Battling Detonation After Piston Upgrade

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Shadoobie
Posts: 97
Joined: Mon Mar 03, 2014 10:07 pm
Your car is a: 1979 Pininfarina Spider 2000

Battling Detonation After Piston Upgrade

Postby Shadoobie » Mon Apr 16, 2018 2:40 pm

Hello everyone, I'm about 3500 miles into the new engine and I'm having a battle with my most feared enemy; detonation :( I've been pulling the timing back, but now I'd really like to try and deal with it once and for all. As a reminder, my build is as follows:
-1979 2L block, 1mm overbore
-10.9/1 Persan domed pistons
-rebuilt head to stock spec, lightly milled
-early style narrow lobe cams
-stock electronic ignition, new stock icm with standard plugs and wires.
-32/36 DFEV with factory jets
-stock automatic (boo, I know)

As it sits I can run 8 degrees timing with premium (93) gas and an octane booster with no problems, but I'd like to try and eliminate my worries without having to pull the head and install an extra thick head gasket. I'm working on a performance head to drop on in the future for this purpose, but I'm not quite ready yet. My first thoughts are to install a high performance coil and wires with colder plugs. Seeing as I'm just barely on the edge, I'm hoping this should put me in the safe zone at 10 degrees. Any thoughts?

Shadoobie
Posts: 97
Joined: Mon Mar 03, 2014 10:07 pm
Your car is a: 1979 Pininfarina Spider 2000

Re: Battling Detonation After Piston Upgrade

Postby Shadoobie » Mon Apr 16, 2018 4:58 pm

Hey admin, I reposted this thread to the performance section as I realized it belonged there but I can't figure out how to delete this post. Can you delete it for me or explain the process? Thanks.

Nut124
Posts: 42
Joined: Wed Oct 25, 2017 6:39 pm
Your car is a: 1978 124 Spider 1800

Re: Battling Detonation After Piston Upgrade

Postby Nut124 » Mon Apr 16, 2018 8:13 pm

What evidence do you have of the detonation - not doubting it , just asking?

10.9 CR is pushing it. Have you tried race fuel?

A 130TC head gasket could drop CR as much as 1/2 point.

Below is what detonation might do - I found:

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