Check my timing setup please - CorvetteForum - Chevrolet Corvette Forum Discussion

Notices
C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette

Check my timing setup please

Reply

 
 
 
Old 09-15-2018, 11:29 AM
  #1  
stumpshot
CF Senior Member
Thread Starter
 
Member Since: Sep 2011
Location: Humboldt county Ca
Posts: 288
Thanked 22 Times in 22 Posts
Default Check my timing setup please

383 Smeding, alum heads, 680 QF vac secondaries. Dynoed at Smeding, 370 hp, 445 tq, all at flywheel. Don't like the QF at all. Runs rich no matter what I do. Changing to my old 600 Edelbrock 1406 for grins.
Timing set at 16@800, 34@3,000. All in, 50.
Makes 17 lb manifold vac, using full vac advance and 8 lb edelbrock springs.
Timing was set on the dyno and dist and manifold marked at 16.
Seems like maybe I could go a degree or 2 more on the initial and I'm nearly out of room to turn the dist any more.
Any thoughts on where I should be?
Thanks.

Last edited by stumpshot; 09-15-2018 at 11:31 AM.
stumpshot is offline  
Reply With Quote
Old 09-15-2018, 05:15 PM
  #2  
REELAV8R
CF Senior Member
 
REELAV8R's Avatar
 
Member Since: Apr 2011
Location: Hermosa
Posts: 3,943
Thanked 249 Times in 229 Posts
Default

Something isn’t right there. 375 hp for a 383 is low. Jetting could be an issue for sure if you can’t get it to not run rich. Not sure a 600 is going to feed a 383 very well.

What heads, cam, intake and exhaust are we talking about? Something is choking that combo.
REELAV8R is online now  
Reply With Quote
Old 09-15-2018, 05:40 PM
  #3  
HeadsU.P.
CF Senior Member
 
HeadsU.P.'s Avatar
 
Member Since: Aug 2017
Location: Cool Northern Michigan
Posts: 1,408
Thanked 236 Times in 226 Posts
Default

Nothing wrong with a Quick Fuel / Holley except the owners, including myself. Its tough to get any carb just right because of the test runs needed. You can't exactly swap jets all day and drive around the block. Change power valves and run around the block some more. Somebody will call the cops on ya.
All those minor changes to the carb need validation on a track or in your case, a dyno. So we are stuck with a leaving some issues alone.

You are always better off running rich than lean. I little puff of black smoke out the back means there's not a starvation / dentination issues. Your dyno guy likely got the jets just right for high RPM dyno runs, but a little rich for cruising. Float level may be a tad high also.

Your cam timing events may want 18* initial IGN timing. Hard to say. Try it. Check the float level on that QF. Maybe the squirters are too large? Maybe the little plastic accelerator cams are wrong color or the screw is in the wrong location. Here is where a air / Fuel ratio meter would be a godsend.
HeadsU.P. is offline  
Reply With Quote
Old 09-15-2018, 07:45 PM
  #4  
stumpshot
CF Senior Member
Thread Starter
 
Member Since: Sep 2011
Location: Humboldt county Ca
Posts: 288
Thanked 22 Times in 22 Posts
Default

The 370 hp is fine with me since I don't race the car. It was built as a touring motor. Torque comes on at about 2400 and falls off around 4100 with max at 3600. Great for freeways. Runs fine on 89 fuel. Heads are big valve 67 cc with 175 cc port. Intake is performer dual plane. Custom ground hydraulic roller cam, .467 in., .478 ex. 112 lobe ctr. Stock rams horns, true duals.
Actually, the Edelbrock seems to have just as much whack as the QF. I'm not a believer in over carbing something you aint racing.
I like the Edelbrock because of the tuneability and not pulling the carb off to change jetting.
Thanks for the replies.
stumpshot is offline  
Reply With Quote
Old 09-15-2018, 07:54 PM
  #5  
Jebbysan
CF Senior Member
 
Jebbysan's Avatar
 
Member Since: Mar 2012
Location: New Braunfels Texas
Posts: 2,407
Thanked 228 Times in 204 Posts
Default

17in of vacuum = small cam = it will pull hard on the Holley jets.........the Edelbrock was a fairly smart move as this is not a radical setup. It is not an issue with the Quick Fuel as much as it needs to be jetted.
Timing depends on what chamber they used in the head......fast burn kidney bean chamber wants 33-34.....old style D shaped chamber will want 36-37 total.
You have a initial spot on......14-16 is what it would like........make sure you are pulling the right amount of vacuum advance.

Jebby
Jebbysan is offline  
Reply With Quote
Old 09-15-2018, 09:06 PM
  #6  
stumpshot
CF Senior Member
Thread Starter
 
Member Since: Sep 2011
Location: Humboldt county Ca
Posts: 288
Thanked 22 Times in 22 Posts
Default

Jebby. Thanks for the reply. Just changed vac cans so havent checked advance on new can yet. Don't know about the heads. You are right about the QF. Jets would probably do it. Idle was an eye burner. Chgd out the IA jets. No difference. May have been I needed to knock the floats down some.
Now I'm chasing an off idle miss on the Edelbrock.
Roy
stumpshot is offline  
Reply With Quote
Old 09-15-2018, 10:54 PM
  #7  
Jebbysan
CF Senior Member
 
Jebbysan's Avatar
 
Member Since: Mar 2012
Location: New Braunfels Texas
Posts: 2,407
Thanked 228 Times in 204 Posts
Default

Off idle miss is almost always the Accel pump....change it out with a high quality viton unit....I get mine from Allstate Carburation in Long Island....
They are Viton if they are blue

The IA jets are not the right way to adjust with this cam....use the screws and a vacuum gauge for the Quick Fuel to set idle mixture.

Find out what Smeding put on your engine for a cylinder head....should be easy enough....

Jebby

Jebbysan is offline  
Reply With Quote
Old 09-15-2018, 11:08 PM
  #8  
stumpshot
CF Senior Member
Thread Starter
 
Member Since: Sep 2011
Location: Humboldt county Ca
Posts: 288
Thanked 22 Times in 22 Posts
Default

Jebby. I always adjust with a vac gauge but seemed to make no difference in the rich condition at idle. I then went to the air bleed changes-- didn't change anything. Another thing about the QF is I couldnt get the idle below 1100 with the vac advance in. Turned the secondary blade screw all the way out,
made sure the transfer slots were square, did everything I could think of. If I hooked to timed port the idle dropped. I could push the throttle arm forward hard and idle will drop---let go, it comes right back up. Take throttle cable off, same thing again so no cable binding.
Just kinda gave up dorking with it.
stumpshot is offline  
Reply With Quote
Old 09-17-2018, 05:17 PM
  #9  
Strokemyaxe
CF Senior Member
 
Strokemyaxe's Avatar
 
Member Since: Jul 2014
Location: Arlington TX
Posts: 522
Thanked 17 Times in 16 Posts
Default

Originally Posted by stumpshot View Post
383 Smeding, alum heads, 680 QF vac secondaries. Dynoed at Smeding, 370 hp, 445 tq, all at flywheel. Don't like the QF at all. Runs rich no matter what I do. Changing to my old 600 Edelbrock 1406 for grins.
Timing set at 16@800, 34@3,000. All in, 50.
Makes 17 lb manifold vac, using full vac advance and 8 lb edelbrock springs.
Timing was set on the dyno and dist and manifold marked at 16.
Seems like maybe I could go a degree or 2 more on the initial and I'm nearly out of room to turn the dist any more.
Any thoughts on where I should be?
Thanks.
Why would you think you could benefit from more timing on initial? As opposed to less or maybe even more/less on the full mechanical?

-stroke

Last edited by Strokemyaxe; 09-17-2018 at 05:37 PM.
Strokemyaxe is offline  
Reply With Quote
 
 
 


Thread Tools
Search this Thread
Sponsored Ads
Vendor Directory

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: