solid, roller or hydraulic?
 

Guys,

My 540's have been nothing short of a nightmare eating cams and spitting out lifters like chicklets...

We started with hydraulic lifters and the valvetrain just will not stay together...my mechanic is using ultradyne camshafts and crane hyd lifters. I dunno what the lift and duration is, but my question is this:

What is the best cam configuration with a tall deck 540, team g manifold and holley 1050 dominator carb? Do we go with solid or roller and what should the lift/duration be?

I think we've already decided that hydraulic is not a good choice here...

Ultradyne has some wild profiles. It would help to know what you have. I'm using Crane 651 hyd roller, merlin heads, merlin intake, 1050. Runs great, idles good at 800 rpm. No plug fouling or wierd problems. From what people here say the secret to making these valve trains live is keep rpms down below 5600 and check and replace springs and lifters often

If you've had a series of cam/lifter/valvetrain failures, I would attempt to try to find the source of the problem before making the assumption that you need to go to a solid roller setup. Specifically, what is failing? Assuming that you are using high-quality parts designed for the intended use, which it sounds like you are, I would make sure you don't have geometry, coil bind, interference, or oil pressure/volume issues first.

If you know the flow specs for your heads/intake, it will give you a good idea of what you're valve lift and intensity should be. Duration is more related to the target operating rpm range, engine displacement, static compression and fuel quality, and exhaust system design.

Most (it not all) Merc performance are using hyd. rollers clear down the the 454 Mag. A straight Hyd cam will not work in your situation. I wiped a lobe off 2 different cams in my 454 Mag EFI (hyd cam). I found that later models Merc upgraded to a hyd. roller. The profile is very subjective to type of operation, HP, dependability and life. Call the CAM manufacturer directly for suggestions. Crane was very helpful and knowledgeable for me. They said they did not have a better cam than what I already had for my requirements.

Soilds can be a maintence nightmare for the common boater. The lash on the rockers will need to be adjusted every few weekends. This assumes to can get your valve covers off easily and you know what your doing.

If you are wiping out flat tappet cams ,when the block is at the machinist have the lifter bores checked for squareness to the crankshaft centerline .Poorly machined lifter bores are common and a lot of engine builders bush the lifter bores with bronze bushings.

Rob

MOnty,

Admittedly I am not a mechanic, but I know enough to make me dangerous...therefore, I'd like to know more...

can you elaborate on:

"geometry, coil bind, interference, or oil pressure/volume issues"

Oil pressure has always been good, at around 75lbs running and not below 50 at idle...

I've never run th boat above 5K...more to follw as i get info...

Sean,

I was just suggesting that you attempt to find the cause of your problems before you go through another set of cams/lifters, etc or change to a solid roller. There's got to be a reason you are breaking parts. They are either unsuitable for what you are trying to do, or somethings not set up correctly. Proper valvetrain setup is often a trial and error process, and since you ahve a tall-deck block, the geometry is different than a standard deck height block. You will need longer pushrods, and the proper length typically needs to be determined with an adjustable pushrod length checking tool.

I've got nothing against solid rollers, I run one in my twin turbo Corvette street car. They can be made very reliable, with minimal maintenance, when set up correctly. Due to the lifters ability to handle very intense lobe profiles, they almost always offer a performance advantage over other cam/lifter types. however, the benefit isn't typically realized until higher rpms, beyond the normal operating range of most pleasure boats in many cases. With good lifters (I use Jesel), and a rigid valvetrain, valve lash adjustments will not be required as often. Many cam companies offer "street" rollers which utilize relatively tight valve lash and feature lobe ramps which aren't as hard on the valvetrain as teh more agressive race oriented solid rollers are.

When I mentioned "geometry, coil bind, interference, or oil pressure/volume issues", I was just suggesting that you check the obvious stuff first. Valvetrain geometry is an inclusive term which includes the rockers contact path with the valve stem, as well as the valve, rocker, psuhrod, and lifter relationships. As you are aware, BBC heads have compound valve angles, if the pushrod/valve stem length, and rocker height aren't right, there are side loads imposed that greatly increase wear and negatively impact relaibility and durability. Coil bind means that the individual coils of the valve spring come in contact with each other before or at maximum valve lift. BAsically, the valve is too short or installed too short and the sping becomes "solid" hwile the rocker is still trying to compress it. Bend pushrods are typically the result. Interference can come from many areas, the rocker can contact the retainer, the pushrods can contact the cylinder head, etc. I mentioned oil pressure/oil volume because hydraulic lifters require sufficient oil pressure and voume for proper operation. It is fairly common to restrict oil flow to the top end and valvetrain on high performance engines, although this should never be done when hydraulic lifters are used.

If you could be mor specific about what your problems are, what parts are failing, you can more easily pinpoint what the problem might be.

If your cam has more lift than your springs will allow you are in coil bind. Your springs become a solid mass and will not compress further. Some thing has to give. Also check pushrod length. The rockers should wipe an area across the center of tip of the valves without coming in contact with the spring retainers. Spring pressure is an issue. A lot of people I talk to think that more pressure is better than not enough. It helps keep the valves from floating. 150-160lbs on the seat,450 open. Just some ideas.

Guys,

Thanks for all your help and advice. I've got a lot to learn, but spoke with the mechainc and found out a few things...

Blocks are "Bowtie green siamese" blocks---what does that mean?

Rods are Carillo and pisotns are Wiseco. Heads are Merlin cast iron, but that is about all i know about them. Manley severe duty valves are used.

My hydraulic cam was ultradyne 590 lift. it seems we are going to a solid roller Comp cam with a 625 lift. valve springs are also being replaced with 200lb seat pressure when closed.

whadda ya'll think and what else do i need to find out to determine what this setup will do for me? does it sound reliable?

I have a feeling that the pushrods are correct bcause none of them are bent. The old cam lost a lobe and the bottom of one of the lifters was blown out. all parts were found in the valley...

"Bowtie Green Siamesed" means it's a brand new GM Bowtie block with siamesed cylinders. "Green" means it's brand new and hasn't been seasoned by repeated heat cycles. You'd think an engine block is very rigid, but in actuality the bores and mains will move slightly as the brand new casting is heat cycled through normal use. Obviously these movements are measured in thousandths of an inch, but they can affect piston ring sealing and main bearing wear. It is not uncommon to rehone a "green" block after it's used a bit to accomodate account for the movement.

Siamese means that the water jackets do not completely surround the cylinder. The cylinder walls are solid between the adjacent cylinders and no coolant can pass between them. This greatly increases the rigidity and stability of the bores. In the early days, overheating problems were attributed to this, but it's really not an issue these now.

Bowtie block are GM high-performance blocks sold for racing and high-performance use. They are not production blocks, they have many upgrades such as thicker decks, cylinder walls, splayed maines, blind deck holes, etc. Actually, alot of them are cast and machined by Dart. They are good blocks for high-performance use.

The parts you've listed are generally regarded as high-quality, high-performance, so you should have no problems there.

I'm sure that if you're machinist is competent he has selected the appropriate valvesprings for you cam profile. It's hard to say given teh info provided, you need to know the coil bind and installed height to know for sure.

If you're losing hydraulic roller lifters, the usual cause is either too little or too much spring pressure or insufficient oil supply. There have been manufacturing/material issues with some hydraulic rollers, most notably Comp Cam's Xtreme roller lifters, but those are the exceptions.

I had a Comp Cams solid roller come apart on me recently. 2.5 seasons, 100 hrs. It was on a .690 lift cam. I'm hoping for better this time with a less agressive cam.

Sean,
If you want the info right from the horses mouth you can call Harold Brookshire the former owner and designer of the Ultradyne profiles. He is currently doing a complete redesign of the Lunati line including an updated marine category. He is very helpful and will most likely help you find a solution to your problem.
He designed and made the 440 Magnum cam for Mercury Marine's 454, and the 700 BHP FI 482's roller cam. Also the original 502 cam. He can be reached at 1-901-365-0950 x135. I would suggest you get the grind and lifter part #s before you call him if at all possible. Feel free to email me if you need and further info.
Hope this helps,
Bob

Sean,
Solid rollers are probably not the correct solution in your application. They rely heavily on splash lubrication and can experience lack of proper oiling in no-wake zones or around the dock (under 2000 rpm operation). You wont be operating in an rpm range to really optimize the benefits. Add to that the additional maintenance and the best solution is to correct the existing problems with your hyd roller setup. Proper spring pressures and geometry are absolutely necessary in endurance applications. Try not to rely on generic spring pressure recommendations, find out the specific needs of your particular cam and make sure your springs are providing those specs.
If you are interested in researching this further here are some links to try. Hope this helps.
Bob
Rocker arm geometry
http://www.compcams.com/information/Products/Pushrods/
http://www.jimcookperformance.com/Te...olRocGeom.html
Spring pressures
http://www.rehermorrison.com/techTalk/03b.htm
Lifters
http://www.cranecams.com/instruction...in/camfail.htm
http://www.newcovenant.com/speedcraf...camshaft/5.htm

Thanks to everyone who responded.

it seems the valvetrains really is the "brains" of the motor.

i never realized how important proper cam selection was or how many choices there are out there.

in the end, i left it up to the builder to work his magic...but mostly i wanted to be a little more informed and not just a guy with a wallet(although mine is quite small).

i'm told we're going to hydraulic roller cams which should do the trick. I'll find out more about lift and duration, but for now all i know is they were ordered from CompCams...any suggestions on part numbers?

should pushrods and valves be matched or do you just need to match the cams and lifters?

thanks again for all your help!

GOOD CHOICE!!

Sean,
I would absolutely invest in the recommended valve springs for the cam profile you go with. It is quite probable that was the original problem you were encountering. Set the springs at the closed values rather than suggested installed height, if you have the opportunity check the open pressure also. Once your heads are set up on the motor determine your geometry with a pushrod length check and you'll have a very reliable valvetrain.
Hope this helps,
Bob

I suggest the Comp Cams XM284HR with 230/236 intake/exhaust duration, .547/.547 lift, 112 LSA, installed with the intake lobe centerline at 112 degrees (no cam advance). If you use the recommended lifters, valve springs and push rods it should last as long as any stock GM valve-train. Horsepower should peak at 5,000 rpm.
Dennis Moore

454
 

Dennis that looks like a great cam, how well would it work in a 454?

Sean- Aftermarket Head Company's will roll the Valve angle to increase the flow of the head. If this is the case with your heads...then custom length pushrods are in order. This should be found while checking the geometry of the valve train as explain in Monty's post.

Ask lots of question from your engine builder. Remember it's your money! He should be more than willing to explain everything as long as your don't take up all of his time.

Good Luck!

Duoprop Enticer

It would be ok but a slightly smaller camshaft with a 110 LSA would work just as well on a 454. The Comp Cams XR276HR, 224/230 int/ex, .510/.510 lift, 110 LSA, installed with no cam advance (110 Int. Lobe Cent.), would be perfect with no water reversion.
Dennis Moore