Aluxes Posted January 25, 2015 Share Posted January 25, 2015 Hey everyone I have question on a valve job. Doing a valve job on a pair of 2.2 heads, 97 single port. Both intake valves in # 3 combustion chamber are slightly bent. The piston tops have no indication the they came in contact with the valves. I'm wondering what would cause this? Obviously these two are being replaced, but I still need to grind the seats. Since I can't use the bent valves to grind the seats will using the new valves to grind the seats be ok? Plus would the bent valves have caused any issues with the guides? I'm installing some deltas, and putting these heads on a rebuilt block so I want to make sure its gonna be all good. Thanks for any advice! Link to comment Share on other sites More sharing options...
Fairtax4me Posted January 25, 2015 Share Posted January 25, 2015 You're supposed to use the new valves to grind the seats. The whole point of grinding is to get the profile of the new valve to match the seat so that it seals properly. It takes very little force to bend these valves, so a lack of marks on the piston is not surprising. 1 Link to comment Share on other sites More sharing options...
Aluxes Posted January 25, 2015 Author Share Posted January 25, 2015 Alright cool! Thanks for that! Do you think the guides are ok? Link to comment Share on other sites More sharing options...
mikaleda Posted January 25, 2015 Share Posted January 25, 2015 I would check for air leaks in the exahst just to be on the safe side, but like fairtax said it doesn't take much to bend the valves Link to comment Share on other sites More sharing options...
mikaleda Posted January 25, 2015 Share Posted January 25, 2015 Alright cool! Thanks for that! Do you think the guides are ok? You might as well replace them while your there Link to comment Share on other sites More sharing options...
Gloyale Posted January 25, 2015 Share Posted January 25, 2015 What you are describing is lapping, not grinding. Good for freshing up old vavle seats.....but won't cut it for seating new. No matter how much compound you use. Grinding is done with a special tool/bit that matches the seat and valve......but doesn't do them "toghether". It's got a guide rod that slips into the valve guide and then grinds the seat while slipped over said guide rod, ensuring the centering. If you need new vavles installed I would recommend having them installed by a machine shop that can truely "grind" the new valve and seat to the proper match. It's a real downer to put a "new" engine toghether and have it suffer missing and poor compression. 1 Link to comment Share on other sites More sharing options...
Aluxes Posted January 25, 2015 Author Share Posted January 25, 2015 What you are describing is lapping, not grinding. Good for freshing up old vavle seats.....but won't cut it for seating new. No matter how much compound you use. Grinding is done with a special tool/bit that matches the seat and valve......but doesn't do them "toghether". It's got a guide rod that slips into the valve guide and then grinds the seat while slipped over said guide rod, ensuring the centering. If you need new vavles installed I would recommend having them installed by a machine shop that can truely "grind" the new valve and seat to the proper match. It's a real downer to put a "new" engine toghether and have it suffer missing and poor compression. . Thank you! I guess this is the info I was looking for. Wouldnt want missing and low comp! I'll take it to a machine shop then. Link to comment Share on other sites More sharing options...
mikaleda Posted January 25, 2015 Share Posted January 25, 2015 I wouldnt suggest grinding the valves unless your compleatly rebuilding the entire engine. By rebuilding and grinding the valves it will have like new compression that is going to put exessive pressure on the lower end causing failure of the lower end sooner than if you just install and lap the new valves in. Just my 2 cents and what I've heard from every mechanic I know. Link to comment Share on other sites More sharing options...
Gloyale Posted January 25, 2015 Share Posted January 25, 2015 I wouldnt suggest grinding the valves unless your compleatly rebuilding the entire engine. By rebuilding and grinding the valves it will have like new compression that is going to put exessive pressure on the lower end causing failure of the lower end sooner than if you just install and lap the new valves in. Just my 2 cents and what I've heard from every mechanic I know. New valves won't just "lap in" I am suggesting he replace just the bent 2 and have them ground. Lapping will work for all the rest if it was a decent running engine anyway. besides, 2.2 bottom ends don't fail unless run out of oil or otherwise abused. Link to comment Share on other sites More sharing options...
mikaleda Posted January 26, 2015 Share Posted January 26, 2015 New valves won't just "lap in".Why would they be different than any other head? I've never had any problem with compression when I lap a new valve in. Granted I've never done this job on a subaru, but have done this on many older v8s and 6s and single cylinder motors. Thatsthe reason the sell valve grinding material and valve lapping tools, it just needs the valve and seat to properly fit together. Unless your rebulding the head there should be no reason you can't Lapp the valves in and get good compression. Link to comment Share on other sites More sharing options...
Fairtax4me Posted January 26, 2015 Share Posted January 26, 2015 As long as the new valves are lapped to the correct seat width they'll be fine. On a race car or high performance build I would say otherwise. Machine shops charge an arm and a leg here for valve service and some won't touch it unless you let them do every valve on the head. Makes a two valve replacement job cost more than a used head. Your shop may vary. 1 Link to comment Share on other sites More sharing options...
Aluxes Posted January 26, 2015 Author Share Posted January 26, 2015 Yea I'm rebuilding the heads. Deltas, New springs, New seals, and I lapped all the other valves. But now I think I may just take to a machine shop and have a 3 angle job done. These heads are going on a block that is getting rebuilt too so I don't want any problems. Thanks for all the input. Link to comment Share on other sites More sharing options...
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