yep ,fraid so ,. pops 430 done that to me greg ,,. btdt , and merry Christmas to you too .. ,, it was caused from a bad rather wrong head gasket it had set for 5 yrs ,,. wouldn't ya know it ,.that water crud got all over the rocker arm assembly and rusted it awful in those 5 yrs ,..I bought pops 430 from mom and got some atf and wd 40 , and some lucas do gooder in the new oils , and with a channel lox I got everthin going again ,, and it started rite upp,,and run out fine , wen t immediately to Case expo at Lanesville.. then raked and baled hay on the way home ,.even ran the nh 847 round baler andmade 30 bales ,,. everyone was happy ,.. then one day ,,. it happened again ,, this time done a valve job ,, all the seats needed replaced ,, and all the exhust valves ,, if I would put in new springs too my problem woulda been solved ,, but instead ,, one cold day just like yours ,, I started pops 430 and it was just sittng here idling smooth as can be ,, when upjumpt the devil,.. A MISS AND A CLATTER ,.. one of them kinda rusty springs that we cleaned up and judged ok had broke..and droppt the valve , thus the clatter ,,. off comes the head again , john and chris sent another gasket set , new valves springs,.. got it back and stuck it back together late one nite ,,and the next day the world took off at a gallop again,,.and I have not got back to it all summer or fall ,. I ought to be out there torqueing the head down and firing up pops 430 ,,. but I still got 3 acres of beans to get ,, my 750 massey sits in the rain 4 miles away,. yes greg ,, I kinda know how you mite be feeling , but you MUST PERSERVERE ,,. I know I will ,, and pops 430 will be a real powerto be reckoned with again ... hang in there with the 630 ,,.. if you wanna throw in the towel ,, I could dig out some mad money and find space at my place , ,