Intake and carb questions?

[Bear601]

Ok I'm sorry in advance for any dumb questions I may ask.
I recently bought a 1985 silverado swb with a 305 bolted to a turbo 350 3spd
What I do know is everything says edelbrock on the top end valve covers, intake, carb, and air filter.
I was told from previous owner the cam is a 262
Accel dist cap with Accel wires and plugs needless to say truck runs like s%&@.
Things I've done so far is swapped wires to Taylor noticed a lil smoother idle.
Not knowing I watched countless carb tuning videos and I believe it's as tunes as I can get it noticed a lil better take off.
Replaced all vacuum lines noticed it's shifting smoother.
Ok I'm looking for any and all advice on what I should do next I'm wanting to replace carb and intake but I haven't a clue on what kind of intake or what kind of carb to go with but everyone I talk to says holly street avenger 670cfm.
It's still a hei distributor. Should I change it to or ?
I'm wanting a good strong street truck out of what I have I just don't know much about carbs etc.
I plan on building a ls style 6.0l and swapping it to carb instead of fuel injected and 4l80e combo to swap into the truck within a few years but just looking for any and all pointers for now and remember I'm still trying to reverse my knowledge for modern to old school because my other car is a 560hp 2012 camaro ss and going from building that to this is just mind blowing for me lol I'm still looking for some where to plug up my laptop to this c10 j/k but no where seems to work lol thank you in advance for any and all advice

 

[Bear601]

If more info is needed to properly answer any of my questions or to give me better advice I'll do my best to provide anymore info I can. Thanks again can't wait to get ole red running right so I can begin using her as my daily and start keeping the miles off my camaro

 

[Quadrajet Power]

For street cruising, and best performance, consider one of my custom built quadrajets.

Sounds like your trucks previous owner bolted on a bunch of pretty stuff and wasnt concerned about how it ran. you are off to a god start it sounds like. Intake should be ok. You just need to get everything matched up and working together.

 

[rich weyand]

What is your base timing set at?

What vacuum advance can is on it? (You should be able to see the stamping numbers on the arm of the vacuum advance unit if you look straight down between the vac advance can and the distributor cap.)

Where is your vacuum advance connected, to the passenger side of the Edelbrock carb or to the drivers side?

 

[Bear601]

I'i don't see see anything but edelbrock on the intake don't see any casting # and a edelbrock 750cfm carb #1407 and how do I find out if the distributor needs intake vacuum or carb vacuum I believe I'm wording that right

 

[Bear601]

Okay rich it has 691 stamped on it and it's hooked to the pass. Side of the carb

 

[Bear601]

As far as the timing goes I haven't a clue I'm supposed to be getting a timing light later today

 

[rich weyand]

OK, so the problem is that you have a mix of stuff on the engine that is pre-emissions and emissions-era.

The vacuum canister is a '691 20 (you didn't give me the second number, but that is what should be on a '691), which is an emissions-era can that will give you too much vacuum advance (20*). Get an AR23/VC1853 pre-emissions vacuum advance can. NAPA has the VC1853. Put that on there.

If you have a lot of crap between the vacuum advance can and the carb (vacuum dash pot and such), bypass all of that and connect the vacuum advance can directly to the DRIVER SIDE port of the Edelbrock. This is the pre-emissions connection to manifold vacuum. Cork off the passenger side vacuum port; nothing on a non-emission engine connects there.

Set the base timing to 12* BTDC as a starting point. Make sure you don't get knocking when you get on it at low speed up a hill. You can probably go to 16* BTDC in a couple of steps of 2*, checking for knocking each time. 16* BTDC is where you want to be if you can.

All of the SBCs in these trucks pull a hellatious amount of vacuum compared to the stock setup for the Edelbrock carbs. Change the pop-up springs in the Edelbrock from the stock 5" springs to the 8" springs. That's not their length, it's the vacuum at which they pull down to the cruise mixture. They will pull down way too soon with 5" springs.

Make those changes, and report back.

 

[rich weyand]

Here's the vacuum can:
http://www.napaonline.com/Catalog/C...cuum-Advance-Control/_/R-ECHVC1853_0168354142

Here's the springs kit:
http://www.summitracing.com/parts/edl-1464?seid=srese1&gclid=CKim1s38rsoCFZGMaQod_YsEMw

 

[Bear601]

Awesome thanks for the info and part numbers WOW I will definitely keep you up to date and I had a chance to check the timing today and it was 22° advanced backed it down to 14 and tinkered with the carb to get idle back right and running better but now it's got a popping sound when coming off the gas I'm hoping that the parts you've listed will help correct that and I'm hearing clatter about every 3-4sec from the passenger side head Now so yeah me

 

[rich weyand]

Make sure you check the base timing with the vacuum advance disconnected. People will tell you that you should block the port, but you don't have to just to set the base timing. But you do have to disconnect the vacuum advance!

 

[Bear601]

I did have the vacuum unplugged from the vacuum advance but I did plug the vacuum line and any idea on the popping or the clatter I'm thinking clatter=loose rocker arm but I'm lost on the popping.

P.S. I also realized that I have a exhaust leak on the pass. Side header collector where I can't get to to seal it up could this be causing the popping or the clatter

 

[chengny]

P.S. I also realized that I have a exhaust leak on the pass. Side header collector where I can't get to to seal it up could this be causing the popping or the clatter

but now it's got a popping sound when coming off the gas

Oh yeah, for sure. Leaks in the exhaust system - especially near the manifolds - will actually draw air in at decel. That added oxygen will often cause secondary combustion of any unburned fuel in the exhaust gas stream. The result is a rapid-fire popping sound - it sounds different than the random loud bang of an exhaust backfire.

and I'm hearing clatter about every 3-4sec from the passenger side head Now

Another cause of secondary combustion in the exhaust is a sticking exhaust valve. If an exhaust valve hangs open, each time the plug fires, the noise of the "explosion" (that is supposed to be contained within the combustion chamber by the closed valve) can more easily be heard. That will result in a popping sound.

Also if the valve is open - and allowing the introduction of hot combustion gases into the manifold - that can cause secondary ignition of any unburned fuel that exists in the exhaust stream.

Another thing to consider; when a valve is first starting to stick in it's guide, it doesn't usually stay stuck. It will many times free itself up temporarily but it usually starts sticking more and more often.

And, it follows that an exhaust valve stuck in the open/down position will allow for excessive clearance between the rocker arm and the face of the valve stem. When this condition exists, a rap is produced each time the rocker arm contacts the top of the valve stem. But eventually, the valve pops free and the rapping sound under the valve covers subsides - for a while.

Maybe there's a connection?

 

[Bear601]

Ok so is there a way to keep the valve from sticking or should I just pull the heads and replace it or just new heads all together if that turns out to be the issue

 

[rich weyand]

You should fix the problems you know about before you go off fixing problems that may or may not exist.

Get the exhaust leak fixed. Change the vac advance can. Change the pop-up springs.