Cam Suggestions

DorianL

DorianL

solid fixture here in the forum
Staff member
Time for one of our favorite games: Suggest a cam o_O

What am I looking for ?

It has to be from Summit Racing... cuz I’ll be ordering my cam button and gaskets from them. I am also looking for a retro roller cam.

The cam that I have is an unknown. But it’s probably bigger than I think. I’m told it’s a “custom ground 488-522 lift 239-248 duration at .050 288”. The rockers are 1.55:1.

I have found that anything under 1500 rpm it doesn’t like and I have to downshift. I’m pulling 14.5 inches of vacuum... which is enough to run my vacuum accessories.

So I’m looking for something more tame. Hmm. A good compromise of low end torque yet not running out of steam at 4000.

The car is a 1969 corvette with a T5 transmission. That’s a 2.95 first. The rear gears are 3.55:1

The block is a 400. Aluminum heads with 205cc runners with 64cc chambers. Compression is 10:1.

Performer EPS intake. Fi-Tech EFI good to 500 HP. Full headers.

To be honest I’m not sure that I know what I’m looking for other than something funner and easier to drive at low rpm. Maybe a tiny bit of idle compromise for the exhaust note ? Torque over hp ?
 
with that "pulling 14.5 inches of vacuum"
I doubt its got " 239-248 duration at .050 "
for your application,
Id be looking for something in the 215-218 duration @.050 on the intake ,
to maximize the lower and mid rpm torque curve but still have decent mid range power.
and about 220-225 on the exhaust with a bit over .520 lift on a 110-112 lsa
I'm sure if you call lunati , crower or erson they have something in that range
Id install it strait up, (split overlap) not 4 degrees advanced
something like that should make you smile and pull well to about 5800 rpm
the issue youll have with a lower duration cam with that 10:1 compression is potential detonation damage
and going much larger will destroy lower rpm power


ID personally go this route as it gives you a bit more of a safety cushion on the issue of detonation damage
Chevrolet Hydraulic Roller Camshaft crower
SKU# 00468

from an old Hot Rod Tech article with this comment from Joe Sherman:

“Fully assembled, the engine's static compression ratio came in at 11.02:1. Yikes! Compression is good for making power if the engine doesn't get into detonation, but at first glance, this high a ratio seems excessive for an iron-headed engine on 91-octane. However, with the big-overlap cam, cranking compression was only 182-185 psi, well within Sherman's comfort zone. In his experience, anything less than 200 psi is permissible for running a small-block Chevy successfully on pump gas. And in fact, running 91-octane, the engine would make its best numbers with 36 degrees of total advance with no evidence of detonation using NGK UR6 plugs gapped at 0.039 inch.”
Click to expand...
why not call 3-too-5 cam company's and discuss your needs
links in thread below
http://garage.grumpysperformance.com/index.php?threads/semi-fool-proof-cam-sellection.82/

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

http://garage.grumpysperformance.com/index.php?threads/cam-degreeing.9010/#post-32126

http://garage.grumpysperformance.com/index.php?threads/dynamic-vs-static-compression.727/
 
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Comp Cams has one that is right in line with what Grumpy suggested!
Mfg # 12-422-8
Summit # CCA-12-422-8
Grind # CSXR270HR-10
https://www.summitracing.com/parts/cca-12-422-8/make/chevrolet
RPM range = 1600-5400
Adv Duration= int270/exh276
Duration @ 0.050= int218/exh224
Lift @ 1.5 rocker= int 0.495/exh0.502
Lift @ 1.55 rocker= int 0.511.5/exh 0.518.7
LSA= 110

Per Grumpy’s duration chart, that operational range is pretty close, it may differ with your engine. I think you'd have plenty of low end torque with that cam, but the only drawback is its made by CompCams.
 
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I did some guessing with your Compression 9.8:1, didn't know what heads you had so used stock with fully ported with 2.02/1.6 valves. I used that cam, 750 carb, dual plane intake, quench @ .045, retarded the cam 4 degrees. Results from DD2000 are below!
Torque was approximately 400 ft/lbs @ 1500
peak 500 ft/lbs @ 4500
Horsepower was approximately 450 - 465 @ 5500.
Now take into consideration this is with DD2000, Indycars could probably be more accurate than I am, and if you can find a cam with the same specs from Lunati, Crower, or Erson, I would for sure use it. JMHO!
 
Thank you gentlemen...

Opening up a quick parenthesis here... I have installed a retrofit roller cam before on a 400 SBC. All I needed to adapt was a cam button, special rollers and also different pushrods.

I am intrigued. The Comp Cams camshaft above, CSXR270HR-10, requires a wear plate. From what I understand, that is a 0.030 thrust washer that goes between the front of the block and the cam sprocket. I also think I understand that the cam sprocket needs to be machined down .030 to accommodate. Am I understanding this correctly ?

I also notice there is no mention of the distributor gear.
 
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as always you;ll need to verify clearances, but remember max lift occurs well past tdc,
the piston is closest to the valves at some point between 20 degrees before or after tdc not at max lift on most sbc engines

http://garage.grumpysperformance.com/index.php?threads/checking-piston-to-valve-clearances.399/

http://garage.grumpysperformance.com/index.php?threads/dynamic-vs-static-compression.727/
PtV3.jpg

why not call 3-too-5 cam company's and discuss your needs and power concerns and their thoughts about detonation potential
links in thread below
http://garage.grumpysperformance.com/index.php?threads/semi-fool-proof-cam-sellection.82/
 
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Interesting... it seems Crower went more conservative and Crane and Com Cams recommended the same as above

Crane and Comp Cams both recommended the same cam: Comp Cams 12-422-8
Duration at 050 inch Lift:218 int./224 exh.
Valve Lift with Factory Rocker Arm Ratio:0.495 int./0.502 exh.
Lobe Separation (degrees):110

Crower recommends:
https://www.crower.com/chevy-262-400-hyd-roller-cam-cast-steel-5.html
Performance level - BeastINT/EXH - Dur @ .050” Lift: 200°/212° RR: 1.5/1.5 Gross Lift: .435”/.462” LSA: 112° RPM: 2000 to 4500 Redline: 5000

Lunati (the guy there was much more willing to chat)
Voodoo 20120711
https://www.lunatipower.com/voodoo-retro-fit-hydraulic-roller-cam-chevrolet-small-block-270-278.html
Duration @ .050 (Int/Exh): 219/227;
Gross Valve Lift (Int/Exh): .515/.530;
LSA/ICL: 112/106; Valve Lash (Int/Exh)

Grumpy Cam ;)
INT/EXH - Dur @ .050” Lift: 225°/232° RR: 1.5/1.5 Gross Lift: .535”/.550” LSA: 110° RPM: 2200 to 5850 Redline: 6350
 
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If you want to supply the required info to run some Dynomation 6 simulations I would be glad to do that.

Dynomation 6 Input Variables

Bore & Stroke:
Displacement: cubic inches
Rod Length:
Heads Make/Model with flow numbers: Flow (CFM) at several lift points.
Combustion Chamber Size in CC’s:
Dome Volume: For a domed piston use a (-) negative number.
Valve Relief Volume: For a piston with valve reliefs or dish, use a (+) positive number.
Deck Clearance:
Head Gasket Bore:
Head Gasket Thickness:
Valve Sizes Intake/Exhaust:
Intake Manifold Model Type: [Single or Dual Plane]
Model #:
Carburetor Size or EFI (CFM):
Blower/Turbo Make/Model:
Belt Ratio:
SCR & DCR: Or the info to calculate SCR & DCR [ http://garage.grumpysperformance.co...comp-ratio-cranking-pressure-calculator.4458/ ]
Header Tube Diameter: Small, Medium, Large (1-5/8", or , or)
Cam Card: Need all 8 valve timing events at seat-to-seat and at 0.050” & lobe lift or valve lift
Rocker Ratio - Intake/Exhaust:
Cam Installed per Cam Card, or Retarded or Advanced:
Fuel Used: Gasoline, Methanol, Ethanol, E85 .....
 
Thanks Indy. The issue here is I have no idea on several of these variables such as pistons, head gasket, deck clearance...
 
DorianL said:
Thanks Indy. The issue here is I have no idea on several of these variables such as pistons, head gasket, deck clearance...
Click to expand...
How will you know if you have any problems then ???

Do you have a Bore Scope to look at the piston tops or just look up a stock replacement. Most
likely it has a 5-7cc valve reliefs in a flat top piston.

Since we are only comparing camshafts and NOT looking for absolute HP/TQ numbers, then
we could assume a quench distance, head gasket thickness and head gasket bore.

BTW, there are two different camshaft thrust plates, so make sure you get the right one. The
distance between the two bolt holes is different. On my build there was no machining of any
kind concerning the cam gear or thrust plate.

https://www.summitracing.com/parts/nal-10168501
https://www.summitracing.com/parts/nal-10088128

CamshaftThrustPlateSBC.jpg
.
 
That cam comes in OEM roller, or the retrofit style roller that uses a cam button. The first number: 08 is OEM, 12 is retrofit. Click the link, it should take you to the retrofit!
 
The crower CRO -00466 looks to be close, but has somewhat more lift. With your 1.55 rockers it would be int .531/exh.552. It is retrofit like you are wanting?
 
busterrm said:
The crower CRO -00466 looks to be close, but has somewhat more lift. With your 1.55 rockers it would be int .531/exh.552. It is retrofit like you are wanting?
Click to expand...
Looks like an excellent choice as well. And yes. Retrofit is what I’m after.
 
roller cam lobes are not ground at an angle like flat tappet cam lobes are,
so the retainer plate or cam button is mandatory,
to keep the cam lobes rotational center stationary under the roller lifters

read, and ask questions before ordering parts
http://garage.grumpysperformance.co...-the-extra-cost-vs-a-flat-tappet-design.3802/

http://garage.grumpysperformance.com/index.php?threads/oil-system-mods-that-help.2187/

http://garage.grumpysperformance.com/index.php?threads/trimming-a-cam-button.15449/#post-91353

http://garage.grumpysperformance.co...ped-nose-cam-in-early-block.14182/#post-71937

http://garage.grumpysperformance.co...d-high-spring-pressures-don-t-work-well.1489/

http://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/

http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/

http://garage.grumpysperformance.com/index.php?threads/rocker-push-rod-wear-issues.9815/
 
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