Valve lifters…solid/hydraulic/roller tappet/flat tappet?

[xb-60]

Last time I rebuilt an engine, it was a simple solid lifter setup with flat tappets. That was …hmm…a while ago. Things have changed with lifters since then.
So, my questions….
- Is it a no-brainer to go the roller tappet route, or are there circumstances where flat tappets are preferable? I know the cam lobe tip radius is larger on a roller cam, so maximum lift is maintained for longer. I assume cam lobe and lifter wear is less on a roller setup.
- What are the benefits of hydraulic lifters over solid lifters apart from maintenance and arguably noise? (I say ‘arguably’ because I like the noise).
- Conversely, what advantages do solid lifters have over hydraulic lifters.

I need an update to bring me into “C21”

Cheers,
Glen

[blykins]

In a SBF, the difference between a flat tappet and a roller cam is just a few hundred bucks. It's well worth it to dodge any break-in issues.

My criteria for choosing which cam is pretty simple:

If you plan to stay under 6000-6200, then a hydraulic roller will fit the bill quite nicely.

If you plan to spin the engine up over 6500-7000, then a solid roller is easier to deal with. The caveat to the solid roller cams is that you have to run high spring pressures. The lifters take a pounding from valve lash, so they will need to be monitored in 7500-10000 mile increments.

For most street engines, the hydraulic roller is the way to go. No break-in, no worries, no maintenance.

[xb-60]

Thanks Brent. So when you say the lifters take a pounding, that's only if the clearances aren't maintained to correct limits? If clearances are correct, and 7500 - 10000 mile intervals isn't a deal-breaker, then no other down side?
What precentage of motors do you build that have solid roller lifters?
Cheers,
Glen

[Gaz64]

Originally Posted by xb-60

Last time I rebuilt an engine, it was a simple solid lifter setup with flat tappets. That was …hmm…a while ago. Things have changed with lifters since then.
So, my questions….
- Is it a no-brainer to go the roller tappet route, or are there circumstances where flat tappets are preferable? I know the cam lobe tip radius is larger on a roller cam, so maximum lift is maintained for longer. I assume cam lobe and lifter wear is less on a roller setup.
- What are the benefits of hydraulic lifters over solid lifters apart from maintenance and arguably noise? (I say ‘arguably’ because I like the noise).
- Conversely, what advantages do solid lifters have over hydraulic lifters.

I need an update to bring me into “C21”

Cheers,
Glen

Glen,

The roller cam lobe has a larger radius nose, the reason being the lifter only has wheel contact ( a line of contact ), versus the sweep of a flat tappet cam across the base of a flat tappet lifter.

You can certainly get more aggressive lobes with a roller, versus flat tappet ramps limited by tappet diameter.

Solid roller wheels suffer from the pounding of tappet clearance, once the wheels skid and flat spot, it's goodbye to the cam and lifters.

Each has their advantages and disadvantages.

The higher you wish to spin the engine, the more it costs to have adequate parts for the job, the more likely for long term failure, and the more periodic maintenance required.

A roller cam of either tappet type will give a better spread of torque, than a flat tappet cam of comparable duration.

I'd go for a solid roller every time, but if you don't ticker with your own engines, I'd recommend you either pick a mild - warm hydraulic roller or a solid flat tappet as the maximum.

[blykins]

Originally Posted by xb-60

Thanks Brent. So when you say the lifters take a pounding, that's only if the clearances aren't maintained to correct limits? If clearances are correct, and 7500 - 10000 mile intervals isn't a deal-breaker, then no other down side?
What precentage of motors do you build that have solid roller lifters?
Cheers,
Glen

No, they take a pounding just by nature. With a hydraulic lifter, there's lifter preload. The lifter is in constant contact with the lobe and the hydraulic internals absorb a lot of the action. With a solid lifter, there's valve lash, which is extra clearance between parts. If a high quality solid roller lifter was in constant contact with the lobe, it would probably last an extremely long time. However, with valve lash and no hydraulics to dampen the system, the "slop" in the valvetrain exposes the lifter bearings to a "shock" load when it re-contacts the lobe.

I'd say about 30% of my engines are solid roller engines.

[RICK LAKE]

xb-60 Glen Look at this from another side, what are you doing with the car?? shows, racing, autocross, roadcourse, or just street driver. Here are a couple of questions that will deceide what valve train to use also
Rpm limit and range of motor?
Motor size?
Amount of work done to heads and compression of motor
A BIGGIE Exhaust system, under car, side pipes,(street or race pipes) size of pipes?
Trans mission, how many gears, rearend ratio?
Top speed you like in your comfort zone?
Answer these question and we can come up with a good setup for the application.

there are plusses and minusses with running each valve train you have listed. I think most goods and bads are there. IMO a complete roller valve train is the first step. Matching the rest of the parts to this is important for power, sound,duribility, and even gas mileage too. I run a hydro setup for 6 years and race. No problems after getting Erson rockers. Limit of motor is 6,200 rpm with hydro crane roller lifters. A also run Beehive springs going on 12 years without any failures from BBC motors. I build torque motors not high RPM HP motors. 2 thing that are a no-no with a solid setup are idling the motor for any period of time and not check valve lash and keeping note on which ones needed adjustment. Fill in the questions and see where we go with parts and setup. Rick L. ps look at some of the buildup of your motor size for other ideas. DON'T get glassy eye with some of these dyno sheet in the rag/mags. They get a little over the top with numbers. Rick L.

[LightNFast]

........................

[xb-60]

Originally Posted by RICK LAKE

xb-60 Glen Look at this from another side, what are you doing with the car?? shows, racing, autocross, roadcourse, or just street driver. Here are a couple of questions that will deceide what valve train to use also
Rpm limit and range of motor?
Motor size?
Amount of work done to heads and compression of motor
A BIGGIE Exhaust system, under car, side pipes,(street or race pipes) size of pipes?
Trans mission, how many gears, rearend ratio?
Top speed you like in your comfort zone?
Answer these question and we can come up with a good setup for the application.

there are plusses and minusses with running each valve train you have listed. I think most goods and bads are there. IMO a complete roller valve train is the first step. Matching the rest of the parts to this is important for power, sound,duribility, and even gas mileage too. I run a hydro setup for 6 years and race. No problems after getting Erson rockers. Limit of motor is 6,200 rpm with hydro crane roller lifters. A also run Beehive springs going on 12 years without any failures from BBC motors. I build torque motors not high RPM HP motors. 2 thing that are a no-no with a solid setup are idling the motor for any period of time and not check valve lash and keeping note on which ones needed adjustment. Fill in the questions and see where we go with parts and setup. Rick L. ps look at some of the buildup of your motor size for other ideas. DON'T get glassy eye with some of these dyno sheet in the rag/mags. They get a little over the top with numbers. Rick L.

The car doesn’t exist yet, and the engine doesn’t exist yet…..but it definitely will eventually. So, I’m in the planning / gathering information / theorizing / gathering bits stage, with folders filling with information. One of the larger ‘bits’ is the engine, hence the question about things like lifters.

Here are my thoughts about what I want in an engine, and these are idealistic:

Vintage appearance 302, with stock capacity except for cleanup overbore
Intended use is street
RPM range is 2000 to 7000. I want reasonable (but not stump-pulling) torque at the lower end to suit my preferred diff ratio, and that free-revving feeling at the top end. Target power and torque figures aren’t that important, as the power-to-weight will be good, no matter what the power is.
Heads would preferably be CI for authenticity, but I’m also persuadable towards alloy heads.
Exhaust will need cats, will be undercar but both pipes exiting ahead of rear wheel on driver’s side; pipes sized to suit engine, not eye.
Gearbox will be a WR Toploader
Diff ratio will be 3.07:1
Top speed? Not important.
Reasonable cost
Fuel consumption not excessive, however this is low down the list as annual mileage will be low.
I should also add that emissions tuneability may, or may not, be an issue. Let’s say at this stage it’s not an issue.
Webers, as this is a wish list.

Thanks for your interest,
Cheers,
Glen

[xb-60]

Originally Posted by LightNFast

Glen,

Shelby’s 289 “High-Rev” Cobra engines were rollers and produced about 390HP @ 7000. So even back in the 60’s they knew it was better to roll…

Kurt,
Yes I’ve read a few old tests where rev limits of 7000 or even higher were mentioned for 289s. These were probably accompanied by grumpiness at lower revs, but that being almost 50 years ago, I’m assuming that developments in cams / heads / carburation / fuel injection has made available better compromises.
One of my other cars is a mid-seventies Alfa twin cam (unmodified) with side draft Webers. This engine has stacks of grunt from not far above idle, and at the 6000 redline, it feels like it wants to keep going forever. My daily driver, an Australian built ‘cooking’ V6, is redlined at 6200, sees the redline at least once a day and loves it. That’s what I want in a 302.
Cheers,
Glen

[blykins]

We'll have to have a talk.....

There's a familiar saying, "You can't have your cake and eat it too..."

With a small displacement such as a 302, making horsepower at 7000 rpm will pretty much insure that you won't have any power at all at 2000 rpm. The cylinder head and cam necessary to make horsepower that high will knock you out of any low end power. Even with a stroked 302 (331-347), you can definitely make horsepower at 7000, but you won't be making much at all at 2000.

Coupling a very high strung engine with a 3.07 rearend is also not the best route to take. You certainly have weight on your side with a Cobra, but using a 3.07 gear with an engine without a bottom end is like getting on a bicycle and taking off in 10th gear. You will have no power or acceleration whatsoever in the lower rpms and it will really labor the engine.

My advice would be to hit somewhere in the middle. A stroked 302 (331-347 cubic inches) would be the route to take. If your plan to use 3.07 rear gears is definite, then I would choose a cylinder head and cam to take advantage of that. You would need more low end and mid range power with a higher rearend gear. If I were building this engine for you, I would cam the engine so that the horsepower peak would be around 5500-6000, so that you actually would have some power at 2000-2500 where you'll be spending a lot of your driving time.

I may sound like a broken record as I say this on all the forums and in all my magazine articles, but plan the engine around the rpm range that you will be running in the most. There's nothing wrong with wanting horsepower at 6500-7000, but just remember that when you move the horsepower curve to the right, it takes away power from the left. And when you start with a very small engine to begin with, you really cut yourself short.

As for the heads, there are some nice flowing cast iron heads out there, specifically the ones from RHS.

[xb-60]

Thanks Brent. Definitely agreed that the engine needs to be friendly in its main operating rev range. What I do want to avoid though is an engine that really feels like it’s tapering off after say 5500. I want the same eagerness approaching the redline that my other two cars show, so if an engine has that, but a redline of ‘only’ 6200 to 6500, then I could be talked around. When I say ‘eagerness’ at or close to redline, I don’t necessarily mean ‘big power’, I just don’t want it to seem like it’s starting to strangle. That make sense?
Cheers,
Glen

[blykins]

Most engines won't just fall on their faces when they hit the peak horsepower rpm, unless they have valve float or some other issues. They usually taper off a little at first, then at a more pronounced rate.

You'll find that in a Cobra with any horsepower at all, you'll be more concerned about keeping the car on the road than making sure the tach goes to 6200 instead of 6000....

[Gaz64]

Originally Posted by blykins

Most engines won't just fall on their faces when they hit the peak horsepower rpm, unless they have valve float or some other issues. They usually taper off a little at first, then at a more pronounced rate.

You'll find that in a Cobra with any horsepower at all, you'll be more concerned about keeping the car on the road than making sure the tach goes to 6200 instead of 6000....

Agreed.

Another point worth noting is with any high powered car, watching the road is more important than watching your gauges.

As well as your normal gauges, I recommend a shift light, a high brightness LED warning lamp for vitals and a rev limiter.

[RICK LAKE]

xb-60 Glen at this point being a paper motor we have alot of room to play
First Brent likes cookies and milk, so he can forget the cake.
The 3.07 is a problem without bottom end torque, answer is a 5 or 6 speed trans. You don't need an over drive with 3.07. 1st gear will need to be in the 2.80 range if you want some quickness out of the car before it gets into the power bands. Webers will help in the power bands if setup right. Top end will also improve too if running 48MM. Stroker kit with a 331 is a good way to go.As far as heads, Do the Clevor heads fit on a 302 windsor block?? With a little work you will have a large rpm range. They remind me of the old 1970 Boss heads, no power under 2,500 rpms but then O-YEA and this was with a 780dp holley. Sorry I am going hydro valvetrain and setup valve with a .015" plunger depth, good set of valve springs and a cam with 112 LSA, in the .550-.580 lifter range. Key thing will be springs. I like and run beehives for 12 years. same set no failures IF you follow there setup and binding clearances of between .085-.100" I'm at .95" My motor does fall off a little at 5,800 rpms but still pulls to 6,200 rpm with valve float. IMO the lifters are pumped up with 85 psi and act like solids. I do think that they start to float with the lite spring pressure at 365pounds at open. I am looking for a higher rate spring. PAC sells them in the 400+ rate in pounds. I think you build a little lower power range you will be more than happy, should get around emmisions check and still haul the bacon. Going to work. Rick L. Ps cobra are flying barn doors, you need to go about 135 and start to feel the front end get real lite. Mine did this with a paxton hood scoop on. I have gone back to the oem hood and little scoop alot more stable.

[CHANMADD]

I use a little talked about kit. Rev Kit .......What this is , is a set of springs between the head and the lifter. This keeps the roller permanently in contact with the cam.....no skidding or bouncing liters. Also now you can still keep a low spring pressure at the valve because the valve spring has only the valve itself to control and not the whole valve train . This is also going to prevent broken rockers etc. I have stock , springs that come with the Edelbrock heads and can rev happily 8000rpm. I do have the proper components in the bottom including a full balance job on all the spinning parts.

[blykins]

So how much horsepower do you think you're making at 8000 rpm?

I hope you're not using the retainers and locks that come with those Edelbrock heads...

[CHANMADD]

That is the truth of it...... I very seldom rev to higher than 6000rpm, it just is not necessary.......I built the motor for racing , but have as yet not got on the track...yet! I did do alot of track in S.A. and won some trophies.
But you are right no-one needs an 8000 rpm motor in a Cobra for the street,Hell there is a thread here asking how fast guys have taken their cars and most have barely been over 100mph, (thats barely out of 2nd gear)......so yes 350 HP ,6000rpm in a Cobra is actually plenty power.

[blykins]

Yes, and I would watch about spinning the engine to 8000 rpm. How the engine was balanced would be the least of my concerns there.

[CHANMADD]

The motor that I built can live...believe me at 8000rpm all day long.I have built a lot of race motors in my time. The bottom end determines whether or not the motor is going to live at high rpm or not, and the balancing is extrememly important when a motor is expected to live at high revs. Besides having the correct crank and rods, the pistons and all the reciprocating components all need to be correctly weighted to each other...the balance does not simply mean that the crank spins without a vibration. The complete package ,like cc'ing the heads, combustion chambers and ports, not that they just look nice ,but they all need to be exactly the same.
Most all the builders I see here are new to this and do not grasp all that is involved in making an engine live at all rpm's. Most seek highest horse power to put in these little cars that is actually overkill completely.Like expensive ignition systems that do nothing extra above idle..????.
I have taken apart many "Proffessionally Built" engines that don't perform right because they were not properly balanced/blueprinted, even to the point of cracking bell housings, that are blamed on everything else. Overkill is not always the correct answer.
Likewise I do not like to run to much tire , so as not to strain the driveline....I would rather spin the tires than break a sideshaft or driveshaft......which I have seen more than once,and inevitably leaves one on the side of the road.

[blykins]

So what kind of engine is it, and what parts did you use?