tuning my 350

[BamaDave]

I am trying to tune my 350. Like I said it is a 350 with a Holley 80555 650cfm carb and Edelbrock Performer intake. It is a spread bore carb. I don't know what cam is in it but it has a lope to it. When I tried to see what the timing was I couldn't see the mark on the crank damper. What should it be at? Also, when I hooked my VAC gauge up to the manifold vacuum was between 10 & 15. Idle was about 1000rpm. With the jets 1 1/2 turns out, if I tried to turn down the idle, it died. Lowest I could get it and keep it running was like 900rpm, but it was real rough, when put in gear it barely ran. I am also concerned with how the gauge read. When I first started it was steady, when I reved it, it would go way down then back up. Usually when it went back up it rarely stopped in the same place it started. After fiddeling with it a while it started a quick bounce between 10 and 15. I am pretty sure I was hooked up to full manifold, but the cruise and AC control VAC was hooked up to it too. I just bought the gauge today from AutoZ. and the needle when unhooked starts on the fuel pressure side of the gauge on 1. I will try to get pics. I know this is long but I am freakin' out. I don't want to have to tear into the engine. I have a rebuild kit on the way for the carb.

PLEASE SOMEONE HELP!(edit-what is the thing circled in 2nd pic? 3rd pic is where I got mani. vac.)

[willstruck]

I was getting just about 21 psi on the vacuum gauge when I tuned mine. Timing on a SBC seems to run 11-13 BTC. Is your truck all warmed up before you tune it? If my truck is cold, it idles like sh!t because I don't have a choke. I set the idle by ear with it warmed up. Previous owner had idle set way to high.

[BamaDave]

yeah, full operating temp.

[BamaDave]

anyone?

[notyo_cheez]

If it doesn't improve after the carb rebuild check your compression. It will remove all doubt.

[cr34t3d_by_d4rkd3n]

Originally Posted by willstruck

I was getting just about 21 psi on the vacuum gauge when I tuned mine. Timing on a SBC seems to run 11-13 BTC. Is your truck all warmed up before you tune it? If my truck is cold, it idles like sh!t because I don't have a choke. I set the idle by ear with it warmed up. Previous owner had idle set way to high.

21 psi? u mean inches?

__________________
Ok lets start with the basics. Ur engine only makes vaccum at idle. as you speed up and rpm's increase u loose vaccum... this is how chevy and everyonther carm manf. of the 70's knew when to make the transmission shift, ac cycles, exc exc, because u loose vacc as u increase rpm.... so if u loose vacc what does that mean to.... lets say ur tranny....???... it means ur moving......in a nut shell...

so whenu rev her up and loose vacc, thats normal. dont worry.

IDLE ISSUES: u need to know if it has a cam forsure, or if its missing. Thats the first step, if it does have a milid cam that provides a <b>rough</b> idle u need a higher stall converter... please google to learn more on as to why, i dont feel like writing a book but as u describe," i set idle when in gear, it sounds good, i put it in park and suddenly it shoots up to 3000rpm."... if that happens, ur cam is too wicked, and needs a stall converter.

As far as tuning, yes with that carb u can change jets but they come pertty spot on from factory....

1)HOW TO SET IDLE FUEL MIXTURE:
2)SET IDLE!!.
3)Screw in(lean) right screw until the motor begins to stumble and sputter.
Grab the throttle and rev it up, it should go: vroom....sputter sputter sputter again, it SHOULD NOT idle okay. Reasoning: accelator pump messes with tuning the idle fuel mixture screws, u need to rev it up now n then while screwing in the screws to insure u are getting an accuare reading.
4) after u have her sputtering, unscrew the right screw(ritchen) until idle comes back up and stops sputtering, then go 1/4 more out(ritcher).
5)repeat steps on left screw.

AND THATS IT LOL.

Read ur plugs! u cant tune and ask for help without knowing what the plugs are reading.

then theres timing, vacc advance tuning with springs...... its just begun my friend.

[BamaDave]

thanks c.b.d., I guess that will get me going in the right direction. Once I get this solved, maybe the thing won't burn my eyes when it sits there ideling!

[cr34t3d_by_d4rkd3n]

if shes burning ur eyes shes burning coolant, its a nasty smell, will burn the eyes and sting the nose, its the glycol burning in the coolant........read the plugs and get back to us, pics help!

good luck!

[BamaDave]

I don't think I know what reading the plugs means. How in the world is it burning coolant? It smells like fuel.

[rayfinseats]

Sounds like the cam is too "big"

[LONGHAIR]

Originally Posted by BamaDave

I don't think I know what reading the plugs means. How in the world is it burning coolant? It smells like fuel.

You "burn" coolant in one of three ways:
By having a head gasket leaking into the cylinders
Cracked head
Cracked cylinderwall

It doesn't really burn, it just gets turned into steam durning the combustion process. It smells sweet, I have never heard of it burning the eyes.

Eye and nose burning sounds like excess fuel to me, (extreme richness) If it's that bad, you will usually see black smoke too.

Sounds to me like you may have a few problems.
You need to be sure to locate the "zero" mark on the balancer and get the timing correct first. Many "carburetor problems" are a result of timing issues.
Then address the carburetor....vacuum leaks, jetting, etc.
You may also have more cam then your torque convertor can stand. If the convertor is "too tight", it creates a big drop in idle speed when you put it in gear.

[BamaDave]

So this morning I tinkered with it again. The plugs were fairly new, couple months old, with little to no mileage.(Truck is a project) So after messing with it over two mornings for a total time of about 4 hrs., the plugs are fouled. No fuel or oil or anything wet, just complete black carbon. I will have to clean them up to start again. I also found a vac leak on one of the rubber caps that came from the factory on the carb, one that is at the base of the carb right on top of the intake. Also checked my timing, put white out on the indicator on the balancer. Timing was waaayyy advanced but running without any pinging or other problems. Do I need to pull the vac advance loose to check the timing?

[cr34t3d_by_d4rkd3n]

Originally Posted by BamaDave

So this morning I tinkered with it again. The plugs were fairly new, couple months old, with little to no mileage.(Truck is a project) So after messing with it over two mornings for a total time of about 4 hrs., the plugs are fouled. No fuel or oil or anything wet, just complete black carbon. I will have to clean them up to start again. I also found a vac leak on one of the rubber caps that came from the factory on the carb, one that is at the base of the carb right on top of the intake. Also checked my timing, put white out on the indicator on the balancer. Timing was waaayyy advanced but running without any pinging or other problems. Do I need to pull the vac advance loose to check the timing?

Iell black carbon is generally lean condition mixed with oil burning, i forgot to add, coolant will burn the eyes and nose esp when it his the cat converter..

Id play with your timing, does ur truck still have points? if so go hei, it sounds like shes missing and dragging a dead cylinder. due to foul.

THE OBVIOUS: wrong plugs... dont use autolites, just dont. get a ac delco, cheap and reliable... the guys at napa should know, call 2 stores ask for same thing and compair part numbers....

check the timing, (remember, connect +&- from gun to batt, wire clip on number 1 cylinder)
From there, well we'll see lol take a pic of #1 and #5 plugs if u can. I wanna see.....

[LONGHAIR]

Originally Posted by BamaDave

Do I need to pull the vac advance loose to check the timing?

Yes, and plug the hose while it's disconnected.

[BamaDave]

The plugs are Delco's and yes I have HEI. Yes there was a miss. I am going to clean the plugs. Now have to check timing with the vacuum adv. disconnected.

[BamaDave]

bump for pics added

[motornut]

kinda got the same setup had some same issues
still working threw some but with mine
I found the vac advance weights rusted up
the PO had the vac advance on the wrong place on the carb
mine is a 350 with an "unknown cam"
and the PO used the dist,fuel pump .....
various other parts reused from the 33year old stock 305
changing what i can with time

[jrcaprai]

Originally Posted by cr34t3d_by_d4rkd3n

21 psi? u mean inches?

__________________
Ok lets start with the basics. Ur engine only makes vaccum at idle. as you speed up and rpm's increase u loose vaccum... this is how chevy and everyonther carm manf. of the 70's knew when to make the transmission shift, ac cycles, exc exc, because u loose vacc as u increase rpm.... so if u loose vacc what does that mean to.... lets say ur tranny....???... it means ur moving......in a nut shell...

so whenu rev her up and loose vacc, thats normal. dont worry.

IDLE ISSUES: u need to know if it has a cam forsure, or if its missing. Thats the first step, if it does have a milid cam that provides a <b>rough</b> idle u need a higher stall converter... please google to learn more on as to why, i dont feel like writing a book but as u describe," i set idle when in gear, it sounds good, i put it in park and suddenly it shoots up to 3000rpm."... if that happens, ur cam is too wicked, and needs a stall converter.

As far as tuning, yes with that carb u can change jets but they come pertty spot on from factory....

1)HOW TO SET IDLE FUEL MIXTURE:
2)SET IDLE!!.
3)Screw in(lean) right screw until the motor begins to stumble and sputter.
Grab the throttle and rev it up, it should go: vroom....sputter sputter sputter again, it SHOULD NOT idle okay. Reasoning: accelator pump messes with tuning the idle fuel mixture screws, u need to rev it up now n then while screwing in the screws to insure u are getting an accuare reading.
4) after u have her sputtering, unscrew the right screw(ritchen) until idle comes back up and stops sputtering, then go 1/4 more out(ritcher).
5)repeat steps on left screw.

AND THATS IT LOL.

Read ur plugs! u cant tune and ask for help without knowing what the plugs are reading.

then theres timing, vacc advance tuning with springs...... its just begun my friend.

Dude, you have got to stop spreading misinformation!
A torque converter has nothing to do with Setting idle.
you can tune without reading the plugs just fine.


1st

Unhook the Vaccum from the HEI Distributor, which is obvious from the pic.
attach the vaccuum gauge and adjust for highest vaccuum... and lowest Idle Speed.

Use a timing light and adjust the timing to about 12-14 degrees BTDC,
this will get you in the ball park

[jrcaprai]

Originally Posted by cr34t3d_by_d4rkd3n

if shes burning ur eyes shes burning coolant, its a nasty smell, will burn the eyes and sting the nose, its the glycol burning in the coolant........read the plugs and get back to us, pics help!

good luck!

Again, misinformation.... burning eyes is due to the mixture being rich, Not Coolant....

[jrcaprai]

Originally Posted by cr34t3d_by_d4rkd3n

Iell black carbon is generally lean condition mixed with oil burning, i forgot to add, coolant will burn the eyes and nose esp when it his the cat converter..

Id play with your timing, does ur truck still have points? if so go hei, it sounds like shes missing and dragging a dead cylinder. due to foul.

THE OBVIOUS: wrong plugs... dont use autolites, just dont. get a ac delco, cheap and reliable... the guys at napa should know, call 2 stores ask for same thing and compair part numbers....

check the timing, (remember, connect +&- from gun to batt, wire clip on number 1 cylinder)
From there, well we'll see lol take a pic of #1 and #5 plugs if u can. I wanna see.....

More misinformation: Black smoke = Rich Mixture, and burning eyes nose is from the rich mixture....
Blue Smoke = oil in combustion chamber, from rings not sealing or valve guide.

Dude, just stop

[foamypirate]

Originally Posted by jrcaprai

More misinformation: Black smoke = Rich Mixture, and burning eyes nose is from the rich mixture....
Blue Smoke = oil in combustion chamber, from rings not sealing or valve guide.

Dude, just stop

Not to mention you don't get carbon covered plugs from running lean and burning oil. If you are burning oil, they will get fouled with nasty looking shiny crap, and if you are running lean, your plugs will be whiter in color...not covered in carbon!

[Hoods69BadBowTie]

Yea the burning eyes and nose to me sounds like its burning way to rich not burning coolant. White smoke should be coolant, blue being oil and black being to much fuel. If you have any way to find out what cam is it that would greatly help out as well. Just curious have you checked on compression yet?

[BamaDave]

Haven't checked compression yet. Don't know what the cam is. Thanks for the timing help
Posted via Mobile Device

[LONGHAIR]

Originally Posted by jrcaprai

Dude, you have got to stop spreading misinformation!
A torque converter has nothing to do with Setting idle.

It certainly can. If you have a cam that requires a looser convertor to perform properly, it wouldn't idle well with a "stock" convertor.
You would have a huge RPM drop when shifting from neutral into drive.
This can cause other problems too. A low vacuum signal can affect the carburetor and the distributor, making the idle even more erratic.

I have disagreed with quite a bit of the other things said....but this one is accurate.

[jrcaprai]

Originally Posted by LONGHAIR

It certainly can. If you have a cam that requires a looser convertor to perform properly, it wouldn't idle well with a "stock" convertor.
You would have a huge RPM drop when shifting from neutral into drive.
This can cause other problems too. A low vacuum signal can affect the carburetor and the distributor, making the idle even more erratic.

I have disagreed with quite a bit of the other things said....but this one is accurate.

I agree with you in Gear, I was talking about in neutral