What material is stock headgasket?

[yieldsign2]

I have an 89 3.9L RRC, what should the stock headgasket material be? The one I removed is all metal (steel?), just wondering if it is stock that way or if there is fiber/fabric type as well.

[bartell]

Originally Posted by yieldsign2

I have an 89 3.9L RRC, what should the stock headgasket material be? The one I removed is all metal (steel?), just wondering if it is stock that way or if there is fiber/fabric type as well.

There is. Pre-4.0/4.6 engines use metal head gaskets and 4.0/4.6 use composite fiber gaskets. The later gaskets are much better.

However, they are also thicker. To keep up the engine compression, LR skimmed the 4.0/4.6 heads (which also reduced the size of the combustion chamber). If you use these gaskets with your heads, your engine compression will drop and you can expect a power drop of 15-20bhp (8-11%) Of course if that doesn't bother you, your engine will last longer and be less likely to ever blow a head gasket again.

BTW, a cheap move for more power for a 4.0/4.6 is to switch to the earlier metal head gaskets. The compression rises to 10.1:1 and there is another 20+bhp.

James

[yieldsign2]

Very interesting on the HP! I would assume you cant double up gaskets on the 3.9 and get more power

[bartell]

Originally Posted by yieldsign2

Very interesting on the HP! I would assume you can't double up gaskets on the 3.9 and get more power

No Devon. It works the other way.

All other things being equal, the size of the combustion chamber influences engine compression. If you reduce the size of the combustion chamber, the more it will compress the same air/fuel mixture and the bigger a bang that will result. If you increase the size of the combustion chamber, you will reduce the force of the combustion.

The size of the combustion chambers are determined by their shape in the head and part of their height is the thickness of the head gasket. Racers often skim the heads to lower the combustion chamber height and increase horsepower.

LR head gaskets for the Buick 215s, 3.5s, 3.9s, 4.2s are thin metal. The thick composite gaskets were made for the 4.0 and 4.6s and are/were an attempt to cure the constant issue of easily blown head gaskets with the earlier models. However, by switching to thicker gaskets and nothing else, LR would have increased the height/size of the combustion chambers and that would have lowered the compression and bhp. So they compensated by skimming the heads (lower) to match the added height difference between their new composite gasket and the old metal ones.

Moving a 3.9 to composite head gaskets makes your engine far less likely to have a head gasket issue, lowers its compression (which makes it easier on the bottom end) and lowers its horsepower. If you want to have the same compression and a composite gasket, either skim your heads or switch to 4.0/4.6 heads (though I would be concerned with the lower row of bolt holes...4.0/4.6s have 10 head bolts each and the other engines have 14).

For the 4.0/4.6 people, the switch is hassleless. Switch in an older metal gasket for the composite. As the heads are already skimmed, that increases the compression to 1960s levels and bhp increases accordingly.

There are so many ways to increase horsepower...especially with these engines. I would take a wholly different route with your model. However, whatever the model, it must be remembered that a vehicle is designed as a cohesive assemblage. Change one thing, and you begin a domino effect.

James

[p76rangie]

Once the head is tightened down, the difference between the thicknesses of the two types of gaskets is bugger all. In theory, there will be a very slight change in compression and power, but nothing you will notice and certainly not 10% change.

If you are doing head gaskets, you should have the heads skimmed anyhow. The skimming will adjust for the majority of the thicker head gasket.

[bartell]

Originally Posted by p76rangie

Once the head is tightened down, the difference between the thicknesses of the two types of gaskets is bugger all. In theory, there will be a very slight change in compression and power, but nothing you will notice and certainly not 10% change

Where DO you get your information from?! Here is note from a guy trying to SELL Rover composite gaskets and yet admitting the compression drop. RPi Engineering - V8 Engine and Component List

Please ask around a bit more or, alternatively do hands on research..like we do. There is not an single Rover race engine builder alive who would back up what you say. Alternatively, if you do not have facilities, simply examine NEW 4.0/4.6 heads next to 3.5 or 3.9s and then explain why the former are measurably skimmed. It will only take you a few seconds.

James (sigh)

[p76rangie]

Originally Posted by bartell

Where DO you get your information from?! Here is note from a guy trying to SELL Rover composite gaskets and yet admitting the compression drop. RPi Engineering - V8 Engine and Component List

Please ask around a bit more or, alternatively do hands on research..like we do. There is not an single Rover race engine builder alive who would back up what you say. Alternatively, if you do not have facilities, simply examine NEW 4.0/4.6 heads next to 3.5 or 3.9s and then explain why the former are measurably skimmed. It will only take you a few seconds.

James (sigh)

Look up the difference in power between a 4.0 or 4.6 high compression motor to a low compression motor. Then look at what compression ratio drop you could expect with just changing the head gasket. Not 10% power drop. Find on the RPi site where a 10% power drop is listed.

You might be stupid enough to replace a head gasket without getting the head skimmed, but not many people would. So back to my original statement, the difference in power is 5/8ths of FA.

Seeing that you want to quote RPi, here is an extract from their website:
"Fit composite gaskets. This is the surest way of getting the best head gasket seal, but unlike the above option, will lower the compression ratio by a factor of about 0.6-1 (important to some but not to most).

How much lower? As an example, a 9.35-1 compression engine would realize a compression of about. 8.65-1 using composite gaskets (composite gaskets are thicker than conventional gaskets by a compression factor of about 0.6-1)."

Now the difference between a high compression Rover V8 and a low compression is 9.35 to 8.13, or double the drop in compression ratio caused by the change in head gasket. For a 3.9 motor the drop in power between a high comp motor and a low comp motor is 5.2% and for the 4.0 it is 5.7%. So with double the drop in compression ratio it still only affects the power by HALF what you are quoting.

So what "RESEARCH" do you do besides working out whether it is better using the left hand or right hand.

[TerryS]

I'm not interested in interfering with the great rapor the two of you have developed, but I'll add my two cents on the topic, based upon hands on experience, and the results of some yankee curiosity thrown in.

First off, the idea of a Rover Race engine is somewhat an oxymoron. The best engine design in the family was purchased more than thirty years ago from General motors, and before it was ever put into production in the UK, it was altered for the worse. The original Buick 215 was an 18 head bolt design, where there were six equally spaced head bolts surrounding each combustion chamber, equidistant from the bore centerline. The brains that recognized the change to 14 as a poor idea, was not sufficient to say "lets go back to 18". It decided that too many engines out there, so it would be better going to 10, so that's where they went. (all the change did was negate "The Possibity of cantilever effect)
The Buick engine used the steel gasket, which is not simply a sheet of steel, but pressed with a waffle texture which increases the surface forming the actual seal, the engineering being that many smalled raised surfaces are better than a single flat surface (otherwise, why use a gasket at all?)
The composite gasket design is nothing new, and has been used on large diesels for years, whose compressions are many times greater than these puny aluminum V8 engines.
Comparing the two ROVER head gaskets (on Brown & Sharp validators, whose accuracy, admittedly, is only to +/- 100 Microns) says that the uncompressed thinkness of the composite gasket is only marginally thicker than the uncompressed waffle steel gasket. The copper ring surrounding the combustion chamber is fairly compressable as compared to the overall surface area of the graphite impregnated material, but will only compress to the maximum the total surface will allow.
The steel gasket does not compress substantially below it's uninstalled thinkness.
I have only scratch built a couple of these engines, but rebuilt quite a few more. Using a scrap 3.9 block (easier to get on the table of the validator than my whole 110) we put one of each on the block, compressed in the manner each individual gasket was supposed to be installed and found the difference to be so small, that normal engine rebuilding practice of "Surface To Flat" would most likely negate any differences. I have always done "STF plus .010" (and actually did my 4.2 STF+.020)
I will say that I think using the composite gasket would allow a person to install without any skimming, but the known propensity of the aluminum head to "move" requires skimming to flat if the steel gasket was used.
In real life, the EFI engines perform with such irregular repeatability, that A) I seriously doubt the difference in HP is any where near 10%, and B) I doubt, without measuring on a lab dyno, anyone would detect a difference.
It's been many years since we did the measuring and I haven't any idea if I even saved my notes, but I really don't think we came up with anything like
.6/1 change in CR (6.6%) maybe more like 3-4%

[ArmyRover]

I was wondering when Bartell and Ian would meet.

I would however agree with Terry on this one. Oddly enough I guess I agree with Ian as well. Hmmm gotta check with Satan to see if hell froze over.......













Nope hell didn't freeze my mom said the weather was great

[bartell]

Originally Posted by p76rangie

Find on the RPi site where a 10% power drop is listed.

I did and linked to it. To make it easier for you. here it is "
"These gaskets are made of alternate layered material and are slightly thicker than the standard tin gaskets (lower compression by a factor of 0.7-1)

Originally Posted by p76rangie

You might be stupid enough to replace a head gasket without getting the head skimmed, but not many people would. So back to my original statement, the difference in power is 5/8ths of FA.

Dear Skimmer,

Try again. I said twice (now three times) that the 4.0/4.6 heads come effectively pre-skimmed to make up for the loss of compression from their thicker gaskets.

You ignore that and run to point defective old heads and the new gaskets. You deny any compression change because any "stupid" should skim heads whether they need or not.

Firstly, why did you move us from new head 4.0/4.6 to old? Secondly, why on earth would someone skim perfect heads? No one skims heads for the fun of it. That is idiotic. We have tested scores of heads. You can find out how to do it in every manual for this engine ever written. Buy one.

My RESEARCH is done hands with a racing team and racing circuits. Yours is apparently the last person who you spoke to. Presenting facts to you is futile. You do not seek to help the needy or find knowledge, you are simply here to win arguments by any means.

I know first hand that your information is erroneous. I am only saddened for the damage you may be causing to the innocent.

James

[bartell]

Originally Posted by TerryS

I'm not interested in interfering with the great rapor the two of you have developed,

Yes. Do not deny us our new found passion! It does get the adrenalin going! (Admittedly I have been mesmerized by the finger in his nose from the first.)

Originally Posted by TerryS

The best engine design in the family was purchased more than thirty years ago from General motors, and before it was ever put into production in the UK, it was altered for the worse.

Er...I respectfully beg to differ. I have no problem in pointing out bad mistakes Rover and LR have made but they developed the engine far beyond anything Buick/Olds could do. They only REALLY ruined the engine much later. However, they have recently come back with style

On the heads issue, their move from 4 bolts to 10 cured the problem, Nuff said. It is a little late to tell them go back to 18 bolts to cure a problem that no longer exists.

The Buick 215 was remarkable for its time though riddled with flaws..not the least of which was GM couldn't cast the thing. At the end, they were tossing more blocks than not. The Brits solved that.

However, it wasn't until the Australians showed what was really possible with this engine that things significantly developed. The SD1 was a huge step forward and the "stiffer" Vitesse version adopted ball for almost 2 decades. Both are FAR superior to US originals.

The point they hurt the block when they over-bored it to 94mm for the 3.9, 4.2, 4.0, 4.6. That heralded the inevitable demise of the engine block as it was cast then. As the mixtures became leaner, blocks cracked and loose liners became epidemic.

However, top hat liners can take care of these issues and the Coscast block is marvelous. Have you examined one closely yet?

Originally Posted by TerryS

Comparing the two ROVER head gaskets (on Brown & Sharp validators, whose accuracy, admittedly, is only to +/- 100 Microns) says that the uncompressed thinkness of the composite gasket is only marginally thicker than the uncompressed waffle steel gasket.

"Marginally" is a relative term. What seems a minor difference has a substantial effect on compression. Trust me. I live in a world where every whp makes a difference.

Originally Posted by TerryS

I will say that I think using the composite gasket would allow a person to install without any skimming, but the known propensity of the aluminum head to "move" requires skimming to flat if the steel gasket was used.

We have verified scores of used heads. We have not seen the propensity you speak of. Some heads do require skimming but no where near the majority. Or are you referring to Buick 215 heads? I am not deeply familiar with them. We have worked with Buick 300 heads.

Frankly, if I was a road driver, I would have no problem in switching to composite with an earlier engine. If the engine is that old, a little less "pop" is better for it in the long run and the missing bhp is worth the security of the better gaskets.

Originally Posted by TerryS

In real life, the EFI engines perform with such irregular repeatability, that A) I seriously doubt the difference in HP is any where near 10%, and B) I doubt, without measuring on a lab dyno, anyone would detect a difference.

We measure EVERYTHING on the dyno..best tuning tool in the world but often humbling.

Originally Posted by TerryS

IIt's been many years since we did the measuring and I haven't any idea if I even saved my notes, but I really don't think we came up with anything like .6/1 change in CR (6.6%) maybe more like 3-4%

We do. And we have been doing it weekly, if not more, for ages.

Originally Posted by TerryS

First off, the idea of a Rover Race engine is somewhat an oxymoron.

You should tell that to TVR, Ginetta, Caterham, Marcos, Morgan and the others. They would probably disagree.

Terry, the cutting edge for the development and tuning of these engines long ago moved to the UK..with some great stuff from Downunder (in engine management) on occasion. Racing 4.6s produce comfortably in the high 300s. 5.5s are common and now, with the remarkable new Coscast block, I know of 6 liter projects in the works. (!)

You have to visit Britain to see what has happened in the last few decades and what iis happening now. Go see J.E. Developments or Real Steel or JanSpeed, or even John Eales. Stop in at the Coscast plant, check out Wildcat Engineering.... Best of all, go to see all their products race at Silverstone, Brands Hatch, Oulton Park, Donington, Mallory..etc or the Spa in Belgium. Watch a phalanx of LR V8 engines come screaming down the turn and reconsider your oxymoron.

Probably be one of the best trips of your life (if it doesn't rain).

Things have happened since 1964.

James

[TerryS]

Originally Posted by bartell

On the heads issue, their move from 4 bolts to 10 cured the problem, Nuff said. It is a little late to tell them go back to 18 bolts to cure a problem that no longer exists.

Didn't I say that?

Originally Posted by bartell

The Buick 215 was remarkable for its time though riddled with flaws..not the least of which was GM couldn't cast the thing. At the end, they were tossing more blocks than not. The Brits solved that.

Well, if writing a check was solving it. The casting developement work was performed by Kohler General, in Wisconson, after the rights were sold to the Rover Group.

Originally Posted by bartell

However, top hat liners can take care of these issues and the Coscast block is marvelous. Have you examined one closely yet?

The tophat sleeve was a logical move. Too bad Rover hadn't adopted it, instead of some of the very qualified aftermarket engine builders.
Point of fact, GM Diesels (53,71, 110, 215 &278 series 2 cycle engines, not the little car engines) have used lipped liners since, oh, about WW2.
I don't know what Coscast is. Is it another name for Replicast, the ceramic shell, lost foam process? That's a UK developement (CTI) of which I was the only successful licensee in the US.

Originally Posted by bartell

We have verified scores of used heads. We have not seen the propensity you speak of. Some heads do require skimming but no where near the majority. Or are you referring to Buick 215 heads? I am not deeply familiar with them. We have worked with Buick 300 heads.

The internal coring of the buick head is entirely different. These changes to the core boxes first came with the switch to 14 head bolts. About the same time as the crossbolted block came out, there were additional changes to the core design. I think it would be pretty rare to see a head off a pre Bosch engine still flat.

Originally Posted by bartell

Frankly, if I was a road driver, I would have no problem in switching to composite with an earlier engine. If the engine is that old, a little less "pop" is better for it in the long run and the missing bhp is worth the security of the better gaskets.

No argument here. I doubt anyone replaces the steel gaskets with the like.

Originally Posted by bartell

You should tell that to TVR, Ginetta, Caterham, Marcos, Morgan and the others. They would probably disagree.

No thanks. My only experience with Caterham was to visit the plant, (after having two original Sevens of my own, One a 7A (BMC, the other a Cosworth SCA) The success of that application may be in part that each of those cars are less than half the weight of a RR. This is aside from the fact that I learned fairly early on that you can't tell a British Engineer anything. I have never met a group with a bigger "Not Invented Here" attitude.

Originally Posted by bartell

You have to visit Britain
Probably be one of the best trips of your life (if it doesn't rain).

Uh, I did. 4 to 6 times a year for 14 years, working with CTI (Casting Technology International, in Sheffield, formerly know as SCRATA, Steel Casting Reasearch and Trade Association. In addition I was the US representative for Lloyds Burton, a large steel foundry, (Burton On Trent) for many years. The only rewarding part of that was that BASS was directly across Wellington Road, and The Bridge, oldest Pub in the Midlands, was just up the street.

[p76rangie]

Originally Posted by ArmyRover

I was wondering when Bartell and Ian would meet

We met in the engine flush thread a few months back. He spat out his stupid facts then too and ended up running away with his tail between his legs. Pity he only stayed away for 1 1/2 months.

[ArmyRover]

really? I must have missed him....

[bartell]

Originally Posted by TerryS

Well, if writing a check was solving it. The casting developement work was performed by Kohler General, in Wisconson, after the rights were sold to the Rover Group.

No argument. But Rover did it, Buick did not.

Originally Posted by TerryS

The tophat sleeve was a logical move. Too bad Rover hadn't adopted it, instead of some of the very qualified aftermarket engine builders.

No argument. However, by the end, the production line had aged to the point where the castings were hit or miss. The economics of refurbishing a line that large were not as financially attractive as opting for another engine.

Originally Posted by TerryS

I don't know what Coscast is. Is it another name for Replicast, the ceramic shell, lost foam process? That's a UK developement (CTI) of which I was the only successful licensee in the US.

No. Coscast is a UK casting company with a foundry just outside of Worcestor. I would have thought they had a world wide reputation but maybe not. You might place them better as Cosworth...from their origins.

The aftermarket builders you refer to were not completely satisfied with the top hat solution, essentially an after-the-fact fix (albeit a successful one). They mandated Coscast to redesign the block once again, mold and cast them. The blocks are extraordinary.

Originally Posted by TerryS

My only experience with Caterham was to visit the plant, (after having two original Sevens of my own, One a 7A (BMC, the other a Cosworth SCA) The success of that application may be in part that each of those cars are less than half the weight of a RR.

Absolutely. LRs are too heavy to see what these engines can do. Put one in a 2000 lb racer and they are much fun.

Originally Posted by TerryS

This is aside from the fact that I learned fairly early on that you can't tell a British Engineer anything. I have never met a group with a bigger "Not Invented Here" attitude.

Agreed. But that is not a characteristic privy to the UK. Many in the US, Australia have it as well if truth be told. There is something that makes so many, from engineers to owners, shun anything they cannot source at home, regardless of quality, engineering or ultimate origin. I have seen people pay triple for the same part or avoid a better one just for the thrill of getting a bill from a fellow citizen. Why buy a vehicle from another country?

As you note, the attitude makes cross-fertilization difficult. On the other hand, most countries are notoriously receptive to good ideas or supply from anywhere.

Originally Posted by TerryS

Uh, I did. 4 to 6 times a year for 14 years, working with CTI (Casting Technology International, in Sheffield, formerly know as SCRATA, Steel Casting Reasearch and Trade Association. In addition I was the US representative for Lloyds Burton, a large steel foundry, (Burton On Trent) for many years. The only rewarding part of that was that BASS was directly across Wellington Road, and The Bridge, oldest Pub in the Midlands, was just up the street.

Sure. I know it. The Pub with two floors, gas lamps on the second landing. Proper pub.

Did you get into the Rover production or aftermarket while you were there?

James