1970 Chevelle Malibu "400" Clone

[regal403]

Let's see a burnout video or a hard acceleration video. This thing is too cool for such limited clips.

 

[80' 427]

let me get the carb sorted out then I will work on that. Hate to melt a piston ****ing around

 

[80' 427]

For the purpose of tracking Stock specs
List 80804-1
PMJ-84 SMJ-84
PMAB-.033 SMAB- .033
PIFR-.036H SIFR-.036H
PIAB-.066 SIAB-.066
PPV# 4.5 SPV# 4.5
PPVRC-.069 SPVRC-.069
PE1 .029 SE1 .029
PE2 .029 SE2 .029
PE3 .029 SE3 .029
PE4 Plug SE4 Plug
PE5 .029 SE5 .029
Kill Bleeds-.012 P&S

Moved IFR to lower holes and removed upper IFR.

 

[folkenheath]

You still have a lot of patience for the carbs.

 

[80' 427]

I like to prove you don't NEED EFI

 

[folkenheath]

Of course you don't, you don't need a big block Chevelle either, but we all want one...

 

[80' 427]

Well no, you could also have a big block camaro, regal, monza, vega, C10, K10-30, Nova, Caprice Kingswood wagon, Supra,..... the list goes on.

 

[80' 427]

Current carb calibration
List 80804-1
PMJ-84 SMJ-92 With extensions
PMAB- .029 SMAB- .029
PIFR-.033L SIFR-.033L
PIAB-.066 SIAB-.066
PPV# 4.5 SPV# Plug
PPVRC-.069 SPVRC-.069
PE1 .029 SE1 .029
PE2 Plug SE2 Plug
PE3 Plug SE3 Plug
PE4 .029 SE4 .029
PE5 Plug SE5 Plug
Kill Bleeds-.012 P&S

Found a vac can in my pile that had 10* by 8in/hg and the idle is now at 30 deg at idle Vac+intial (626-10). Idles at 12-13in/hg at 1050 (900 with the ac running). Air screws out 1.5 turns. Idle seems much smoother. Need to double check the squaring of the throttle blades and the idle slot.

I ordered a vac can from napa that is supposed to be 16 deg at 8in/hg (might be closer to 9in/hg) I am going to try tomorrow.

Took the day off to tune it good enough to take to the cars and coffee in lincoln NE at Speedway Sat morning.

 

[folkenheath]

I was wondering why you were running a secondary power valve and square jetting. This tune makes more sense, simpler.

 

[80' 427]

I just left how it was stock to start.

 

[76zimmer]

John, excuse my ignorance, but can you explain these or correct me if I’m wrong where I have a ?

PIFR-.033L SIFR-.033L…Primary and Secondary..idle?..fuel ratio?
PIAB-.066 SIAB-.066…Primary and Secondary…idle?..air bleed?

PPVRC-.069 SPVRC-.069..Primary and Secondary..power valve?..RC?
PE1 .029 SE1 .029..??
PE2 Plug SE2 Plug..??
PE3 Plug SE3 Plug..??
PE4 .029 SE4 .029..??
PE5 Plug SE5 Plug..??
Kill Bleeds-.012 P&S..??

Thanks and thats some serious tuning!

 

[folkenheath]

Here is a diagram to help...

Anything P is primary, and S is secondary metering.(except for PV = Power Valve)

IFR is Idle Feed(Fuel) Restriction
IAB is Idle Air Bleed (in the main body)
PVCR is Power Valve Channel Restriction, (Not shown: It meters how much fuel can go through the power valve, too large will need a high flow power valve, its under the power valve when you remove it if I remember correctly.
PE1 - 5 is emulsion 1 - 5 on the metering block.

I don't know what he's calling the kill bleed. When you dig into this stuff get ready for your hands to smell like gas for days, because that's what happens to me when I did, and I never even messed with the "kill bleeds", sounds dangerous, ha ha.

 

[76zimmer]

Cool, thanks Heath…so how do you know what to change and how much….I’d probably do more harm than good, messing with all of those.

 

[folkenheath]

I think there are entire books written on that subject Dave.

In general, air bleeds change the "curve" of the fuel, more air boosts the signal down low but flattens it out up high as more air is mixed in. It changes the slope of the curve, not just a flow amount.

Fuel restrictions change the amount of fuel like a jet, but for idle, or for when the power valve opens, how much extra fuel does it add, etc.

I've read pages and pages of that stuff and tried a lot of it, but I have forgotten some of it, as I got so tired of dumping fuel out of the bowls so many times and smelling like gas I kind of got over it, I rebuilt another Holley a couple years ago for the boat. Still have a lot of Holley parts, rarely use them much anymore.

 

[76zimmer]

Seems like a dyno would be the best place to test all of the posibilties?

 

[82355]

Some of it, but not all of it. A lot of what he is tuning for is part throttle drivability. Actual test drives for that.

Martin

 

[80' 427]

The kill bleed is in the dog leg above the emulsion bleeds, it works as a syphon brake.

Tried the Napa Vac Canister and was unhappy, moved back to the 626-10 can I found in my pile. It now idles at 11-12inhg at 950-1000rpm. Seems happy. Screws 1.5 turns out.

I drove it to cars and coffee in Lincoln Saturday.

Cruises at 13.2-12.8a/f with 80 jets. Need to go to 78s and likely on to 76s but we will see.

A little fat on the idle circuit of 12.5-13.0. Not sure if it will be happy at that low of a speed with a smaller ifr, for now I am leaving it.


Finally hooked up the Vac Gauge in the dash and the 4.5 powervalve is way too late.
It cruises at 17+in/hg at 70 mph at 2875 RPM, so a 8.5 is a much better valve (maybe 10.5) it starts to get lean (16+) at higher throttle opening down in the lower vac (8-6in/hg)

Drilled the PVRC to a .077, but it appears it wasn't close to opening.

 

[80' 427]

Here is a chart to help visualize changes

 

[82355]

How was cars and coffee? Pics?

Martin

 

[80' 427]

OK, it rained so 150 cars? Supposedly they had over 500 the month before. No pics, you know I don't know how. Museum is cool. Coffee was good, Doughnuts looked good but I am trying to be less fat.

Trying to get one started in Fairbury.