theczechone Posted June 15, 2018 Share Posted June 15, 2018 So i am rebuilding an N42 head with some mild porting, it will also get a street cam which needs new springs(outers only). I'm installing new seats and guides, should i also spring for new valves? Or can i just get the used OEM ones cleaned and inspected? Do the Z valves experience a lot of keeper groove wear? If i choose the replace route, what are good manufacturers? I see ferrea offers some nice valves but the price is high ($420 on their website, $330 on ebay) Datsun Spirit Offers their set for $230 which seems fair... and then we have the ITM and DNJ valves that are questionable for $8/piece for a total of $96 from RockAuto.... Is there someone else? Quote Link to comment Share on other sites More sharing options...
turbogrill Posted June 15, 2018 Share Posted June 15, 2018 Make sure they are not bent, mine was. Quote Link to comment Share on other sites More sharing options...
theczechone Posted June 19, 2018 Author Share Posted June 19, 2018 Ended up ordering from SI Valves. New stainless valves available in 44 or 46 for intake and 35 or 38 for exhaust. I went with a stock size, and they were 10.50 a piece! for a shipped priced below 140 for the set! Quote Link to comment Share on other sites More sharing options...
HuD 91gt Posted June 19, 2018 Share Posted June 19, 2018 Just make Sure you have proper guides to go with those valves, or very large clearances within your stock guides. Was a costly mistake for me. Quote Link to comment Share on other sites More sharing options...
theczechone Posted June 19, 2018 Author Share Posted June 19, 2018 @HuD 91gt i'm getting new guides installed , i will provide the valves to the machine shop so they should be able to size the guides after the installation to the new valves. Is the stem diameter on SI valves larger than stock? Any issues with valve seals? Quote Link to comment Share on other sites More sharing options...
HuD 91gt Posted June 19, 2018 Share Posted June 19, 2018 (edited) Make sure they use a bronze guide. Cast steel will cause gulling (sp? Might not be the correct term, but extreme wear from different expansion rates and metal on metal love). My guides were brand new cast, built by a reputable Canadian Datsun shop. Valves seized in the guides when the engine was warm. After more research apparently using bronze guides with stainless valves is a well known fact. SI valves seem to show this issue more prevalently. A well known L series builder in Australia gave me some advice afterwards about using these valves. He said excessive clearances or bronze guides are the only way to use these without issue. Edited June 19, 2018 by HuD 91gt Quote Link to comment Share on other sites More sharing options...
theczechone Posted June 19, 2018 Author Share Posted June 19, 2018 Interesting, I did source bronze guides. Perhaps i should check what the proper clearance needs to be. The factory guides were bronze and the factory valves were stainless so there is no change of material so i would assume same clearance is expected. I will take some measurements on the valves when they get here and compare to the stock ones. Quote Link to comment Share on other sites More sharing options...
theczechone Posted June 19, 2018 Author Share Posted June 19, 2018 FWIW i spoke with Dave Rebello and he seemed to think that the valves would be fine as long as used with bronze guides. Great guy, I've only bought a cam kit from him and he has been super helpful with every step along the way. Quote Link to comment Share on other sites More sharing options...
HuD 91gt Posted June 19, 2018 Share Posted June 19, 2018 (edited) That makes two experienced engine builders on board with the bronze. Wish I had that info prior too... Ive only talked to Dave once but he was great over the phone and I really regret not working with him for my engine build. Live and learn. Edited June 19, 2018 by HuD 91gt Quote Link to comment Share on other sites More sharing options...
HuD 91gt Posted June 19, 2018 Share Posted June 19, 2018 3 hours ago, theczechone said: Interesting, I did source bronze guides. Perhaps i should check what the proper clearance needs to be. The factory guides were bronze and the factory valves were stainless so there is no change of material so i would assume same clearance is expected. I will take some measurements on the valves when they get here and compare to the stock ones. Someone please correct if im wrong, but are stock guides not cast steel? Quote Link to comment Share on other sites More sharing options...
Leon Posted June 20, 2018 Share Posted June 20, 2018 I've had similar poor experiences with SI valves, with the caveat that I ran them on OEM guides. When I talked to Dave about it, he mentioned hearing about others with similar issues. Went with OEM exhaust valves and Supertech intakes on his recommendation. Had him work the head on the second go-around... Quote Link to comment Share on other sites More sharing options...
madkaw Posted June 20, 2018 Share Posted June 20, 2018 Bad results with my SI valves . OEM valves are good Quote Link to comment Share on other sites More sharing options...
theczechone Posted June 21, 2018 Author Share Posted June 21, 2018 (edited) are oem valves still available from Nissan? What happened with your SI valves? Edited June 21, 2018 by theczechone Quote Link to comment Share on other sites More sharing options...
Leon Posted June 21, 2018 Share Posted June 21, 2018 In my case, they ate the OEM guides in about 1000 miles. Quote Link to comment Share on other sites More sharing options...
Chickenman Posted June 28, 2018 Share Posted June 28, 2018 Anyone have experience with ITM valves? I scored a fantastic deal on a P79 head. All new bronze guides, all new valves. Head looks like it has just had a very, very light skim. This thing looks almost Virgin. But I'm worried about the valves. The valve stems appear to have a slight dimple effect to them. Very fine... but it's thee. Not the mirror smooth finish that you normally get on factory valves. Brand is unknown. They do not appear have a Chrome finish like the factory valves. ITM valves are a reasonable price. I believe that is what my engine builder used when he re-built my engine in 2014. Heads looked a bit bulky. But I didn't get a good look at the stems. Quote Link to comment Share on other sites More sharing options...
Bruggles Posted July 3, 2018 Share Posted July 3, 2018 I just got ITM valves with bronze guides, so far so good. I have autocrossed them and tracked them and have like 500 street miles on them. Quote Link to comment Share on other sites More sharing options...
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