Calling Cam experts, 70 LS-5
Thread Starter
Burning Brakes
Joined: Dec 2012
Posts: 1,243
Likes: 19
From: Edmond Oklahoma
Calling Cam experts, 70 LS-5
Gang
Helping my friend with his 70 LS-5 do some tuning.
Attached is the actual Cam specs of the cam used to rebuild his engine.
Can anyone comment on this cam and inform on the difference in this one verses the bone stock original cam specs for the 454, 390 horse.
Based on this analysis I'm wanting to understand what the dwell setting should be and what timing recommendations folks would have.
We are having his carb (Q-Jet) checked over for proper jets, rods etc and then want tune it out.
Without having the luxury of sending his distributor out to Lars I don't fully understand what the parameters are we should be shooting for.
Thanks for any help
Helping my friend with his 70 LS-5 do some tuning.
Attached is the actual Cam specs of the cam used to rebuild his engine.
Can anyone comment on this cam and inform on the difference in this one verses the bone stock original cam specs for the 454, 390 horse.
Based on this analysis I'm wanting to understand what the dwell setting should be and what timing recommendations folks would have.
We are having his carb (Q-Jet) checked over for proper jets, rods etc and then want tune it out.
Without having the luxury of sending his distributor out to Lars I don't fully understand what the parameters are we should be shooting for.
Thanks for any help
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
It has about 10 more dgr of intake duration compared to stock. And more lift.
If the car does not have headers, it's not the best choice as it's a single pattern cam.
As for timing advance, you'd look to advance the timing faster at low rpm. Idle around 20-25 dgr advance (including vacuum). Max it just before 3000 rpm. You'll want the vacuum can attached to manifold vacuum (factory was ported). You may need to limit the amount of advance the vacuum can pulls. It should pull about 10 dgrs.
If the car does not have headers, it's not the best choice as it's a single pattern cam.
As for timing advance, you'd look to advance the timing faster at low rpm. Idle around 20-25 dgr advance (including vacuum). Max it just before 3000 rpm. You'll want the vacuum can attached to manifold vacuum (factory was ported). You may need to limit the amount of advance the vacuum can pulls. It should pull about 10 dgrs.
Race Director
Joined: May 2006
Posts: 18,742
Likes: 2,583
the dwell setting will alway be 30 degress regardless of cam.
if you install an aftermarket spring kit and advance stop bushing using a dial back timing light you want a total of 36 degrees advance fully in by 3K with the vacuum disconnected.
if you install an aftermarket spring kit and advance stop bushing using a dial back timing light you want a total of 36 degrees advance fully in by 3K with the vacuum disconnected.
Thread Starter
Burning Brakes
Joined: Dec 2012
Posts: 1,243
Likes: 19
From: Edmond Oklahoma
Instructor
Joined: Aug 2012
Posts: 162
Likes: 5
From: Visalia CA
Point dwell will be between 28 and 30. Timing depends on several things...compression ratio, cam timing, combustion chamber design etc.
Too much and you may have detonation too little will create higher than normal exhaust temps. I would start out at 32* total and see how it "acts". Drive it, listen for detonation. This will occur when you stand on it. How does it start after it's hot? Does the floor feel excessively hot? Hope this helps.
Too much and you may have detonation too little will create higher than normal exhaust temps. I would start out at 32* total and see how it "acts". Drive it, listen for detonation. This will occur when you stand on it. How does it start after it's hot? Does the floor feel excessively hot? Hope this helps.
