I checked the timing on my mix match 390 and it's set right off
the marks past 30degrees btc. My other 390 could't stand more than
14 degrees. Whats up with this? Could a different cam call
for different timing? I set the timing to 8-10 degrees(fat piece of
chalk) and noticed a little low end loss.
This engine confuses me

 

Set your initial to about 12 degrees. Make sure your timing is advancing when engine rpm increases. It is possible that your balancer has slipped a little causing a false indication but I doubt it.

 

Not a problem was jes kinda curoius.

Fe power

 

I have high duration cam and it like to be advanced well beyond 10 BTDC at idle. It will idle best with the inital timing even above 20, but then the advance at higher RPMs results in pinging.

In short, I think some cams will require higher initial timing. It is even mentioned in my Edelbrock carb tuning guide.

 

I am having the same problem.

I used a dwell meter to set my points to 26 (gapping them was way off) and my timing to 6. It advances to almost 40 degrees at 2000 rpms in the driveway and it dogs down at highway speed and I have lost top end speed set to factory specs. I still get a shaking at crusing speed (60 mph). Mine is a mixmatched mess too.

I am going to try 12 degrees as suggested.

 

This thing only lacks a wee in the low end until I change the
timing back to where it was, the truck will pass a
3 car line up on the highway pretty quick, I've had
cars ruin my passing schemes before cause they just don't
have the guts to make it all the way.



Fe power

 

that is one heck of allot for initial timing, regardless of your cam. While its true cam profiles can benefit from different advances, Rats advice of 12 initial is a good place to start. Typically, even the radical FEs don't have more than @18 btdc to begin with, and 42 total in. I've found that mine is happiest at 14btdc and 38 total, in by 2700 rpm. It can handle 18 initial with 42 total but then I start to worry about detonation. Timing tape is a cheap and valuable tool in dialing in your timing, have fun.

 

[updated:LAST EDITED ON 24-Nov-02 AT 06:42 PM (EST)]Check to make sure your centrifugal advance is working.

When I first got my truck it needed lot of advance, too. First I checked to make sure the timing marks were right. There is a thread out there where the folks here helped me quite a bit. The marks were spot-on. As it turned out, the centrifugal advance was frozen solid. This was diagnosed by disconnecting the vacuum advance, reving the engine, and reading the timing (it didn't budge). It needed a lot of initial to run right. Once I pulled the distributor and got the advance mechanism loosened up, it runs pretty well with 10-15deg initial.

--Matt




1972 F250 Custom Sport Camper Special 4x2 360 2v C6 3.73
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