Thoughts About This Sbc Cam?

T

Thunderbolt

Well-Known Member
This caught my attention since i have 2500 stall, 3.42 gears and 8.7:1 compression (but with small boost...)

Hydraulic Flat Tappet. Strong mid-range power. Great street cam. 2500+ Stall converter, 3.42+ gear, & 9:1 -9.5:1 compression recommended. ;Advertised Duration (Int/Exh): 269/296 ;Duration @ .050 (Int/Exh): 224/236 ;Gross Valve Lift (Int/Exh): .485/.485 ;LSA/ICL: 108/104 ;Valve Lash (Int/Exh): Hyd/Hyd ;RPM Range: 2600-5800

Just curios what knowledgeable members would think of it?

For comparsion i have this cam now: Crane 274H06 274/274° Advertised, 218/218° @.050" duration, .450"/.450" lift, 106° LSA.
 
you failed to mention the cylinder heads you use, the , engine displacement, basic info on the supercharger and intake, headers and exhaust system,
the current car/trucks weight, rear gear ratio, the current transmission, tire diameter, and any other related info
carb/ injected? what type of supercharger?
without the related info were all guessing here??
it might be a great match, but without knowing the details????

hey I just picked up FUELIE HEADS FOR CHEAP..

"hey GRUMPYVETTE,I just picked up 492 FUELIE HEADS FOR CHEAP..CAN I GET THEM TO PRODUCE 400 HP!" SURE you can get those heads to produce 400hp, but for the same money you could most likely make an additional 40-60 more hp with better aftermarket cylinder heads,TECHNOLOGY HAS ADVANCED A GREAT...
garage.grumpysperformance.com
 
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350 cui with fulie heads (aluminum heads planned)
Weiand 177 blower kit,
medium length headers (removed the full length headers due to ground clearence issues),
dual 2.5 exhaust with straight thru muffler type,
TH350, stalls about 2700 rpm,
3.42 gears with posi
stock Impala -67 2DHT weight, guess??? 4000?
E85 fuel carbed, 650 cfm, have also a 850cfm but it lacks ported vacuum port, need to adress that...
265-35-18 (about 25 inch) or 225-75-15 (about 28 inch) tyres, depends on the mood
 
yeah the cam you listed should provide a noticeable boost in power/performance
 
Your blower is going to want more CFM's .. The carb is the choke point with a blower.
The 108 LSA is going to bleed off alot of boost... should be around 112-114
Also... E85 Loves compression.
 
I think the "boost bleed off" may be a myth? Or i have watched to many episodes with Richard Holdener on Youtube ;)
I have to make new fuel lines before upgrading the carb, im out of fuel in first gear, work is in progress right now.
The cam swap is years away, slowly buying parts to rebuild a new long block, but its fun to compare cams.
The cam above is the mildest Lunati Bootlegger cam, and now i will be shot down because its a "poser cam" :D
 
Thunderbolt said:
I think the "boost bleed off" may be a myth?
Click to expand...

You can't build pressure if both valves are open for very long.
Some guys use a lower LSA to remove some of the cylinder pressure and still retain the reversion sound effect that a Lower
LSA produces. I think this kinda defeats the purpose of having a blower in the first place.
 
keep in mind "TIME" is a factor
at idle your close to 13 revolutions per second and the intake stroke is every other revolution,
theres not much time for an intake charge (boosted pressure or not) to leak out during the few degrees of valve over lap
theres a significantly shorter time span in the 4000-6500 rpm power band

lsadig.jpg


TIGHTER 104-110 LSA tend to increase scavenging efficincy but at the cost of less smooth idle
pistonposition2.jpg
 
What Unforgiven is trying to say, is at the end of the exhaust stroke the intake opens and starts to refill the cylinder. With a cam with a 108 Intake Centerline, the overlap(int and exh open) will be greater and the forced induction of the blower is going to push some of the new fuel and air out the exhaust instead of staying in the cylinder. Lose of power and torque is the result. Most of guys in the Nova club here with blowers try to keep the overlap between 55-60! I am not a power adder person, but my friends with blowers live this rule, “less overlap and more exhaust duration!”
 
I understand what Unforgiven is saying, and what overlap is.

Is there a way to calculate overlap degrees with only these cam specs?
Advertised Duration (Int/Exh): 269/296 ;Duration @ .050 (Int/Exh): 224/236 ;Gross Valve Lift (Int/Exh): .485/.485 ;LSA/ICL: 108/104
Could it be 66.5 degrees?

I am not arguing, just curios,
Its just coincidence i looked at Bootlegger cams.
 
Thunderbolt its rather easy, if you have the cam card for that cam. Look at when the intake valve opens BTDC and when the exhaust closes ATDC. Add those two numbers together and the sum is your overlap!
For instance: My Compcams Magnum 280 Hyd Roller is as follows
Intake Opens 34 degrees BTDC
Exhaust Closes 26 degrees ATDC
So my overlap is 60 degrees
So according to my buddies in the Nova Club I would be borderline for forced induction.
I could drop my intake rocker ratio to 1.5 to shorten the intake duration about 3 degrees or so and then drop my compression to allow for the added boost of the blower and could be in the ballpark!
 
.
Yes you are correct the overlap is 66.5°. Calculated by Dynomation version 6.03.21

upload_2021-3-26_10-20-34.png
upload_2021-3-26_10-21-46.png

Who makes this camshaft, part number ?
 
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if you want a bit more peak power, the crower 00471 is great for impressive torque and better peak power,
but at a very minimal loss of low rpm street/traffic drive-ability and really requires a 3000 rpm stall converter,
and best matched to a 3.73:1-4.11:1 rear gear with an over drive trans
its the cam RICKs using in the t-bucket and chevy 406 sb
crower00471.jpg

or you can effectively split the difference and select the hydraulic roller cam I use in my similar 383,
and yes it really requires a 3000 rpm stall converter,
in my much heavier corvette, the crane 119661,
and yes still best matched to a 3.73:1- or -4.11:1 rear gear with an over drive trans
crane119661.png
 
Well i cant afford steeper gears and roller cams, and i think i need more torque @2500-3000 rpm as it is now, but i have a bigger carb and a bigger crank pulley (needs machining) that might be a band aid for torque until i have finished my new engine (about 2 years left in build time i guess) :D
 
Grumpy.... He only has 8.7 compression. I think that cam you spec'ed (which looks awesome in my engine) would be too big in his 350 cc engine. Also he is running stock fuelie heads,
I think the lift would be too large.
 
your correct that its on the larger end of what will work, but the Weiand 177 blower kit, compensates for a great deal of the potential lower rpm loss and lack of static compression
 
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