Detonation? lifter clater? small hampsters?

[ToiletDuck]

We are just breaking in my brothers freshly rebuilt 360 and noticed a slight clatter or knock coming from the engine. It only happens at about 2000 rpm and when ya shift to the next gear to soon and give it a little gas. Doesnt do it when ya give her plenty of gas and shift at higher rpm, just when under load like the above mentioned.


From reading through the archives here are some things i can think of.

-Timing to advanced (we have messed with it but nothing seems to help, although we havent had a light on it)

-running lean (primaries might be lean? or vacuume leak)

-worn valve springs??? (original valve springs)

-lifter clatter (we did no adjusting, goin to pull the valve covers to see how things are doin in there)



engine specs.

360 bored .030 w/ 200 miles on it
edelbrock performer intake
edelbrock 1406 carb
stock heads
stock cr
comp cams 268H 218/218 @ .050 duration .454 lift
hedgman headers
Mopar dist. and orange box



Thanks for the help.

[72Challenger]

Definitely the symptom of detonation. Since it only happens at a light load and small throttle opening, I believe you have too much vacuum advance. The easiest way to tell is to plug the vacuum line to the distributor. If it goes away or gets better, you're on the right track. You should certainly get the distributor curved. You can do it yourself with a dial-back timing light and some mechanical skills, or you can pay a bargain price to get it done on a machine. The problem with the machines is that they can't fine-tune to your exact combination. Do a search, there has been some fine info on DIY distributor curving posted here.