It's time for my '52 straight eight to get a valve job and possibly new seats. I pulled it apart and it's suffering from pretty bad regression. I have been told not to use hardened seats because it will ruin the head, but haven't gotten an explanation as to why. I did a search and found this about nailheads... "Don't let anyone talk you into 'hardened valve seats'. The Nailhead is cast from a very high nickel content alloy and doesn't require hardened seats. Also, the water jacket is in very close proximity to the seats and installing hardened seats will more than likely, ruin the heads." Does this apply to the straight 8 as well? It's a 1952, 263ci. Has any one had any good or bad experiences with hardened seats in this motor?
Not sure on that motor. I had hardened seats put into a 351W and ran it like hell without any problems in about 40K miles.
I think in the nailhead, they are saying the cutting for the seat inserts might get into the water jacket and ruin the head. I know my engine guy has put seat inserts in nailheads without issues.
Be careful. I am not familiar with that engine but I have seen seats come loose and destroy an engine. It happens every now and then no matter how good the shop is. What I usually do is find another valve with a similar configuration but with a slightly larger head, cut the seat slightly larger to make it fresh again, and then cut the valve to fit the new seat. That adds a bit of extra performance and avoids the risk of seat inserts. Unless you know exactly how the water jackets are shaped and where the thin spots are, seat inserts can be a real gamble.
So it sounds like the damage could be done during the machining, but hardened seats couldn't harm the head once installed and running, correct? (unless it comes loose)? Does anyone know if hitting the water jacket is a real threat on the 263? Anyone else ever see hardened seats come loose?
Valves seats comming loose ..WTF! wake up guys it aint gonna happen! . Get the heads sonic tested for density. Around here Aero engineers use an Xray firm to look closely at heads and cylinders so if you are that worried get the head boiled and tested first. A competent machine shop will insert them properly for you. Stellite valves are another option. Vintage car guys get them made all the time by merely cutting down larger valves. Because fuel quality is getting poorer every year a seat of hardened exhaust seats and valves is a wise investment. Are you sure it's valve reccesion from fuel issues or just poor maintenance? . Buicks had rotocaps ? ,in that case the valves,if not adjusted or the tappets are wornthe valves turn excessivly eventually wearing the seats/valve heads quicker than usual.
I'm not sure what you mean by rotocaps. As for the valve recession, I can't be sure as to what caused it. The car has been around longer than I've been alive.
Rotocaps are how the valve rotates a little bit each time it goes up and down. this means every time it closes it moved a little and closes in a different spot in relation to the seat. This helps even wear. From the amount of sludge in the pushrod chamber there, it looks like this ain;t a fresh engine. And it looks like the intakes were a little leaky, it should be clean in the intake. I'd just get the valves and seats resurfaced, and new springs and put er back together. Are all eight looking like them three? That would be good. Frank
Just get stainless valves. You shouldn't have to worry about running unleaded with the factory seats. A fresh, good quality valve job and SS valves, and you'll be good. Trust me. ~Scotch~
I don't see you have much choice the way the head looks. I've put seats in nailheads and they are a very thin seat. Go to a good machine shop and have them look in there catalog. I used SBI or Martin Wells for seats. They are usually a good resource letting you know how much room there is for seats. If I had doubts I wouldn't cut the full depth of the seat, just enough to have a good ledge for the seat to set on, and cut the top of the seat down flush after it's installed. Jeff
Scotch- Any idea if valves from Egge are stainless? The web site doesn't specify, otherwise I'll just call. Gas pumper-The motor is far from fresh and all eight are pretty similar. Two more and the valves...
Chub- Call my pal John Beck at Pro Machine (530) 892-9711 He set me up with mine. You've seen the pics of my I-8 head, right? ~Scotch~
Yeah, it looks exactly like mine. Just kidding, I've seen them and I love watching your progress. How's it coming? Thanks for the # and for the help. -scott
The Jalopy Journal
