08-18-2024, 02:20 PM | #1 |
Sb 400 club
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Which CAM?
1977 350 truck short block (stock dish pistons )
64cc iron heads with 2.02/1.6 valves and 184cc intake runners Edelbrock 2101 intake Stock Qjet (77 k10 auto) Hooker super comps 1.875 primary tubes Transmission is BW super T-10 Rear gear is a 3.08 but will go to 3.55 /3:73 in future Tire size is 265/60r15 Weigh is # 3500 (1980 corvette not a truck) Driving will be street not a race car, no towing. Would like some recommendations in both flat tap and roller. Would also consider solid lift cams. Somethibg like a COMP 268h? Thanks for any input!
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1984 chevy c10, built 400sb,.(SOLD) 77 K10 Project / daily driver "The Grinch" http://67-72chevytrucks.com/vboard/s...d.php?t=318363 1956 Willys Wagon (327 chevy) Project (Now Buick 225) 1980 Corvette L-48 4 speed 1992 Mustang GT built 5.0 5 speed 1985 C10 LWB Sold 1982 K10 SWB plow truck Parted out 1986 D30 M1028 fire brush truck Parted out Last edited by 84 400; 08-19-2024 at 10:01 PM. |
08-18-2024, 02:45 PM | #2 |
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Re: Which CAM?
I ran both the HE and XE 268 cams. Don't really remember the HE, it was over 25 years ago. But XE sounded wicked in my TBI406, pulled like a freight train. But can't go wrong with either.
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08-18-2024, 03:55 PM | #3 |
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Re: Which CAM?
Two items in your combination need serious consideration when selecting a cam.. Those dish pistons = low compression.. Most performance cams need a minimum of 9.0 + compression. Longer duration moves the power band up the RPM range. That 3.08 rearend ratio and low compression just hinders any moves in that direction..
Carburetor, intake manifold, camshaft profile, if automatic transmission the torque converter stall speed, rearend ratio AND distributor curve -- all play an important part in the "package"... |
08-18-2024, 06:01 PM | #4 | |
Sb 400 club
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Re: Which CAM?
Quote:
Those are good points. With my 64CC heads and a .015 or .018 head gasket should my compression be 9.0 or closer to 8.5? My current short block would be no good for a cam making power above 6,000 rpm. Feel free to offer opinions and recommendations i am reading and learning as much as i can. I think the manual transmission and planned reqr gear change really helps what i am tryibg to do.
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1984 chevy c10, built 400sb,.(SOLD) 77 K10 Project / daily driver "The Grinch" http://67-72chevytrucks.com/vboard/s...d.php?t=318363 1956 Willys Wagon (327 chevy) Project (Now Buick 225) 1980 Corvette L-48 4 speed 1992 Mustang GT built 5.0 5 speed 1985 C10 LWB Sold 1982 K10 SWB plow truck Parted out 1986 D30 M1028 fire brush truck Parted out |
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08-18-2024, 10:18 PM | #5 |
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Re: Which CAM?
The actual final compression ratio not only depends on the combustion chamber volume, but also the volume of the dished area of the piston.. Long duration camshafts require higher compression ratios..
As for the lifter recommendation.. Solid lifters are not very friendly on the street. There's nothing wrong with quality hydraulic lifters. Because of the modern oil formulas, flat tappet lifters are at risk. |
08-19-2024, 03:12 PM | #6 |
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Re: Which CAM?
Assumptions:
1. Bore 4.125 2. Stroke 3.75 3. Cylinder Head Volume = 64cc 4. Dish Pistons = +12cc 5. Deck Clearance = 0.00 6. Compressed Head Gasket Thickness = .041 = Static Compression Ratio of 10.66:1 With iron heads and the siamesed bore of the 400, you are definitely going to need some duration to bleed off compression to arrive at a dynamic ratio that wont detonate. I don't think the XE 268 would be enough as it will produce a dynamic ratio of 9.8 when installed "straight up". I would say you will want something that will shave at least one point off of that ratio. With the bigger engine - relative to factory small blocks - you should be able to use a bigger cam and not have the truck feel overcammed.
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08-19-2024, 03:56 PM | #7 | ||
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Re: Which CAM?
Was thinking the same thing... is it a 400 or a 350?
And for me, the Quadrajet would be the first thing to be eliminated. Gary
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08-19-2024, 04:49 PM | #8 |
driving is in my blood
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Re: Which CAM?
How did you get the truck down to 3500lbs?
This seems like a bad combo. Iron heads and over 10:1 compression, 3.08 rear gears, 1 3/4" primary headers but a normal performer intake and Qjet carb [not even a performer RPM]. Hard to pick a cam with such a matchup of parts.
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-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
08-19-2024, 06:41 PM | #9 |
Sb 400 club
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Re: Which CAM?
Guys where are you getting 400?
This is a 350. It is the 350 out of my 77 K10. It lives in my 1980 Corvette now that my 1977 K10 is diesel swapped. Stock 1977 k10 short block ( pistons and bore) 64cc iron head 184 intake runners Hooker super comp headers Preformer dual plane intake Qjet carb. Car weighs about 3500 pounds Car has a Super T -10 4 speed Online compression ratios put me close to 9:1. Unless i am messing that up?
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1984 chevy c10, built 400sb,.(SOLD) 77 K10 Project / daily driver "The Grinch" http://67-72chevytrucks.com/vboard/s...d.php?t=318363 1956 Willys Wagon (327 chevy) Project (Now Buick 225) 1980 Corvette L-48 4 speed 1992 Mustang GT built 5.0 5 speed 1985 C10 LWB Sold 1982 K10 SWB plow truck Parted out 1986 D30 M1028 fire brush truck Parted out |
08-19-2024, 07:49 PM | #10 |
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Re: Which CAM?
The first line in your sig does mention a 400sb, just before the SOLD marker.
Just to clear things up: The vehicle is a 1980 Corvette The block is a 350 formerly installed in a 77 K10. The application is street car. Am I close? |
08-19-2024, 09:59 PM | #11 |
Sb 400 club
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Re: Which CAM?
You are exactly correct. I forgot to write it was the 350 out of my K10, that is my fault sorry for the confusion. All charges to the engine are in first post. I may have put this in the wrong sub form and i am sorry if it was confusing or misleading.
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1984 chevy c10, built 400sb,.(SOLD) 77 K10 Project / daily driver "The Grinch" http://67-72chevytrucks.com/vboard/s...d.php?t=318363 1956 Willys Wagon (327 chevy) Project (Now Buick 225) 1980 Corvette L-48 4 speed 1992 Mustang GT built 5.0 5 speed 1985 C10 LWB Sold 1982 K10 SWB plow truck Parted out 1986 D30 M1028 fire brush truck Parted out |
08-20-2024, 05:01 PM | #12 |
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Re: Which CAM?
ARGH! Sorry about that! That makes a BIG difference! Static: 9.48:1 Dynamic for the 268H: 8.16 That seems pretty safe to me from a detonation standpoint! Now I'd consider more holistically your setup from transmission ratios, to final drive, tire height, and the most common type of driving (e.g., city or highway) you intend to do and run some simulations to see at what RPM the motor would be at under various conditions (e.g., approaching a hill on the highway) compared to the power band suggested for the cam you are considering (e.g., a cam with a lower power band might keep you from having to downshift as the engine is sitting at a cruising RPM right in the torque notch on the left of the dynosheet where torque actually increases a little as RPM declines).
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08-20-2024, 07:56 PM | #13 |
driving is in my blood
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Re: Which CAM?
You name has 400 in it.
The sentence under it says SB 400 club In this case yes, something like a 268 would be a great choice. Lunati voodoo or comp XE would be my choices.
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-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
08-24-2024, 10:44 AM | #14 |
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Re: Which CAM?
All good advice. Do you know what RPM ranges you'll be running?
Most work/daily driver trucks do better with a cam with more advance for better low-end torque - branded by Comp Cams as "4x4" cams - vs. cams intended for power > 5500 RPM. |
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