ignition timing set

Reply Subscribe

Thread Tools

Search this Thread

Apr 14, 2005 | 01:39 PM

smoke n tires

Thread Starter

Elder User

Joined: Sep 2004

Posts: 500

Likes: 0

From: midwest

ignition timing set

when you guys set up a straight up timing set on a later 70s 460 do you still set base timing the same? i have a early timing set in mine and i run about 12 degrees but at 2500-3000 im at like 45 degrees. i think my vac advance is causing to much advance. do you turn the screw in or out to lessen the amount of vac?

Apr 14, 2005 | 02:36 PM

wtroger

Cargo Master

Joined: May 2001

Posts: 3,208

Likes: 13

Sound like you need to chack the dist and make sure the mechanical advance springs are ok if they are streched or broken or came off it will allow to much advance and 45 degrees is to much. 30 to 32 is about max

Apr 14, 2005 | 07:12 PM

Bear 45/70

Post Fiend

Joined: Mar 2004

Posts: 6,056

Likes: 8

From: Union, Washington

Never check timing with the vacuum hooked up. The only time you do that is if you are checking how much vacuum advance you get. To do that at idle connect the vacuum advance to the manifold vacuum and read how much advance you have and at what rpm. Now disconnect the vacuum and run the engine at the same rpms and check the timing again. Subtract second number from first, will tell you how much vacuum advance you have. The reason you are seeing such a large advance is the mechanical advance is pretty much all the way in and the vacuum advance is seeing max advance also ( no load on engine = maximum vacuum). With no load on the engine this will generally hurt nothing. If you were driving down the road you would never see this much advance as you can't pull that much vacuum except on deacelleration and then ported vacuum would be closed and wouldn't matter anyway.

Apr 15, 2005 | 09:28 AM

smoke n tires

Thread Starter

Elder User

Joined: Sep 2004

Posts: 500

Likes: 0

From: midwest

so to check total timing you disconnect your vac adv. completely? do you still set your timing at factory specs even if you installed a straight up timing set?

Apr 15, 2005 | 12:24 PM

Bear 45/70

Post Fiend

Joined: Mar 2004

Posts: 6,056

Likes: 8

From: Union, Washington

YES, always. How you set the timing chain and cam and crank relationship does not change the amount of timing you can run. That is a function of compression, stroke and the grade of fuel you are running.

Apr 15, 2005 | 06:25 PM

quehele

Senior User

Joined: Jan 2005

Posts: 389

Likes: 4

From: Visalia, California

Just a thought...adjust the vacuum module?

I just replaced the vacuum advance module on my 77 F250 with a 460 and had to adjust the vacuum module. If you insert a 1/8" allen wrench into the advance module through the nozzle you'll find a set screw. The instructions that came with my vacuum module say to set it the same as the one you're replacing. It says to screw the set-screw in as far as it will go then back it out the same amount as the original.

Mine was 5 full turns out from the bottom.

Hope this helps some.

Jim

Last edited by quehele; Apr 15, 2005 at 06:27 PM. Reason: correction

Apr 15, 2005 | 06:33 PM

SwOkcOffRoader

Postmaster

Joined: Jul 2003

Posts: 2,544

Likes: 2

From: okc

dont the older 460s have less advance?? im working on a 71 lincoln mark III at the shop i work at, the sticker on the 460 in it calls for 4 degrees BTDC at 600 rpms, my 78 model 460 calls for 12* BTDC at 650 rpms, so wouldnt any 460 with the earlier timing set need to be set at 4-8* BTDC??? if so, what would the total advance be??