 Pls Help Diagnose Tapping Noise, Started after a 15mi drive |
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| Chaznaster |
 Sep 26 2021, 04:56 PM
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Member  Group: Members Posts: 302 Joined: 22-November 15 From: Concord, MA Member No.: 19,389 Region Association: North East States 
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Hi. My 74 1.8, 123ignition with single Weber 32/36 has developed a new sound. A buddy pointed it out and now I cannot unhear it. It seems to have started after a 15mi drive (long for me - I am still getting everything dialed in).
At all speeds under 2500 I get a steady tapping or knocking sound at the speed of the engine. It sounds louder on the passenger side but with the stethoscope #2 the valve tappety tapping sounds a bit louder than the others (-scope on the intake nuts). Not sure if it is a normal sound for a T4 engine. Valves checked last weekend at .006. Timing 7.5 BTDC at idle. 123 increases advance linearly +22 between 1000 and 3200RPM (total advance 30). Plugs gapped. Carb tuned. Compression at 1=120, 2=120, 3=100, 4=140. I tried snugging up the exhaust manifold bolts (#2 was a bit loose) but no change. Power is fine but it does backfire on deceleration. Pic of plugs (1-4 bottom to top) below. 4 has some carbon. I’d appreciate some insight. Different diagnostics? Ready for tear down? Nothing to worry about? Thanks a ton. Attached thumbnail(s) 
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Posts in this topic
Chaznaster Pls Help Diagnose Tapping Noise Sep 26 2021, 04:56 PM
Chaznaster
Hi. My 74 1.8, 123ignition with single Weber 32/3... Sep 27 2021, 06:54 PM Shivers Back fire could be an exhaust leak. Sep 27 2021, 07:39 PM Chaznaster Thank you! I will double check the exhaust wit... Sep 27 2021, 07:53 PM
Superhawk996
I read that detonation knock is not likely at id... Sep 28 2021, 05:36 AM rfinegan Check your valve lash first.
Once that is ruled ... Sep 28 2021, 06:48 AM Chaznaster Thanks Superhawk996 and rfinegan. This is really h... Sep 28 2021, 05:48 PM rhodyguy For a single outlet exh just press a piece of 2x4 ... Sep 29 2021, 09:29 AM Chaznaster UPDATE***
I tinkered with the car this past week ... Oct 3 2021, 04:39 PM Superhawk996 Nice Job. Glad to hear its running better.
Y... Oct 3 2021, 06:29 PM Chaznaster I am checking back in on this one - most issues ar... Oct 17 2021, 04:35 PM Superhawk996 Sounds like you're making progress.
Post pic... Oct 17 2021, 04:54 PM rick 918-S Hate to even bring it up. Loose valve seat? Oct 17 2021, 07:03 PM Chaznaster Update - re-read of plugs (pic below) after carb r... Nov 2 2021, 05:17 PM Chaznaster UPDATE
I upped the main carb jets by 10 to 160 pri... Nov 18 2021, 05:59 PM  |
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