I just put in a stock 74 hei dist in my 455. No matter how far I retard the timing, vacuum plugged, I get detonation at at anything above idle. What are the chances my springs are weak and I just need to put a kit in? Thanks for y'all's help.

 

Sorry, I said 74 meant 76.

 

Have you put a timing light on it to see what the timing is actually doing?

 

+1. Verify operation, or none of us has any idea what we're talking about.

- Eric

 

I reviewed some of you posts, and wanted to offer at least a suggestion or two if it helps.

Can you verify your flex plate bolts are tight and its not cracked somewhere?

Now, about the exhaust, Are you sure you don't have a small leak or your exhaust isn't hitting on something?

In other words..Is something hitting something making these sounds? Have we discussed the possible loose motor mount? Its worth a good look over.

And...X2 what are your timing readings?

 

What are your motor specs? If anything the stock springs are very stiff, unless someone changed them.

 

Not trying to be rude here but liken your post to bellying up the the parts counter and saying to the parts guy hey I need a part for my 455.... Hes gona look at you funny cuz he has a warehouse full and hasn't a clue as to what you want....
Post more info on the engine/trans...Stock 455 or warmed over, high or low compression, stick or auto trans, carb, factory intake, plugs, cap, rotor, wires etc... Verify your not a tooth off. Verify you DID NOT use the points feed wire to feed "12v" to the new HEI. Verify theres zero vacuum leaks, Does it have an EGR valve? If so is it working? Do the weights under the rotor move freely, open and spring back to closed?? They do require a dab of lube. Verify the first 2 timing settings. Base timing 12ish, then whats does the vacuum canister add to that base setting at warm idle, 8-10ish for a total of 20-22ish at idle? DO you have a vacuum gauge and a setback timing light?
One can not expect to stab a smog curved HEI into a non-smog or hi-po engine without a significant re-curving of the distributors vacuum an centrifugal timing events.