P0421 code

[Wallythacker]

Ah, when talk digresses to Holly, Carter, Rochester Quadrajet, Autolite you can tell we's be from another era, maybe even dimension.

7, if your Holly is not properly dialed in you'll get a rich shot that is as bad as the lean stumble. A well downplayed fact is that none of the lower grade Holly fuel pumps are not well matched to their line of carbs. I ran Holly blue on my Boss 429 because the Holly rep I spoke with told me it would be fine. It wasn't until I ponied up to a Black at 2x the cost did my Boss come alive. Recently I was stunned to see a Holly 735cfm vacuum single pumper is $600 or more. The double pump 750 is what, $800 or more now. Man I remember buying Hooker or Hedmans for $100 or less on sale. Cragar SS steel chromies for $39/each.

[littlemoule]

you can tell we's be from another era, maybe even dimension.

Definitely another dimension because:

7, if your Holly is not properly dialed in

this almost sounded like a sexual reference. I think I will pretend my thread got hijacked lol and just stay quiet until dust settles down (or until the next time CEL shows up lol)

[7milesout]

It's spelled Holley, so maybe it sounds a bit more innocent!

I bought Edelbrock's latest greatest AVS2 (1905) with annular boosters (on sale (low $300's from my memory), because they were supposed to eliminate the lean stumble. They lied. I'm a sucker. Cannot tune this AVS2 as well as I had my mechanical secondary (1405) tuned. A buddy is trying to find a Holley he has in storage and is going to gimme it for free. I hope he finds it.

My idea of "tuned right" and others are different. My sons love driving the Scamp because they say the throttle pedal is so responsive. Every little move made by their foot is felt, it's like their foot is part of the carb. And they're correct. Today's computer controlled fuel injected engines just don't have the responsiveness that these carbs I've tuned do (although they have serious advantages). This tune could be better (according to the AFR gauge), so my tuning continues.

Wally - The rich pump shot might work great for this LA360. This sucker just loves gas. I don't think I could flood the engine. It would growl YUMMMMM and fire right off.

[Fummins]

I ran a holley blue pump on my 02' dodge truck like 7milesout has. Factory lift pump crapped out killing the injection pump, installed an overpriced bd diesel pump that lasted maybe a month before it rusted solid and took out injection pump#2. Took a blue holley pump from my bosses 67' Chevelle that he returned to stock and truck ran flawlessly, I never did put the warrantied bd diesel pump back on that truck iirc.

I've got an edelbrock on my toolbox that I pulled off a 66' merc hard top 390 a few weeks ago. It had an off idle bog, to the point that it was sketchy to pull out in front of or cross an intersection. Played with timing and the adjuster screws. Owner just bought a new carb and now it's 95% better. It's no rocket but it's a bit of a tank.

[7milesout]

I ran a holley blue pump on my 02' dodge truck like 7milesout has. Factory lift pump crapped out killing the injection pump, installed an overpriced bd diesel pump that lasted maybe a month before it rusted solid and took out injection pump#2. Took a blue holley pump from my bosses 67' Chevelle that he returned to stock and truck ran flawlessly, I never did put the warrantied bd diesel pump back on that truck iirc.

I've got an edelbrock on my toolbox that I pulled off a 66' merc hard top 390 a few weeks ago. It had an off idle bog, to the point that it was sketchy to pull out in front of or cross an intersection. Played with timing and the adjuster screws. Owner just bought a new carb and now it's 95% better. It's no rocket but it's a bit of a tank.

AFR gauge is unbelievably useful. It's like cheating. If the guy who gave me the Scamp would have ever had an AFR gauge, he would have been in hog-heaven. That off-idle bog is the friggin lean stumble. Annoying, annoying, annoying.

You can double pump the gas pedal when pulling away from a stop and that 2nd pump shot helps a lot. If the pump is not hooked up, that lean stumble would be a nightmare. I wish there were some magic way to increase the capacity and drag out that initial pump shot, yet once the car is rolling, to totally disconnect the pump and save gas. That sort of magic is programmed into ECUs (advantage EFI) by smart engineers.

[littlemoule]

I kept saying to myself "must..resist". But I can't help it anymore. So what's a holley?

[7milesout]

A brand of carburetor.

[littlemoule]

*Update: Alright so the CEL is back on again with the same P0421 code, and with logical deduction we reached in this thread - O2 Sensor has been ruled out so I am going to get a new Catalytic Converter and have that welded and report back on how it went.

[littlemoule]

Actually I need something, I am looking at Universal fit Magnaflow Cat Converter - what should be the inlet and outlet diameter size of the pipe for easiest fit?

[klroger]

What about going here & try to find a used one??? https://oara.com/parts-locator/ Maybe with the growing hobby of stealing Cats, can you even buy used ones anymore???