454 Timing Issues?

[savatreatabvr]

I came across a timing light at a yardsale so I checked the timing on my mid 70's 454, the harmonic balancer timing mark wasn't on the tab on the timing cover! I adjusted the distributor to where it's at about 10 degrees BTC now but it idles low and doesn't seem to have done much for performance! I'll adjust the idle screw and mess with the air/fuel mixture tomorrow but now my question what is the manufacturers timing specs on a 1976 stock 454 with HEI distributor? I've found online it vary's from 4 degrees to 16 degrees depending on who posted the info!

[Corts60]

Did the engine run fine before? You might either have the wrong harmonic balancer installed, or the wrong timing cover. I know on different year smallblocks, some timing covers had the timing "tube" that you had to look down behind the water pump to find the marks, where as many others had the timing tab off to the driver side.

Just some ideas.

[savatreatabvr]

No idea if the balancer is the correct one but it has a timing tab, not a tube! I was told to start at 8 degrees but don't go over 12 degrees, does this sound right?

[Corts60]

Yes, that is right. Also, I forgot to ask, is your vacuum advance disconnected? If not, and you are hooked to manifold vacuum, that is why you cannot see your mark because you are advanced at idle. Always set timing with this disconnected.

[savatreatabvr]

That's what it is, I didn't unhook and plug the vacuum advance before timing it! Thank you for the info, but now when I set it correctly if the idle is still low I should just raise it and call it good right?

Originally Posted by Corts60

Yes, that is right. Also, I forgot to ask, is your vacuum advance disconnected? If not, and you are hooked to manifold vacuum, that is why you cannot see your mark because you are advanced at idle. Always set timing with this disconnected.

[Corts60]

If your timing is right on and the engine doesn't stumble or pop or any of that, then yes, adjust your idle as you wish.

[raceman6135]

I'm not sure I'd make a lot of adjustments to an engine that was running well, based on what a yard sale (i.e. USED) timing light was telling me, especially if I had not checked the timing light's accuracy.

With regard to initial timing, yes, depending upon the engine RPO, anything between 0 and 8 degrees is stock for a mid-1970's 454 (with the vacuum advance disconnected and the line plugged). I don't think I've ever seen a mid-1970's Chevrolet (either small block or big block) that called for more than 8 degrees of initial timing. Don't forget that those engines were laden with early smog-reduction systems and meant to burn crappy gas, so running a lot of ignition advance was just not done.

[savatreatabvr]

Yeah, I was wondering how accurate of these old Penske timing lights were plus my 454 has no smog system on it at all, not even an EGR! Main reason for all this is I just don't think the 454 has the power it should, I know it's a big heavy truck but it feels like I'm dragging an anchor, not much take off power!

Originally Posted by raceman6135

I'm not sure I'd make a lot of adjustments to an engine that was running well, based on what a yard sale (i.e. USED) timing light was telling me, especially if I had not checked the timing light's accuracy.

With regard to initial timing, yes, depending upon the engine RPO, anything between 0 and 8 degrees is stock for a mid-1970's 454 (with the vacuum advance disconnected and the line plugged). I don't think I've ever seen a mid-1970's Chevrolet (either small block or big block) that called for more than 8 degrees of initial timing. Don't forget that those engines were laden with early smog-reduction systems and meant to burn crappy gas, so running a lot of ignition advance was just not done.