I also have a chirping sound in my new build. Mine sounds like it is located near the distributor. It goes away over 1200rpm, returns at idle. Morel high rpm lifters 5w30 dino oil.

I will be tearing the engine down to rectify a blown head gasket on my AFR 305 heads I bought here on OSO, so I will look at the cam and lifters.

What kind of head gaskets are you running? That is another thing that I thought might cause this sound, although it would have to be blown pretty bad to make that much noise, I would think. Compression and/or leakdown test should reveal that if I have anything in that area going on. It would surprise me, because I am running Cometics with head studs, and CR is only a little over 9:1. Flat top pistons.

Plugs looked OK when I pulled them last year. I'm sure they are pretty fouled now. I had a brain fart and started the motor on the hose last fall with the electric choke disconnected, so it idled real fat. It smelled rich at idle this last time I had it out, and I suspect that I may need to check my float levels. Probably need to drop it in the water to get that right, because the attitude will probably be wrong sitting on the trailer.

Did you check your guide clearances when assembling the engine ?

Nope!

Engine has about 20 hours on it now. Wouldn't I expect that to rear its ugly head within the first few hours? It hasn't been run in any extremely cold water. Lake water temp was about 89* when I ran it last weekend.

What kind of head gaskets are you running?

Fel-Pro 1017-1 head gaskets

ARP bolts

cometic head gaskets,arp bolts

I've got the same noise I believe. Much more noticeable from the engine than the exhaust.July 28, 2015: https://youtu.be/QX6qU_QzkLE

is that a staggered 38 larry smith scarab??

Yeah. I always thought it sounded like crickets. The sound and video deteriorated quite a bit during the upload. Much more noticeable on the original.