Lsab ? - Chevelle Tech
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post #1 of 12 (permalink) Old Feb 25th, 20, 4:57 PM Thread Starter
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Lsab ?

Will increasing LSAB size lean idle mixture ? Would like to reduce gassy idle smell.
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post #2 of 12 (permalink) Old Feb 25th, 20, 9:10 PM
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Chris
 
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Re: Lsab ?

I would think a larger hole would delay it.
I think what you need to do is lean the IFR's, not the low speed.
Could be wrong tho.
How much overlap is in your cam? If is has a lot, there's no getting rid of it. May get better tho.

73 nova,3515#(all steel)Pump gas!(91octane)406ci N/A, best 1/4,1.45 '60,[email protected],10.6 @ 122.38, short shifting,NO tuning!


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post #3 of 12 (permalink) Old Feb 25th, 20, 9:21 PM Thread Starter
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I can’t change out IFR’s on my carb.
228/238 at 114
I believe your right saying IFR’s are for idle.

Biggest concern is fuel washed cylinders at idle, but after idling for five minutes or so, plug is nice and white.
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post #4 of 12 (permalink) Old Feb 25th, 20, 9:40 PM
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Chris
 
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Re: Lsab ?

I can't remember but I think you do the wire thing in the IFR in the metering block

https://bangshift.com/forum/forum/ba...-at-idle/page2
https://www.chevelles.com/forums/13-...-passages.html

73 nova,3515#(all steel)Pump gas!(91octane)406ci N/A, best 1/4,1.45 '60,[email protected],10.6 @ 122.38, short shifting,NO tuning!


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post #5 of 12 (permalink) Old Feb 25th, 20, 9:53 PM
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Mark Whitener
 
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Re: Lsab ?

What carb? Engine Combo? Timing curve?

Mark Whitener

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post #6 of 12 (permalink) Old Feb 25th, 20, 10:00 PM Thread Starter
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Mild 396, 750 Holley DP, 36’ in about 1600, vacuum adv bottom of carb. Idles 750-800. I think primary jets are 66. Idle screws 3/4-7/8 turn out. HP mid body.

Engine has Rhodes lifters which pull out some duration at idle ?

I’ve heard of paper clip, might try that, Thanks, WHT !

Last edited by Reelysalty; Feb 25th, 20 at 10:20 PM.
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post #7 of 12 (permalink) Old Feb 25th, 20, 10:13 PM
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Chris
 
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Re: Lsab ?

Mark's the man!

73 nova,3515#(all steel)Pump gas!(91octane)406ci N/A, best 1/4,1.45 '60,[email protected],10.6 @ 122.38, short shifting,NO tuning!


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post #8 of 12 (permalink) Old Feb 26th, 20, 1:42 AM
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Kerry
 
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Where are the IFR located? You can tap the metering blocks to have them in the proper lower location, or if they are there easily remove the pressed in jet, tap it, and make your own.

How many degrees advance at idle?

Are the primary transfer slots exposed as square at idle?
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post #9 of 12 (permalink) Old Feb 26th, 20, 8:38 AM Thread Starter
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pockets, I’d rather not get involved in drilling, tapping etc metering blocks.

Idle timing is about 25 static plus VA or around 50. Idle vacuum is 15”.

Good call on primary transfer slots !
I can kill engine by turning one idle mixture screw, engine is very responsive to 1/8 IMS adjustments. Also very responsive to idle speed screw. Makes me think factory primary transfer slots are OK.

Since I adjusted lifters, seems I get a slight “roll” up and down maybe 100 RPM at low idle (650-700) which was cured by going to (750-800), my “standard” idle.

Whenever I make a change, I try to become more aware of consequences. I might be imagining gassy smell, breeze could have been blowing exhaust in garage ! Plug checked is beautiful light gray after 5 minutes idle.
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post #10 of 12 (permalink) Old Feb 26th, 20, 9:14 PM
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Re: Lsab ?

Quote:
Originally Posted by Reelysalty View Post
Will increasing LSAB size lean idle mixture ? Would like to reduce gassy idle smell.
How much of the transfer slot is showing on the primary side?. .020 to .025 would help with reducing the rich smell.


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post #11 of 12 (permalink) Old Feb 26th, 20, 9:44 PM Thread Starter
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I haven’t pulled carb to check but, I can kill engine by turning one idle mixture screw, engine is very responsive to 1/8 IMS adjustments. Also very responsive to idle speed screw. Makes me think factory primary transfer slots are OK.
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post #12 of 12 (permalink) Old Feb 26th, 20, 10:26 PM
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Chris
 
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Re: Lsab ?

I sent my blocks to Mark and he moved mine years ago.

73 nova,3515#(all steel)Pump gas!(91octane)406ci N/A, best 1/4,1.45 '60,[email protected],10.6 @ 122.38, short shifting,NO tuning!


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