1966 c10 spark knock

[codymwaits]

I have a 1966 c10 inline 6 250. I just did the hei conversion, when my old distributer vacuum advance went out, I did everything right and installed it, set the timing. It idles perfect and revs up but if you hold the throttle down at any rpm like as if you were driving it will sound like gun shots going off. But won't do it at idle or reving. I've taken the valve cover off checked the valves and valve springs, then checked the rocker Arms everything works and look brand new. The motor has 40,000 miles. I need help! Any other things tht could be going wrong other than what I've checked
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[PGSigns]

You need to see what the timing curve is. The total timing is more than likely to high.
Jimmy

[TJ's Chevy]

Your sounding to advanced. What HEI conversion did you purchase? Here's the settings for these:

8 degrees advanced NO vacuum.
20-25 degree WITH vacuum.
And no more than 38 degrees under full load. Most of the time it is that your advanced to far and your detonating. Don't run it to much actually not at all because you can ruin the engine running it like that. Also, if your running 87 octane then the HEI was a waste of time, run 92 when running an HEI. Why put more spark through the plug if you don't have the octane to burn? Check your plugs, what type are you running? They may be a few heat ranges to hot. If it detonates under rpm you have to much advance and not enough octane. Back the distributor to 6 degrees advanced without vacuum and see what happens. You may have to have your distributor re-worked to a different timing curve if backing it down doesn't help. Stupid question but...you used a timing light and all that right?

[codymwaits]

It has the vacuum advance on it but is all electronic, the wires are universal kit made by accel, for hei conversions. I've used a timing light we ever reset it because it can run and be off 180 degrees it wasn't wrong on timing and I've always ran 93 octane and a bottle of seafood through it at every oil change. I'm so lost on what it could be. Next thing is to check leak in intake gasket or gasket on my manifold. Thanks, TJ's Chevy

[GASoline71]

Are your plugs gapped between .045 and .055? Gotta widen the gap when you run an HEI.

A lot of HEI's running on a lot of engines out there without having to run high octane fuel.

Gary

[jjzepplin]

Originally Posted by codymwaits

It has the vacuum advance on it but is all electronic, the wires are universal kit made by accel, for hei conversions. I've used a timing light we ever reset it because it can run and be off 180 degrees it wasn't wrong on timing and I've always ran 93 octane and a bottle of seafood through it at every oil change. I'm so lost on what it could be. Next thing is to check leak in intake gasket or gasket on my manifold. Thanks, TJ's Chevy

I found the problem- It's the seafood you are running in your engine. BWahaha!
Yeah - sounds like a curve kit is in order as well as the plug gap checked. Amazing what a curve kit can do. I run low octane and my engine is almost 10-1 compression. No ping= curve kit! It runs better on the high octane but I cannot justify it cuz it still sets me in the seat pretty good.

[TJ's Chevy]

Originally Posted by jjzepplin

I found the problem- It's the seafood you are running in your engine. BWahaha!

I got a good laugh to...for half a second I believed it! Then I realized he meant sea foam. lol

[cadillac_al]

It sure sounds like some crossed wires to me, idles fine then gunshots when you stomp on it.

[codymwaits]

Originally Posted by jjzepplin

I found the problem- It's the seafood you are running in your engine. BWahaha!
Yeah - sounds like a curve kit is in order as well as the plug gap checked. Amazing what a curve kit can do. I run low octane and my engine is almost 10-1 compression. No ping= curve kit! It runs better on the high octane but I cannot justify it cuz it still sets me in the seat pretty good.

I found that the valve cover gasket has been needing to be change which I already knew but I saw a little bit of oil bubbling on the intake manifold gasket, which means it's leaking and that's what is causing it to blow blue some out the tail pipe, and then I found the butterfly valve has the spring missing and was hung and I opened it up and held it up with wire and now it's not booming out the tail pipe as bad. But I think with the oil getting sucked it. It's causing it to backfire.
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[GASoline71]

Sucking in oil won't cause a backfire.

Gary