Snow day Weird spark knock on my 84 k30

[30backs]

So we got some snow the other day and I couldn't wait to fire up the old truck and go play it as we never get snow. When I got out on the road my truck seemed kind of underpowered and had a spark knock that get worst when it's under load. I checked the distributor and my fuel filter and they seem to be good any idea?

 

[chevyk10]

So you checked the timing at full advance. What is it set at? Is the gas old? What size engine and any mods?


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[30backs]

So you checked the timing at full advance. What is it set at? Is the gas old? What size engine and any mods?


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We'll had to set timing by ear because there is know tab on my timing cover. I moved it to several different locations with same result of spark knock. The gas should be finei Irgun the truck a couple times a month and put gas in it every time. As far as motor it is a 350 with headers and an rv cam nothing special. I hope this helps.

 

[chevyk10]

Generally a knock like you describe is related to timing, low octane fuel or even a lifter maybe. Just no way to set timing by ear. Could be a broken spring in the distributor.


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[30backs]

We have set like that for two years no problems until it snowed and got real cold. I took distributor apart and only thing I saw was the diaphragm in the vacuum advance appeared to be bad so I changed it.

 

[chevyk10]

So the centrifugal advance was intact?


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[30backs]

yes weights and all seem to be in great shape

 

[chevyk10]

Hmmmm. Beats me one of those play with it and see


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[30backs]

man I guess that is the plan right now....loli was hoping someone might have a beter idea than me