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86 Veloce
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Discussion Starter #1
Well, this engine has been flawless since the rebuild, .020 off the head, ported, performance cams, Isky springs, flat top Motronics, yadda,yadda,yadda... I've ran a couple of tanks of fuel through it, doesnt burn a bit of oil, water is clear....
I have been opening it up a bit more and right about 4K I start getting a valve train noise that sounds like a tappet rap. It gets louder as RPMs progress but I back off when I start hearing it. I know big cams are prone to be more noisy than stock but this sounds a lot like a singular cylinder. After a few hundred miles I checked lash and all was good but one exhaust was about .001 loose and an intake was .002 tight. Within spec but will deal with those in a couple hundred miles at next oil change. Normal for an Alfa? Any knowledgeable input would be appreciated!
 

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It is common for valves to settle in after a rebuild with gap closing up a little. Most high performance cams do not have quietening ramps and are louder than stock cams.
 

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86 Veloce
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Discussion Starter #3
Thanks Ed, I am hoping that is the issue. Certainly more clatter at idle, better when warm but the "clacking" at higher rpm is unsettling. Your words from experience calm me some. I will keep an "ear" on it and pull the cover and investigate if things change...
 

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Did you use new or used tappets? Several people have had problems with new ones.
 

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86 Veloce
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Discussion Starter #5
PM sent...
 

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86 Veloce
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Discussion Starter #7
I think you nailed it. Ignition timing is set by the computer so not much I can do about that but...... on my way to the gym this morning i noticed i achieve that rpm regularly, but not under WOT and heavy load. With the high compression numbers now and fuel that is in question of being able to deliver what the engine needs in those circumstances it most likely IS preignition. I will be stopping by the race fuel station to fill up with some high test and see if that cures the problem. It runs fine with typical casual driving but yesterday when I tried to push it I got that clatter that I mistook for valve train noise. Time will tell, I will be filling up later this morning and give it another stress test.... you win the diagnostic prize! (At least I hope so...)
 

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So you are using L-Jet ignition and Weber fuel management?
 

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86 Veloce
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Discussion Starter #9
No, totally stock L-jet setup. Have to, this is California.
 

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I think you nailed it. Ignition timing is set by the computer so not much I can do about that but...... on my way to the gym this morning i noticed i achieve that rpm regularly, but not under WOT and heavy load. With the high compression numbers now and fuel that is in question of being able to deliver what the engine needs in those circumstances it most likely IS preignition. I will be stopping by the race fuel station to fill up with some high test and see if that cures the problem. It runs fine with typical casual driving but yesterday when I tried to push it I got that clatter that I mistook for valve train noise. Time will tell, I will be filling up later this morning and give it another stress test.... you win the diagnostic prize! (At least I hope so...)
If there is still lots of fuel in the gastank you can also buy octanebooster to spice that 92 or 93 up a bit.
 

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86 Veloce
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Discussion Starter #11
All you can get at a regular gas station here is 91, which is equivalent to 97 on your side of the pond. At the race fuel station I can get 93 ethanol free..... I am gonna put some booster in it for the rest if this tank and see what happens.
 

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I think that you should install a wideband AFR. L-Let wants to run pretty lean and you need to verify that you are under 13.5 at high power.
 

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86 Veloce
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Discussion Starter #13
A gauge would let me know my ratio but dealing with it in a state strict on emissions and modifications is difficult.
 

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But Mad North-Northwest
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If there is still lots of fuel in the gastank you can also buy octanebooster to spice that 92 or 93 up a bit.
Unfortunately that stuff doesn't help much. If the bottle says "raises octane by 3 points!" that's 0.3 octane, which isn't much at all.

The off-road octane boosters with MMT can be more effective but that isn't really great for your engine or cat converter.
 

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86 Veloce
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Discussion Starter #15
Ahhhhhh. That is good to know. I wont expect much then.... I will fill up with good fuel next time and I have other means in the works👍. If needed I could detune a bit but that is a last resort. Thanks for the knowledge!
 

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A gauge would let me know my ratio but dealing with it in a state strict on emissions and modifications is difficult.
It took only a few seconds for detonation to blow my head gasket when I ran lean at WOT. I was lucky. Richard Jemison holed a piston for the same reason once when I was with him.
 

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86 Veloce
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Discussion Starter #17
I will surely be careful until I get this under control. Larry at APE is shipping me something that will help me deal with the inherent lean issues of the Bosch FI .......
 

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86 Veloce
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Discussion Starter #18
Ordered a wideband fuel ratio gauge. I will be installing it on Wednesday so I can monitor mix through rpm range, then I can address any lean conditions.
 

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Ordered a wideband fuel ratio gauge. I will be installing it on Wednesday so I can monitor mix through rpm range, then I can address any lean conditions.
Let us know what make/model wideband you are using and if you are having luck with it.
 
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