timing
Tech Contributor
Joined: May 2005
Posts: 15,576
Likes: 118
From: Conroe Texas
327/330?
Do you mean 327/340?
If so, at the moment I have my 62 327/340 set at 20@750 RPM. My distributor is a mechanical advance only distributor which adds another 20 degrees of timing, so I'm all-in at 40 degrees@3,000 RPM.
Do you mean 327/340?
If so, at the moment I have my 62 327/340 set at 20@750 RPM. My distributor is a mechanical advance only distributor which adds another 20 degrees of timing, so I'm all-in at 40 degrees@3,000 RPM.
Last edited by 62Jeff; May 18, 2010 at 01:30 AM.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
A 300 hp engine will have different timing requirements than a 340/360 hp engine.
Team Owner
Joined: Aug 2007
Posts: 58,061
Likes: 7,145
Army
You can get carried away with 'optimization'. I had my 283ci/270hp timing cranked up to 16* initial at one point and it was quicker on response but started 'bucking' at light throttle. Set it back to the factory spec of 12* and no more bucking and the response is VERY slightly less snappy but still quite decent. Mileage improved too.
Instructor
Joined: Dec 2009
Posts: 216
Likes: 2
From: Simi Valley California
327ci - 300 hp - mild cam
Vacuum off, 600 rpm, 10*
Vacuum off, 3000 rpm, 35*
Vacuum on, 600 rpm, 17*
Vacuum on, 3000 rpm, 50*
Thanks BarryK for the post it really helped!
Thread Starter
Pro
Joined: Jan 2003
Posts: 528
Likes: 5
From: Templeton Ca
timing/heat
Looks like I got a little fumble fingered , it should have been 327/300 and not 330 . Anyway ,I'm gonna try 10* with vacuum disconnected and see what happens .
I'm still working on getting my engine temp down . It's a fresh rebuild and wants to run at about 225-235 . new fan clutch , flushed out radiator ,new thermostat (180), and plenty of new antifreeze . I hope I'm not having a head gasket problem . Maybe the timing change will help !
I'm still working on getting my engine temp down . It's a fresh rebuild and wants to run at about 225-235 . new fan clutch , flushed out radiator ,new thermostat (180), and plenty of new antifreeze . I hope I'm not having a head gasket problem . Maybe the timing change will help !
Instructor
Joined: Dec 2009
Posts: 216
Likes: 2
From: Simi Valley California
After reading what BarryK wrote, if I understand him correctly, you are shooting for 36* @ 2,500 to 3,000 RPM vacuum disconnected. You may need to let the 600 RPM vacuum disconnected reading fall where it goes. The 36* is the most important part. You might want to read his post on the topic.
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
Be advised some engines will not take 36* @ 2500/3000 without spark knock when the vacuum advance is pulled in on top of that.
Unless the timing is 10* or more slow, I don't think timing will give you a hesitation, just a soggy throttle.
Too much timing at low speed will cause bucking and trailer hitching even without spark knock.
Check your ignition point condition and dwell while you're in there tinkering around.
Unless the timing is 10* or more slow, I don't think timing will give you a hesitation, just a soggy throttle.
Too much timing at low speed will cause bucking and trailer hitching even without spark knock.
Check your ignition point condition and dwell while you're in there tinkering around.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Instructor
Joined: Dec 2009
Posts: 216
Likes: 2
From: Simi Valley California
[QUOTE=MikeM;1574110875]Be advised some engines will not take 36* @ 2500/3000 without spark knock when the vacuum advance is pulled in on top of that.
QUOTE]
Thanks MikeM as you are probably aware by now, all I know on the subject is what I read from the post by BarryK.
BarryK recommends to test for knock by leaving the vacuum line off (line plugged with a golf tee) and driving the car. While in fourth gear, at about 1200 to 1500 RPM, accelerate and listen for knocking. If none then you are okay. I would think you might have a different result with hot weather vs. cold weather.
QUOTE]
Thanks MikeM as you are probably aware by now, all I know on the subject is what I read from the post by BarryK.
BarryK recommends to test for knock by leaving the vacuum line off (line plugged with a golf tee) and driving the car. While in fourth gear, at about 1200 to 1500 RPM, accelerate and listen for knocking. If none then you are okay. I would think you might have a different result with hot weather vs. cold weather.
Last edited by 63 corvette; May 18, 2010 at 03:59 PM.
Melting Slicks
Joined: Jul 2004
Posts: 2,865
Likes: 195
From: Maryland
Looks like I got a little fumble fingered , it should have been 327/300 and not 330 . Anyway ,I'm gonna try 10* with vacuum disconnected and see what happens .
I'm still working on getting my engine temp down . It's a fresh rebuild and wants to run at about 225-235 . new fan clutch , flushed out radiator ,new thermostat (180), and plenty of new antifreeze . I hope I'm not having a head gasket problem . Maybe the timing change will help !
I'm still working on getting my engine temp down . It's a fresh rebuild and wants to run at about 225-235 . new fan clutch , flushed out radiator ,new thermostat (180), and plenty of new antifreeze . I hope I'm not having a head gasket problem . Maybe the timing change will help !
A good map for 327-300 hp
Start 0* @ 900 rpm
12* @ 1500 rpm
26* @ 3200 rpm.
