1963 s/w vette "x heads" valve job/seats

[JULIA SERRANO]

I am a long time owner of a 1963 s/w vette vin#30837S106652, 327/340 in excellent restored condition, engine cast#3782870, engine cast date K282, head#3782461, head cast date K302, and have been told by a local corvette specialty machine shop that I need a valve job. The owner and his machinist advised that I have the early production heads commonly refered to as "X Heads" and therefore have a thin casting between the water jacket and valve seat area. They advise that putting in new valve seats may damage the heads because the machining of the valve seat area may break through the water jacket thereby ruining the heads. They advise that the "X Heads" are valuable and would sell for approximately for $1200-$1500 in their current condition. They advise that Chevrolet engineered a second design of these heads with the same part # with thicker casting to correct the earlier design thin cast.

They advise that they can machine the "X Heads" and risk ruining them or not fully seating the valve seats into the heads and grind off the top of the valve seats and risk the valve seats popping out during vehicle operation and risk ruining the motor.

They recommend I use the second design heads and either sell the "X Heads" or place them in storage for numismatic value. I drive this vehicle daily and take it on cross country drives however I have always placed sentimental and numismatic value in keeping this car original in all of its repairs. Please advise if there is a technique to machine the "X Heads" or use oversized valve seats or not fully seating the valve seats and grinding the valve seats, or ???????.

[William C.]

Re: 1963 s/w vette "x heads" valve job/seats

The need for hardened seats is generally a myth, unless you use the car for heavy trailer pulling or plowing. A conventional valve job will save you the $ and risk associated with the use of hardened seats and you will be fine. That said, my '62 had hardened seats installed in my "X" series heads without difficulty or leakage, so if you need the name of a competent shop, email me.

[mike cobine]

Re: 1963 s/w vette "x heads" valve job/seats

A trusted friend who ran a machine shop back in the 80s told me he had found that this was greatly exaggerated. In his experience, the worse cases were such that if they would have had a valve job with leaded at 100,000, they were now getting a valve job at 80,000. So in that line, at 300,000 miles, instead of getting your third valve job, you would be apporaching your fourth shortly.

Remember, that is the worse case.

I didn't get hardened seats back the. I got a regular Chevy three-angle valve job.

Another friend running a machine shop, who had built most of my race motors for free, said that his experience were more heads were ruined with the hardened seats than without. He had seen the hardened seats pop out, cause cracks in the area, and being installed wrong far too many times by shops supposedly competent.

I still have not had hardened seats installed in any heads I have. Unfortunately, I don't have enough miles to give any good proof of what they say.

[John H.]

Re: 1963 s/w vette "x heads" valve job/seats

Don't bother with hardened seats - you don't need them; just get a regular 3-angle valve job and drive it!

[Mike M.]

Re: 1963 s/w vette "x heads" valve job/seats

i wasunder the imporession that 461X heads were used up until about jan or feb of 62 and that a 63 probably ounght not to have the 461X. simply flip the head on to its combustion face and look for an embossed X that stands alone. I had my 61 rpo 461x heads trated to case hardened inserts when i rebuilt it about 10 years ago and didn't hit H2O.I agree with the othres that case hardened seats really aren't necessary the way most vettes are driven. mike

[Duke W.]

Re: 1963 s/w vette "x heads" valve job/seats

Just have the seats ground. You don't need inserts. I pocket ported my 461X heads and did a three angle valve job with .040" inlet seats and .060" exhaust seats.

Also recommend you use the LT-1 cam instead of a new or repro Duntov cam. The secret to keeping the valve seats in good shape is to adjust the valves properly, which means using other than the OE clearance specs. E-mail me and I will sent you the procedure along with the technical reasons why the OE specs are not correct.

Duke