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hey guys just got my engine together and once it started. from around 3000rpm there is a rattle from the top end. at first it sounded like a broken valve spring. but at idle car is quiet. so decided to take head off and have it sent off to be inspected and checked. head came back a week later and turned out fine. all parts were inspected and checked for clearances. also in mean time i checked the piston heights incase it was a bottom end bearing. but motor before 26 head conversion was very sound. so head go's back on and start car up and noise is still there. now the ecu is a haltech elite witch has just got a base map on it. one person from the machine shop where the head was done. said it could be detonation ?  car is running e85 with 2200cc injectors. im just looking for some feedback or ideas. as this is got me stuffed and i dont wanna give the car to the tuner with issues

 

cheers guys

 

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It won't detonate running no load, unless one of the injectors is spraying only a tiny % of what it is supposed to.  And even then, I wouldn't expect it to ping so that you could hear it and think it was mechanical noise.

And it will also be very unlikely to ping audibly on E85 anyway.

2 minutes ago, Rusty Nuts said:

Check the cam gear bolts, recently had a rattle in this area on a RB25 the bolts were clipping the inside of the cas.

ah ok ive heard this. especially when not running the cam cover. witch im not. i would of thought the noise would be from idle. not from certain rpm. but i will have a look at that. cheers mate

The same thing happened with mine, I think the camshaft is pulled fowards very slightly as revs increase, I found very very fine aluminium filings on the back of the cas. Otherwise did you have lifter bores checked they can stick if they rock in the bores. Were small end bushes new??

9 minutes ago, Rusty Nuts said:

There are small steel bushes in the cam belt cover that space the cas the correct distance. Make sure you have original mounting bolts for cam gear installed ,the original bolts have quite shallow heads. 

I did order the oem cam gear bolts from Nissan but ill check the spacing of the cas to gear tomorrow. Thanks for your help so far

  • 5 years later...

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