73-87chevytrucks.com

73-87 Chevy _ GMC Trucks => Performance => Topic started by: philo_beddoe on March 12, 2016, 11:30:35 am

Title: A little popping From carb.
Post by: philo_beddoe on March 12, 2016, 11:30:35 am
I dont want to bother vile, as he's going through a lot right now, but why am i getting a little popping from the carb when i floor it? Thanks
Title: Re: A little popping From carb.
Post by: gunrac on March 12, 2016, 12:25:07 pm
Sounds a little lean. Maybe timing slipped a bit. I'd check vac. lines 1st. I'm sure vile would be very interested in knowing this.....
Title: Re: A little popping From carb.
Post by: roundhouse on March 12, 2016, 08:36:44 pm
Describe the popping in more detail

Just a couple times and then it accelerates fine ?

Or does it happen when you wind it up to higher RPM?
And keep popping as long as you keep your foot down ?


Sent from my iPhone using Tapatalk
Title: Re: A little popping From carb.
Post by: philo_beddoe on March 12, 2016, 09:33:32 pm
Describe the popping in more detail

Just a couple times and then it accelerates fine ?

Or does it happen when you wind it up to higher RPM?
And keep popping as long as you keep your foot down ?


Sent from my iPhone using Tapatalk
Just a couple times, or even once and then accelerates fine.
Title: Re: A little popping From carb.
Post by: LTZ C20 on March 12, 2016, 11:34:07 pm
My best advice to you would be to wait until Vile can take a look. He just spent a lot of time on the truck, any issues you have he will want to address himself directly. It's best not to fiddle around and mess with or change things, you could inadvertently cause other problems. Let him figure it out.
Title: Re: A little popping From carb.
Post by: philo_beddoe on March 13, 2016, 04:25:39 pm

My best advice to you would be to wait until Vile can take a look. He just spent a lot of time on the truck, any issues you have he will want to address himself directly. It's best not to fiddle around and mess with or change things, you could inadvertently cause other problems. Let him figure it out.

Exactly, i'm sure he'll catch this post and get back to me.
Title: Re: A little popping From carb.
Post by: VileZambonie on March 13, 2016, 07:58:45 pm
Did you knock a vacuum cap off when you painted your alternator? Sounds like a lean miss. Touch base with me this week
Title: Re: A little popping From carb.
Post by: philo_beddoe on March 13, 2016, 09:07:54 pm
As a matter of fact both bottom ports were missing those little blue caps you had on there. I found one on top of the manifold and had to make one. They are both capped now. But it did pop after i capped those ports off. I thought for sure that would have been it. I'll get in touch with you.
Title: Re: A little popping From carb.
Post by: blazer74 on March 13, 2016, 11:16:54 pm
  They were blown off when u experienced the popping more than likely. Intake backfire.
Take in mind the carb was originally on a 305 correct.
350's tad bit more demanding.
Title: A little popping From carb.
Post by: philo_beddoe on March 14, 2016, 10:09:31 pm
Vile, if you catch this....(i know i said i'd email you) the tech at national carb said to adjust the throttle linkage, to slightly bend the rod, so the secondaries open a little sooner. Something like that, does that sound right?
Title: Re: A little popping From carb.
Post by: VileZambonie on March 15, 2016, 07:14:34 pm
No it doesn't. What I wanted you to find out was it's calibration. Is it calibrated specifically for the 305? If you had a 350 would they sell you a different carb? If so how do they set that one up?  They should be able to answer that for you fairly quickly and easily. With a remanufactured carburetor that you bought specifically for a 305, I need to know it's baseline settings. You have a crate 350 essentially stock configuration so this should be a no brainer response from them. Who did you buy it from?
Title: Re: A little popping From carb.
Post by: philo_beddoe on March 15, 2016, 08:42:09 pm
National carburetor. I can call them tomorrow and ask them that exactly as you stated.
Title: A little popping From carb.
Post by: philo_beddoe on March 16, 2016, 07:08:23 am
Ok, it was not configured for my 305. It is for a 305 - 350, non computer engine. The M4ME was my only choice for the 305. I guess now with the 350, it looks like the M4MC.  Or....4MV. I have read a lot of articles where the 4MV is a pre emissions carb, 60's, early 70's. However it is a manifold choke, what does that mean?? How is that set-up?
(http://uploads.tapatalk-cdn.com/20160316/91a37457db8edd97e70a89db13061da9.jpg)

(http://uploads.tapatalk-cdn.com/20160316/330c30fa68b5c968ca7bc2e01e51d8a7.jpg)

Now what?? Can i keep my current carb and be fine? The engine feels like it has a lot more power than the carb is allowing, a little boggy. But i'm not complaining, smooth as glass.
Title: Re: A little popping From carb.
Post by: VileZambonie on March 16, 2016, 02:59:01 pm
You have an electric choke which is what you want. Find out their settings and jet/metering between the two applications. It's anyone's guess how they calibrated the carburetor you purchased. In the interim a little tweaking may be in order. That base gasket they sent you generally does require re-torquing so pop your air cleaner off and snug the carburetor bolts in an X pattern. Don't overtighten them, just re-snug them. Q-jets require a lot of tinkering to get dialed in but when I drove your truck it wasn't bogging or popping so something changed. Need to ensure secondary air valves aren't too loose and accelerator pump is working good correctly, need to recheck and adjust timing
Title: A little popping From carb.
Post by: philo_beddoe on March 16, 2016, 05:10:07 pm
In other words, you want me to swing by on saturday with some Dunkin goodies and we'll have a look at it?

(http://uploads.tapatalk-cdn.com/20160316/6a8877a0405be523b780002ea76f4d2c.jpg)

(http://uploads.tapatalk-cdn.com/20160316/980c38cfa29c4747b255b8f1b4678386.jpg)
Title: Re: A little popping From carb.
Post by: Irish_Alley on March 16, 2016, 05:13:41 pm
mind if i come by?
Title: A little popping From carb.
Post by: philo_beddoe on March 16, 2016, 05:16:16 pm
LOL!!!

Seriously, i wish several of us could get together and have a little 73-87 tune-up party.  That would be great.
Title: Re: A little popping From carb.
Post by: VileZambonie on March 16, 2016, 05:21:59 pm
Check those simple things first, it's my Birthday Friday and my woman has plans for us so I am not sure how the weekend will pan out but I did find out today she is planning a "surprise" party for me. Hopefully things will calm down a little Sunday and beyond. Maybe you can swing by Sunday and we can do some tinkering. Have to play it by ear
Title: Re: A little popping From carb.
Post by: philo_beddoe on March 16, 2016, 05:27:14 pm
Sounds good, i get out of church at noon, and there is a brand new DD in tolland on rt. 32, its on the way. 

Send me a text if things work out, and Thanks!

....and HAPPY BIRTHDAY!!

Ps. Irish Alley might stop by. Lol
Title: Re: A little popping From carb.
Post by: VileZambonie on March 16, 2016, 05:43:52 pm
Well if that's the case skip DD and go to the package store
Title: Re: A little popping From carb.
Post by: philo_beddoe on March 16, 2016, 08:30:33 pm
LOL !!!!
Title: A little popping From carb.
Post by: philo_beddoe on March 19, 2016, 08:01:13 pm
Check those simple things first, it's my Birthday Friday and my woman has plans for us so I am not sure how the weekend will pan out but I did find out today she is planning a "surprise" party for me. Hopefully things will calm down a little Sunday and beyond. Maybe you can swing by Sunday and we can do some tinkering. Have to play it by ear
The only thing simple there is the re-snugging of the base plate, and i would love to do that. I've been painting since friday morning, only to stop to eat and sleep. I am totally burnt out. I really hate painting. I had to paint all trim, then cut the entire room three times and roll three times in three rooms. Thats how you have to do it when you go from a light to darker color. I wish i wasnt cursed with this skill,,,and could transfer it to 73-87's instead!!
Title: Re: A little popping From carb.
Post by: philo_beddoe on March 26, 2016, 07:40:43 am
Well, i just slightly moved the choke a little to the left (rich) and it starts right up now when cold. For a while it would start right away then die after a few seconds. Vile is still going to check some timing advance stuff among a couple other things. Still get a pop or two when i punch it.
Title: Re: A little popping From carb.
Post by: philo_beddoe on March 26, 2016, 06:44:17 pm
Popping and bogging resolved, see "bad vibration"

If a moderator catches this, perhaps combine to "bad vibration" but just prior to post # 456.  Usually Irish catches these things.
Title: A little popping From carb.
Post by: philo_beddoe on August 02, 2016, 05:31:00 pm
The pop returned. One pop only when engine was warm and a quick WOT. So VZ had me advance timing a tad. So i turned the dist a teensie weensie clockwise. Popping was worse. I KNOW, WRONG WAY! so i went back the other way. Popping totally gone, running smooth and fast. Technically speaking, what did we do? Why did the popping go away and why is she nice and quick and smooth now?
Title: Re: A little popping From carb.
Post by: zieg85 on August 02, 2016, 06:42:00 pm
You advanced the timing.  Makes a night an day difference sometimes.
Title: Re: A little popping From carb.
Post by: philo_beddoe on August 02, 2016, 10:12:40 pm
I know i advanced the timing, but how does that technically make such a difference, i mean with the popping and all?
Title: Re: A little popping From carb.
Post by: zieg85 on August 02, 2016, 11:02:53 pm
I know i advanced the timing, but how does that technically make such a difference, i mean with the popping and all?

When you floor it, you dump a bunch of fuel and if the timing isn't advanced enough the engine won't rev fast enough and the carb pops some of the fuel out.  I've had to tighten the spring on the secondaries to keep the back barrels from opening too soon on WOT, running 36 degrees total advance.  Fine balancing act to get everything right running a stock quadrajet on a stock car.
Title: A little popping From carb.
Post by: philo_beddoe on August 03, 2016, 02:43:24 pm
Not that im going to, but how do you tighten that spring on the secondaries?
Title: Re: A little popping From carb.
Post by: zieg85 on August 03, 2016, 04:09:51 pm
Not that im going to, but how do you tighten that spring on the secondaries?

To be honest I don't remember, my sponsor at the time of my stock car did the fine tuning.  All I remember is I had an occasional pop but a hesitation every time I floored it.  He used a small screw driver and fixed it right up.  Mind you this was an early 70's Rochester on a put together junk yard 350 engine in my hobby stock
Title: Re: A little popping From carb.
Post by: Stewart G Griffin on August 03, 2016, 09:03:54 pm
I know i advanced the timing, but how does that technically make such a difference, i mean with the popping and all?

When you floor it, you dump a bunch of fuel and if the timing isn't advanced enough the engine won't rev fast enough and the carb pops some of the fuel out.  I've had to tighten the spring on the secondaries to keep the back barrels from opening too soon on WOT, running 36 degrees total advance.  Fine balancing act to get everything right running a stock quadrajet on a stock car.

Word:

i had a backfire out of the carb a few days ago right after i started the new engine.    Not to mention trouble keeping the engine running.  i advanced the timing a bit and it took care of those problems.
Title: Re: A little popping From carb.
Post by: Stewart G Griffin on August 03, 2016, 09:22:00 pm
LOL!!!

Seriously, i wish several of us could get together and have a little 73-87 tune-up party.  That would be great.

SQUAREFEST

i actually have access to a suitable space---both outdoors AND indoors.  And yes, a tune-up clinic should definitely be a part of it.
Title: A little popping From carb.
Post by: philo_beddoe on August 03, 2016, 09:41:58 pm
That would be awesome! We could walk around to each others truck and just keep fixing and tuning stuff. We could invite a AC DELCO rep. with tons of parts on hand. Lol
Title: Re: A little popping From carb.
Post by: philo_beddoe on August 03, 2016, 09:43:38 pm
Not that im going to, but how do you tighten that spring on the secondaries?

To be honest I don't remember, my sponsor at the time of my stock car did the fine tuning.  All I remember is I had an occasional pop but a hesitation every time I floored it.  He used a small screw driver and fixed it right up.  Mind you this was an early 70's Rochester on a put together junk yard 350 engine in my hobby stock

NICE!!!
Title: Re: A little popping From carb.
Post by: Irish_Alley on August 04, 2016, 12:19:53 am
my mud truck would occasionally back fire. tilli took rich's advice and hooked my vacuum advance to the manifold and made sure it was working then went to 16 or so on the timing
Title: Re: A little popping From carb.
Post by: philo_beddoe on August 04, 2016, 01:01:32 pm
Thats probably where im at now. Truck starts better, faster, smoother, feels like more hp.