bb69

Virtually every OEM rocker body is stamped steel. The reasons are 1)lightweight 2)stiffness 3)surface hardness. One major reason for making the aftermarket rockers out of AL, is because they can be extruded. Extrusion equipment is less expensive than stamping equipment and the related tools. An extrusion die is magnitudes less expensive than a progressive die. The AL rockers then have to have a steel cup or a roller tip added at the interface with the valve so it won't wear out. Without that, the rocker wouldn't last a day.

Lots of things are different today than they were when GM was cranking out 427's in the 60's. You don't see too many distributors or carbs, or gear drive oil pumps these days. Does that mean coil packs, EFI, and gerotors aren't as good? No. It means that the technology and the understanding of the engine has increased. GM went to full roller, I mean roller trunnions and roller lifters, to decrease friction and increase durability.

Guru_4_hire

So the LT4 was an abortion with the aluminum roller lifters?

Tom454

"As for the tips, a properly designed tip has a larger diameter and crown than a roller tipped rocker. The result is higher contact pressure, and resulting friction and wear, than a non-roller tip."

So... to restate... A stamped rocker has a larger contact patch with the valve tip than a roller tip rocker, and the load is distributed over a wider area.... less load per unit area translates into less friction, and less wear. ?

Assuming the roller tip actually rolls and there is a resulting reduction in stem/guide side loading, then it becomes a trade-off between less side loading/guide stem wear vs less tip/rocker wear?

Doesn't the "rolling" of the tip already offset the detrimental loss of contact patch ?

Just trying to add it all up.

Would love to see actual "lab" results regarding this.

This has all been beaten to death but I still enjoy it.

The Money Pit

I bet the vender with the hottest booth babe sold the most engines.

mandm1200

Dep, I believe there was no real discussion on the price of roller rockers. You choose the Crane Gold Race Rockers which are about $300 in the Summit catalog.
Here are some prices of other rollers from Summit:
Summit's $189
Harland Sharp $200
Trick Flow $215
Summit's (different set) $160
Proform $149
Crane Energizer $195

I would hope the Crane Gold rockers are better as they cost quite a bit more. Do you think the above rockers self destruct all by themselves? If that were the case, I don't think they would keep selling them. I wouldn't automatically change them if I had stamped rockers. When building a new engine with new parts, the above rocker will add $100 to the price; give or take a few bucks.

If replying, try and make a reasonable point. Not like, 'if these Proform rockers are so good why don't the Nextel Cup teams use them'. That answer is simple. They have 2 millions dollars to spend on engines and if they don't spend all of it, they'll have a tougher time getting the sponser to pay more the follwing year.

DJ Dep

The fact is, the "rolling action" on the tip is non-existent. The tips DON'T roll at all. The roller tip merely stays in contact better. That's it.

Dep

DJ Dep

'if these Proform rockers are so good why don't the Nextel Cup teams use them'

Well..that's a dang good question!!!
NASCAR cup teams don't put crap on the cars that will break in 100 miles. And NASCAR spending is not like governmental spending. They DON'T have to keep spending a fortune in order to get a fortune.

What's the difference in the roller rockers you listed above? I would think longevity/life expectance is the main one. Roller rockers are one of the items that you REALLY "get what you pay for". Buy cheap....get cheap. Don't use NASCAR as a guideline, though. Use NHRA, since they make much more use of them. And don't go by the decals on the cars. Look at the actual parts.

I suspect roller rockers "caught on" because of both advertising and the possibility of an "easy" 15HP. Plus the pros use them. Same thing with 4 tube equal length headers. Forum members LOVE headers.
They will clam HUGE horsepower gains based on how cool they sound or look, plus distorted info from fellow members. "I gained 50HP by just bolting on headers".
4-tube is great for the strip on a race engine. Much LESS effective bottled up with pipes and mufflers. The Tri-Y design is actually the best header setup for the street. But nobody wants to use them because they aren't what the racers use. Oh well...blissful ignorance

Dep

mandm1200

[QUOTE=DJ Dep
Same thing with 4 tube equal length headers. Forum members LOVE headers.
They will clam HUGE horsepower gains based on how cool they sound or look, plus distorted info from fellow members. "I gained 50HP by just bolting on headers".
4-tube is great for the strip on a race engine. Much LESS effective bottled up with pipes and mufflers. [/QUOTE]

Dep: I don’t recall seeing those posts. However; there was some posting about gaining 30-50 hp by changing the complete exhaust including the addition of headers. If you’re looking to put a 2 into 1 exhaust system on your ‘drag’ car, I’m sure there are members here who will give you all the pieces including the catalytic converter. Using roller rockers could make up the slight loss of horsepower from using the mid/late 70’s exhaust.

The car/engine does not care nor does it know if the pedal is floored on the highway or drag strip. If there is no reason to have a free flowing exhaust, then why do they even make them? I certainly would not have spent hundreds of dollars if there were no difference. I do not have money to throw around and I am not planning to place stickers on my car letting others know I have equal length 4 tube headers and true duals.

bb69

Tom,
I had a long reply typed up, but the server apparently didn't like it and it was lost. Dep is correct, the roller doesn't really roll. At best, it just rocks back and forth a little. The load on the valve and guide is a function of the relative position between the rocker tip/roller and the valve tip. We designed the interface so that the rocker tip was as close to centered over the valve when the valve was at max lift/spring pressure. However, this is not always possible because the valve tip can "fall off" the crowned surface. As the rocker and valve move, the contact patch also moves. It is a compromise. Anything other than a 90 deg angle between the valve and the rocker is going to put a side load into the valve and guide no matter what tip you have.

DJ Dep

[QUOTE=mandm1200]<sigh> Misunderstood as usual

If anyone is gaining 30-50 HP by JUST installing headers, then they are using an L-88. That is the ONLY engine I know that would give that level of boost without doing a whole lot of ADDITIONAL stuff to the car. I don't give a crap WHAT muffler or pipe system you use, you can't GAIN horsepower by RESTRICTING exhaust flow. Catalytic converter???? WTF is THAT???? My car is a 1972. Even if I had a 1980 I would NOT have a catalytic converter on it. Not unless I was trying to compete in that NCRS stuff. Roller rockers give you 3-5 HP and an expensive bill for buying them. No thanks.

I NEVER said there was no reason for a free flowing exhaust. What I said was 4 into 1 headers were not the BEST setup for you street Stroker Aces. They are made to give maximum HP gain at HIGH RPM. That would fit MY need...not some top down bling-bling machine cruising to McDonalds.
Best gain from 4 into 1 headers on the street is loss of weight. Cork them up with muffler and pipes and you won't get anywhere near the amount of horsepower that they could give wide open.

Dep

flood

Wouldn't a sliding piece of metal introduce more loading than a bearing?

What about with high lift? It just seems to make sense that a bearing is better suited for the job.

DJ Dep

[QUOTE=mandm1200][QUOTE=DJ Dep
Same thing with 4 tube equal length headers. Forum members LOVE headers.
They will clam HUGE horsepower gains based on how cool they sound or look, plus distorted info from fellow members. "I gained 50HP by just bolting on headers".
4-tube is great for the strip on a race engine. Much LESS effective bottled up with pipes and mufflers.

Dep: I don’t recall seeing those posts. However; there was some posting about gaining 30-50 hp by changing the complete exhaust including the addition of headers. If you’re looking to put a 2 into 1 exhaust system on your ‘drag’ car, I’m sure there are members here who will give you all the pieces including the catalytic converter. Using roller rockers could make up the slight loss of horsepower from using the mid/late 70’s exhaust.

The car/engine does not care nor does it know if the pedal is floored on the highway or drag strip. If there is no reason to have a free flowing exhaust, then why do they even make them? I certainly would not have spent hundreds of dollars if there were no difference. I do not have money to throw around and I am not planning to place stickers on my car letting others know I have equal length 4 tube headers and true duals.[/QUOTE]


<sigh> Misunderstood as usual

If anyone is gaining 30-50 HP by JUST installing headers, then they are using an L-88. That is the ONLY engine I know that would give that level of boost without doing a whole lot of ADDITIONAL stuff to the car. I don't give a crap WHAT muffler or pipe system you use, you can't GAIN horsepower by RESTRICTING exhaust flow. Catalytic converter???? WTF is THAT???? My car is a 1972. Even if I had a 1980 I would NOT have a catalytic converter on it. Not unless I was trying to compete in that NCRS stuff. Roller rockers give you 3-5 HP and an expensive bill for buying them. No thanks.

I NEVER said there was no reason for a free flowing exhaust. What I said was 4 into 1 headers were not the BEST setup for you street Stroker Aces. They are made to give maximum HP gain at HIGH RPM. That would fit MY need...not some top down bling-bling machine cruising to McDonalds.
Best gain from 4 into 1 headers on the street is loss of weight. Cork them up with muffler and pipes and you won't get anywhere near the amount of horsepower that they could give wide open.

Dep

flood

Or trying to drive it legally on the street Thats what your always talking about right? Street use?

mandm1200

What are you talking about. The only mention of gaining 50hp by headers only is your post. The people gaining a decent amount of hp are people who had the 2-1 with cats and changed out the complete system.
I'll repeat it since you keep missing it. The people gaining a decent amount of hp are people who had the 2-1 with cats and changed out the complete system.

So what you are saying in a round about way is that changing the restrictive exhaust on the mid 70's will give horsepower. I knew you would not come out and say it, but never the less you admitted it. Don't be bashful, just come out and say it.

DJ Dep

Yeah right. Only I CAN drive legally on the street WITHOUT a catalytic as long as I have antique plates. So if I did buy a Caprice-engined smog motor, the catalytic and smog pump would be the first two items of removal
Still trying to figure out the reason someone needs 5000HP to drive to Wallmart to buy groceries in a car that can barely carry a box of Kleenex

Dep

flood

Im going out on a limb here, but maybe because its fun?

DJ Dep

Okay....let me take you by the hand and explain this. There are MANY claims on the forum stating the 30-50 HP gain by installing headers. If there were a poll of most popular change on a Vette, I'm sure headers would finish in first place, followed by gold roller rockers

Let me repeat....the MAXIMUM amount of HP gain from 4 tube headers is when they are WIDE OPEN with NO mufflers or pipes or catalytic crap at HIGH RPM. I don't give two squirts about people with loud Flowmasters or "true duals" who base their power numbers on how loud the neighborhood windows rattle or on seat-of-the-pants "feel" or BS advertising claims by muffler manufacturers.

I HAVE NO USE FOR ANY EXHAUST SYSTEM. There...is that plain enough for you??? Open 4-tube headers make the maximum power at high RPM. Hooking up anything that makes them "streetable" LOSES power. No round about to it.

Dep

DJ Dep

Well let me try and figure this out. I suppose if you're into the engine-building part of hot rodding (which I am), it IS fun to BUILD an engine that makes 500HP. But I would get more FUN seeing how quick it ran at the strip.

Certainly if you consider spending money "FUN", you can have a blast with making 500HP.

But driving to WALLMART with a 500HP engine, when the speed limit is 35MPH, I can't see the "fun" in that.

Dep

flood

Speedlimts? I think its a blast driving even the speed limits in a way overpowered car.

Also Federal law makes it illegal for ANYONE to tamper with, disconnect, remove or otherwise render inoperative ANY emissions-related control device.

Just depends on the laws you want to break I suppose. Your less likely to get caught tampering with emissions-related controls than speeding but both are against the law.

mandm1200

Maybe that would be a good poll.
'How much horspower gain is attainable by swapping out my 2 into 1 exhaust with cat to headers, true duals, and no cat':
5hp
10hp
20hp
30hp
40hp
50hp

As for the MANY that claim 50hp by changing stock exhaust manifolds to headers without changing anything else, I must have missed them posts. If that's what they claim, I'm on your side and will also toss out the flag.