My build has been posted previously, for those who are aware of what I've got: We're up and running, spending time trying all sorts of setups to get around the dreaded pinging when on the throttle. Started at 10 btdc with a total of 32 or so, vacuum adds about 15. Pings when nearing 3000 rpm and up on the throttle, even with vacuum adv. disconnected. Tried lower initial settings. Now down to 0 initial, with about 22 total and the 15 vacuum. With premium it's near acceptable, but still under heavy throttle I'm getting some pinging, again, even without the vacuum advance in. Under light throttle all is fine, only under moderate/heavy throttle it pings. I can't give her the berries as it is. Checked cranking pressure and I've got about 170 PSI (checked hot, throttle open, all plugs out)

Also tried colder UR5's no change, will try UR6's but doubt that will make a difference. Main jets are 120-300, showing clear with trace of white. Reamed the mains to slightly larger diameter, no change on pinging, but plugs have a nice tan to them now after some proper plug checks. Engine runs great, pulls great, no surging, stumbling etc. just pings when getting into the throttle and especially nearing 3000rpm and up.

I believe I've got to much compression with this cam (RV15/295RDP and it's suspect specs) I've got.

Question: Where can I get thicker copper gaskets? Or hows about a steel shim with two composites?? Aready running a composite of about .038 or so. so I'm thinking of popping in a thicker gasket and maybe doing more chamber work to increase the cc's

Any thoughts?

How many cc's are heads" and how far in the bore are the pistons?
Is this engine broken in and too tight and running too hot?
What temp is the thermostat?
What did you dial the cam to? 99 degrees?

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Remind us what is the static comp, installed cam centerline, and have you checked the damper for slippage?

170 psi is not that high, but is nearing the edge for pump premium. I would probably not run over 26-28 deg total mech adv with that cranking psi.

How do you know you are not too lean at/near WOT?? Best money and time you can likely spend now is on a wideband O2 gauge ($200 for AEM or Innovate + weld in a bung). Even a narrow band is worlds better than nothing.

From the Slant 6 banquet in Pigeon Forge, TN!

Lou

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Home of Slant6-powered fun machines since 1988

Remind us about your build.

Last I knew, you had a BBD in there.

I've run as high as 11:1 with that cam in my long rod stroker. All in I carry 24.5° with no vacc can. Currently at 10.7:1

I run it straight up per the card with a loose lash.

CJ

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Part of Tyrde-Browne Racing

It's supposed to be 9.25 based on the engine shop setting it per my request...cc'ing the chambers (57cc), using a composite gasket (.040 I think they said, I got .038 when I measured it), being bored .060 over etc etc. The deck height is now about .097 as far as I could measure with a dial caliper. With my measuring and using the various compression calculators I've come up with about 9:1
I'm sure the shop was a little more accurate vs what I have
Cam is installed at 108 (2 degrees retarded) 180 thermostat, runs at 172 down the highway, and around town so no problem with excessive heat.....yet. (gonna get hot round these parts soon so that'll be interesting) Damper is spot on, all checked when I set assembled everything. Have'nt gotten to WOT yet, can't/won't with the pinging. Stock BBD, stock (ported a little) exhaust manifold w/ 2 1/4" pipe, pocket ported head with Engnbldr oversize valves, Chry ECU w/.035 gap.....hmmm, what else......thats about it.
I'm thinking as a trial and error test: I keep it at TDC initial and maybe limited total to a range of 15-20 just to see what it does and fiddle with the vacuum, but just to see where it'll run at as of now.

I vote for lean mixture. Also, that is a fair bit of compression for a basically stock cam, but shouldn't be too much.

Lou

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Home of Slant6-powered fun machines since 1988

Well I do have to sort out the carb as a given, I would'nt expect to do what I've done and not be leaner on carb settings, even though there are countless posts by some who say that messing with jets and such should'nt be a concern. Even though my rebuilt BBD by Autoline does have throttle shaft bushings and looked beautiful when I got it (almost looked factory new) I've discovered that the mains are different 299/300 and the metering rods have uneven wear (though that would make things richer a little and/or unbalanced) and those hollow bolts for the discharge cluster are different sizes. Hmm....maybe anothe crappy rebuilt of a new
holley 350

Lean condition will definitely cause pinging at higher loads. You will fall in love with an O2 sensor.

Lou

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Home of Slant6-powered fun machines since 1988

Don't think I'll be springing for an o2 sensor at this point, I'll just be sticking with the old school methods of trial and error seat of the pants for now. They've always worked, and I got too much time on my hands anyhow!
Maybe someday I'll get with the times....

I got a feeling I'll be sticking in a thicker copper gasket soon though, even with jetting. But at least by then it'll be really dialed in

OK, next would be to get a spare set of BBD main jets and drill them oversize, or look for some oversize jets, or sand down the metering rods a little (when you have some spares).

Lou

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Home of Slant6-powered fun machines since 1988