Effect of tight lashing and / or hydraulic lifters on a solid roller camshaft.

[DuckRyder]

Background.

I'm trying to make my current combination as good as possible with respect to my desired behavior, before I order another cam, I feel like making it as good as possible allows me to give better information / input to the new cam.

My questions.

We are talking about a Crower "street roller" 280R - 280/288, 234/244. 581/.583. Specified clearance is .026/.028 I've already tight lashed it to .018/.018

Typically Hydraulic cams are advertised at .006, i assume (we know where that gets us) that solid cams are advertised at the specified lash? So by tight lashing it the durations are already longer? Lifts higher?

Is there a way to calculate this change?

What if we run hydraulic roller lifters. (zero lash)?

With respect to running hydraulic lifters if we look at differences in advertised and .050 durations we are at 46/44 on the solid roller, if we compare to the edelbrock 2220 hyd roller 53/51 (and it has more lift), comparing to a Howards with the same 280/288 but 227/235 with .572/.572 we get 53/53. There seems to be agreement that the Edlelbrock lobes are aggressive so that's going to make Crowers very aggressive no? Possibly so aggressive the Hyd lifters wont work? As previously mentioned Crane back in the day had issues with too aggressive of a lobe causing issues with the heavy FE valve train.

[DuckRyder]

Ok If youtube is to be believed i may have answered a couple of my own questions.

Seems the solid roller cam was probably rated at .020 (vs .006) so at a lash of .020 advertised should match.

But the other valve events are quoted at tappet lift (zero lash). Also the lobe lift times the rocker ratio = .5808 so the actual lift is less by the amount of lash....

Makes it difficult to compare the aggressiveness of the lobe.

We've already established that math isn't my thing, but is there a way to calculate the change in duration due to changes in lash?

[Joe-JDC]

Back in the late '80s when the EFI 5.0s came out, I wanted to put a 351W EFI in my '86 GT.  I was one of the first, if not the first to do that conversion with the hydraulic roller camshaft.  I talked with the technical representative at Crane Cams who was in the process of making 10 custom roller camshafts with the small base circle for installing in the 289/302/351W blocks.  We ordered 7 or those first 10 camshafts, and I installed one in my 351/376W.  When asking if we could install SR lifters on the HR camshaft, he suggested .004" lash.  I used the Ford Motorsports HR lifters, and that engine ran fine for about 20,000 miles before trashing a lifter wheel and needles ruined a cylinder wall and oil pump.  I know that SR lifters have been used on an EMC engine HR camshaft with success, but going the opposite way with HR lifters on a SR camshaft would not be something I would advise.  JMO, but not a good idea.  Joe-JDC

[blykins]

...but going the opposite way with HR lifters on a SR camshaft would not be something I would advise.  JMO, but not a good idea.  Joe-JDC

Same thing I advised the OP over email. 

Any time you are trying to change the cam with swapping lifters one way or the other, the cam is not correct for the application.

[DuckRyder]

Acknowledged on both points. I was intentionally leaving out the "He said/He said" (no she's have said in this case) on purpose so we could perhaps have a dialogue.

If we discard the whole hydraulic lifter on a solid cam idea, what about calculating change in durations and particularly IVC events as a result of changes in lash? OR is it so inconsequential that it isn't worth it?

[blykins]

You'd have to map it out with a degree wheel.

[DuckRyder]

Noted:

One last question and i promise i'll shut up at least about this.

How tight is too tight - iron heads and block. .012? .010?

[blykins]

I wouldn’t have went as far as you’ve gone….

[My427stang]

Noted:

One last question and i promise i'll shut up at least about this.

How tight is too tight - iron heads and block. .012? .010?

Too tight is when the valves don't seal at a given temp based on expansion.  In some cases, usually un-naturally aspirated, you need seat time on the exhaust to cool when EGTs get very high, can be an issue on Cummins with guys who won't drop a gear pulling hard.  Too much duration, however you get it, is the issue, not the lash itself.  However, think boosted diesel pulling a grade with a load, your truck would never get there.

What problem are you trying to solve?  If it's octane tolerance, you can't get a whole lot more.  If you want to see what more cam is like, just remember you are adding overlap too by tightening lash. 

I will say this, plenty of us have a ton of cam experience with a combo like yours.  If you want a modern custom cam, it will be better than this experiment will indicate. 

Now, if you want to try a set of hyd rollers on the cam just to pave new roads LOL, I really see no reason a mild solid roller lash ramp would bother a set of hyd rollers, but you'd have to be ready if somehow noisy.   Of course, I'd rather see you get the right cam.  Going the other way solids on a hyd cam, can be rough on lifters

 

[DuckRyder]

I guess Im really not trying to fix a problem anymore, since i know what it need to do, but i do have one thing that's bugging me.

I do like to understand the why's. This is not me arguing or not listening to experienced parties, it's just me trying to wrap my head around stuff.

"The problem" is that 20 years ago my machine shop had to take more off the heads than desired, leaving them with small chambers which raised the compression a little over half point from where i wanted it. I shoulda bought another set of heads then, but hindsight is 20/20.

I guess the second "problem" is that I don't hate the cam, it is not right for the combo but it isn't bad wrong, it'd be easier if it was awful and we weren't old friends. I suspect it's leaving a lot of power on the table because i have to keep the timing very conservative. Perhaps it's worse than i think. It already has more power than traction though.

So - I need to start collecting parts to swap the cam and I need to decide if i want to replace the heads. Probably a set of 72cc heads would solve the timing problem and make room for a more conservative cam, at this point in my life i might like a slightly more conservative cam (not TOO conservative.)... any way, y'all probably don't even care about me rambling on.

Heres what i don't understand though (AKA is "bugging me"). If i run the current combination through wallace racings calculator (need to see if i have a copy of P Kelleys on the old toughbook and if they agree. - edit - I do have a copy it comes up as 8.254- ) i get this:

C8AE-H / Crower cam 110icl

Static compression ratio of 10.6:1.
Effective stroke is 3.16 inches.
Your dynamic compression ratio is 8.14:1 .
Your dynamic cranking pressure is 162.48 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 7.96 :1.
V/P (Volume to Pressure Index) is 161

These are their notes:

Dynamic Cranking Pressure: (at 150 rpm starter rpm)
  Note=> after 7 to 10 needle pulses on a hi-quality Compression Tester
         The slower the cranking RPM, the lower the cranking psi
         The faster the cranking RPM, the higher the cranking psi
         The poorer the Piston Ring seal, the lower the cranking psi
         The poorer the Valve Seat (and guide) seal, the lower the cranking psi
         In addition, aluminum Blocks may show lower cranking psi
         Also Engine should be between 140 F to 180 F temperature for Tests

  The compression tester's needle should swing over to 90+ or more psi on the 1st Pulse
  this indicates great Hone Job, Valve Guides, and Valve Job

I have WAY more than that - like 190-195 psi after 5 pulses, it is perhaps turning faster than 150 rpm, but still it is not even in the ballpark. (is their calculator that wrong or is something amiss in the engine?) also i guess if advertised isn't actually where the events are happening that throws the shooting match off.

I did degree it when i first put it in but i probably used the .050 events because that is what is on the cam card. (Did i mention i really need to start writing stuff down.)

Guess I need to break out the dial indicator and figure out if the ICL and IVC is where it is supposed to be and if not why not.

Guess I will set the valves back to recommended when I change the distributor. (Going to get the ECU controlling timing this is an attempt to improve the drive engagement and idle).

Edit again- Also, i did think that getting this combination as good as possible would be mutually beneficial in getting a better cam, you know -i have this, it acts like this. id like it to act like___. Maybe that's not useful information though. <shrug>

[frnkeore]

It would help, if we knew the bore & stroke, deck clearance, ICL and head & piston cc or, how much you cut the C8-H's and piston number.

If things aren't to out of wack, you might be able to just retard the cam and put a thicker head gasket on and cure most of your problems.

[blykins]

Something in the engine doesn’t match what you think is in there.  Theory really goes down the tube when your actual results show something totally different.

Before you buy a cam, I’d try to nail down your exact compression ratio.  You don’t want to get another cam that’s made for a specific ratio and then it behave the same way. 

[DuckRyder]

Hi Frank,

It's a 445. 4.08 bore, 4.25 stroke, Mahle 930264480 (18cc Dish), .006 below deck, the heads are 65cc. (the dish, heads and deck were all measured.) it has 8554PT head gaskets.

The cam is already retarded which theoretically makes the IVC 70. it is a 110 LSA installed at 110 ICL

Also, Joe thanks for your feedback earlier.

Agreed Brent, is the cranking compression what makes you say this? Its way too high isn't it?

[blykins]

On a cast iron factory head with a factory chamber, it's higher than what I would want to see.  But there's also a flag that the numbers don't match.  The cranking compression calculators aren't perfect, but they should be closer than 35-40 psi.

Everything on your engine is higher (static, dynamic, crank) than what I would want to see for an iron headed pump gas street engine. 

[blykins]

BTW, I get lower numbers when I calculate it.  ~10.4 and ~8.0.  It would be a hair less than that with a little crevice volume factored in.