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Stock Eliminator secrets?

General engine tech -- Drag Racing to Circle Track

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dannobee
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Re: Stock Eliminator secrets?

Post by dannobee »

Q-Jet rich at WOT is usually a metering rod problem. First make sure that the fuel pressure isn't creeping up or the float level isn't doing something goofy. There's a plastic stick tool to check float level with the engine running.

I used to have a chart with all of the metering rods listed from lean to rich. There are two letters stamped into all of the factory metering rods for identification. I'm sure it's still available somewhere. The metering rods with the skinny tips run the richest when the air valve is open. It looks like GM didn't want their engines to ever run lean at WOT, so they dump fuel in like crazy when the air valve is wide open.

The hanger height is critical. Spacing the hanger higher makes it richer. Bending the tangs to lower the metering rods makes it leaner. Carefully measure the hanger height (I used to use two aluminum plates and hang the hanger over the edge of one and measure the gap to the other plate). It might only need a 0.020" adjustment, but you need to know where you started first.

The tape trick helps too, but it's likely a hanger height adjustment that'll make the difference.

And for those not familiar with a Q-Jet, the two outboard "tubes" act more like a secondary accelerator pump than an "emulsion tube." The tubes feed fuel through holes just under the secondary air valve to add fuel just as the air valve cracks open.
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Re: Stock Eliminator secrets?

Post by chevyfreak »

Details i have on the qjet sec rods and hanger.

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Re: Stock Eliminator secrets?

Post by BOOT »

I've always found this type racing interesting not that I've done it or any class racing myself, I'm more of a budget street guy. Grew up watching people blow up expensive engines all the time and decided to build mild more reliable engines and try to make gains on the rest. Very interesting stuff, not always budget friendly but still useful in understanding things.

Odds n ends are a lot of work and why my car runs faster than it should, beat guys with more power and better parts plenty of times.

Owens used a bowtie block, I asked him bout the holes years ago.
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Re: Stock Eliminator secrets?

Post by BOOT »

tenxal wrote: Fri Sep 25, 2020 11:54 am With a Physics background, I can likely extrapolate without need to sharpen a pencil nor dust off an abacus. :wink:

Back to our regularly scheduled program. Here's a NHRA accepted (stock depth) oil pan for a Stocker. Looking beyond the obvious, what's there that makes it work so well?

Apologies to those that don't like oil pan talk. :lol:

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I like that rear anti climb baffle, only noticed some aftermarket pans with those a few yrs ago. But those use a straight piece, I'll have to make mine sim to that one for the stock pick-up stock pan I'm gonna mod. People always call those side baffles a pan scrapper but I've always thought of em as a side anti-climb baffles as well, more so for a kick-out-less pan.
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Re: Stock Eliminator secrets?

Post by tenxal »

BOOT wrote: Sun Oct 04, 2020 2:39 amI like that rear anti climb baffle, only noticed some aftermarket pans with those a few yrs ago. But those use a straight piece, I'll have to make mine sim to that one for the stock pick-up stock pan I'm gonna mod.
This approach works well and offers some additional benefits.

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Re: Stock Eliminator secrets?

Post by tenxal »

novadude wrote: Fri Oct 02, 2020 10:44 amLooking very close at the pic of the secondary air bleed tubes... depth would matter, as does position of Holley Emulsion bleeds. Do class rules allow you to modify those tubes? I've got some thoughts....
The secondary air bleeds orifice/depth/height and the secondary pull over enrichment system are two areas that need addressing on a QJet. On the primary side, it may be beneficial to eliminate the metering rods....it depends on the specific car.
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Re: Stock Eliminator secrets?

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tenxal wrote: Mon Oct 05, 2020 12:35 pm
BOOT wrote: Sun Oct 04, 2020 2:39 amI like that rear anti climb baffle, only noticed some aftermarket pans with those a few yrs ago. But those use a straight piece, I'll have to make mine sim to that one for the stock pick-up stock pan I'm gonna mod.
This approach works well and offers some additional benefits.

Image
Got that same pic! Also one of the tings I'd like to try n make.
Channel about my projects https://www.youtube.com/user/BOOT350V

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Re: Stock Eliminator secrets?

Post by tenxal »

Back to work. A good title for this pic would be: Three hundredths for three bucks. :wink:

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Re: Stock Eliminator secrets?

Post by 1972ho »

Hmm does this engine use pushrods and studs for the rockers.
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Re: Stock Eliminator secrets?

Post by novadude »

tenxal wrote: Mon Oct 05, 2020 12:46 pm
novadude wrote: Fri Oct 02, 2020 10:44 amLooking very close at the pic of the secondary air bleed tubes... depth would matter, as does position of Holley Emulsion bleeds. Do class rules allow you to modify those tubes? I've got some thoughts....
The secondary air bleeds orifice/depth/height and the secondary pull over enrichment system are two areas that need addressing on a QJet. On the primary side, it may be beneficial to eliminate the metering rods....it depends on the specific car.
Do class rules allow you to modify those tubes at all (additional holes, etc). Talking about the bleed tubes AND the POE tubes.
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Re: Stock Eliminator secrets?

Post by tenxal »

1972ho wrote: Tue Oct 06, 2020 10:47 amHmm does this engine use pushrods and studs for the rockers.
Per NHRA rules, the valve train style must remain as original...no shafts if originally studs.
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Re: Stock Eliminator secrets?

Post by tenxal »

novadude wrote: Tue Oct 06, 2020 11:31 am Do class rules allow you to modify those tubes at all (additional holes, etc). Talking about the bleed tubes AND the POE tubes.
Yes. We do a lot of work in that area.
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Re: Stock Eliminator secrets?

Post by novadude »

tenxal wrote: Wed Oct 07, 2020 7:56 am
novadude wrote: Tue Oct 06, 2020 11:31 am Do class rules allow you to modify those tubes at all (additional holes, etc). Talking about the bleed tubes AND the POE tubes.
Yes. We do a lot of work in that area.
I'd ask you to share, but I'm sure you don't want to give away your secrets. LOL I love playing with these carbs for my street car... always looking to find ways to improve the already-great Q-jet.
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Re: Stock Eliminator secrets?

Post by tenxal »

novadude wrote: Wed Oct 07, 2020 4:23 pm I love playing with these carbs for my street car... always looking to find ways to improve the already-great Q-jet.
To get things really right requires going beyond jets/hangers/metering rods. As you know, these QJets are pretty sophisticated...basically multiple, very controlled, air leaks.

It's also important to note that due to it's triple venturi design (the notable exception being a few of the Pontiac SD/HO carbs that have a double primary booster), fully 40% of fuel flow through a QJet at W.O.T. comes from the primary side.
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Re: Stock Eliminator secrets?

Post by tenxal »

A big part of my program has been the Elston 4-2-1 headers. We were testing headers and had four sets on the engine during one dyno session. What we saw with the Elston's led me to further conversation with Calvin and further gains both on the dyno and at the track. Where we ended up is about 180 degrees from how most approach things with a 305 or 350 Stocker engine, but it's worked well.

You have to have a good short block with minimal rotating drag, good heads and intake. Given that, I can't imagine doing another Stocker without starting with a set of Calvin's 4-2-1's and working backwards....starting at the collector and ending up at the cam.

On the dyno, we test the headers as they are run on the car. :wink:

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