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Comments on these chambers' burn pattern?

General engine tech -- Drag Racing to Circle Track

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BradH
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Re: Comments on these chambers' burn pattern?

Post by BradH » Thu Apr 11, 2019 9:19 pm

Powertrip wrote:
Thu Apr 11, 2019 4:49 am
What is the quench clearance?
Same as it was in my 2nd post... :lol:
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Mummert
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Re: Comments on these chambers' burn pattern?

Post by Mummert » Thu Apr 11, 2019 9:39 pm

Doesn't look to bad for an engine with an E-I-I-E-E-I-I-E valve layout, and the chamber being bore crowded. Make sure you have defined angles on the intake valve job, (no radius). Make sure intake port has a burr finish (no sanding) Don't add extra exhaust duration to it. (Especially cause the exh valve diameter look like they are pretty high percentage of the intakes). Lobe centers a little wider than narrower if your running a good size cam.
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Re: Comments on these chambers' burn pattern?

Post by Powertrip » Thu Apr 11, 2019 11:40 pm

#-o

Edelbrock Victors with the chambers CNC'd by a small Mopar-oriented shop. CR is a hair under 11.5 with flat-top 4.380" pistons and .040" quench.

The carbon buildup seems a little heavy for a day at the dyno, but that could be from the witches' brew gas. But not bad at all.
The price of progress is trouble.

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Re: Comments on these chambers' burn pattern?

Post by ClassAct » Fri Apr 12, 2019 12:00 am

BradH wrote:
Thu Apr 11, 2019 8:52 pm
Plugs for 1/3/5/7 and 8/6/4/2
.
Plugs 1-3-5-7.jpg
.
Plugs 8-6-4-2.jpg


Can't see the fuel ring with the shells on but it's definitely rich at a cruise. Can't see the ground strap well enough to see the timing marks. Also, the plug looks a bit hot but I don't use autolite plugs very often.

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Re: Comments on these chambers' burn pattern?

Post by steve cowan » Fri Apr 12, 2019 5:47 am

ClassAct wrote:
Fri Apr 12, 2019 12:00 am
BradH wrote:
Thu Apr 11, 2019 8:52 pm
Plugs for 1/3/5/7 and 8/6/4/2
.
Plugs 1-3-5-7.jpg
.
Plugs 8-6-4-2.jpg


Can't see the fuel ring with the shells on but it's definitely rich at a cruise. Can't see the ground strap well enough to see the timing marks. Also, the plug looks a bit hot but I don't use autolite plugs very often.
in comparison to an NGK plug
they are 3 ranges colder than standard heat range
NGK-
standard heat range -5
1 x colder -6
2 x colder -7
3 x colder -8
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Re: Comments on these chambers' burn pattern?

Post by Tuner » Fri Apr 12, 2019 6:16 am

BradH wrote:
Thu Apr 11, 2019 8:52 pm
Plugs for 1/3/5/7 and 8/6/4/2
.
Plugs 1-3-5-7.jpg
Image
Plugs 8-6-4-2.jpg
Image
Plugs look too rich, too much advance, evidence of detonation - tiny black specks, weak spark, no spark mark on electrodes. It may be more timing made more power because ignition energy is weak. Chambers and pistons definitely show too much fuel, if not at WOT part-throttle is way rich. A WBO2 may show leaner than actual A/F because of weak spark.

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Re: Comments on these chambers' burn pattern?

Post by mag2555 » Fri Apr 12, 2019 6:43 am

I can't see the ground strap as I would like since its got too much run time on it to judge the temperature change over point , but it looks to be either too rich , not a hot enough heat range or a bit of both.

Also now that the heads are off now would be the time to knock them apart and unpolished the Intake runners if they are such and get some texture back on the port walls which will help out with the fuel wash that I see going on it the chambers.
This will help to allow you to lean things out and make greater power to boot!

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Re: Comments on these chambers' burn pattern?

Post by BradH » Fri Apr 12, 2019 7:34 am

Miscellaneous responses to comments & questions above...

The plugs weren't pulled straight from the last WOT pull, so I don't think they're going to show exactly what people are looking for.

Cylinder head intake runner texture is either 60 or 80 grit.

Intake manifold plenum & runner texture is still 95% as cast; the only work I did was minor plenum cleanup and the runner dividers.

Valve sizes are 2.20 / 1.81.
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Re: Comments on these chambers' burn pattern?

Post by arlancam509 » Fri Apr 12, 2019 8:55 am

Mummert wrote:
Thu Apr 11, 2019 9:39 pm
... and the chamber being bore crowded.
i am young and naive, so please forgive the ignorance of my question -

what does "bore crowded" mean? the bore on this engine is 4.34, which seems big to me.
"as" does not always equal "because". overuse of "as" is ambiguous and lazy.

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Re: Comments on these chambers' burn pattern?

Post by BradH » Fri Apr 12, 2019 11:27 am

More misc comments, etc.

Plugs are Autolite AR3911.

Valve seat config shown prior to assembling heads; definitely not a radius. IIRC, it's a 35 or 38 top, 45 seat, 60, 70, and the 70 has been blended into the port.

Cam is a single-pattern 266 at .050" x .650" solid roller w/ 108 LSA installed on 104 ICL.

For anyone who is interested, this is the engine that was the focus of my old thread https://www.speed-talk.com/forum/viewtopic.php?f=15&t=49826 that got moved to the Advanced Tech section.
.
PRH_Victor 72cc chamber.jpg
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Last edited by BradH on Fri Apr 12, 2019 11:33 am, edited 1 time in total.
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Re: Comments on these chambers' burn pattern?

Post by ClassAct » Fri Apr 12, 2019 11:30 am

steve cowan wrote:
Fri Apr 12, 2019 5:47 am
ClassAct wrote:
Fri Apr 12, 2019 12:00 am
BradH wrote:
Thu Apr 11, 2019 8:52 pm
Plugs for 1/3/5/7 and 8/6/4/2
.
Plugs 1-3-5-7.jpg
.
Plugs 8-6-4-2.jpg


Can't see the fuel ring with the shells on but it's definitely rich at a cruise. Can't see the ground strap well enough to see the timing marks. Also, the plug looks a bit hot but I don't use autolite plugs very often.
in comparison to an NGK plug
they are 3 ranges colder than standard heat range
NGK-
standard heat range -5
1 x colder -6
2 x colder -7
3 x colder -8

Different brands of plugs read differently. A Champion doesn't read like an NGK doesn't read like an autolite etc.

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Re: Comments on these chambers' burn pattern?

Post by rebelrouser » Fri Apr 12, 2019 11:36 am

BradH wrote:
Thu Apr 11, 2019 8:51 pm
Piston tops for 1 & 3 (same as chambers shown) and 8 & 6
.
Piston tops 1_3.jpg
.
Piston tops 8_6.jpg
I have a 514 mopar, with the edelbrock victor Jr. heads, and my piston tops look exactly like yours. dual quad with 750 afb's Plugs look about the same as well. I run autolites and a couple said they look too rich, but on my engine if you lean it, it does not like it at all. I have twin O2's and the engine runs best when I am seeing 12.2 to 12.5 on the widebands.

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Re: Comments on these chambers' burn pattern?

Post by BradH » Fri Apr 12, 2019 11:49 am

Tuner wrote:
Fri Apr 12, 2019 6:16 am
Plugs look too rich, too much advance, evidence of detonation - tiny black specks, weak spark, no spark mark on electrodes. It may be more timing made more power because ignition energy is weak. Chambers and pistons definitely show too much fuel, if not at WOT part-throttle is way rich. A WBO2 may show leaner than actual A/F because of weak spark.
At least one of the carbs tested at the start of the day got ONE partial pull, and then Dwayne aborted it 'cuz it went absurdly lean early in the pull. We also ended up going up 8#s on the 1.50" v downleg to get the AFR at least in the ballpark, so there were some lean pulls in the early part of the testing.

I can't speak to whether the ignition setup was "weak", but there wasn't (and hasn't been during previous dyno sessions there, either) any indications of issues w/ either my distributor, etc., or the dyno's ignition box.

Part-throttle on the two carbs we tested the most were definitely on the fat side, even when the WOT pulls were still lean. Those particular carbs' tunes have been changed a good bit since then, but haven't been back on a live engine to validate what's been revised.
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Re: Comments on these chambers' burn pattern?

Post by Mummert » Fri Apr 12, 2019 4:17 pm

arlancam509 wrote:
Fri Apr 12, 2019 8:55 am
Mummert wrote:
Thu Apr 11, 2019 9:39 pm
... and the chamber being bore crowded.
i am young and naive, so please forgive the ignorance of my question -

what does "bore crowded" mean? the bore on this engine is 4.34, which seems big to me.
Essentially 180 degrees of the chamber is sitting on the bore. Very common to many 50's designs. No squish on the plug side.
Looking at the "burn pattern" all the fuel is directly beside the intake valve. Virtually none around the cylinder side or directly out in front.
There is pretty good burn coverage, we play with old 50's motors as well and have seen some things that help them.
Aluminum heads with bigger modern ports flow better but the architecture (valve proximity to bore) is what it is.

I was curious to why the engine is apart.
Last edited by Mummert on Fri Apr 12, 2019 4:40 pm, edited 2 times in total.
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Re: Comments on these chambers' burn pattern?

Post by steve cowan » Fri Apr 12, 2019 4:31 pm

ClassAct wrote:
Fri Apr 12, 2019 11:30 am
steve cowan wrote:
Fri Apr 12, 2019 5:47 am
ClassAct wrote:
Fri Apr 12, 2019 12:00 am




Can't see the fuel ring with the shells on but it's definitely rich at a cruise. Can't see the ground strap well enough to see the timing marks. Also, the plug looks a bit hot but I don't use autolite plugs very often.
in comparison to an NGK plug
they are 3 ranges colder than standard heat range
NGK-
standard heat range -5
1 x colder -6
2 x colder -7
3 x colder -8

Different brands of plugs read differently. A Champion doesn't read like an NGK doesn't read like an autolite etc.
ClassAct,
i agree, cant compare brands etc between sparkplugs -apples to oranges
AR3911 racing plug cold range (4) by Autolite
cross reference NGK R5672A-8 spark plug
i was curious with the spark plugs as i only use NGK and dont know the #s of autolite
there has been a couple of references of black specks/salt and pepper on the porcelain due to detonation (possibly) or maybe carbon blowing off the piston or chamber during a pull and sticking to the sparkplug ??
i have zero dyno experience so i cant comment on the dyno side of things
i would think the brake specifics would be in the toilet if they were being measured
i would think the exhaust temps would be down being overly rich and go down even more if the engine runs into detonation if they were being checked on the dyno.
again i have'' 0 ''dyno time just putting it on the keyboard.
steve c

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