You said it didn't change with 10 degrees timing, how about a little mid grade fuel?

I have never seen a slant 6 with a deck reading of .210?? That would definitely be the largest I have heard of but maybe others have seen it.

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12.70 @ 104.6

I have seen a couple of blocks in the 0.200-0.220" range.

Lou

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The original block I was building off of had .180 deck. But my machinist screwed me told me my block was good at .060 just needed a hone. So I ordered pistons. I got block back with huge ring ridges. Since I was stuck with pistons I couldn't return with out a hefty restocking fee and shipping I found a different block and bored .060. Which ended up with the .210 deck. Annoying but what can ya do...

When the usual suspects turn out not to be responsible for the crime at hand, it's time to do some more detective work. Restricted exhaust, for example, will cause pinging at high load/wide throttle no matter what is done with the ignition timing, spark plug heat range, etc.

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Too many people who were born on third base actually believe they've hit a triple.

Too restricted exhaust would cause vacuum gauge to drop near zero and slowly rise at idle, if I'm not mistaken. I've always planned on having the exhaust re-done to 2.25" just never got around to it yet

If you are going up long steep hills have you tried downshifting?

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A partially blocked muffler could have enough resistance to flow under load to cause detonation (pinging) without affecting vacuum readings.

I would expect performance to suffer but maybe not enough to notice if the blockage is only partial.

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Exhaust restriction doesn't necessarily show itself at idle. More than once I've solved open-throttle/heavy-load ping problems by replacing a muffler with broken/collapsed internals that allowed enough flow to accommodate low engine speeds, but not high engine speeds.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'm a bit confused with all the stuff going on here but I think I read you have a cam that isn't stock and maby head or block deck cgangescganges. The factory timing specs are fore stock cam and cam timming ect. Possibly you could have an engine with cam timing over advanced also. Just try like someone else said a mud grade fuel. Or just turning timming back a bit and see what happens.

I'm surprised no one has mentioned jetting yet. If it's just a little too lean at WOT you can get detonation. Even if it isn't the root cause going up a main jet size might be enough to tame the problem.

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I understand you have a certain distributor set up that should give you a suitable advance curve...but have you actually confirmed this with timing light? I read through your post,forgive me if you've already mentioned it,but what is the total advance and what rpm is it "all in" by? What is the cranking compression? Are all cylinders similar compression readings? I wouldn't bother with ZFR5N plugs,in my experience they will need less advance,which makes sense since the electrode is placed ever so slightly closer to the centre of the chamber and needs less time for combustion, but get decent quality plugs like NGK, I'm sure it's the same over there but in Australia a lot of Motorcraft stuff comes from outsourced suppliers and you get rebranded generic stuff which isn't a patch on what they used to be. HEI is a great upgrade if you haven't already done it,people have been using this system for years as a retro fit on just about any engine you can think of, and for a Slant it's more than enough...probably not your core issue however.

I did (5th reply, March 3, 23:21:00 PST)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Ahh... missed it.
But I do agree.

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I have been struggling with uphill/loads and "sounds" from the engine. I was suffering from exhaust manifold leaks here and there, worked to correct those over the weekend, including pulling my manifolds and replaning them to align the surfaces, the rear modified OEM manifold was warped a bit out of alignment with the offy intake. I don't have a table disc sander, but if you're careful a hand held belt sander with 40 grit does the job nicely, just have to have steady strong hands.

http://s785.photobucket.com/user/67dart ... sort=3&o=0

I found carbon tracks on the manifold gasket at the head on two of the exhaust ports. And it was pretty loud going uphill, barely discernable on the flats.

Anyway, it is much quieter today, but still uphill i had a ticking noise when I drove into work. I noticed it more after the engine had warmed up.

With all this talk of pinging, I'm wondering if my manifold leaks weren't also masking a pinging. I'm fairly sure I fixed the leaks, but I'll check that first. I don't think its a restricted exhaust issue, as I'm running Dutra duals to 2.5" pipe.

I always run 91 octane in it, but is it winter blend, I can't say. If I can't find any further signs of exhaust leaks, I'll dial back the timing and see if that makes a difference. I checked with a timing light, I'm running 10 degrees advanced, it runs well there, but whose to say it's not too high. This is a modified build with 8:1 DCR; Dutra Duals, larger valves, not too aggressive street cam. Idles very well, smooth, starts up instantly, quick response, no issues there.

Thanks for this valuable discussion guys.

Brian

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I meant to say 2" pipes from the exhaust manifolds, down to Y pipe and then 2.5" from there. Narrow to 2 1/4 at the muffler and 2 1/4 rest of the way back.

b

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