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Wed Jul 23, 2025 4:56 pm

Having a spark knock on my 1776cc engine in my single cab . The engine is timed. To 32 dregs total and have the points set .016 in . I have a engl 110 cam. Stock heads pic34 empi carb . Set as good as I can get it . Valves I adjust .004-.006 on all . Exhaust is a vintage speed w/ heater boxes . The truck seems to run pretty good but I’m thinking at 60 mph with GRB on her still I’m spinning it pretty good RPMs . I don’t know if I should do anything with the timing to help . I’m seeing the spark knock mainly in like 3rd gear when accelerating to shift into fourth. Also I do run 87-89 octane I know that is an issue also don’t hit me too hard !! Would octane alone help ?? Timing ?? Thanks

Wed Jul 23, 2025 5:06 pm

You should probably explain in more detail what your referring to as “spark knock”

Wed Jul 23, 2025 6:21 pm

What’s your static compression ratio? Do you know your deck height? What are you running for spark control? Running a 34 PICT3? What main jet are you running? What fuel are you running?

Getting rid of spark knock is a balance of all the above, and BFB is not wrong either…

Please don’t take offense, we do want to help!

Wed Jul 23, 2025 8:05 pm

Drive it till it reaches operating temperature.

When you are approaching your residence turn off the key and coast to a stop.

Let it cool a bit, pull plugs then post pics.

Wed Jul 23, 2025 8:23 pm

As far as I understood
the definition of "spark knock" is that retarding the timing stops the knocking.

Wed Jul 23, 2025 8:45 pm

Of course, but 32*, while a little hot, should not be setting the house on fire.

Seems like something else is up.

Wed Jul 23, 2025 10:43 pm

It may be lean, or the static compression ratio too high, or the timing is not at 32 BTDC at full advance, or the timing advance can be too fast, or too hot of spark plugs, or hot spots in chambers, or too much deck, and the octane is too low.

Those are a few.

Easiest one to test first is up the octane.

Thu Jul 24, 2025 5:37 am

74 Thing wrote: It may be lean, or the static compression ratio too high, or the timing is not at 32 BTDC at full advance, or the timing advance can be too fast, or too hot of spark plugs, or hot spots in chambers, or too much deck, and the octane is too low.

Those are a few.

Easiest one to test first is up the octane.

Badda- bing. 8)

Race gas fixes everything.

If it still pings on 100 octane you're driving a '74 Pinto.

.
.

Thu Jul 24, 2025 5:47 am

modok wrote: As far as I understood
the definition of "spark knock" is that retarding the timing stops the knocking.

exactly. otherwise its either preignition or detonation which are two different things

Thu Jul 24, 2025 9:46 pm

Seems to me the easiest thing to try is crank the timing back to 28* not drain the tank and put in race fuel.

Is this a new 009 or an old Bosch 009. The chances of a new one having consistent advance is not 100%, so check that first

To see if it's lean find a quiet road. Take it for a hard acceleration until it starts pinging. Once it starts pinging, shut it off and clutch at the same time. You want the engine to stop drawing in fuel, then pull over and check the plugs. If you just take it for a drive and pill a plug when you get home, you won't know if it's lean and when. Is it at idle or cruise or load? Chopping the engine will give you the best plug reading under the circumstances you're trying to see about.

Fri Jul 25, 2025 4:48 am

BFB wrote: modok wrote: As far as I understood
the definition of "spark knock" is that retarding the timing stops the knocking.

exactly. otherwise its either preignition or detonation which are two different things
Ah yes but what about "predetonation"?

:roll:

:lol:

Fri Jul 25, 2025 6:00 am

heh heh

Mon Jul 28, 2025 7:29 am

I agree with plug reading.
In the end plug reading is the quickest way to decide what your engine needs. Sure you can just pull timing and say I’m good but it can be so many other things, in the end you may be loosing /leaving a lot of power on the table .
- let’s say for example with detonation you kill the engine and pull plugs or at least 1 from each side to start like # 2 and 4.
If you see black speckles on the porcelain it’s from too much heat ,it will either require a small timing change or a slightly richer jet to cool combustion temperatures or a 1 step colder plug then retest . Shiny specs are aluminum. Pull timing now ! and retest.
- I learned a lot running and turning nitrous and chased my tail more than once.
Plug pulling and reading seams like it takes so much time but always saved me more in the long run