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New Valves?


theczechone

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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? 

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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 by HuD 91gt
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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. 

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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 by HuD 91gt
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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? 

 

 

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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...

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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. 

 

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