Which CAM?

[84 400]

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!

[b454rat]

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.

[RustyPile]

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"...

[84 400]

Originally Posted by RustyPile

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"...

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.

[RustyPile]

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.

[scottofksu]

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.

[GASoline71]

Originally Posted by scottofksu

Assumptions:
1. Bore 4.125
2. Stroke 3.75

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

[Tom]

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.

[84 400]

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?

[Dead Parrot]

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?

[84 400]

Originally Posted by Dead Parrot

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?

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.

[scottofksu]

Originally Posted by 84 400

Guys where are you getting 400?

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).

[Tom]

Originally Posted by 84 400

Guys where are you getting 400?

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.

[Willshook]

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.