406 rebuild questions...
I’ve been lurking/reading here for a while now, but this is my first post. I recently bought a ’73 Vette that I’m going to restore that has a 406 small block. The previous owner said he mainly ran 1/8 mile with it. When I rebuild the motor, I’d like to make it a little more mellow for street driving. The car does run great and the compression check ranged from 162-172. Can I get away with just a milder cam kit? I called Comp Cams. They suggested a 12-211-2 or maybe a 12-240-4 (to help with the vacuum). Maybe I should also be looking at swapping out the single plane intake? I’ll never take it to the strip…only around town weekend driving. I appreciate any help…
Here’s the current setup...
406 small block (1970 400 +.030)
9:1 compression (per previous owner)
Speed Pro 7066P pistons
Competition Cams 12-214-4 (http://www.compcams.com/Technical/Se...umber=12-214-4)
Victor Jr. 2975 Intake
Holley 800 CFM #4780-2
Open chamber (smog) heads 2.02/1.60
HEI dist, Accel Supercoil, MSD 6AL
Super T-10 trans.
Overall this sounds like a nice combo, I wouldn't rush in to make changes.
pass on the 305H cam and rhoads lifters.
Instead use a Comp Xe284H-10 12-250-3 cam and conventional hyd lifters.
Consider using a RPM type manifold. Will give up but a few few top end ponies but add a lot of mid range torque right where you'll be using it the most.
This combo will make plenty of power yet will drive a lot lot nicer.
Trying to tame a big race cam with rhoads lifters is snot going to work for ya.
if you were to swap the old smogger heads for a AFR 195 Eliminator head, you would think you'd bolted on a afterburner.
reuse the 800cfm carb
swap to a RPM hi rise dual plane manifold
swap the 305H cam and lifters for a Comp XE284H-10 can and hyd lifters
change the cylinder heads A brodix IK200 is a very good head also.
I could not find the specs on your pistons. If flat top use a 70cc head.
if dished use a 64cc head.
With the ignition timing set up properly, your power brakes will function fine.
it will still have the bad boy idle but will be a lot nicer to drive overall.
It will be much faster.
Thanks for the feedback. I couldn't find any info on the pistons either, but the po definitely says they're flat top. I really hadn't planned on swapping out the heads at this time at $1000-1500, so I'll probably just look at the cam and intake for now. And, if I was going to be doing much highway driving the 3.70s would have to go...but for around town they're ok.
If you want to slow the hwy cruise rpm down a bit go to a taller 28" tire P235-70-15
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