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

[DuckRyder]

So i guess I am trying to solve a problem.

WHY is the cranking compression so high? I'm pretty sure of the static is in the 10.4-10.6:1 range maybe I'm a cc off or a a thousands or two due to piston rock (i did use a deck bridge), a little on the head gasket but not that much.

In fact just playing with the calculator I would have to have done something (else) stupid like advanced the cam 4 degrees instead of retarding (There are only 3 slots)  AND the cam would have to have 10 degrees less actual duration on the intake lobe to even come close to 190 PSI cranking on the calculator.

I guess the other option is the compression gauge is garbage?



When I get a chance to work on it I will map out the actual events for opening and closing at the valve, and redo the compression test. It'll be a while, i'm building a basement...

[My427stang]

So degreeing the cam can tell you what the lobe is really doing, in the end, you can do that in the truck.  However ultimately, your compression ratio does not match the cam and fuel.

That cam at 106 is going to be too small for a 10.5:1 compression, or better put, the compression is too high for that cam.

At 110 ICL, IMO, you are right on the edge for a light car, stiff gear, good fuel, which could lead you to tighter lash as we talked about before.  Other band aids would be slowing down the curve, running richer, etc.  However I think you are out of runway on the lash, it won't hurt to try if you want, I run my Mustang at .014 cold, but there is only so much you can do.

If you were to rock that cam back another 4 degrees or so, using a 9 position gear, at 114 I bet it would knock the edge off, and making sure it isn't hot, lean and the curve is right, would do OK on fuel.

But, later cam timing will drop idle vacuum if that's a concern.

However, if I was chasing it.  I'd chase curve, plugs, and mixture now as a band aid to avoid going inside.  Then resolve that I need to swap cams at some point.

A slightly larger lobe at .006, with .050 to match use of the truck, then spread the centers to meet vacuum and drivability requirements.  No more messing around and you can get to what you want.  That being said, to get that cam, need to get a real compression number and then degree the cam when installed. 

Now there is a curve ball, because you are backing into a cam with high compression, there likely will be trade offs.  A 445 in a truck is usually not a 10.5 motor, we'd be closer to 9.75-10 for a cam to match use.  In fact, my own is exactly that, 9.75 with a 280 adv lobe and it does fine.  That likely means you'd have to accept it being alittle more rowdy than we'd normally do it, or if you have room to still have decent quench, try to drop compression a bit, maybe both.

[frnkeore]

Here's some more exact numbers, regarding CR/DCR, for the info given, using a 8554 head gasket, of 12.7cc and 110 ICL, as well as a 1.11cc crevice volume:

CR of 10.28, DCR 7.89. 10.39 CR and 7.97 DCR w/o the crevice volume.

Depending on the real octane rating, that should be manageable. You can drop it a tenth with a .061 thick FT gasket.

If the ICL is installed to the cam card 106 ( ICL), that rises you to 8.16/8.24 with and w/o crevice vol.

But, if you might of advanced the cam, instead of retarding it 4° (102 ICL), that would put you up to 8.4/8.49

I think you should check the ICL and the IVC, to see where you actually are.

[blykins]

The crevice volume is actually .7cc on that piston. 

[My427stang]

A couple comments as I read back

1 - You do not need to add lash, .018 is not too tight.  Too loose is hard on parts, but you could go to absolute zero and if heat didn't reduce it, it'd run fine.  The only thing that makes it rough is if you have too much lash and it hits the lift ramp before the lash is taken up.  Not enough hurts nothing

2 - If this is EFI, fatten it up, stoich is only a chemical reaction number, not what the engine needs to see.  Play with it 1/2 a point fatter if you have to.  You can be in the high 13s at cruise and play with enrichment and WOT numbers

3 - I feel like Brent said earlier, you either have some parts you didn't expect, the cam in wrong as you said, the high cranking compression seems wrong, but it's a calculator, tune what you have

4 - Finding IVO and IVC can be from the top of a rockers at zero lash and tell you a lot

5 - If you do have the ability to use a computer controlled distributor, use it and put in 14 initial, WOT at 38, set it linear max to 3000 rpm, add 8 to cruise

6 - If you have a Sniper and you do not have the latest Holley ECM and handheld update, full stop.  I have had so many things seem untunable and when I update it, it magically works as advertised

[My427stang]

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.

X2

Also tunable numbers, made a smidge tougher by weight and gearing, but still doable if not, hot, lean or too quick of timing. 

[blykins]

A couple of notes...

In past discussions of crevice volume, I've made the point that it just depends on the piston.  Could be very low, could be high, just depends on the design/shape of the piston.  As the piston grows, it also changes. 

Not trying to contradict anyone on changing the lash by a great amount, but in times past, where I've ordered cams for testing, etc., both Comp and Bullet have both told me what the "extremes" were on the lobes that I had chosen.  It's usually about a .004" swing in each direction.  The lash ramp varies from lobe to lobe, manufacturer to manufacturer. 

Now, with that being said, guys have tried different things and have succeeded, but in this scenario, something isn't playing right in the overall combination.  A ~10.4:1 compression ratio and a ~8:1 DCR (or hair under) will live just fine on pump gas.  Something else is amiss.  Ignition timing, cam wasn't degreed correctly, oil consumption causing detonation, plugs in the wrong range, etc. 

[Joe-JDC]

The tighter the lash, the shorter time for cool down between strokes for the valve heads.  I recently had a camshaft that required .009" lash, and after about 20 dyno pulls, the intake valves started to tulip and closed off the lash completely.  This was with 5/16" valve stems.  Opened up the lash to .016" and did not have any further issues with the valves growing in length.  Just my experience, but don't band-aid the problem, fix it.  Joe-JDC

[WConley]

Joe has an excellent point.  IMHO, unless you're running a Pro Stock engine, lash should not be used as a tuning tool.  There are a lot of hidden effects from going outside the specified range.  Aside from heat rejection to the seat, you get into pretty crazy dynamics.  I'm with the guys who are advising attention to the real issue with the parts combination.

[My427stang]

I don't agree at all that it should not be used as a tuning tool, in fact, I think it's a great thing and you just need to know what you are doing.

In fact, my 168K mile Cummins runs tight intake lash, very tight and has since I did it in 2015 with about 10k on it, but exhaust I run the low side of stock specs for cooling.  It helped boost, noise and valve bridge wear common to these

My Mustang has run .014 since 2006 with solid flats.

A lash ramp is there to slowly accelerate the lifter to be able to go more vertical...starting where the manufacturer wants you to of course is no problem, but starting late means you hit the steep ramp without a transition. Starting early doesn't hurt mechanical operation (aside from extremes, like Joe and I both pointed out, but .006 isn't .018) and more importantly, lobe families have lash values based on that design, not based on specific duration, so it's really not a valve cooling issue when the manufacturer gives a recommendation, it's a mechanical recommendation.

Aside from unique dyno mule or power adder issues that drive up EGTs, I'd buy a .004 limit on the loose side, I'd actually don't go measurably looser at all, but I have never had a lobe, lifter or otherwise an issue from starting closer to the base circle

Now, I 100% believe that there is something else going on in this engine, probably cam timing related due to not being what it is supposed to be, or advanced too far, and I also don't think that lash reduction will fix it.  However, tight lash is not a boogie man and, in many cases, can improve durability and allow some tuning.

[WConley]

Ross - I should have put some more context into my comment.  Playing with lash can get you some nice (subtle) benefits, but as you said, you must know what you are doing and where you are with your combo!  Most of us with our street engines don't need that level of precision.  When you see a typical solid valvetrain actually running, the dynamic lash ends up pretty far away from what you measured statically.  It takes experience to understand what will work, and how far you can go.  Most of us don't have that...

In the OP's case, there is stuff an order of magnitude more important going on.  I'd say the jeweler's screwdriver can come out when you're done with the big tools.

[My427stang]

Ross - I should have put some more context into my comment.  Playing with lash can get you some nice (subtle) benefits, but as you said, you must know what you are doing and where you are with your combo!  Most of us with our street engines don't need that level of precision.  When you see a typical solid valvetrain actually running, the dynamic lash ends up pretty far away from what you measured statically.  It takes experience to understand what will work, and how far you can go.  Most of us don't have that...

In the OP's case, there is stuff an order of magnitude more important going on.  I'd say the jeweler's screwdriver can come out when you're done with the big tools.

Thanks for clarifying and I hope I didn't sound too challenging as well.  I agree completely, small changes can be accomplished, but not the overall characteristic of the cam. 

The neat thing is that IVO on this cam at .020 should be about 30 degrees BTDC, looking for an 8 degree error could be found with a dial indicator on the pushrod side at zero lash and be seen on a balancer...since he corrected his timing marks before, wouldn't have to do much more than pop a valve cover, get on the base circle, adjust to zero lash, and turn it clockwise until it reads .020.  If it's nowhere near the 30 mark yet....it's wrong

[DuckRyder]

OK I appreciate all the input, plenty to consider.

I think I've reached the acceptance phase on changing the cam and will procure parts to change it to a hydraulic roller. I think i will likely change the heads too and i need to make that decision finally before the cam.

Even when this engine was a 390 it behaved similarly with this cam, it was very sensitive to octane and timing and really did not want more than 32 or 33 with a somewhat slow curve. It does not have vac advance. When it was built as a 390 i suspected the dcr was going to be a problem and considered retarding the cam then, Mayhem Bob (RIP Bob) talked me out of it because it did not seem like it should be that bad.

When i rebuilt it as a 445 Ross and I had a lot of discussion and we decided to retard the cam and run the 8554 gaskets instead of 1020 in an effort to improve the situation, he wanted me to change the cam then, and I should have, but time and money was an issue. (mostly time, i needed it running to move it to another state). I checked all the measurements deck, head and piston ccs, bearing clearances - everything. I just did not write any of it down. I know i checked the cam when i first put it in the 390, but i might not have when i did the 445.

Im pretty sure the static is right as we've calculated it (i get 10.5-10.6 depending on the numbers i use for the head gasket)., Brent is probably closer. The rotating assembly came from a reputable supplier and i went back and looked at the pictures an its all the right stuff. Plus it measured out as it should. The heads i CCed at between 65 and 66 i use 65 because the smallest chamber was 65.1cc, This jives with what the machine shop originally cc'ed them at (they told me 66). Again this is not me arguing, it's just me saying i don't see how the static could be that far off.

The cam - It also came from a reputable supplier way back it was sort of a last minute change in the build because this was at the time that everyone was using johnson lifters and all of a sudden no one could get them and Flat Tappets were wiping out right and left, Hydraulic Rollers for FEs were in their infancy - Crane made them but they were having trouble too. My original plan had been about 10.0:1 and a Crane 343801, i had debated the 290R but did not want it that rowdy. I also have the cam cards for a number of other cams i considered and calculated DCRs on - weird i have this kind of stuff but not clearances cam degrees and so forth, i had just crammed them in some of my books. Anyway - trip down memory lane.

Also Crower did confirm they use .020 as advertised on this cam.

Based on the feedback i will degree the cam in the truck, I really don't think I advanced it but will check. I'll also "rent" a compression tester when i do that and see if it agrees with mine. Because according the the calculators even that should not get this cam anywhere near 195psi cranking compression. As Brent said yes it's just a calculator but 30-40 PSI seems too far off.

Plugs and timing were mentioned. It currently has Autolite 45's, it has an MSD distributor currently with 12 degrees initial, a blue bushing and 1 light silver and 1 heavy silver spring.

I believe the target AF is set to 13.6 but will have to double check that,

Also i will get the Termiantor controlling the Timing and see if that changes anything.

I'm planning to change the cam, but need to figure out why it's acting the way it is.

[blykins]

Can you show me a detailed picture of the insulator, threads, and ground strap of the plug?

[DuckRyder]

I can: Depending on internet speed give em a second.