Loud air sucking noise on acceleration

[Steeveedee]

Originally Posted by Asshat

No, regular dry air filter.

OK, just checking off another box.

[88Stanger]

So I have a 1966 C10, took rearend out, had complete new carrier and gears installed. with the carrier i have you can only go to 3:42 which i did, the other carrier allows for much taller gears, above 4:11. cost was not cheap, but with stock carrier i had, only could go to 3:42. you mentioned 14 bolt GM rear, did you mean 12 Bolt? i have GM 12 Bolt Truck rearend.

as for the exhaust leak.... i would no rule out vacuum leak. i had a 1966 Chevelle that had a 327ci that made a wierd sucking like sound that ended up being a damn vacuum leak, BUT it ran ok because we had timing and carb adjusted enough to cover the vacuum leak, or so we thought. fixed it and damn, what a difference.

fix? carb base plate was leaking along with the damn main rod that holds the butterflys in the carb. so crazy.... so, if after exhaust, start with basics, vacuum: air cleaner, intake, vacuum advance on dist., other potential vacuum lines that could be split, carb base plate or rods. I understand that the carb may be new, but you never know, also gaskets could be messed up. not sure what you hooked up, but check the PVC too maybe??
Good luck on this quest.

[CousinTone]

What was the result of water along the intake /head area, haven’t seen that reply, may have missed it. I’ve got 64, 292 with a new rock auto carb. I customized an old oil bath to house a paper filter from more modern snorkel. It is louder, like back in high school when we flipped the covers upside down and pissed off our parents from the increased noise.

Intake /vacuum leak is distinctively different from exhaust noise, I’d like to know the water test result. Also check thermostat housing, some have vacuum port. Look up the vacuum schematic and trace each line for connection and quality/crack(s). My 3¢.
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[Asshat]

Going to start it tomorrow (Saturday) and see what I can find. Will do some water spray and carb cleaner tests.
The connections to the vacuum tubing look pretty solid I really don’t think it’s leaking where a clamp is on the tubing. The PCV valve is a bit cocked, so I may pickup some more vacuum tubing and make that connection more secure.

And, the gasket at the base of the carb is secure and the carb mounting nuts are pretty tight.

[CousinTone]

Nice looking work!1

[Asshat]

Originally Posted by CousinTone

Nice looking work!1

Thank you!

[Steeveedee]

Where does the hose on the tee in the PCV hose go? I would only expect the PCV valve on that circuit.

[Asshat]

Originally Posted by Steeveedee

Where does the hose on the tee in the PCV hose go? I would only expect the PCV valve on that circuit.

To the distributor. I had the distributor plumbed to the port on the base of the carb, however, it did not provide any vacuum at idle.

[Asshat]

Here a video of it running, but not driving.

https://youtube.com/shorts/GdwXpFyJmJE

[cwcarpenter98]

Might be me, but that sounds like normal carb noise. I've only had a stock 2 barrel and a Quadrajet though, so my experience is limited

[Asshat]

Originally Posted by 88Stanger

So I have a 1966 C10, took rearend out, had complete new carrier and gears installed. with the carrier i have you can only go to 3:42 which i did, the other carrier allows for much taller gears, above 4:11. cost was not cheap, but with stock carrier i had, only could go to 3:42. you mentioned 14 bolt GM rear, did you mean 12 Bolt? i have GM 12 Bolt Truck rearend.

as for the exhaust leak.... i would no rule out vacuum leak. i had a 1966 Chevelle that had a 327ci that made a wierd sucking like sound that ended up being a damn vacuum leak, BUT it ran ok because we had timing and carb adjusted enough to cover the vacuum leak, or so we thought. fixed it and damn, what a difference.

fix? carb base plate was leaking along with the damn main rod that holds the butterflys in the carb. so crazy.... so, if after exhaust, start with basics, vacuum: air cleaner, intake, vacuum advance on dist., other potential vacuum lines that could be split, carb base plate or rods. I understand that the carb may be new, but you never know, also gaskets could be messed up. not sure what you hooked up, but check the PVC too maybe??
Good luck on this quest.

It’s definitely 14 bolt, yours is 12 bolt because it’s 1/2 ton; mine is 3/4 ton, 8 lugs.

[Asshat]

Did the 63 c10 and c20 have oil bath air cleaners?

And, if I installed one, do you guys think it will quiet it down?

[Steeveedee]

Originally Posted by Asshat

Did the 63 c10 and c20 have oil bath air cleaners?

And, if I installed one, do you guys think it will quiet it down?

Doesn't sound all that bad, like Christian says. Play it again, this time with the air cleaner housing installed. I can understand all the second guessing you may be doing, with all the trials you have had. You are driving it around with the air cleaner on it, right?

Oil bath air cleaners are old school, but some of the vehicles even newer than yours had them. I'm not convinced that they are quieter, but it's been decades since I've worked on a vehicle with an oil bath air cleaner. To be honest, I was only interested in making the vehicle run well, and the noise (beyond some obvious mechanical problem that needed fixing) was a secondary issue.

Also, there is a lot more valve train noise than I would expect in a rebuilt engine. What was your method for adjusting the valve lash? Is it a mechanical lifter setup? I'm not inclined to go looking for the old threads, right now.

[88Stanger]

Originally Posted by Asshat

It’s definitely 14 bolt, yours is 12 bolt because it’s 1/2 ton; mine is 3/4 ton, 8 lugs.

Oh damn, im sorry, i did not see that. my apologies. Looking clean though, nice work so far

[jayoldschool]

Originally Posted by Asshat

To the distributor. I had the distributor plumbed to the port on the base of the carb, however, it did not provide any vacuum at idle.

That's definitely not correct.

[Asshat]

Originally Posted by jayoldschool

That's definitely not correct.

I have heard from others here that manifold vacuum can be ported to the distributor.

[1966Step]

Here's a video link to my '63 292 w/1 barrel similar to yours. I just blew out my muffler a while back (long story) so I'm going to get that fixed this week but you can hear the carb pretty well for a comparison. I'm having issues also, but at least she's running.

https://youtu.be/tRspz7VyVAo

[Asshat]

Originally Posted by 1966Step

Here's a video link to my '63 292 w/1 barrel similar to yours. I just blew out my muffler a while back (long story) so I'm going to get that fixed this week but you can hear the carb pretty well for a comparison. I'm having issues also, but at least she's running.

https://youtu.be/tRspz7VyVAo

How do you have your vacuum advance plumbed? To the manifold or carb base?

[1966Step]

Carb base

[Asshat]

Originally Posted by 1966Step

Carb base

Can you do a close-up pic? Trying to see if your carb base is different than mine.

[1966Step]

Here ya go..

[Asshat]

Originally Posted by 1966Step

Here ya go..

Do you get vacuum at that port? Does it advance the timing when you put it to the distributor? Mine does not.

[1966Step]

Yes, I think that's standard.. From the 63 manual if it's any help

[Asshat]

Originally Posted by 1966Step

Yes, I think that's standard.. From the 63 manual if it's any help

So, maybe the smaller diameter throat cause a louder sound when opening the throttle?

[1966Step]

I think you need to send that plumbing back to the carb base as you shouldn't experience any vacuum at idle which you said was the case. Vacuum should come on as the throttle is opened. Others can correct me if I'm wrong here.