26B]

Lee,The objective is to complete the testing before any head gaskets are offered to the public. Of course, we all realize that a short test is just a glimpse and that problems may arise well into the future where the difficulty lies in the absence of a controlled environment.

if the test is successful, I will have one set left over that I could offer for sale immediately after the testing.

Todd,

Is this a 350 LT5? Engine dyno or chassis?

Engine Dyno


One more question... what is the compressed thickness on these?

Projected, installed thickness is 0.055".

Here's the long-winded version as per my measurements.

OEM Gasket Thickness
New @ fire ring 0.0765"
New @ resin surface 0.072"
New @ silicone bead 0.079"~0.081"

Used @ fire ring 0.0653"~ 0.0682" (variance across diff cylinders)
Used @ resin surface 0.0635" ~ 0.0633" (variance across deck)
Used @ silicone bead 0.0645" (no variance noted)

Note 1: Resin compound is thermally activated & hardens @ eng operating temp. Assume rebound does not occur
Note 2: Since cylinder sleeve gasket deck is installed at 0.0015" ~ 0.0020" pride height above block deck, AND used gasket fire ring is appx. 0.002" thicker than gasket surface, fire ring "rebound" from installed height is estimated @ 0.002" ~ 0.003".


Jerrys Gaskets Thickness
New @ fire ring 0.0605"
New @ graphite surface 0.0603
New @ silicone bead n/a

Used @ fire ring "pending actual measurement"
Used @ graphite surface "pending actual measurement"
Used @ silicone bead "n/a"

Projected installed thickness and the difference

OEM 0.067"
J/G 0.055" (0.012" thinner than OEM)

[HAWAIIZR-1]

Hi Jerry,

Thanks for the reply and further explanation on the status. I would have just shot you an email but you already know about the issues I'm having with the Yahoo server over the past week. I know that nothing will come out from you unless it is tested with proven results. It is great to have a dedicated, true professional like you as stated and I can feel more assured about the future of the Z with you in our corner. You know I almost gave up and parted mine out recently; thanks for keeping me in the game and I know I won't regret it once I get to drive it.

I guess I recently bought the last left side head gasket on planet Earth for $31.68 from a GM dealer in Texas (wanted to buy more) and Kurt hooked me up on the right side gasket. I was just asking for the future even though I hope to never have to pull heads again in my lifetime and looking to have a spare set on the shelf.

:fahne:

Craig

[Polo-1]

The good old days, when you could a head gasket for under $40.

[A26B]

The good old days, when you could a head gasket for under $40.

Ain't it the truth!!

I've been working on new head bolts. Original manufacturer told me it would be about $7,000 for tooling and would need to do a min run of 5,000 bolts. I said can't we run less? He said "sure, but it'll cost you the same as 5,000 bolts." I never had the guts to ask him how much 5,000 bolts would cost. Imagine what that would make a set of head bolts cost if you were trying to just get even in 3 or 4 years.:icon_scra

[A26B]

Hi Jerry,

Thanks for the reply and further explanation on the status. I would have just shot you an email but you already know about the issues I'm having with the Yahoo server over the past week. I know that nothing will come out from you unless it is tested with proven results. It is great to have a dedicated, true professional like you as stated and I can feel more assured about the future of the Z with you in our corner. You know I almost gave up and parted mine out recently; thanks for keeping me in the game and I know I won't regret it once I get to drive it.

I guess I recently bought the last left side head gasket on planet Earth for $31.68 from a GM dealer in Texas (wanted to buy more) and Kurt hooked me up on the right side gasket. I was just asking for the future even though I hope to never have to pull heads again in my lifetime and looking to have a spare set on the shelf.

:fahne:

Craig

If you look at the bright side (look at how good you've gotten at working on the LT5.:dancing I hope you never have to pull heads again either Craig. If these head gaskets work out, I will always have them available. Wisah I knew who is going to take over this little LT5 biddness in a few years when I retire again!!:dancing

[HAWAIIZR-1]

If you look at the bright side (look at how good you've gotten at working on the LT5.:dancing I hope you never have to pull heads again either Craig. If these head gaskets work out, I will always have them available. Wisah I knew who is going to take over this little LT5 biddness in a few years when I retire again!!:dancing

Thanks, but I hope you're not planning to retire within the next 20 years or so. Isn't there a Jerry Jr. to take over? :cheers:

[HAWAIIZR-1]

Ain't it the truth!!

I've been working on new head bolts. Original manufacturer told me it would be about $7,000 for tooling and would need to do a min run of 5,000 bolts. I said can't we run less? He said "sure, but it'll cost you the same as 5,000 bolts." I never had the guts to ask him how much 5,000 bolts would cost. Imagine what that would make a set of head bolts cost if you were trying to just get even in 3 or 4 years.:icon_scra

Speaking of head bolts, I was told by someone that got the info from Graham Behan that even though torque to yield bolts are supposed to be used only once, it is safe to reuse another time. How many times can they safely be reused for heads?

[LGAFF]

I have heard of these being reused multiple times(3 or more)

[QB93Z]

..... Wish I knew who is going to take over this little LT5 biddness in a few years when I retire again!!:dancing

Jerry,

The LT5 Business IS your retirement. Everyone needs a project, or retirement would be boring.

Thank you Sir for everything you do for the ZR-1 Comunity.

If you will be the Technical Advisor, I'll take over the business any time you want.

Jim

[-=Jeff=-]

Jerry,

The LT5 Business IS your retirement. Everyone needs a project, or retirement would be boring.

Thank you Sir for everything you do for the ZR-1 Comunity.

If you will be the Technical Advisor, I'll take over the business any time you want.

Jim

I would possibly be interested in that business when you both retire!!

[Pete]

Speaking of head bolts, I was told by someone that got the info from Graham Behan that even though torque to yield bolts are supposed to be used only once, it is safe to reuse another time. How many times can they safely be reused for heads?


If we are talking about head bolts they are not torque to yield bolts you torque them to 118 ftlbs.

I have reused my head bolts i would say about 5-6 times with no issues.

Pete

[A26B]

Speaking of head bolts, I was told by someone that got the info from Graham Behan that even though torque to yield bolts are supposed to be used only once, it is safe to reuse another time. How many times can they safely be reused for heads?

There is no way to quantify how many times a bolt can be reused, whether torque only or torque to yield.

Think of a bolt as being elastic, because it does have those properties. The elastic range of the bolt occurs prior to exceeding the yield strength of the bolt, once a certain amount of axial force has been applied. Once a bolt has exceeded its yield strength and "yielded" then it will have streched permenantly i.e. permenant deformation has occurred.

Permenant deformation can happen in one use or several uses. The only way to know would be to serialize each bolt, have accurate flats machined/ground on both ends of the bolt and an accurate measurement of each bolt taken & recorded. Then when the bolt is removed, it can be measured again & compared to the original measurement. If it is longer, then yield strength has been exceeded and permenant deformation has occurred. The bolt is no longer reliable for its intended purpose.

Now, regarding the elastic range. The idea behind torque to yield bolts is to tighten them very accurately (hence torque-angle procedure) so the bolt will be in the elastic range. When in the elastic range, the bolt act like a bungee cord, maintaining the same clamping force when pressure or temperature changes create additional forces on the parts being clamped/bolted. Constant clamping force prevents damage to certain types of seals, bearing & mating surfaces.

Think of it this way. The upper & lower crankcase parts of the LT5 engine are aluminum. The bolts are steel. You assemble the engine at ambient temperature, but it operates maybe 200F higher than that. Aluminum expands at roughly 2-times the rate as steel with an increase in heat, i.e. coefficient of thermal expansion. As such, the clamping force applied to the lower crankcase at ambient temperature would be higher at operating temperature because the thickness of the lower crankcase increased more than the bolt grew longer.

However, because the bolt was in its elastic range, it stretched (below the yield point), maintaining the same clamping force. Now, you can see that bigger bolts are not the answer to all problems. They can actually cause problems. Bigger is not always better.

I developed a concept to test used head bolts and discussed it with a bolt engineering firm. In short, bolts do not always behave exactly the same way (longer story) so there is no way to definitively determine if a used bolt can still be used, by testing. This particular engineer tried many procedures and came up with varying results, noe of which gave a predictable answer. Measurement is the only accurate way.

So, in summary, every time you reuse a bolt that has been installed as a torque to yield application, it's a gamble. The degree of risk is essentially unknown, but has been somewhat established by practice. I say somewhat because cam sprocket bolts have broken in service.

To the best of my knowledge, there have been no head bolt failures from re-use.

[Polo-1]

Ain't it the truth!!

I've been working on new head bolts. Original manufacturer told me it would be about $7,000 for tooling and would need to do a min run of 5,000 bolts. I said can't we run less? He said "sure, but it'll cost you the same as 5,000 bolts." I never had the guts to ask him how much 5,000 bolts would cost. Imagine what that would make a set of head bolts cost if you were trying to just get even in 3 or 4 years.:icon_scra

ARP told me after I gave them my spec's $171 per stud ( not including nut and washer)... This was for the mains.

[HAWAIIZR-1]

Thanks for all the information and as always I appreciate the input by all as I am trying to be a sponge for information and learn as I go. I understand that a lot of information is available on the internet and in books but nothing beats real, first hand information from folks with the exact application and experience. I am going to reuse my head bolts because I can't afford to buy new ones at this point and I surely don't want to be the first to break head bolts but it sound like they have been reused way more times than I plan to.

I know one thing, I am not going to get crazy with higher than recommended redline or disregard recommendations about oil, or attempt any forced induction or nitrous applications to my LT5. :fahne::handshak:

[BOB HDZ]

i use a cotton polishing wheel on my bolts works the same and doesn't take any metal off the bolts!

[Pete]

Hi Jerry
Can you give us an idea on the price for a set.

Thanks
Pete

[A26B]

Pete, I will be better able to do that once all the testing & verification is done.

[A26B]

Jerrys Gaskets Head Gasket Testing is Sucessfully Completed

Testing was performed on a stock, 90 model, 375Hp engine over a two day period.

I have placed an initial stock order for 50 LH and 50 RH head gaskets, which should be available for immediate shipment on Oct 7th.

J/G head gaskets can be purchased individually but should not be installed in conjunction with any other type of head gasket as differences in compressed thickness will result in un-equal compression between cylinder banks.

Pricing is $79.75 per gasket. Gaskets are individually packaged.

A technical data sheet and installation guide is being prepared and can be viewed on the J/G website when the gaskets are in stock for sale.

Thanks to everyone and all of your support. Without you, J/G would not have been able to develop the head gaskets, as well as several other new parts that are in critical short supply or no longer available.

J/G has also developed and ordered into production, Cam Sprocket bolts and Valve Spring Seats. Both items are improvements on the OEM part, made from higher strength alloy steel.

Cam Sprocket bolts were specially made to duplicate the OEM design with a tall, 6pt hex drive to better facilitate torque-angle tightening during the cam timing procedure. Availability is expected around Nov 25th.

[-=Jeff=-]

Sept. 7? Or do you mean Oct?

otherwise congrats on the successful test

[A26B]

Sept. 7? Or do you mean Oct?

otherwise congrats on the successful test

:icon_scraWhy of course I meant Oct 7th!!

(thanks)

[tpepmeie]

Jerrys Gaskets Head Gasket Testing is Sucessfully Completed





Jerry,
The :thumbsup:icon just isn't big enough. Many thanks for pulling this off.

Todd

[-=Jeff=-]

:icon_scraWhy of course I meant Oct 7th!!

(thanks)


No Problem, Sept 07 is a long way off now

:cheers:

[White Bullet]

That is great Jerry. Without your support we would be in deep ###t. You are the man. :cheers:

[Paul Workman]

Jerrys Gaskets Head Gasket Testing is Sucessfully Completed

Testing was performed on a stock, 90 model, 375Hp engine over a two day period.

I have placed an initial stock order for 50 LH and 50 RH head gaskets, which should be available for immediate shipment on Oct 7th.

J/G head gaskets can be purchased individually but should not be installed in conjunction with any other type of head gasket as differences in compressed thickness will result in un-equal compression between cylinder banks.

Pricing is $79.75 per gasket. Gaskets are individually packaged.

A technical data sheet and installation guide is being prepared and can be viewed on the J/G website when the gaskets are in stock for sale.

Thanks to everyone and all of your support. Without you, J/G would not have been able to develop the head gaskets, as well as several other new parts that are in critical short supply or no longer available.

J/G has also developed and ordered into production, Cam Sprocket bolts and Valve Spring Seats. Both items are improvements on the OEM part, made from higher strength alloy steel.

Cam Sprocket bolts were specially made to duplicate the OEM design with a tall, 6pt hex drive to better facilitate torque-angle tightening during the cam timing procedure. Availability is expected around Nov 25th.

Great news, Jerry!!

And btw, your valve stem seals seem to be top notch as well. I've been cycling my LT5 a bit, and there isn't a bit of smoke on fire up, even after sitting for a week! :thumbsup::thumbsup: Thanks for all you do for all of us!!

P.

[A26B]

Thanks all.
BTW, I've put the gaskets up on the website, along with the Tech Data Sheet. If you see anything in the data that looks odd, let me know. Photos of the gaskets are up too.

[shaynezrl]

Jerry, Thank you for all your effort. One more part i will ad to my collection soon.

Shayne

[A26B]

When the stress is sufficient to permanently deform the metal, it is called plastic deformation. This applies to camshaft sprocket bolts.

Now having said that.....what is the relationship between bolt torque, thread lubrication, and bolt tension?

The preload on a bolt, when determined via the torque method, can be off by as much as 25% even with proper precautions being taken especially between lubricated and dry bolt threads.

The purpose of bolt thread lubrication is to ensure that the applied torque deforms the bolt along its axis (stretch) instead of around its diameter (twist).

I have seen a statement that the standard for thread lubrication is a light coat of oil of about 10W viscosity. A thin coat of most engine oils does just fine. The idea is to allow the threads to move against one another and light oil does that reliably. Of course, this standard assumes that the threads of the bolt and nut, or case, or whatever, have reasonably smooth finishes. Exotic or extreme-pressure lubricants such as gear oils or moly pastes are mostly a waste of time and can actually be harmful if they reduce friction too much.

I on the other hand for oil pan bolts and other bolts on engine components such as the water pump, front engine cover (especially threaded into aluminum) use blue thread locker which by itself is a bolt lubricant. I clean and dry the bolt hole and bolt threads (I use a fine wire wheel on bolt threads including head bolts) with gasoline on a que tip for example cleaning out debree and oil films as much as possible. This applies to head bolt threaded holes as well.

You can reuse head bolts but I prefer to use new head bolts since I have no clue how they were first installed. It also depends on how hard they were to remove.

So.....the debate is not if you can reuse head bolts but rather should you use any kind of lubricant or sealer such as permatex gasket sealant when you install the head bolts :D

I use a light coat of permatex gasket sealer on the head bolt threads which it is my thinking will help prevent corrosion and bolt locking next time I want to remove a head bolt.

The permatex gasket sealer displaces moisture and oils that might remain or find there way into the threaded hole receiving the head bolt. The permatex gasket sealant (wipe the thread with paper towel so coating is very thin) assures consistant bolt torque/bolt tension relationships.


What say you ;)

I say.... follow the GM Service manual. The LT5 engine was engineered by some of the best in the world. If they recommend a light coat of oil on the head bolts, then I think that's what should be done. As such, I don't see a debate here, nor do I concur with the use of permatex on the head bolts.

I am concerned that the post "pointed to" in this thread by "Solutions" may mislead a casual reader. I would recommend that the point to Dynomites post be modified to the entire thread instead, so that the reader may form his decision objectively, based on the reading of the entire subject matter.

[a1991zr1]

re used head bolts here with no problems 15 k later I oiled them like the sm said.