Bad valve seats

[toupee]

Hi all. 
I bought my car turn key so I didn't build the engine.  It does have a 68' 383 with 906 heads.  My question is this... since I didn't build it I don't know if it has hardened valve seats and if it doesn't I don't have a way of knowing if it has had lead substitute added to the fuel in the past.  So what symptons should you look for to let you know if the valve seats are bad?  Compression loss seems like an obvious one to me... but any other by sight symptoms or by ear symptoms?

[mally69]

Well mine had a sucking sound when the engine was being cranked over and also I could NEVER get it leaned out enough to stop burning rich and when I would punch the gas and let the engine slow me down it would make popping sounds. It was then I decided to pull my heads of.

[craigandlynda]

a compression test will tell the tale...cylinders should be pretty close..160, 180...or 180, 200...ususally within 20 pounds...if you suspect something, get a stethoscope and listen carefully to the edge of the head near any valve where the compression is off...you may have to lift the valve cover, let it idle, and listen with the stethoscope tip right next to the vlve  spring...but all this onlyif compression is funky...

we use to race these cars when they were new, back in the late sixties...most guys chose one of two fuels....sunoco 260, or amoco clear- amoco clear was an unleaded gas...and valve seat problems were something we didn't hear about...but, then again, we ran the crap out of these motors, knowing we were going to buy a new one the following year...