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View Full Version : Of all people to join the club, I joined the club



opethmike
09-19-2017, 06:48 PM
53541

Rich_NYS
09-19-2017, 07:49 PM
Is that a new manifold that fits the PRV, or is it for a different engine?

opethmike
09-19-2017, 07:51 PM
It's for an LS.

Michael
09-19-2017, 08:27 PM
53542

opethmike
09-19-2017, 08:30 PM
53542

LOL amazing

OverlandMan
09-19-2017, 10:53 PM
I also recently joined the club of carbureted outcasts. I feel like I'm back in high school smoking cigarettes and drinking screwdrivers in the parking lot before class. :)

opethmike
09-19-2017, 11:04 PM
Lol.

I'm going real strange - modern LS4 engine, but with a carb.

Spittybug
09-19-2017, 11:07 PM
​Why???

opethmike
09-19-2017, 11:11 PM
​Why???

Several reasons:

1. I've always wanted to learn carbs
2. The EFI intake manifold for the LS4 motor presents a number of packaging issues in the DeLorean's engine bay
3. Cost. Very much a consideration in a project that is going to run close to $10,000
4. Ease. After the enormous complexity of putting an LS V8 into a DeLorean, I will want simplicity

OverlandMan
09-19-2017, 11:16 PM
​Why???

https://media.giphy.com/media/4JcUtBL3jXiuY/giphy.gif

Sorry - had to try out my "meme" skillz

DMC-81
09-20-2017, 07:08 AM
Very cool Mike! What kind of carb is that?

I remember doing the same thing (learning carbs) on my V8 Fiero project a number of years ago. I rebuilt a 750 cfm Rochester Quadrajet for it. My brother called it a Quadrabog lol. The 305 sbc came out of a stock car and the carb came with it. Rebuilding it was like having a clock apart. But it worked beautifully after rebuilding and tuning. I eventually realized that for the street application, it was too big for the engine cfm wise, and replaced it with a 650 Holley "double pumper". Good memories!

As for the reasons why a carb on an LS4? I'll can add that hearing the sound of the secondaries opening up behind you on a V8 is totally an experience not to be missed. I'd like to hear that when you get it all together.

P.S. The memes made me laugh as well.

opethmike
09-20-2017, 09:44 AM
Very cool Mike! What kind of carb is that?

I remember doing the same thing (learning carbs) on my V8 Fiero project a number of years ago. I rebuilt a 750 cfm Rochester Quadrajet for it. My brother called it a Quadrabog lol. The 305 sbc came out of a stock car and the carb came with it. Rebuilding it was like having a clock apart. But it worked beautifully after rebuilding and tuning. I eventually realized that for the street application, it was too big for the engine cfm wise, and replaced it with a 650 Holley "double pumper". Good memories!

As for the reasons why a carb on an LS4? I'll can add that hearing the sound of the secondaries opening up behind you on a V8 is totally an experience not to be missed. I'd like to hear that when you get it all together.

P.S. The memes made me laugh as well.

It's an Edelbrock; 600cfm. I have a few reasons for going with the carb instead of the EFI setup that comes with the engine:

1. I've done an EFI setup before (on my PRV), so it's not a new learning experience, and I've never used a carb before
2. The swap is going to take long enough as it is, so I know that by the time I get ready to start the car I'll just want the simplicity of the carb
3. The GM LS EFI manifold presents several packaging issues when put into the DeLorean engine bay. The carb manifold gets around all of those.

I'm very much looking forward to the experience of learning all about carb fuel delivery.

Timebender
09-20-2017, 07:26 PM
Aaaannnddd, once you get tired of the smell of fuel from your carb, and the way the exhaust smells, no matter how well dialed in it is, you'll throw on a nice EFI throttle body for another $1000 and never worry about those things, flooding, choking the engine, etc. etc. etcetera...

I know this only because my 350 from an 85 Corvette is carbed, and on its third one no less...

Josh
09-20-2017, 10:49 PM
Aaaannnddd, once you get tired of the smell of fuel from your carb, and the way the exhaust smells, no matter how well dialed in it is, you'll throw on a nice EFI throttle body for another $1000 and never worry about those things, flooding, choking the engine, etc. etc. etcetera...

I know this only because my 350 from an 85 Corvette is carbed, and on its third one no less...

Sounds like a poorly tuned carb.

If you can't figure your way around a carb, you will find efi much more challenging.

Michael
09-20-2017, 10:54 PM
Aaaannnddd, once you get tired of the smell of fuel from your carb, and the way the exhaust smells, no matter how well dialed in it is, you'll throw on a nice EFI throttle body for another $1000 and never worry about those things, flooding, choking the engine, etc. etc. etcetera...

I know this only because my 350 from an 85 Corvette is carbed, and on its third one no less...

I had a Honda Accord with 170xxx miles on her before i sold it. After driving it daily for 4 years, I never smelled fuel, and the engine was in front of me! Maybe the problem was with your carb and not a blanket issue with every carbed car out there.

Timebender
09-21-2017, 03:07 PM
I had a Honda Accord with 170xxx miles on her before i sold it. After driving it daily for 4 years, I never smelled fuel, and the engine was in front of me! Maybe the problem was with your carb and not a blanket issue with every carbed car out there.

Possibly, but this is a fairly new one- put on straight out of the box (Edelbrock 4600), and adjusted a little not to run so rich.

Same with the rebuilt one I had that was tuned for a 350.

Any ideas beyond that?

DMC-81
09-21-2017, 08:29 PM
Possibly, but this is a fairly new one- put on straight out of the box (Edelbrock 4600), and adjusted a little not to run so rich.

Same with the rebuilt one I had that was tuned for a 350.

Any ideas beyond that?

Well, for rebuilding its more involved as you need to adjust more internal things like the float level, but straight out of the box, should just need to tune things like the air/fuel mixture and the idle air speed.

It is not that difficult, but it is like tuning a guitar. I'm not familiar with the 4600 ( is that the actual model number?) but I found these videos good enough to get you started:

Tuning:
https://youtu.be/wR_AfQjyT-A

Troubleshooting:

http://youtu.be/OeD1UCnDHF8

Perhaps you can post a new thread with your results/questions?

Timebender
09-22-2017, 03:13 PM
Well, for rebuilding its more involved as you need to adjust more internal things like the float level, but straight out of the box, should just need to tune things like the air/fuel mixture and the idle air speed.

It is not that difficult, but it is like tuning a guitar. I'm not familiar with the 4600 ( is that the actual model number?) but I found these videos good enough to get you started:

Tuning:
https://youtu.be/wR_AfQjyT-A

Troubleshooting:

http://youtu.be/OeD1UCnDHF8

Perhaps you can post a new thread with your results/questions?

Sorry - itís a 1406- long day yesterday and typed in the first number that popped in my head. And I have adjusted both mixture screws, but get a pretty heavy exhaust smell, and like mentioned, fuel smell from it as well- but then all my previous carbs (even on my VW bus) smelled about the same.

opethmike
09-22-2017, 06:03 PM
Are you using any sort of tool to get feedback, like a manometer or a wideband oxygen sensor?

If your exhaust smells of gas, you're running rich. Simple as that.

DMC-81
09-22-2017, 08:09 PM
^ I agree with Mike (question and comment)

OK, let's try to narrow the problem down a little.

A few other questions:

1) You said that the carb is a 1406 => to confirm...600 cfm, electric choke correct?
2) What is your fuel delivery setup... I'm assuming a stock Delorean pump with a regulator?
3) If so, do you have a gauge on the regulator? Basically, what is your fuel pressure?
4) The engine is from a 1985 Corvette => is it stock? Any modified cams?
5) Can you post pictures of both sides of the carb installed including vacuum hoses attached to it?
6) Did you experience the same symptoms with the last 2 carbs? Also, what prompted the 2 changes?
7) Adding to Mike's question, what procedure did you use to set the metering screws?
8 ) I assume you didn't change the metering rods or step up springs yet, correct?

Thanks.

opethmike
09-22-2017, 09:09 PM
I can confirm the 1406 has an electric choke and is 600 cfm; that's what I purchased for my LS4 swap. The carb is configured for the LS family out of the box, so my initial gut instinct is that it is too much carb for that 350 you have, as that is a much more mild engine.

I would definitely recommend getting some tools for tuning your carb. At an absolute minimum, a vacuum gauge. A bit nicer would be a manometer, and really nice would be a wideband O2.

DMC-81
09-23-2017, 09:25 AM
^Yeah, that's what I was suspecting.

Timebender, I calculate the optimal carb size as 516 cfm based on these assumed specs:

Engine size = 350
Max RPM = 6,000
Volumetric Efficiency = 0.85

That's close to 600 cfm, but assuming everything else checks out, perhaps it needs tuning on the metering jets as the out of the box tuning is for a slightly different setup. If the jets are too big, adjusting the metering screws won't be effective to solve a rich condition.

Given a carb in the right ballpark CFM wise, I think of jets as a large adjustment and metering screws as a fine adjustment.

For tuning kits, see if for Edelbrock 1487 is the right one for your carb.