gapimpin

i was porting a set of 305 vortecs and found one of my exhaust valves is bent... not too bad but it does cause some friction at high lift... i was wondering if i can just use one of the vavles from my 91 305 tbi heads as a replacement. are the vavles the same size ? i wont be able to pull the head till this weekend id like to know before i go out thier so i can get my engine back in by sunday.

Sonix

iTrader: (1)

I'm not sure if the valve angles are the same, but I was trying to use my valves off one cylinder head onto another one, and exhaust valves are notorious for wearing out. Might as well just buy one new one, the machine shop wanted $8/valve so....

gapimpin

cant find a machine shop around here is the problem... i hate this place so much but i guess ill be going down to austin any ways so i can always drop by one down there.

Guest

Sorry I cant answer your question, but I have one. Why is it bent? I'd be checking the other 7, or just replacing them all. There was a problem somewhere, need to find the cause so you can check for damage and prevent it from reoccuring. Sounds like its time to have those heads visit a machine shop though, have the seats cut, valves checked and cut if they can be, check the guides, etc. Might be more issues than just a single bent valve, without some experience and some appropriate tools you might end up with a leaky valve and thats no fun to fix.

gapimpin

i took all the valves out that was the only one that was bent... the heads wher just rebuilt the guy slapped them on a motor and said the engine failed now i suspect valve to piston contact but they are in great shape otherwise.

Guest

How do you know it was bent? Just the guide resistance? For sure determine what caused it or you're bound to run into the same issue again.

Best way to find a bent valve is with a valve grinder, a bent valve shows up clear as day when you try to cut the face of the valve. If you have no intentions of sending them out get some valve grinding compound and a tool (dont know the name, its just a wooden stick with a suction cup) and lap the valves. From that, you can see if there's any lack of contact and it'll help mate the valves and seats in case there are any problems there. All it takes is put some compound on the valve face, use the tool to spin the valve back and forth while pushing it against the seat. It'll leave a slightly ground surface on the valve and seat. Make sure to clean that stuff off real good when you're done, dont want that nasty stuff in there when its assembled together.

gapimpin

i knew it was bent because it was hard as hell to get out... its not the guide cause another valve worked just fine... i did lap all the valves when i ported them. i ended up using one of the valves out of my tbi head when i lapped it thier was a smooth shiny surface on the vavle and the seat so im guessing the angle was correct. it had those umbrella seals on it though.. wher those old valves lift limited? that second groove in the top of the vavle stem for the o ring would catch if i just tried to slide the valve slow but if i pulled it out and put it in really fast it never caught.