Lean Holley 1,000 HP Carb

[Shovelrick]

3+ yrs ago I bought a this carb from a local TC member after he went EFI on his 700hp 540 in his 71 Chevelle, I used it WO any changes on my 489 when we dynoed the engine and after installing the engine I adjusted the carb with a vacuum gauge and a few months ago put an AFR gauge in the car and it shows it’s way too lean, where to start? checking floats then adjust the 4 corner mixture screws or just rely on what the plugs look like?

 

[cheveslakr]

Map the afr across the rpm range under load. Record it with your phone with the tach visible. I'd start with idle mixture, but it's most likely going to take jet changes. 2 incriments up at a time.

 

[77cruiser]

How does it run?

 

[Shovelrick]

How does it run?

Runs great but did overheat a few months ago, well didn’t actually OH just got up around 200-210 but too hot for my liking, last time I drove it at 20 mph 1,500 rpm it was in the 15.1-15.4 AFR range IIRC I was in 2nd gear when I took pics, warm idles in the 13’s and revving it goes to 17-18 then gauge goes blank till I let off gas

 

[Nashville Cat]

Adjust it as close for starters without touching jets or PV : idle mixture screws , floats and idle speed.
Then I would take it cruising (2000-2500 rpm) and make sure the power valve is 2" below the cruise vacuum.
If you cruise at 13" on level ground, use a 10.5" PV.
Adjust the front jets to get the cruise AF ratio 14.7 to 15.3. The power valve should not be adding any fuel.

Then check WOT : you want 12.8 to 13.2 ; somewhere in that range. Change the rear jets to achieve that.

With the HP 1000 double-pumper, you also have front and rear squirters that add fuel, so you may have to downsize those to hit your target.
This carb was on a bigger motor so the size of the squirters could make it run rich.

 

[Nashville Cat]

The cruise and wide-open throttle measurements require changes in jets, pv and squirters whereas the idle doesn't.
So once you get the cruise and WOT good , finalize the idle screws and speed. If it idles too fast, close the secondaries a little with the screw from the bottom.
Idle O2 readings are worthless. Just use a vacuum gauge and set to highest vacuum reading.

 

[Shovelrick]

I had a chance to drive today, I think It’s ok with 11’s cruise AFR, bounces around with rpm’s but I think that’s expected with more than stock cam

 

[Nashville Cat]

At cruise on level ground, the PV should be closed and the AFR should be 15. You had 14.1 ? Tha's slightly rich.
You would want to lean that a small amount, maybe go down 3 jet sizes on the primaries.
The pics look like you had 11.1 at wide-open. That's "pig-rich !"
Leaning that down to 12.5 should pick up some hp.
So if you go down in jet size 3 sizes front & back, that might do it.

 

[68Chevele]

Is this a A/D Holley 1000hp? if so, my buddy had to make a ton of changes to get my old one right, as it was lean as all hell on the dyno but even so it made over 800hp with it.

 

[Shovelrick]

It’s a Holley 1000HP that came off a 540 with 700+ hp, I haven’t done anything but adjust to a vac gauge, the engine builder and dyno owner said to bring it to him when I get it in the car but that was 3 yrs ago so I’m thinking of taking it to a carb builder I’ve bought a very nice 3310 from, he also has a carb flow bench, really needing to get the front end aligned it’s bad but all new parts, forgot to mention never had it above 3,000 rpm or not much while taking the pics front end is to out of alignment to safely take pics WOT

 

[Nashville Cat]

It’s a Holley 1000HP that came off a 540 with 700+ hp, I haven’t done anything but adjust to a vac gauge, the engine builder and dyno owner said to bring it to him when I get it in the car but that was 3 yrs ago so I’m thinking of taking it to a carb builder I’ve bought a very nice 3310 from, he also has a carb flow bench, really needing to get the front end aligned it’s bad but all new parts, forgot to mention never had it above 3,000 rpm or not much while taking the pics front end is to out of alignment to safely take pics WOT

Get it aligned and see what the AFR meter says. I think you're getting close by changing jets.

 

[Shovelrick]

When it was dynoed it had a 1” open spacer under the carb but we didn’t have 02 sensors hooked up so guess it don’t matter

 

[Nashville Cat]

When it was dynoed it had a 1” open spacer under the carb but we didn’t have 02 sensors hooked up so guess it don’t matter

I had room for a 1/2" open spacer on my 66. You should have enough room for that ?

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[Shovelrick]

I had room for a 1/2" open spacer on my 66. You should have enough room for that ?

[URLunfurl="true"]https://www.summitracing.com/parts/trd-2180?rrec=true[/URL] With an Eddy Air Gap intake?

 

[Shovelrick]

A cloudless days ago I put the Corvette type drop base back on it but needed the base spacer that came with it to clear throttle linkage, I crumpled some tin foil and seemed like more room but I was in a bit of a hurry so hoping to be able to put the 1” spacer back on or at least a 1/2”, I’ll check it this week

 

[Nashville Cat]

I had room for a 1/2" open spacer on my 66. You should have enough room for that ?
[URLunfurl="true"]https://www.summitracing.com/parts/trd-2180?rrec=true[/URL]
With an Eddy Air Gap intake?
---------
Sure, the air gap is the same intake as the Performer RPM. Same height and same runners, just no "gap" under the runners.
My cast iron 427/390 hp qj intake is also the same height as both eddy intakes.
I bet you have 3/4" clearance above your air cleaner lid.

 

[Shovelrick]

I had room for a 1/2" open spacer on my 66. You should have enough room for that ?
[URLunfurl="true"]https://www.summitracing.com/parts/trd-2180?rrec=true[/URL]
With an Eddy Air Gap intake?
---------
Sure, the air gap is the same intake as the Performer RPM. Same height and same runners, just no "gap" under the runners.
My cast iron 427/390 hp qj intake is also the same height as both eddy intakes.
I bet you have 3/4" clearance above your air cleaner lid.

Going to use alum foil today then post what I find, I think the Energy Suspension motor mounts are supposed to be same height as factory rubber so the engine would be a normal height

 

[Shovelrick]

Finally got over there and remembered to check for air filter to hood clearance, thought it would be closest at the front of the AF lid since the engine angles upward but actually it’s closest right behind the wing nut with about 1/2” clearance and I think with a 1/2” spacer and a little engine movement it would touch the hood, right now I have a Vette type drop base with a small roughly 3/8” spacer that came with the DB to keep from hitting moving carb parts, I’ll try the Cheapo chrome DB and see if it makes any difference but IIRC I did this 3 yrs ago when I dropped the 489 in