Fresh 383 not running right!
Thread Starter
Heel & Toe
Joined: Oct 2003
Posts: 19
Likes: 0
From: Bergen Co. NJ
Fresh 383 not running right!
Just got my fresh 383 in and running from a local machine shop.The engine dynoed at 380 hp and 400 ft lbs.After start up I took it for a "ride",and it falls on it's face at startoff.After it gets going it's not as bad with the spitting out the carb and exhaust but on the hyway it feels like it's got a miss.Seems only under a load.I have a dial back and checked the timing all in 35 degrees at 2500 rpm.I tried the original carb 650 holley and it runs the same as the 750 I bought from the dyno guy.I had this engine rebuilt because of wear and it ran real good before the rebuild!It has a hydraulic roller in place of the mechanical flat tappet.If the cam was installed 180 out what would that do? The cam timing should be at 12 o'clock crank and 12 o'clock cam on the sprockets not 12 crank and 6 cam correct?Any idea before I see this guy on monday? Thanks John W................
Melting Slicks
Joined: Aug 2004
Posts: 2,165
Likes: 950
From: Keizer Oregon
good luck.
Race Director
Joined: Jul 2004
Posts: 12,706
Likes: 329
From: Scottsdale Arizona
The cam can't be installed 180 degrees out. Remember that the cam rotates once for two rotations of the crank. When you install the cam, you usually do it with the mark on the crank at 12 and the cam at 6 oclock so that you can do it accurately. If you rotate the crank shaft 360 degrees, the crank will be at 12 oclock as well as the cam. This is # 1 cylinder at TDC.
Pro
Joined: Jun 2005
Posts: 725
Likes: 1
From: FL.
Hope this helps
Tom
Instructor
Joined: Mar 2006
Posts: 246
Likes: 1
From: west melbourne florida
I Had The Same Issue With My Vette Falling On Its Face. It Was A Fuel Issue With My Edelbrock Had To Change Metering Rods And Springs. Then Changed Main Squirter And Accelerator Pump. Seems Good Now But Im Going To Install A Air/fuel Guage To Set Carb
Thread Starter
Heel & Toe
Joined: Oct 2003
Posts: 19
Likes: 0
From: Bergen Co. NJ
Re:383
Thanks I undestand the cam timing now,manifold vacuum at 14-15,fuel pressure at 8 psi.Tried three different carbs all the same outcome.Checked compression 210 psi all cylinders.So internally it should be ok?Has to be carb related?
Pro
Joined: Jun 2005
Posts: 725
Likes: 1
From: FL.
Take it apart, inspect all parts carefully , especially the gaskets and seals , the Floats needle and seats(make sure the float will float too).
Replace any suspect diaphrams and parts. Put it back togeather and you will be able to dial it in correctly.
Good Luck..
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Every now and then there are needle&seats that will work perfectly at 6 PSI but leak at 8 PSI. Since it ran fine on the dyno my first step would be a regulator and set it at 6 PSI.
The other thing to check is that you have good voltage to the distributor.
The other thing to check is that you have good voltage to the distributor.
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Thread Starter
Heel & Toe
Joined: Oct 2003
Posts: 19
Likes: 0
From: Bergen Co. NJ
RE:383 not running right
I changed the carb to no avail.I then advanced the timing and it ran better and by advancing it untill it's off the scale it seems to run good.Did the dampner slip?How can I tell for sure where the timing is?Any ideas? Thanks...John W
Thread Starter
Heel & Toe
Joined: Oct 2003
Posts: 19
Likes: 0
From: Bergen Co. NJ
Re:383
I just got back from a ride and it runs awesome! But now how do I set timing?Do I need to replace the dampner?When I road tested it it pulled real strong and no pinging even pulling 1500 rpms in 4th gear.Plus it spins over with no problem even when hot.Makes me believe the timing is the problem,what if the cam was off a tooth?Would that put the timing mark off the scale?.....Thanks John W.......
Drifting
Joined: Dec 2002
Posts: 1,946
Likes: 28
From: Long Beach CA
If the cam was off by a tooth, it'd barely run, if at all. The best way to check the balancer TDC is to get a dial indicator with a magnetic base. Pull the #1 spark plug, and use the indicator to measure exactly when the #1 piston is at TDC as you turn over the enigine by hand. Then check the timing marks on the balancer. Have you thought about borrowing a buddy's timing light just in case there's a problem with yours?
Pro
Joined: Apr 2007
Posts: 736
Likes: 1
From: Chester VA
You could be using the wrong timing tab. The damper is marked to use with either a tab that is at the 12 O'clock position over the damper, or at about the 2 O'clock position. You may be using the wrong tab which would throw you off. This is an easy fix.
Thread Starter
Heel & Toe
Joined: Oct 2003
Posts: 19
Likes: 0
From: Bergen Co. NJ
Re:383
The timing tab is at 2 o'clock but even with it at 12 it still would be off the tab,,,,,any ideas?What would happen if the cam was off a tooth or more?.......Thanks...John W........