Bits Of Info And Comments On A Bbc Cam Selection

[Grumpy]

heres a rather interesting discussion

Lets play the cam recommendation game
I'm building a 427 BBC for one of my cars. Time to think about what cam for it.

Car specs are :

3300 lbs ( not a chevelle . Sorry)
4 speed manual ( G force 101a ) with 2.75:1 first gear. Mcleod RXT clutch 30 lb flywheel
Currently has 4.10 dana 60 gear set. Might go down to 3.54
29 inch tall rear tire
29 inch tire with 4.10 gears and .77 Overdrive
Engine specs are a little unusual .

New Blueprint Gen VI style 4.25" siamesed block
3.76 Callies Compstar crank one piece seal ( I hate leaks. Hate them )
6.535" Molnar rods
36cc dome racetec pistons for 11:1 compression
AFR 265 heads cnc chamber.
total seal gapless rings
Edelbrock pro flo 4 fuel injection with 60 lbs injectors
4603 Morel lifters
Limited at 7K RPM
427 cubic inches

As you can see by the little heads this is NOT a max power engine. I'd like to get it close to 600 HP but I'd also like it to get 15 MPG or better. This is a 99% street engine that MIGHT see some drag time but the local track sucks and I dont want to build a car for that purpose. It'll need 7-8 inches of vacuum at idle to get the injection to work right. I'm thinking in the 245-250 range at .050" and mid .600 lift at most on 110's.

What do you think for a cam. Again not max effort but I'd like as much oomph as I can get given the design considerations.

this cam was initially suggested
https://www.claysmithcams.com/hr-84...65-or-290-oval-port-heads-to-max-of-6200-rpm/

• Part. No. 160-3103 Grind No. HR-8486-7-CSR
• Advertised Duration - 284/286
• Duration @ .050 - 225/227
• .200” Duration - 137/136
• Lift .559/.530
• Centers 103/111
• LSA 107

before I even read his response I thought to myself... thats not enough duration and that's,a bit less lift than I might have suggested,
for a 427 BBC that has the potential to spin up faster than a 454 BBC with the desire to max performance yet remain street driveable, yes that 225/227 will make it very decent in mid range and instantly accessible torque

Hydraulic roller. 97.3% street or more but some track time.

That Clay smith cam is a terrible grind. Way too short on the duration unless its a 396 and that 107 LSA ? The lift doesnt take advantage of the AFR heads flow characteristics at all. Thats a lousy cam for 265's. Ive run a few sets of those ver the years and they really like mid .600 lift and 240@050' or better duration. Ive run less and more and they respond pretty well to the 240-250 range.

The engine is going to be built to rap up to 7K as needed. Biggest issue is going to be sufficient idle vacuum to operate the injection junk. That my biggest mystery.

heres the cam he eventually went with

Just got back from the strip. Ran a best at 10.72 at 127 . Still getting used to the 5 speed but thats not too shabby for a street car that drove 35 miles there and back. . Put about 500 miles on the car in the last week since moving to South Carolina and its getting around 14 MPG . Not quite where I wanted but I havent done a LOT of "normal" driving. I'm pretty pleased with the 240\244 grind and have been shifting at 6500. The Holley HP injection system is smooth as silk after a few hundred miles of self tuning. Let that throttle off and its down to 800 RPM rain or shine and WOT or part throttle transitions are seamless..

I would have suggested this erson cam (link below)
in that application
I doubt it would hurt peak performance,
but I'd be amazed if it did not provide just a bit,
better low and mid rpm torque, and match the EFI better
https://www.usaperform.com/cams-lif...etro-hyd-roller-cam-238-246-050-lift-676.html
B Chevy 65-96 Retro Hyd Roller Cam - 238°/246° @ .050" Lift .621
Erson Cams newest valve train designs bring the latest in cam technology to the street with its HR Energy Plus Series of hydraulic roller camshafts. Reap the benefits of faster acceleration, smoother performance and better fuel distribution.

Excellent choice for street machines with roots or centrifical type superchargers, running 6-12lbs of boost. 2500 RPM converter and good exhaust. Also works well with fuel injected normally aspirated engines. Will require performance chip.

• Grind# RH-298-365-1
• RPM Range 3000-6000
• Duration @.050 238/246 deg Int/exh
• Lift w/1.7 rocker - .621 in
• Lobe Center 112 deg
• Advance - 0 deg
• Valve Lash - .000 in
• Use Dual spring# 3450 1.460 dia, 120lb @ 1.850 in
• For below 6,200 rpm street only applications use SL931 retro-fit hyd roller lifters
• For Above 6,200 RPM and/or racing use RL931 or RL932 Pro Race Series lifters

Note: Thrust button must be used on Retro-Fit Roller conversions to hold cam to back of engine. Part# PBM325

 

[johnnmo]

97% street I'd say, unless a lot of compression is used, that the 238/246 duration is a bit much.
Cam it for the RPM it will see the most.
Take 10 degrees from both intake and exhaust and it will be more fun to drive, unless you keep RPM about 3,000. But that isn't typical street use.