I Have My Eye On A 400...

DorianL

DorianL

solid fixture here in the forum
Staff member
Greetz all,

many here know my love for the 400 SBC. I have found a guy selling (for legit reasons) a freshly rebuilt, aluminum head 400. It has less than 100 miles on it.

This would be to stuff in my 1969 Corvette.

I probably will go to see it Friday.

Since I have power brakes and vacuum accessories (lights and wiper door) idle quality is a concern. (I’ll be running EFI.)

The stated cam is and I quote:
“A Howard custom grind 488-522 lift, 239-248 duration, advertised at .050 288 degrees.
Power band 2200-5800 rpm.”

LSA he thinks is 110 or 112. The seller doesn’t know.

I don’t know anything about the dark arts of cam selection. However the power band seems to suggest the idle can’t be that bad. He says his power brakes (Monte-Carlo) run well.

What are your thoughts- how many inches do you think it’s pulling.

I’d hate to have to swap out a new cam and lifters.

Also, it comes with a flexplate. I’ll need to swap on a flywheel. Are externally balanced 168 tooth flywheels available ? I think I saw some on Summit.

MTIADC3
 
239-248 duration, in a 400 sbc should put the power band in the 1500rpm- to about 5800rpm range,
ideally ,with that cam duration,
you'll want at least a 10:1 static compression and 10.5:1 would be better ,
with a cam like that.
that cam duration in a street driven corvette should be fine with a manual transmission,
but just on the upper edge of a street car engines power band for a stock auto trans,
unless you install a 3000 rpm stall converter and while power brakes should work,
without one, for smoother lower rpm operation,
you might want a vacuum booster,
if you find its just a bit too radical,
yes I fully realize you have a MANUAL TRANS BUT YEARS FROM NOW SOMEONE READING THROUGH THE THREAD MAY NEED THE INFO,
you can swap to a set of rhodes hydraulic lifters, on that cam, and make a very noticable reduction in how it seems to idle, and adds a bit more torque at off idle rpms,
YES they tick rhythmically like solid lifters,they are not silent,
Ive run them in many engines and really like them.
when properly adjusted but they effectively reduce the effective duration so the cam acts like its smaller and milder,
below about 3500 rpm by 5-7 degrees and give you the full effective
duration only once the engine rpms exceed about 3500rpm.
yes externally balanced 168 tooth flywheels are readily available
GET ONE THATS SFI CERTIFIED
http://garage.grumpysperformance.com/index.php?threads/what-fly-wheel.6124/#post-35034

http://garage.grumpysperformance.co...ectly-installing-bellhousings.584/#post-21690

http://garage.grumpysperformance.com/index.php?threads/a-brief-look-at-clutches.447/

talk to RICK his 406 has a cam of similar duration,
but his is a hydraulic roller cam, yet the power band and street manors will be similar
camcomp.jpg

Duration_v_RPM-Range_wIntakeManifold01.jpg


http://garage.grumpysperformance.com/index.php?threads/rhodes-lifters.1552/#post-6067
 
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Thanks Grumpy !!! :cool:

Now the Rhodes lifters... would that also raise the vacuum at idle ?

The stated compression was 10.0:1
 
I had once one of those vacuum boost pumps. I hated it. Making these annoying popping sounds of one of those portable tire inflation units.

Hmm, I wonder if the higher performance L46 (350HP-380TQ) used solid lifters. It could be a nice hommage :D

EDIT. Nope, the L46 was hydraulic
 
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yes the rhodes lifters do raise the vacuum at idle some what
 
The fellow will measure the vacuum at idle today. I believe I need 11 inches to work everything. :eek:
 
13.3 inches of vacuum... that should be enough

With the EFI, maybe I can massage 14 out of that.
 
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Rhoads VMax lifters increased the vacuum of my Crower 00350 SOLID flat tappet camshaft 302 Chevy from a wandering 4-6" to a steady 9.5" at an 1100 rpm idle. Also revs easily (and quickly) to 8000 rpm on the test stand. Jack Rhoads says that these "hydra-solid" lifters can be used with a solid lifter camshaft. Special adjustment procedure required.
 
Loves302Chevy said:
Rhoads VMax lifters increased the vacuum of my Crower 00350 SOLID flat tappet camshaft 302 Chevy from a wandering 4-6" to a steady 9.5" at an 1100 rpm idle. Also revs easily (and quickly) to 8000 rpm on the test stand. Jack Rhoads says that these "hydra-solid" lifters can be used with a solid lifter camshaft. Special adjustment procedure required.
Click to expand...

Interesting. What did you think of lifter noise with Rhoades ?

could you hear while driving ?
 
@Loves302Chevy how noisy were those Rhoads lifters ?

The visit to see the motor was both conclusive and inconclusive.

I made a down payment on the engine. From what I can see it seems to be as described.

We did go for a drive and I could not detect any odd vibrations, noises or performance. On the other hand, it was difficult to assess the output.

The 400 was dropped into a 1972 Monte Carlo. The TH350 was stock other than for a 10-inch converter. There was no kickdown cable; he was sorta shifting manually with a loose console shifter. The car also had granny gears and a peg leg. None of the combination worked. I’ll bet my crappy corvette could out run the MC at a stop light.

Furthermore, he has not yet installed the header and was going through an iron exhaust manifold and he didn’t really tune the carb either.

The 13+ inches of idle was at 850 RPM. That was surprising. It sure seemed to be closer to 1000-1100. His vacuum brakes seemed to work well.

I'm on the fence for the Rhoads lifters. If I have to swap intake manifold, it would be a good time to do it.
 
rhoads lifters will if properly adjusted have a rhythmic clicking sound, rather similar to a sewing machine,
similar to properly adjusted solid lifters \
but noticeably quieter than solid lifters
certainly not as quiet as hydraulic lifter's
but a nice reassuring soft rhythmic clicking sound
 
DorianL said:
@Loves302Chevy how noisy were those Rhoads lifters ?
Click to expand...
Well, I am running them on a solid lifter camshaft, so they actually are quieter than standard solid flat tappets. This engine is sitting in the basement and never made it into a vehicle. The same for my 267, 334, and 350.
 
Grumpy said:
rhoads lifters will if properly adjusted have a rhythmic clicking sound, rather similar to a sewing machine,
similar to properly adjusted solid lifters \
but noticeably quieter than solid lifters
certainly not as quiet as hydraulic lifter's
but a nice reassuring soft rhythmic clicking sound
Click to expand...
Well said.
 
Hmm.

Here’s the catch, it’s a “while I’m at it” issue again. I suspect that the intake manifold on there is too tall
And will need to be swapped out with mine...

Can we agree that the Rhoads lifters would improve my low end torque, vacuum and idle quality ?

If I installed the lifters, I’d have to go through the cam brake in again- right after the cam just had one, correct ? Any downsides there ?

Finally, can one hear the lifters from driver’s seat?

The idle at 850 seemed ok. Better than I was expecting.

I suppose the right thing to do is drive it as is and then decide. After all, yanking the intake again the s not such a big deal.
 
Can we agree that the Rhoads lifters would improve my low end torque, vacuum and idle quality ?

YES

If I installed the lifters, I’d have to go through the cam brake in again- right after the cam just had one, correct ?
YES

Any downsides there ?
YES A USED CAM IS MARGINALLY (MAYBE 20%) MORE LIKELY TO FAIL DURING A SECOND BREAK IN
, so most guys install both a new cam and lifter combos

Finally, can one hear the lifters from driver’s seat?
depends on the car but yes its likely if you really listen for it, but in a corvette the exhaust rumble generally mutes/muffles most of the sound
 
Thanks grumpy. :cool:

I’m running a standard GM replacement cam (no performance) through headers on an otherwise nondescript powerplant. Low compression. Small valves. Tired overall. My guess it’s making 190 HP on a good day.

For shits and giggles - could some kind soul run a dyno comparo with the 406 :D:D:D
 
DorianL said:
could some kind soul run a dyno comparo with the 406 :D:D
Click to expand...
Well that leaves me out then ! :)

Can you provide the info below ?

Dynomation 6 Input Variables

Bore & Stroke:
Displacement: cubic inches
Rod Length:
Heads Make/Model with flow numbers: Flow (CFM) at several lift points.
Combustion Chamber Size in CC’s:
Dome Volume: For a domed piston use a (-) negative number.
Valve Relief Volume: For a piston with valve reliefs or dish, use a (+) positive number.
Deck Clearance:
Head Gasket Bore:
Head Gasket Thickness:
Valve Sizes Intake/Exhaust:
Intake Manifold Model Type: [Single or Dual Plane]
Model #:
Carburetor Size or EFI (CFM):
Blower/Turbo Make/Model:
Belt Ratio:
SCR & DCR: Or the info to calculate SCR & DCR [ http://garage.grumpysperformance.co...comp-ratio-cranking-pressure-calculator.4458/ ]
Header Tube Diameter: Small, Medium, Large (1-5/8", or , or)
Cam Card: Need all 8 valve timing events at seat-to-seat and at 0.050” & lobe lift or valve lift
Rocker Ratio - Intake/Exhaust:
Cam Installed per Cam Card, or Retarded or Advanced:
Fuel Used: Gasoline, Methanol, Ethanol, E85 .....
 
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