Do it ur-self 1.6:1 /6 rockers

[bohica2xo]

There are a couple of problems regarding roller lifters in slant sixes.

1. There are NO commercially-available slant six blanks for roller cams, but you can get one ground for a cool thousand dollars.:angry3:

2. Once you get the cam ground, you have to acquire a set of workable roller lifters, and devise a way to anchor the lifter bodies in the block to keep them from rotating on their axes.

3. For our particular application (turbocharged) the rpm's are limited to 5,500, so a lot of valve spring pressure is not required to prevent valve float/bounce, relieving us of needing potentially cam-damaging spring pressure. A roller cam is not needed for longivity, in this instance.

4. The problem with excessively steep lift ramps to get the desired amount of lift with short duration cams, can be dealt with by the use of higher-ratio rocker arms. Ours are 1.6:1 (stock is 1.5:1, nominal.)

So, in the final analysis, there seems to be an alternative to roller cams for at least, OUR slant six.

I am too ignorant about mushroom lifters to comment on them.

Hope this explains something about the roller-lifter deal for slant sixes.

Thanks for your interest!

So put an off the shelf mushroom lifter in it an get any cam profile you want. Someone already answered the common lifter bore question, so any chrysler lifter will fit. Long before rollers we ran wild cam profiles with a big mushroom - probably several sets of perfectly good tool steel hemi mushrooms laying around older shops.

B.

 

[hemitheus]

Forgive my slanty newness, but what is the advantage of a 1.6:1 rocker? Increases the amount the valve opens to improve flow?

 

[Bill Dedman]

Forgive my slanty newness, but what is the advantage of a 1.6:1 rocker? Increases the amount the valve opens to improve flow?

The stock /6 rockers are SUPPOSED to be a 1.5:1 ratio, but tests run by some FABO members have shown them to vary,wildly, from 1.35:1 up...

The cam grinders tell me that they can't grind a flat tappet cam with .500"-lift and the mild duration specs I want. About .484"-lift is as good as they can do with stock rockers.

I need to keep the duration down to about 210-220-degrees @ .050"-lift for this turbocharged motor, so boost doesn't get blown out the exhaust valve on overlap.

The answer is 1.6:1 rocker arms. They will give me more total valve-lift and more effective duration (without increasing overlap significantly.)

That is the reason I am using 1.6:1 arms.

 

[Bill Dedman]

So put an off the shelf mushroom lifter in it an get any cam profile you want. Someone already answered the common lifter bore question, so any chrysler lifter will fit. Long before rollers we ran wild cam profiles with a big mushroom - probably several sets of perfectly good tool steel hemi mushrooms laying around older shops.

B.

That sounds like a really good idea! Like I said in an earler post, I am so ignorant about mushroom lifters I can't even make a comment on them, because I've never seen one.

I'll make an effort to learn something about them now, though; you can count on that!:read2:

Thanks for the advice!!!

 

[bohica2xo]

Bill:

At one time we made .904 diameter lifters with a 1.100 head on the end for the elephant motors. Tool Steel lifters were common, especially when someone was running a hardfaced cam - we did not spend a grand for a blank, we welded up the lobes.

I worked next door to Dave Schneider decades ago. Worked for Joe Schubeck at one time too.

But really, this is just a little slant six, and you don't plan on running it to 7500 rpm with a turbo - so here's a thought:

All aircooled VW type 1 engines have mushroom lifters. They are over an inch on the heads, and smaller than the mopar .904 on the body. You could simply bush your old block down to take VW lifters. Since you oil from the top, the bushings are simple. The VW part is a little longer, so you might need to shorten some pushrods - which makes them stiffer anyway.

Look around for a dune buggy or VW shop. They probably have some junk lifters in the trash can you can grab for a look-see in your block.

B.

 

[1wild&crazyguy]

Keep in mind what all the guys did running lift restricted classes. Duration and lobe sep can mean a frikkin LOT. While lift is certainly important, you don't have to have to to run well.

thats right, its called holding the valve open longer, regardless of lift.

it gets done one way or the other.

 

[bad440]

Ed, if ~I~ can do this successfully, ANYBODY can... I am not, nor have I ever been, "mechanically inclined."

The guy who is welding these up for me runs a CNC machine shop, and just does welding in his spare time (IF he has any.)

Well, one of the motors on his best CNC machine was "going out" so he installed a new one.... guess what? It burned up... so, he had to put the old one back on because he is REALLY BUSY with CNC porting, right now.

Bottom line: He hasn't had time to weld up our rocker arms.

That's okay; we weren't going to ue them right away, anyway.

You can't see it because of the camera angle, but on the back side of tha jig I made, my machinist welded a piece of 1" square tubing about 6" long, to clamp in the vise on his vertical mill, to firmly hold that fixture from moving. That is how we located the jig on the bed of the mill. It worked!

The metal saw blade we used was niminally .100" thich, but it was actually about .104".

Unless you are planning a turbocharged engine for your car, I don't think the problem WE have of not being able to buy a cam with sufficient lift at the valve (say, a little over .500") would be a problem for you. The cam grinders all tell us that the lift ramp is too steep, if you try to grind a cam with only 210-degrees duration at .050"-lift and lift the valve over half an inch.

Long duration cams, such as yours, don't need that steep an angle for that valve event, so 1.5 rocker arms work okay for that application.

Do you agree?

just want to tell you guys i admire you, doing alot with a little.100% pure hot rodding

 

[RustyRatRod]

So put an off the shelf mushroom lifter in it an get any cam profile you want. Someone already answered the common lifter bore question, so any chrysler lifter will fit. Long before rollers we ran wild cam profiles with a big mushroom - probably several sets of perfectly good tool steel hemi mushrooms laying around older shops.

B.

Nobody makes a mushroom cam for a slant.

 

[Bill Dedman]

Bill:

At one time we made .904 diameter lifters with a 1.100 head on the end for the elephant motors. Tool Steel lifters were common, especially when someone was running a hardfaced cam - we did not spend a grand for a blank, we welded up the lobes.

I worked next door to Dave Schneider decades ago. Worked for Joe Schubeck at one time too.

But really, this is just a little slant six, and you don't plan on running it to 7500 rpm with a turbo - so here's a thought:

All aircooled VW type 1 engines have mushroom lifters. They are over an inch on the heads, and smaller than the mopar .904 on the body. You could simply bush your old block down to take VW lifters. Since you oil from the top, the bushings are simple. The VW part is a little longer, so you might need to shorten some pushrods - which makes them stiffer anyway.

Look around for a dune buggy or VW shop. They probably have some junk lifters in the trash can you can grab for a look-see in your block.

B.

That's all good information, and sounds like a workable project, but as Strokerscamp has pointed out, there are apparently no mushroom-lifter cams ground for slant sixes. He usually knows what he's talking about...

Once we have our (nominal) 1.6 rockers in place, we may be okay.

Thanks for the VW-lifter idea, though; I LIKE IT!!! :blob:

 

[hemitheus]

The stock /6 rockers are SUPPOSED to be a 1.5:1 ratio, but tests run by some FABO members have shown them to vary,wildly, from 1.35:1 up...

The cam grinders tell me that they can't grind a flat tappet cam with .500"-lift and the mild duration specs I want. About .484"-lift is as good as they can do with stock rockers.

I need to keep the duration down to about 210-220-degrees @ .050"-lift for this turbocharged motor, so boost doesn't get blown out the exhaust valve on overlap.

The answer is 1.6:1 rocker arms. They will give me more total valve-lift and more effective duration (without increasing overlap significantly.)

That is the reason I am using 1.6:1 arms.

Excellent. I hope these work out well for you

 

[Bill Dedman]

just want to tell you guys i admire you, doing alot with a little.100% pure hot rodding

Why, thank you for that nice comment! :glasses7:

I started in this hobby (if you can call it that) in 1955, when I went to my first-ever drag race. I was hooked...

Back then, the aftermarket that we enjoy nowadays, didn't exist, so you had to make your own speed parts, or do without.

I ran an assortment of Gas Coupes and Stockers throughout the late-fifties and all through the sixties, and saw a lot of neat stuff fabricated by guys who simply couldn't buy this or that part, so they made it.

Now, the slant six racers are faced with a milder version of that early scenario, so the old "do-it-yourself" philosophy is applicable to what we try to do.

It's all good, and lots of fun. That's the whole idea of this obsession... to have fun, isn't it???

I call 500-plus horsepower from an engine that was originally rated at 145, FUN! :cheers: LOL!

That's why ~I~ do it... My supercharged 360 Magnum isn't nearly as much fun (nor, as fast!) as this old slant six is going to be when it's finished.

Turbocharged slant 6's are the best-kept secret of the Mopar hot rodding world, I think. We'll just enjoy the anonymity.... :happy1:

I appreciate your interest and inspiring comments!

 

[bohica2xo]

There is really no such thing as a "mushroom cam" - they are just camshafts.

The reason for the mushroom head on the lifter is to move the edge out radially so that it does not dig into the lobe.

When you keep adding lift, at some point the tip of the lobe is past the edge of the lifter. A less aggressive ramp can help this, but you get more duration at lower lifts - nothing you really want

What Bill is looking for is moving the valve off the seat quicker, which means a more aggressive ramp on the lobe.

The air cooled VW is a perfect example. It has 1.1:1 rockers. A performance camshaft has lobes that look like needles, with almost flat ramps. The cam rolls into the lifter almost flat on the ramp, and the valve opens quickly. The narrrow tip holds the valve open as it sweeps across the lifter, and it closes just as fast as it opened.

B.

 

[Bill Dedman]

There is really no such thing as a "mushroom cam" - they are just camshafts.
B.

Let me make sure I understand this correctly (I have a pretty thick skull, obviously!)

When you say, "There is really no such thing as a 'mushoom cam'," do you mean, "There is really no such thing as a mushroom cam lobe profile (as opposed to a "convention-lifter lobe profile?")

By that, I mean, could I just use the cam I already have, and use these mushroom lifters on it to good effect, without grinding the profile to a shape more appropriate to the valve action I am needing to achieve with the stock lifters? (but, with the added lift-rate of the larger-base mushrooms?)

Well, now that I have thought about what I just said, I don't think that's going to work for me, because what I was after was more total lift, not more flow at low-lift (although, that might actually be more beneficial than the added lift I am after.)

Can you clear this up for me in term of the efficacy of using these mushroom lifters on a cam ground for stock-diameter lifters, please? I just want to make sure I understand what you mean.

Sorry; I think my Alzheimer's is kickin' in... ops:

 

[RustyRatRod]

There is really no such thing as a "mushroom cam" - they are just camshafts.

Wrong. Mushroom cams have much more aggressive ramps that a flat lifter cannot handle. That's the whole point behind them.

 

[bohica2xo]

Wrong. Mushroom cams have much more aggressive ramps that a flat lifter cannot handle. That's the whole point behind them.

Next time quote the whole post. I did describe WHY a mushroom is necessary for some camshaft profiles. I specifically mentioned the ramp angles.

Bill can have a camshaft ground that meets his desired specs, IF he enlarges the lifter face. Plain and simple. By reducing the base circle a little more this may be possible on a stock blank. His specs were close without it.

That engine went out of production decades ago. Never was a big performance seller, so it is no surprise than nobody STOCKS specialized cams for them. Companies like Schneider will grind any profile you want.

So no, not "wrong".

B.

 

[moper]

Next time quote the whole post. I did describe WHY a mushroom is necessary for some camshaft profiles. I specifically mentioned the ramp angles.

Bill can have a camshaft ground that meets his desired specs, IF he enlarges the lifter face. Plain and simple. By reducing the base circle a little more this may be possible on a stock blank. His specs were close without it.

That engine went out of production decades ago. Never was a big performance seller, so it is no surprise than nobody STOCKS specialized cams for them. Companies like Schneider will grind any profile you want.

So no, not "wrong".

B.

Exactly!
The cam lobe doesn't know what engine it's in, and the limitation of rate of lift is the lifter diameter. The wider the lifter, the faster you can open the valve. Plain and simple. I routinely get beaten up about this because of the "chevy lobe" internet ignorance.
My plan is use a "core" new aftermarket performance cam and have a madern faster rate lobe ground into it. However I don't know specs because I don't know where the limit for lobe shape simply because I haven't ever tried with a /6 cam, and I don't have the "core" one yet. I'll simply buy the biggest one I can find so they have the most material to work with.

Bill - If you can find someone with cam blanks, you can have any lobe you want ground onto it. Including the most modern "claimer" class fast rates. There are a lot of designs based on the .842 and .875 lifter diameters that are lift-limited by class rules, that I'm sure would be fine for the .904 lifter face an fit your needs. But you have to look at lobe catalogs, not cam catalogs.

 

[Bill Dedman]

That engine went out of production decades ago. Never was a big performance seller.
B.

Why was it never a big performance seller???

Well, there are several reasons, all of which can be traced back to Ma Mopar telling their engineers who designed this engine "We want an engine as short as you can make it."

So, as long as it's going to have six cylinders in a row, how do you do that?

You give it small bore-center spacing.

That dictates small bores. Small bores dictate small valves (we're talking 2-valve technology, here.)

As you know, the original slant six had 170 cubic inches.

The engineers designed a cylinder head that was a good "fit" in terms of flow, for that engine. The ports and valves worked well, even at high rpm's. Witness the original Hyper Pak motors. The made almost one horsepower per cubic inch (148.) Some folks (me, included) think that the 148 figure was deliberately too low. With a 3.125-inch stroke, those engines made great power at rpm's over 6,000.

Comes the next iteration of the slant six (the one-inch stroker, 225) and all that high rpm power vanished like a puff of smoke.

Now, the engine had enough cubic inches to compete with other sixes on the street, but in her infinite wisdom, Ma Mopar did absolutely NOTHING to address the fact that now, there was a reciprocating assembly 33-percent (nominal) larger, trying to breathe through those same, identical, ports and valves.

Wheeze...

Larger valves could be fitted by a machine shop, and the cast iron head could be ported to some extent, but making a 225-cubic inch slant six put out much over one horsepower per cubic inch was not an easy task.

Back then, Ma Mopar offered a ton of great V-8 motors with big bores and short strokes, and they took to normal hot rodding techniques like a fish takes to water, so most folks just decided that trying to hop up a slant six wasn't worth the grief, unless they wanted to build a "class" car and run a modified class, where the sixes were separated from the V-8s, and they ran on pounds-per-cubic-inch formulas. In such a class, a 170 slant six was a KILLER motor; very hard to beat... and, won a lot. of races!

But, on the street, it was hard to be competitive with the V-8 cars, and the larger 292 and 300 sixes from GM and Ford.

That scenario went on for years, and effectively killed the aftermarket supply of hop-up parts for slant sixes.

That's why...

 

[RustyRatRod]

Whatever you say sir.

Next time quote the whole post. I did describe WHY a mushroom is necessary for some camshaft profiles. I specifically mentioned the ramp angles.

Bill can have a camshaft ground that meets his desired specs, IF he enlarges the lifter face. Plain and simple. By reducing the base circle a little more this may be possible on a stock blank. His specs were close without it.

That engine went out of production decades ago. Never was a big performance seller, so it is no surprise than nobody STOCKS specialized cams for them. Companies like Schneider will grind any profile you want.

So no, not "wrong".

B.

 

[Killer6]

Well, I stumbled across this thread last week, so I guess I'll dust it off and give
it a big bump. Like so many threads, the original primary subject got lost, and the
conclusion vanished into the ether......so;

1) Did anyone actually finish a set of these frankenrockers?
2) If so, what ratio did you accomplish?
3) Did you actually press them into service?
4) If so, any durability or oiling /scuffing issues?

After that, why go thru' monkey-motion to put VW tappets in, when there wasn't
an embargo on solid mushroom tappets for SB/BB mopars? Don't tell me to save
a few$, I doubt the cost to bush the stock bores would end up in a savings, and
the bottom of the bores will still need spot-faced from the bottom either way.
And yes, there are "mushroom cams" the same as there are ".904 cams", they
are specifically designed to work w/ the dia. of the tappet being used.

 

[Bill Dedman]

Well, I stumbled across this thread last week, so I guess I'll dust it off and give
it a big bump. Like so many threads, the original primary subject got lost, and the
conclusion vanished into the ether......so;

1) Did anyone actually finish a set of these frankenrockers?
2) If so, what ratio did you accomplish?
3) Did you actually press them into service?
4) If so, any durability or oiling /scuffing issues?

After that, why go thru' monkey-motion to put VW tappets in, when there wasn't
an embargo on solid mushroom tappets for SB/BB mopars? Don't tell me to save
a few$, I doubt the cost to bush the stock bores would end up in a savings, and
the bottom of the bores will still need spot-faced from the bottom either way.
And yes, there are "mushroom cams" the same as there are ".904 cams", they
are specifically designed to work w/ the dia. of the tappet being used.

1. Yes, they have been finished for awhile

2. The actual ratio has not been measured, but if the original, unaltered arns were 1.5:1 (they probably weren't) they would be 1.6:1.

3. No, they have not been used... yet. It's a new car and I wanted to establish a base-line at the strip before I used them, so a valid comparison could be made.

4. Since this is a race-only engine, and will see very little actual running-time, scuffing, et al, should not be a problem... I hope!

If these work the way they should, the mushroom issue becomes moot.

 

[Killer6]

Here's what I observed on my 21yr. old combo when I cracked it open about a
year and a half ago. I knew the exh. stem ht. was a little high because I had used
amc 1.41 units, the 1.74 BB exh. hts. were almost on the money as intakes.
The taller exh. stems managed a 1.48:1 avg. w/ a .490 design lift, but only
a 1.44:1 avg. w/a a stock lift. I had shortened my crane chromoly pushrods a bit
too much, so I installed my checker rod and adj the length in increments, no real
change in gross lift there(maybe .004").However, raising the rocker shaft increased
the lift until I hit .100" above stock ht. That netted an increase of .020" lift and did
check in at a true 1.5:1 , a variation of three adj. threads did not affect lift at that
point. Even w/ the stock stem ht. the lift increased, prob. due to the angle moving
the point of contact out towards the end of the rocker pad. Too high and the arc
became un-sync'd with the stem centerline and resulted in no more increase,just
more scuff.

 

[Bill Dedman]

Here's what I observed on my 21yr. old combo when I cracked it open about a
year and a half ago. I knew the exh. stem ht. was a little high because I had used
amc 1.41 units, the 1.74 BB exh. hts. were almost on the money as intakes.
The taller exh. stems managed a 1.48:1 avg. w/ a .490 design lift, but only
a 1.44:1 avg. w/a a stock lift. I had shortened my crane chromoly pushrods a bit
too much, so I installed my checker rod and adj the length in increments, no real
change in gross lift there(maybe .004").However, raising the rocker shaft increased
the lift until I hit .100" above stock ht. That netted an increase of .020" lift and did
check in at a true 1.5:1 , a variation of three adj. threads did not affect lift at that
point. Even w/ the stock stem ht. the lift increased, prob. due to the angle moving
the point of contact out towards the end of the rocker pad. Too high and the arc
became un-sync'd with the stem centerline and resulted in no more increase,just
more scuff.

When you're working with 20 pounds of boost (as I will be, shortly; only 15 pounds, so far,) and, looking towards 25 pounds, miniscule increases in efffective duration and total lift become insignificant in the scheme of things, I think. That's why I haven't bothered to accurately check the actual lift-ratio on my homebrewed, so-called 1.6 arms; I KNOW they are better than "stock" but, just how much, I am not sure, and am not sure the ratio-change will even matter, given the boost I will (hopefully) be running. More likely, the whole thing will blow up in my face and I can use the time I would have used checking the ratio-change, to build a new engine.... which I will need. :banghead:

But, this is hot rodding... and that's the way we learn! :blob:

 

[Killer6]

What about srixon4406 ? He was movin' along on his set, no word on that set??

 

[Killer6]

https://issuu.com/fabreaus/docs/2014_us_rocker_catalog

 

[Killer6]

http://www.pentastarparts.com.au/store/index.php?l=product_detail&p=811

Even at the favorable currency exchange of $1.32AUS/$1.00US, thats still
$1023.00, holy sniekes !