435 engine miss
Thread Starter
Heel & Toe
Joined: Jun 2002
Posts: 23
Likes: 0
From: Ontario
435 engine miss
I have rebuilt my 35,000 mile 427/435 and put it back to the original TI system. ( Yes I did use a proper TI coil).When it was dyno tested with a point type distributor it ran perfectly.Now it starts easily,idles well,but has a definite miss.It will backfire when cruising along and it generally feels like a car from the sixties did when it had bad points or a bad cap and rotor.The plugs foul and it is using oil.It had a professional rebuild and I did replace the original heads with open chamber LS7 heads to lower the compression ratio rather than changing my pistons which were essentially like new.Any ideas would be appreciated , Dan.
Race Director
Joined: May 2000
Posts: 12,712
Likes: 2,270
The pickup coil wires can fatigue and break due to the constant motion of the base plate under command of the vacuum advance.
Disconnect the pickup coil connector and place an ohmmeter across the leads. Wiggle the wires and use a vaccum pump to exercise the vacuum advance. The meter reading should be dead steady.
Also disconnect the amp connector and carefully inspect all the pins and receptacles for corrosion or other damage.
Last thing would be remove the amp, remove the back cover and inspect the interior. Pay particular attention to the leads from the main transistor (mounted in the heat since) where they are soldered to the board.
I'm assuming the car is properly timed, the wires are indexed properly in the cap and the rotor points toward #1 with balancer notch on the initial timing mark. Also, are you absolutely certain that the drive gear is indexed on the shaft with the dimple pointing the same direction as the rotor tip?
If you are not absolutely, positively certain of the above, then pull the dist. verify proper indexing of the drive gear, verify proper indexing of the plug wires, then reinstall the dist. and set the timing.
Duke
Disconnect the pickup coil connector and place an ohmmeter across the leads. Wiggle the wires and use a vaccum pump to exercise the vacuum advance. The meter reading should be dead steady.
Also disconnect the amp connector and carefully inspect all the pins and receptacles for corrosion or other damage.
Last thing would be remove the amp, remove the back cover and inspect the interior. Pay particular attention to the leads from the main transistor (mounted in the heat since) where they are soldered to the board.
I'm assuming the car is properly timed, the wires are indexed properly in the cap and the rotor points toward #1 with balancer notch on the initial timing mark. Also, are you absolutely certain that the drive gear is indexed on the shaft with the dimple pointing the same direction as the rotor tip?
If you are not absolutely, positively certain of the above, then pull the dist. verify proper indexing of the drive gear, verify proper indexing of the plug wires, then reinstall the dist. and set the timing.
Duke
Last edited by SWCDuke; Oct 20, 2004 at 08:30 PM.
Safety Car
Joined: Feb 2003
Posts: 4,068
Likes: 27
From: St. Joseph Mo
I had a pickup coil short out on my TI. Lucky I had a spare from a Pontiac, they are expensive if you can find one. (Box of misc. for $10 at a swap meet, two coils, an amp and a complete Pancho dist. w/harness.)
Also check the coil, not only at room temperature but also at "underhood" temperature. I had one that would allow the engine to run fine untill it warmed up then it went to intermittent open/short. I thought I had a lean cruise miss.
Now I run a point type dist.
