Valve train rattle/ detonation

[Ether]

Since my bronco is driving/ stopping/ steering so well I’ve spent some time at higher speeds/more load.

I’m getting some rattle at 30%+ throttle under load, I have Edelbrock pro-flo. I don’t think its lean, runs great under less load/throttle. Also seems pretty gutless at the same time.

I suspect my timing is too advanced (set wrong at idle).

Ok to test this theory by turning the distributor CC a few degrees and drive? Or should I start over with TDC/ timing setup.

Bronco runs great otherwise and I’m loving it.

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[pcf_mark]

I assume ProFlo is in 100% control of the distributor? As a sanity check record the rpm of the detonation while driving and then check it with a timing light at that rpm in the driveway to see what you are getting. That will show you the rpm to timing curve w/o adjustments for load. Light throttle I might expect some detonation but 30% I would not.

 

[Brush Hog]

One time I had a massive vacuum leak from brake booster hose I forgot to hook up that acted very similar. Along with my power brakes not working well.

 

[Ether]

Turned the advance back a couple degrees, she runs way better! It was definitely detonation…


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[Ether]

[mention]pcf_mark [/mention] The PF4 does control spark, but it relies on the installer to set dizzy at idle, then it controls it moving forward. I must have been off a few degrees, too advanced.

So when it thought it was at 30, it was actually at 34 or similar.

Runs so much better, has way more power under load.


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