Installing larger valves

Shaun41178(2) · Post by **Shaun41178(2)** » Sun Apr 03, 2005 3:49 pm

I was thinking abuot spending the extra money and have oversized valves put in my iron heads.

I was thinking 1.76 over the 1.72 since the 1.76 are already available.

My questions is do machine shops need to install the larger valve seats for the slightly larger valve? Or can they just cut the old seat to the larger seat of the 1.76 valve? I am not too familiar with how machine shops go about this task so I was hoping someone here knew.

Thanks

The Dark Side of Will · Sun Apr 03, 2005 5:04 pm

GM has been induction hardening the valve seats in iron heads since the lead came out of gasoline. Not sure how far into the head or out from the seat the induction hardening goes. If you cut through it, then you'll have to re-harden the valve seats. Not sure if that's readily possible in most shops. Talk to your machinist about it.

I've heard that hardened valve seats are only important on the exhaust valves, and then only if the engine's going to see hard duty (which I think it will, considering that you're building a turbo setup...)

I guess you're familiar with the tooling to cut a bigger valve seat?

Shaun41178(2) · Post by **Shaun41178(2)** » Sun Apr 03, 2005 5:30 pm

I saw it done years ago. Not sure if anything has changed since then.

I remember seeing this cutting toole and it was on an angle set by the machinist to the seat to cut the angles on the seat.

But yea I dont' know just how much room there is to grow on cutting more of the seat there to get that extra .04 of valve in there.

I have a pic of my finsihed combustion chamber. I dont' think I took too much off the seat if any. I just wonder if it can be cut a tad larger. I wish I had more time to get over to the shop in the area. I might need tot ake a personal day or somethng.

finished chamber. You can see the seat.

donk_316 · Post by **donk_316** » Sun Apr 03, 2005 6:49 pm

Well, I had the seats replaced in my 454 cause the valves were to recessed so i would assume if that little amount is enough to replace them then a machine shop would install the matching valve seats to your new larger valves. Its really cheap man.

p8ntman442 · Post by **p8ntman442** » Wed Apr 06, 2005 12:33 pm

Ok im interested in this now as well. Also, Does anyone know the size of the valves in a 4. 9 cause i have a set of those kicking around, and would like to use them in the fiero heads if possible. Or 2.3 quad 4 valves.

loudias · Post by **loudias** » Sun May 29, 2005 11:21 am

Good idea Shaun...I'll have to add that to my list of things to do to my next 3 . 4 motor...

Pyrthian · Post by **Pyrthian** » Fri Jun 10, 2005 11:45 am

I to dont know for a fact, but I beleive you'll be fine. it's only 0.04".

loudias · Post by **loudias** » Fri Jun 10, 2005 2:59 pm

Pyrthian wrote:I to dont know for a fact, but I beleive you'll be fine. it's only 0.04".

and only .02 at any point of the circumference

Dirty Sanchez · Post by **Dirty Sanchez** » Fri Jun 10, 2005 6:14 pm

Hey Lou, you going to Kick Hill tomorrow? A group of us will be there around 11:00 AM.

loudias · Post by **loudias** » Fri Jun 10, 2005 6:30 pm

No car remember?

Besides, I got to install new locks at my rental property. Bad tenant finally moved out. Me and a friend and his fiancee will be moving in.

I was at kick hill at the Sept. meet in 2002.

Dirty Sanchez · Post by **Dirty Sanchez** » Fri Jun 10, 2005 6:32 pm

Oh well, maybe you can make it to the NEFA swap meet there later this Summer.

loudias · Post by **loudias** » Fri Jun 10, 2005 6:40 pm

Don't plan on buying a car (Fiero) until close to when I can get my license back...which is late August of 2006.