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Thinking of going to smaller cam for torque & MPG
Hello, I haven't been here for quite some time.

Here is what I have:
1972 Monte Carlo
4.56 posi, TH400 with GV OD (3.56 in OD) 3000 RPM convertor
355 with forged flat tops .025" in hole with .015 steel shim head gasket, 4 valve reliefs
stock rods & crank, balanced
Edelbrock ProFlo 3500 EFI
MSD ignition
1-5/8" headers & 2.5" dual exhaust, H-pipe
Summit aluminum heads (rebranded Brodix IK180) 2.02/1.60 64cc 180cc
flow is suppose to be 244/175 cfm @ 28" H2O
Good PAC beehive valve springs & Smith pushrods
Lunati 50156 retro roller cam & lifters 232/242* @ .050" .510/.525 lift (stock rockers),
rated to 6500 RPM + Comp full roller rockers 1.6, lift = .544/.560
SCR = 10.25, DCR @ sea level 8.66, at Denver 5280' about 7.6

I live in Colorado & drive from 5280' to 8500' altitude

It SUCKS gas!

I'm thinking of putting in about 20* smaller cam for street torque & MPG
I have my eye on Howards Cams 113215-08
217/225* @ .050" .495/.500 lift (stock rockers) 108* LSA

With my 10.25 CR, this cam would have a very high DCR of 8.95 at sea level, but about 7.9 @ 5280


vinniekq2 01-04-2013 08:32 PM

you are losing a tonne of HP at that altitude. Maybe look into turbo normalising.. That cam can be changed out too.


Thanks guys,

The Howards cam that I'm looking at would gain low & mid-range torque and MPG.
.3 higher DCR & 12* less overlap. I plan to use my 1.6 rockers for .528/.534 lift
I will loose some HP above 5400 RPM.

The Edelbrock 3500 has only a small control panel that stays attached. It lets me control timing & mixture as cells every 1000 RPM & 3 vacuum ranges. No PC port.

Has storage for 3 data sets, I use 1 for power settings, & 1 for lean mixture.

Unit shows about 4" of vacuum with key on & motor off, due to altitude.

I have an O2 sensor in each side. Passenger is used by 3500 & it displays red/green LED real-time. Drivers side has a seperate gauge that I monitor. They generally agree with each other.

Dizzy is special for & controlled by 3500

As I have low vacuum, I put on a hydroboost brake unit rebuilt from Astro van.

I spent lots of TLC setting up the 12 bolt gears & it's dead quiet. I would hate to tear it down. Next rear tires will be taller so as to turn less RPM on highway.

In OD my gear ratio is 3.56 I usually leave it in Auto mode & it acts like a 4 speed auto.

vinniekq2 01-05-2013 07:38 PM

sounds well thought out. I guess you have no choice when you live at altitude.

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