1971 Base 350 Timing
Thread Starter
Pro
Joined: Mar 2010
Posts: 615
Likes: 25
From: Graham NC
1971 Base 350 Timing
Hello,
how far off can the timing be on my 1971 base engine. I am timing at idle 8 degrees, will the car run bad if I’m off just a couple degrees? Car been running great but went wacky this morning hesitating and wanting to stall. Dwell was good and timing may have been off a few degrees. Would being off just a few degrees make it run poor. Thanks
how far off can the timing be on my 1971 base engine. I am timing at idle 8 degrees, will the car run bad if I’m off just a couple degrees? Car been running great but went wacky this morning hesitating and wanting to stall. Dwell was good and timing may have been off a few degrees. Would being off just a few degrees make it run poor. Thanks
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,172
From: Hermosa
Is that 8* with vacuum advance removed? Are you using port or manifold vacuum for the vacuum advance?
Could be your vacuum advance diaphragm has failed. When you start moving and add throttle the vacuum should advance the timing whether port or manifold is being used.
Could be your vacuum advance diaphragm has failed. When you start moving and add throttle the vacuum should advance the timing whether port or manifold is being used.
Race Director
Joined: Aug 2004
Posts: 10,628
Likes: 132
From: Duvall, WA
You should time it with the vacuum advance removed from the distributor and plugged and the springs removed from the advance weights in the distributor. Total timing, ideally, should be 36° with this done. A few degrees off won't have a huge effect on the engine, but it may be noticeable to you.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
jbakyy,
I take it you have been making adjustments turning the distributor.
Grab the entire dist unit and see if it will budge. Sometimes we think we torqued down the dist clamp, and it's not tight.
Who says its IGN? Could be a fuel issue.
What carb? Fuel filter clean?
I take it you have been making adjustments turning the distributor.
Grab the entire dist unit and see if it will budge. Sometimes we think we torqued down the dist clamp, and it's not tight.
Who says its IGN? Could be a fuel issue.
What carb? Fuel filter clean?
Race Director
Joined: Nov 2006
Posts: 13,301
Likes: 7,876
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Have to agree, could very well be something completely unrelated to your distributor. Yes, certainly check your timing, your advanced timing, when it's all in. Ya know, the basics there. Simply checking idle timing isn't really doing very much however. Then plug the vacuum advance canister back in. Check that.
If that all checks out. Then start looking at other possibilities, as in the more likely possibility that something is up with your carb.
If that all checks out. Then start looking at other possibilities, as in the more likely possibility that something is up with your carb.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
5 Best & 5 Worst Corvette Daily Drivers
Joe Kucinski
The Headlights of Every Corvette Generation Explained
Joe Kucinski
5 Best & 5 Most Overrated Corvette Track Packages of All Time!
Joe Kucinski
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
Tech Contributor
Joined: Aug 1999
Posts: 14,384
Likes: 6,408
From: At my Bar drinking and wrenching in Lafayette Colorado
Don't use that crap. I rebuild more carbs as a result of that stuff being used than for any other reason. Completely unnecessary and useless, and it screws up a carb bad.
You're leaving a lot of performance on the table by timing the engine at 8 initial without checking total.
You're leaving a lot of performance on the table by timing the engine at 8 initial without checking total.
Thread Starter
Pro
Joined: Mar 2010
Posts: 615
Likes: 25
From: Graham NC
thanks
jbakyy,
I take it you have been making adjustments turning the distributor.
Grab the entire dist unit and see if it will budge. Sometimes we think we torqued down the dist clamp, and it's not tight.
Who says its IGN? Could be a fuel issue.
What carb? Fuel filter clean?
I take it you have been making adjustments turning the distributor.
Grab the entire dist unit and see if it will budge. Sometimes we think we torqued down the dist clamp, and it's not tight.
Who says its IGN? Could be a fuel issue.
What carb? Fuel filter clean?
Burning Brakes
Joined: Aug 2011
Posts: 834
Likes: 289
If it was running fine and then all of a sudden went "wacky" then you probably have a issue besides timing. Unless the hold down clamp was loose and the distributor turned.
Bad gas?
Clogged fuel filter?
Crack in a rubber gas line?
Original carb?
Bad gas?
Clogged fuel filter?
Crack in a rubber gas line?
Original carb?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
If all you want to do is set "initial" timing, do yourself a favor and time it at 12 degrees BTDC (compression stroke) with distributor advance plumbing removed and capped to prevent vacuum loss. The 8 degrees recommended by GM detunes the engine for BEST WARRANY COST SAVINGS and for compliance with EPA requirements.
If you really want to do the job properly, get Lars' paper on setting timing for performance and follow it exactly.
If you really want to do the job properly, get Lars' paper on setting timing for performance and follow it exactly.
Thread Starter
Pro
Joined: Mar 2010
Posts: 615
Likes: 25
From: Graham NC
Thank you
tQUOTE=bonesbrakr;1608097690]If it was running fine and then all of a sudden went "wacky" then you probably have an issue besides timing. Unless the hold down clamp was loose and the distributor turned.
Bad gas?
Clogged fuel filter?
Crack in a rubber gas line?
Original carb?[/QUOTE]
tQUOTE=bonesbrakr;1608097690]If it was running fine and then all of a sudden went "wacky" then you probably have an issue besides timing. Unless the hold down clamp was loose and the distributor turned.
Bad gas?
Clogged fuel filter?
Crack in a rubber gas line?
Original carb?[/QUOTE]
Thread Starter
Pro
Joined: Mar 2010
Posts: 615
Likes: 25
From: Graham NC
Yes and thank you, car ran bad yesterday. It’s not timing, running good and then went wacky running bad, missing stalling. Carb is quadrajet and I think original. I’m guessing fuel problem and will probably start with fuel filter.
Thread Starter
Pro
Joined: Mar 2010
Posts: 615
Likes: 25
From: Graham NC
thanks carb is quadrajet and fuel filter will be my next effort to try and fix.
QUOTE=HeadsU.P.;1608088396]jbakyy,
I take it you have been making adjustments turning the distributor.
Grab the entire dist unit and see if it will budge. Sometimes we think we torqued down the dist clamp, and it's not tight.
Who says its IGN? Could be a fuel issue.
What carb? Fuel filter clean?[/QUOTE]
QUOTE=HeadsU.P.;1608088396]jbakyy,
I take it you have been making adjustments turning the distributor.
Grab the entire dist unit and see if it will budge. Sometimes we think we torqued down the dist clamp, and it's not tight.
Who says its IGN? Could be a fuel issue.
What carb? Fuel filter clean?[/QUOTE]