timing off
Thread Starter
Intermediate
Joined: Jul 2011
Posts: 31
Likes: 0
From: Zernovka
timing off
Hello
I have built stroker 390 CID using RMP kit from Edelbrock and rotating balanced assembly from Eagle. I found TDC, accordingly adjusted distributor and started engine. After about 20 minutes of running 2000-2500 RMP I let RMP go to idle and started to set timing more accurately.
Engine reached best RMP and smooth sound when timing was showing 32 degrees advance!
I have dome timing tune up few times before so I should know what I am doing, maybe not!
- I warm up the engine
- disconnected vacuum advance from carburetor
- adjust idle RMP to 800 (GM recommends 8 degrees Advance in SBC)
- Edelbrocks recommends 6 A with their kit
What did I do wrong? If move timing about 10 degrees both ways I start to lose RMP till it stops.
I can see few options but maybe not all of them, please help:
- I have new dumper (harmonic balance) which came with the rotating assembly but maybe outer ring moved?
- I thought my timing tool is broken so I have purchased a new one today wit same result!
- has temperature anything to do with it? It is 32 F in my garage, maybe timing tool needs room temperature to operate correctly?
Thank you in advance for any help or feedback you may have.
I have built stroker 390 CID using RMP kit from Edelbrock and rotating balanced assembly from Eagle. I found TDC, accordingly adjusted distributor and started engine. After about 20 minutes of running 2000-2500 RMP I let RMP go to idle and started to set timing more accurately.
Engine reached best RMP and smooth sound when timing was showing 32 degrees advance!
I have dome timing tune up few times before so I should know what I am doing, maybe not!
- I warm up the engine
- disconnected vacuum advance from carburetor
- adjust idle RMP to 800 (GM recommends 8 degrees Advance in SBC)
- Edelbrocks recommends 6 A with their kit
What did I do wrong? If move timing about 10 degrees both ways I start to lose RMP till it stops.
I can see few options but maybe not all of them, please help:
- I have new dumper (harmonic balance) which came with the rotating assembly but maybe outer ring moved?
- I thought my timing tool is broken so I have purchased a new one today wit same result!
- has temperature anything to do with it? It is 32 F in my garage, maybe timing tool needs room temperature to operate correctly?
Thank you in advance for any help or feedback you may have.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Set the timing as outlined in my paper - e-mail me a request for it if you don't have it:
Set total timing to 36 with vacuum disconnected. Let it drop to idle and verify that initial falls in the 12-18 degree range. Hook up the vacuum advance control unit to manifold vacuum and verify timing at idle ends up in the 28-34 degree range.
Lars
V8FastCars@msn.com
Set total timing to 36 with vacuum disconnected. Let it drop to idle and verify that initial falls in the 12-18 degree range. Hook up the vacuum advance control unit to manifold vacuum and verify timing at idle ends up in the 28-34 degree range.
Lars
V8FastCars@msn.com
