My Cam Research for the Experts Eye

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member


pro-67491_w_ml.jpg


SBC crank socket
https://www.summitracing.com/parts/pro-67491
BBC crank socket
https://www.summitracing.com/parts/pro-67492
chrysler/dodge/mopar
https://www.summitracing.com/parts/pro-67493
Pontiac crank socket
https://www.summitracing.com/parts/pro-67606


you do it off the lifter not the valve spring simply because adding the pushrod and rocker into the process adds far to many variables, like taking up slack, rocker ratios, friction,possiable ratio variations,manufacturing tollerances, etc. that use of the lifter riding directly on the cam lobe alone or that tool replacing the lifter so the dial indicator can be used easier (THE PREFERED, TOOL) totally eliminates, any variables, and allows faster rechecking
DEAL WITH A QUALITY MACHINE SHOP with a GREAT REPUTATION that depends on maintaining good customer feed back for repeat work.
a competent and experienced machine shop, machinist, you can trust to point out whats REQUIRED and what is SUGGESTED is a very valuable asset , you really should look for and researching what you think needs to be done, how that is accomplished and why its likely necessary in any particular application, goes a long way toward preventing both disagreements and wasted money on an engine build AS does having access too or better yet owning some precision measuring tools that allow you to check and verify that any machine work you pay for was in fact correctly done!

http://www.summitracing.com/parts/PRO-66830/?rtype=10
pro-66830_cp.jpg


http://garage.grumpysperformance.co...ectly-and-get-it-to-last-cam-install-info.90/

http://garage.grumpysperformance.co...ifter-for-checking-cam-timing.3745/#post-9950

http://garage.grumpysperformance.com/index.php?threads/degreeing-in-a-cam-correctly.3097/#post-8240

http://garage.grumpysperformance.com/index.php?threads/cam-degree-equipment-tools.1759/#post-4440

http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-12997
 

TXChevy

Well-Known Member
Rick, that's a bit too much work :)
I'll be doing good to get this cam figured out!

Grumpy, with the dial indicator extensions I got (4-48 thread that fits my Starrett and cheaper IGage indicator) I can replicate Ricks setup with my dial gage stand sitting on the deck.
Before I had to have it in the valley and it was a bit fiddly to get the arms into the proper arrangement.
I'll post results after the crank socket/nut gets here.
 

Indycars

Administrator
Staff member
Nah, that's one hell of a lot of work ..... 180 times, then you record the number, turn it two more degrees ...... or 360 or both intake and exhaust.
That's why I made the comment above, I knew it was a 0.3649% chance ! LOL !!! That might have been an optimistic forecast.

I don't know what I was thinking, I will probably go to my grave without one comparison. But it was still fun!
 

TXChevy

Well-Known Member
Just a footnote, I've kept the cylinders lubed, but I swear I've rotated the assembly so many times that the rings may be halfway broken in
:p
 

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
you do realize that piston compression rings have about 600-750 PSI pressure, for about 1/20th-1/50th of a second forcing them outwards,
in a running engine for the first inch or so of travel on the power stroke?
something missing on a mere physical rotation with a breaker bar!
ringsealw2a.jpg
 

TXChevy

Well-Known Member
Yes, it was just a comment on turning that assembly over repeatedly. But that's what it takes to ensure measurements. Still rotates fine and no marks on the bores
 

TXChevy

Well-Known Member
Ok, I'm reasonably confident I degreed the cam correctly.

I used this socket from Jegs, it's got a slot for the crank key and works very well. Takes a 2" wrench, which I have.
1651599614135.png

I added some additional degree notations to my Mr. Gasket degree wheel
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My setup - if you look closely you can see the cam gear dot straight up for #1 TDC
20220503_105933_HDR_resized.jpg

And the indicators in place
20220503_104024_HDR_resized.jpg

Here's what I came up with, I was able to duplicate these results within a degree or two. Cam is installed straight up at 0 degrees.

1651631215314.png

I'm not sure what to do with the intake and exhaust opening, which come up about 4 degrees off (and I take into account a 1-2 degree fudge factor). If I move the crank sprocket (which is slotted at 2 degree intervals) I'm concerned that I may foul up other factors. I'm also getting mixed up if the two different readings are each advanced or retarded. I "think" they are both advanced?

I kept wondering if I was doing something wrong to repeatedly get intake and exhaust opening readings 4 degrees off, yet other readings came out reasonably close to spec.

I'm inclined to leave this alone and move forward - am I ok to do this? What to recheck?

Edit - I went back and made a positive stop for the piston and re-did the entire degree process. I also placed the flat end of the dial indicator extension on the top of the lifter. Meaning that I didn't have the ball end on the extension - this should have ensured that there was no wobble or side movement as the lifter moved. Readings were virtually the same, within a degree or so. I also sent a question to Straub about this. Please note that it's entirely possible I've messed up somewhere.

Edit 2 - I contacted Straub, they suggested to advance the cam so that the intake opening event is where it is on the card.
"The lobes we use for these are not symmetrical, so a quick centerline method can give a false reading. Small changes in the lifter angle in the bore, and even lifter bore angle itself can effect some of these readings as well."
This makes me wonder if the cam is actually ok where it is, maybe I'm just splitting hairs.
What I think I will do is to first try 2 degrees, then 4 degrees advance and see where all of the readings land. If I'm in a bit of a middle zone (meaning my 1-2 degree measuring variance) then I may go with 2 degrees advanced. At any rate, I will have 3 cam settings to compare - 0, 2, and 4 degrees.
 
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TXChevy

Well-Known Member
I hope you can give some input please - I "think" I've got it figured out.

Looking at the chart I made below it appears that the cam was ground with the intake and exhaust openings advanced by about 4 degrees (always taking into account my checking variance of 1-2 degrees).

When I changed the cam installation to +4 degrees (advanced) it really threw off the readings.

When I changed the cam installation to (-)2 degrees the readings all seem to be in a reasonable range of the cam card. Unless I've missed something it appears that this is the setting I should use.

1651862518203.png
 

Indycars

Administrator
Staff member
Edit - I went back and made a positive stop for the piston and re-did the entire degree process.
Roughly how far down in the cylinder did the piston stop block the piston when you checked for TDC ?

The numbers do seem to be jumping around.
 
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TXChevy

Well-Known Member
Roughly how far down in the cylinder did the piston stop block the piston when you checked for TDC ?

The numbers do seem to be jumping around.
About .5 inch.
I had a dial indicator set up as well, so I was able to verify TDC after removing the stop, plus I checked again using .050 on either side of TDC.
In all cases I took care that the stop and dial indicator were over the wrist pin to avoid any piston rock at the edge.
I can say that I'm confident on the readings I got on the last chart for the three cam settings. Each was checked 4 times and the results were repeatable.
 

Indycars

Administrator
Staff member
About .5 inch.
I was just concerned that maybe you were checking too close to the top where the piston had essentially stopped. It was the only thing I could think to check on, but your all good!

How did Straub want you to degree the cam, by the .050 opening/closing timing numbers instead of the Intake Centerline ?
.
 

TXChevy

Well-Known Member
They were specific to check with .050 lift:

"The lobes we use for these are not symmetrical, so a quick centerline method can give a false reading. Small changes in the lifter angle in the bore, and even lifter bore angle itself can effect some of these readings as well."

I'm feeling a lot better with this setting now, I spent days looking up info and generally feeling like a dummy struggling. It seemed to come together today though.
 

TXChevy

Well-Known Member
Received the 1037 head gaskets today, but before I install heads I will get the timing cover/oil pan installed. I'll be using ARP 12pt head bolts with Permatex #2 sealant on the threads since they all go into water jackets.

I've got a good heavy duty engine stand but it's enough for me to turn the engine as a shortblock. Putting 150# of heads on it will be almost impossible to flip it back around. So I'll button up the bottom first. I'll be using a new fel pro 1-piece pan gasket. Had one on before and it worked great.
Pics, cylinder heads are painted , oil pan repaired and prepped for paint.
20220509_143332_HDR_resized.jpg20220509_125642_HDR_resized.jpg20220509_125659_HDR_resized.jpg

Pan is Milodon set up for clearance to steering drag link.
20220509_143339_HDR_resized.jpg
 

TXChevy

Well-Known Member
Although my next tasks will be heads, pushrod length and valve clearance, I'm looking ahead to intake selection to replace the dual plane edelbrock performer intake, the base version.
E-brock air gap won't fit , so I'm considering a Weiand stealth or e-brock rpm.
Looking at the engine components I'm leaning towards the stealth due to its larger runners. The 427 heads are limited with the smaller size valves, but the cam is of healthy duration and lift.
I'm looking at the Grumpy intake articles - there's also a number of knockoffs from summit and jegs that ran very close numbers in the car craft intake test. But I'm concerned over quality as well.
Input is appreciated!
 

TXChevy

Well-Known Member
Postponing intake selection until I can verify what's the most cost effective choice. I need to get the valvetrain sorted first anyway.

Current:
Timing cover installed. Red paint is my verification of final bolt torque check. I re-used the original Chevrolet chrome cover - it was a solid GM part - but I sandblasted/primed/painted it.
20220523_120602_HDR_resized.jpg20220523_123417_HDR_resized.jpg

Last look at crank and rods, then the pan went back on.
20220524_112011_HDR_resized.jpg20220524_112021_HDR_resized.jpg20220524_151736_HDR_resized.jpg

I had made my own rail stiffeners.
20220524_151814_HDR_resized.jpg

Short block is done, now on to heads and setting up pushrod lengths and proper geometry.
20220524_154013_HDR_resized.jpg

I also decided to redo the crappy fuel pump block off, it will get painted to match cover/pan
20220523_143709_HDR_resized.jpg
 
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