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360 small block, 270H cam, 1.6 rocker ratio, 3.23 gears poor low speed TQ

Started by femtnmax, April 02, 2011, 10:51:04 PM

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femtnmax

Snow melted enough to drive the car for first time.  Street driven Challenger with 4 speed, Edel rpm magnum heads, rpm air gap intake, hooker super comp headers, cam is Comp 270H with 224 dur@.05 lift and 110 lsa.  Torque doesn't come on strong until 3000 rpm which is way too late.  Seems like strong torque around 2000 rpm would be better.  Increased idle timing advance to 16* btc helped some.  But engine doesn't have much torque down low, and has low idle vacuum about 10 inches max.
Static compression 10.7, dynamic 8.8, quench .044.  Have drove the car 140 miles, working it to seat the piston rings.  No detonation thus far, using premium pump gas at 5000 foot elevation.
Adding the higher rocker ratio made the cam more 'cammy', and took away the low-mid performance that other users liked about the 270H cam.
To improve low-mid rpm torque, is reducing to 220 duration@.05 and widening the lsa to 112 enough of a change?  Or should I go to around 115 dur@.05 with 112 lsa?
The OEM 340 cam had 110/120 duration@.05 with 114 lsa is that correct?  I thought I should change the specs to that direction, but still account for the rocker ratio increase.
Phil

firefighter3931

Was the cam degreed in ? If so, what was the installed centerline ?

You will be able to pick up some low end power by advancing the cam  :yesnod:



Ron
68 Charger R/T "Black Pig" Street/Strip bruiser, 70 Charger R/T 440-6bbl Cruiser. Firecore ignition  authorized dealer ; contact me with your needs

femtnmax

Quote from: firefighter3931 on April 03, 2011, 10:06:38 AM
Was the cam degreed in ? If so, what was the installed centerline ?
You will be able to pick up some low end power by advancing the cam 
Cam spec is 110/106.  I degreed and installed 2 degrees advanced to account for future chain stretch.
Phil

heyoldguy

quote author=femtnmax link=topic=79595.msg894912#msg894912 date=1301852165]
Quote from: firefighter3931 on April 03, 2011, 10:06:38 AM
Was the cam degreed in ? If so, what was the installed centerline ?
You will be able to pick up some low end power by advancing the cam 
Cam spec is 110/106.  I degreed and installed 2 degrees advanced to account for future chain stretch.
[/quote]
I'm curious, does that mean you installed it at 104 or 108?[

femtnmax

Phil

firefighter3931

I'm sure that the 5000ft elevation is a real cylinder pressure killer ! Something smaller in the 220*@.050 with a 108 lsa to build low speed pressure would be the ticket, inmo. I wouldn't go any tighter than 108* lsa with a closed exhaust system.

An Engle k56/k58 108 lsa is what i would try.  :yesnod:



Ron
68 Charger R/T "Black Pig" Street/Strip bruiser, 70 Charger R/T 440-6bbl Cruiser. Firecore ignition  authorized dealer ; contact me with your needs