My Cam Research for the Experts Eye

I'm going to contact Straub Tech today to talk about cams. But I wanted to reinforce something posted by Grumpy about talking to the mfg and verifying cam specs and not just taking them off of a website.
Earlier, I mentioned about the discrepancy in the Clay Smith cam from BOTH Summit and SC websites. I first thought I was looking at a cam from Summit with .542 duration. The real cam info was very different.
TXChevy said:
I found a discrepancy in the CS cam data that I'll resolve today. Summit lists both the 012 and 013 cams at .542 lift, but the CS website lists them at .510 lift. Using 1.70 ratio.
I'll call the mfg today to ask about this and to see what they recommend for valve springs as well.
Perhaps I'm comparing apples and oranges due to different durations and LCA/ICA but I was anticipating that a bit more lift than the current Erson cam at .514 would be of benefit.

EDIT: I spoke with CS cams and both lift numbers are incorrect. The correct lift is .500, so now I think I may need to look at either a custom grind from them or going back to my other alternatives. I don't think the .5 lift will be my best choice. Is this a reasonable approach?
Click to expand...

I also found another discrepancy in the CS 160-3101 cam. Perhaps small but it reinforces the point about talking with the mfg.
Summit website lift on this is .600/.569, CS website shows .590/.570. Here's another chart I made to look side by side:
1635865143302.png

Since Straub can sell CS as well, I'll ask not just for their cam recommendation, but also what their data shows on the CS cam.
CS cam shown at 1.7 RR, Straub shown at 1.6 RR.
 
I had a lengthy conversation with Chris Straub, went through the parameters we've discussed here. Very good to talk to, took all the time needed to help me.
His recommendation was for his GTA series cam 280-294-9, at LSA 109. We did discuss the SCR, his comment was that with my engine combination it should run on 91-93 octane. I think that looking at head gasket diameter/thickness, and chamber size, perhaps a modification to one or several of these may help to lower the SCR/DCR number? Example is if a .050 gasket thickness was installed, the SCR drops to 7.94.

Here's my updated chart....
1635873244752.png
 
TXChevy said:
That's something looking at the change in the cam HI, its like there's no meet-and-greet at the ramp base, just hit it and go. Is that one of the factors in increasing base circle in "race" cams?
Click to expand...
HI = Hydraulic Intensity

There are probably several reasons, a couple of are .....

Normally you find that you are having to buy a cam with a smaller base circle. This happens
when the the lift + base circle exceeds the diameter of the cam bearings. If you want more lift,
then you have to decrease the base circle diameter so you can increase the lift.

It can help with the clearance between the rods and cam lobes, a clearance you will want to
verify on your engine.

I think you were wanting to see these two cams compared to your original Erson.

Sim06_vs_Sim10_StraubBBC288-300-9_vs_Sim11_CS160-3101.jpg
 
yes reading the links and SUB LINKS MATTERS

a .050 head gasket may cause problems depending on piston and block deck height.


Bbc Quench

Hi was wondering what would be the minimum quench to run on a 540 bbc 10.5 comp, 630 lift, 230@50 duration Alloy heads , 6000rpm
garage.grumpysperformance.com

tumble and swirl, quench & squish

I could fill chapters on these subjects, but its basically not something the average engine builder assembling off the shelf parts needs to be overly concerned with other than to understand the potential power may change due to the parts selected and the careful assembly and measurement during...
garage.grumpysperformance.com

checking piston to valve clearances

this is an old post I got asked to repost, naturally the first step is to install and correctly degree in your cam, http://garage.grumpysperformance.com/index.php?threads/measuring-piston-dome-volume.17255/...
garage.grumpysperformance.com

calculate required octane for compression ratio

What else influences your car's octane requirements? IF YOU DON,T LIKE READING SUB-LINKS, AND LOOKING AT CHARTS , AND DOING A BIT OF MATH 'AND INDIVIDUAL CALCULATIONS, YOUR UN-LIKELY TO BENEFIT FROM MOST OF THE THREADS, ON THIS WEB SITE! LIKE IN MOST AREAS ITS KNOWLEDGE AND THE ABILITY TO THINK...
garage.grumpysperformance.com

dynamic vs static compression

Blows the theory out of the water that short rods give better detonation resistance. The link article & Trigonometry show Long Rods do it instead.
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unshrouding valves, and polishing combustion chambers

yea it would be nice to come up with the cash to do some amazing build but ultimately as is so often the case the finances arent there. gotta work with what we got i guess...
garage.grumpysperformance.com

ccing my heads

HELP I hope some can help me with a prob I am having. I started to cc my heads so i check all and found that they need to be ground. I have one at 64.3 so I started grinding one of them to be at 64.3 or there abouts. I ground a lot off and got a reading of 62 so I ground more off and came up...
garage.grumpysperformance.com
 
while the duration and lift and LSA of the cam you may select are all important factors ,
your effective compression and quench, fuel octane,
and port flow are also factors that need to be considered, as is the valve size, valve seat angles, valve back cut angles,
, valve spring load rates and type of ignition, injector size or carb jetting, accelerator pump, fuel pressure, fuel delivery volume, exhaust scavenging efficiency, exhaust back pressure, also potentially effect results.
and Id also point out that polishing the combustion chamber and blending off sharp edges on the combustion chamber quench area(s) and use of the correct heat range spark plugs all come into play./
and each choice you make has an effect on the results you'll likely see from other changes made, or parts selected.
like when you get married...
theres a whole lot of little things you only learn from on the spot experience, and making changes to see the results.
but just like when getting married...
the guys with more practical hands on experience can help you avoid making mistakes with what you might think are good ideas,
if you have an experienced and honest mentor
and just like marriage..
just because someone else did it and got away with it,
does not indicate you can do it without consequence's you never anticipated.
 
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Thank you both :thumbsup:
Yes I'd looked at Mike Jones but that's pushing my budget further. I'm not just building the engine, I'm doing the entire car over again. Not a rush on anything but at some point there's a cost limit.

Looking at the simulation, looks like SIM 10/11 are virtually identical for my purposes. SIM 12 sees a bit earlier rise in hp/tq that falls off by about the same amount as it increased earlier in the curves. SIM 12 has less overlap, would that help contribute to a slightly better idle quality?

The simulations are great to quickly see even the small differences. For my use it looks like these 3 cams will give driving results too close for me to notice, so I'm thinking about the combination of other factors to enter into that marriage decision.:brokenheart: Not a done deal by any means but considering the engine factors we've discussed, I'm leaning to the Straub 288/294 (SIM 12). That's just expressing my thought.

Edit: I spent several hours going over quench in articles like this one:

tumble and swirl, quench & squish

I could fill chapters on these subjects, but its basically not something the average engine builder assembling off the shelf parts needs to be overly concerned with other than to understand the potential power may change due to the parts selected and the careful assembly and measurement during...
garage.grumpysperformance.com

Still a novice but now I understand much better WHY my comment to simply thicken up the head gasket to help lower DCR was not feasible and could make matters worse by reducing quench/increasing detonation.
 
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Current plan is to not order anything yet. I'll wait to get block back and get crank and at least one rod/piston installed to verify deck height. If all is still on track I'll then order the cam as a kit.
In the meantime it gives me a chance for continued reading.
 
Yes, I'm not fading into the sunset lol.
I think that this cam is a reasonable solution to the question but I want to have the other bits in hand before ordering it. Plus the heads still have to go to the shop, I'll need the new springs for them.
I've read links on spring setup, do you recommend I install to spec or ask the shop to do it? They're a good local shop.
Thanks again for advice and help, I'm a long way from knowing much but I'm also a long way from where I started.
 
Rick I don't have anything, I was going to get the device to measure height but I didn't even think about checking pressure :(
Perhaps it's best to let the shop do it?
 
yes if its a decent shop your far better off letting them assemble and check the valve train components, especially if you don't have access to the tools required, and have a firm grasp on what to check and why the individual clearances, geometry and parts need to be checked
 
That makes sense. I'll still read up on the links but would prefer they do it with more tools and experience. I plan to get a GTA cam kit from Straub which includes that 288/294 cam, springs, retainers, lifters, rockers etc . Springs listed in their quote are their 110-1236 singles w damper. I saw 1.540 dia which matches the measured dia of my current springs. Didn't see # at lift or coil bind but saw 180#@1.900. I'll research the numbers further.

It's going to take some time to get to that first start but I'd like continue in this thread with more questions as I go.
 
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Sorry, incorrect spring pressure listed above.
From the catalog:
OD/ID Seat # In/Rate Bind Damper Max Lift
1636035777246.png

From the quote:
1636036009452.png

Seems that in many cases I keep finding data mismatches, another Grumpy reason to check EVERYTHING....

Probably simple questions to see if I've learned something:
- if I'm using the catalog data, starting at 135# seat pressure and 310# rate/in, at .578 lift, the seat pressure would be 314#?
- if installed height is 1.900", then at .578 max lift the height is 1.322, which is above bind @ 1.22?
 
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TXChevy said:
Rick I don't have anything, I was going to get the device to measure height
Click to expand...
If you are going to assemble this engine you will still need to have a few measuring tools. I would suggest having .....
(I'm sure there is more that I have missed, maybe someone else will chime in.)

Feeler Gauges
Calipers that measure to .001 inches
Snap Gauges
2-3 inch Micrometer that measures to .0001 inches

Other Tools Needed .....

- Degree Wheel [ Moroso 62191 is a good buy ]
www.summitracing.com

Degree Wheels - Free Shipping on Orders Over $109 at Summit Racing

Find Degree Wheels and get Free Shipping on Orders Over $109 at Summit Racing!
www.summitracing.com www.summitracing.com
- Crank Snout Turning Socket
- Push Rod Length Checker
- Oil Pump Primer
- 1/2 Inch Torque Wrench
- Ring Compressor
- Piston Stop [ You can make this ]
- Ring Filer

bare minimum tools

Grumpy? what do you think the bare minimum of tools would be to build or re-build an engine? I'm thinking of rebuilding the 383 V8 in my road runner and while I have a standard set of mechanics tools like wrenches ratchets, sockets and a 1/2" torque wrench I'm certainly not in possession of...
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A Few Basic Precision Tools

Hey GRUMPY, I need a few basic tools to measure bearing clearances and tools for installing a cam, etc, and suggestions? (and yeah, I'm not swimming in cash, so please take that into account!) keep in mind there's a long list of more expensive tools, like mills, lathes, various types of...
garage.grumpysperformance.com
 
Rick, thanks :thumbsup: I've got 40 years of tool collection lol so I have tons of tools, all the measuring stuff in sets for different sizes like the mics, and various diag equipment.
On my list though are a piston ring filer and pushrod length checker.
I decided that the shop I'm using can do the valve spring install to spec, they are long-term established and known for good work.
 
TXChevy said:
On my list though are a piston ring filer and pushrod length checker.
Click to expand...
If you have a 12" caliper, you could make your own push rod checker possibly by cutting
one in half and threading both ends. Then using some all thread to make it adjustable. Use
your calipers to measure when the valve train geometry is correct. You will need some light
weight checking springs.

You will want to read starting at the link below and going thru post #244 on the next page.
Most ring filers won't give you a square gap, when you put the ring in the bore.

TBucket Engine Project (Dart SHP)

theres absolutely nothing wrong with perforated sheet as a shrapnel screen, but obviously theres a wide variation in the types available aluminum perforated sheet used for ceiling air return ducts is once source, stainless perforated sheet and mesh are both available in several places
garage.grumpysperformance.com
 
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