spark plug gap

Reply Subscribe

Thread Tools

Search this Thread

Apr 11, 2004 | 09:10 PM

jitter1976

Thread Starter

New User

Joined: Apr 2004

Posts: 3

Likes: 0

spark plug gap

i have a 1978 F150 4x4 with a 351w new plugs new wires new distributor and rotor but the place that put them on said they had to reset the gap but now it idles perfect but cuts out and backfires at about 2000 rpms but only when in gear and moving it does not do that when sitting still at 2000 rpm could they have gapped the plugs wrong any help would be greatly appreciated oh and weve checked the timing and seems fine

Apr 11, 2004 | 10:12 PM

Mil1ion

New User

Joined: Jan 2008

Posts: 0

Likes: 24

I bet that is a 351M not a Windsor.

The gap is probably .044"

You can ask this in the 351 engine series forum as it is not 73-79 Truck specific

Apr 11, 2004 | 11:34 PM

Matts72

Post Fiend

Joined: Jan 2003

Posts: 10,323

Likes: 2

From: Montana Territory

yeah, 302, 351W,C,M, 400, 429, 460 all have a .044" gap

Apr 12, 2004 | 09:42 AM

beartracks

Lead Driver

Joined: Nov 2000

Posts: 6,620

Likes: 341

From: Albuquerque

Sounds like they messed up a plug or wire.

Apr 12, 2004 | 03:34 PM

bobs75f-250

Senior User

Joined: Nov 2003

Posts: 201

Likes: 0

From: Butler, PA

What's the gap for a 360? Is it .038"? I'm having a very similar problem.

Apr 12, 2004 | 05:27 PM

corv_66

New User

Joined: Mar 2004

Posts: 7

Likes: 0

From: Northern California

Have you checked the vacuum advance? Also, does it backfire when you step on the throttle at all rpms, or does it only do it at 2000 rpm? Because it sounds like a vacuum or carberation problem.