Home › Forum › Ask A Member › 1958 Lark 35 › Re: 1958 Lark 35
OK, you found impeller chunks in the thermostat housing, do I have it right? Uh oh, if so. Could be that pieces of the impeller are getting stuck occasionally causing the engine to stop pumping/overheat.
The loose spark plug insert could pose a threat for preignition. I am not a fan of spark plug inserts but know I am in the minority on this.
In any event, you need to get whatever insert you plan to use properly seated/locked into the head to avoid a threat of preignition, this engine has relatively high compression.
At this point, I would consider removing the head to find the chunks of impeller that might be plugging up the cooling system, and to get that insert properly installed in the head.