My dad's 88 suburban (350 TBI) has started knocking when ever we start going like 70 mph or so, it doesn't happen when you rev it but aren't going fast, only on the freeway. Replaced the EGR valve but that didn't help.
Any ideas??
Thanks

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90 IROC 5.7l (L98)
ram air, K&N's, air foil, full exhaust

LIKE A ROC

http://members.nbci.com/IrocZgarage/home.htm

 

use higher octane gas, that should get rid of the knock(if not I don't know what to tell you)

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'86 IROC 5-speed
305 LG4
edelbrock performer rpm intake
edelbrock 600 cfm carb
msd pro billet hei
'95 3.23 rearend
hotchkis rear suspension