3,4,7,8 Running Lean

[Bob & Sue 110]

Took the car out for a ride on a 80* day about 40 miles total of stop & go traffic. It seemed to have a surging miss like fuel starvation after about 15 miles. 
Some history I put 10 gallons of bad gas in it 1 month ago when this started I added a full can of Sea Foam to the tank & drove it a couple miles to get it through the entire system. It seemed fine I've only had it out for short trips since.

Holley Street Avenger 083570, Holley Dominator Single Plenum, Spectra Performance points dizzy. 351W Mild Cam.

Here's what I did.
1) Changed fuel filter twice (let about 1/2 qt of gas sit in a clear bottle over night it was about 1/4 water from separation)
2) Check timing timing 10* & Points 29.4* dwell
3) Changed plugs they all looked good
4) Rebuilt Holley carb kit # 37-934
5) Ran all the bad gas out before rebuild carb rebuild.
6) PCV 3 months old

I pulled & changed the plugs last night 3,4,7,8 are all lean.

Did I screw up the rebuild or does it sound like maybe I picked up some kind of blockage in the carb.

Bob

[LoneWolf2U 136]

Front 4 plugs must be good as you left them out. As I said before the use of a 1 inch four hole spacer would help.

It allows better fuel/air mixing before it hits the open spaced intake, the rear cylinders have too work at getting fuel to them.

[Bob & Sue 110]

1 hour ago, Mach1Rider said:

Front 4 plugs must be good as you left them out. As I said before the use of a 1 inch four hole spacer would help.

It allows better fuel/air mixing before it hits the open spaced intake, the rear cylinders have too work at getting fuel to them.

Yep front four are perfect, I'm heading up to NAPA later to pickup a four hole spacer & fuel bowl gaskets. Never had a lean problem before the bad gas I may also have a piece of dirt in one of the primary circuits so I'll rip it apart & clean then add the 4 hole spacer & remove the heat isolator. 

[1969_Mach1 333]

You don't need a 4 hole 1" spacer.  That is a small carb (in my mind slightly too small) and even though that is a single plane intake, it is designed for low and mid range power.  4 hole spacers are used when they have installed a carb that is too large and need to increase the signal strength to the boosters in the carb, thus fix low speed surge/stumble issues.  Again your carb is small so that shouldn't be an issue.

Check for vacuum leaks anywhere.  Double check for vacuum leaks where the electric choke and secondary vacuum dash pot attaches to the carb.  Make certain your float levels are not too low.  Make certain the carb is sealing good to the manifold.  Those manifolds were made for both square and spread bore carbs.  If everything looks okay you might need go through the carb again.  

If you order another carburetor rebuild kit, you might want to pick up a couple of main jet kits, 1 and 2 sizes larger than original for that carb.  

[Bob & Sue 110]

1 hour ago, 1969_Mach1 said:

If you order another carburetor rebuild kit, you might want to pick up a couple of main jet kits, 1 and 2 sizes larger than original for that carb.  

I'm just picking up a fuel bowl bowl gasket set just in case I mess one up. I also am going 2 sizes larger on the jets. Will check the whole carb out for leaks before I pull it off with water spray.

[1969_Mach1 333]

I've never used water spray to check for leaks.  How does that work?

I've always used something like carburetor cleaner.  Spray it along gaskets etc.  If there is a vacuum leak, the carburetor cleaner will get pulled into the motor and affect the engine speed, usually increase it and/or smooth out rough running conditions.  You have to be a little careful using carb cleaner to do this.  Too many vapors around the distributor or a leaking spark plug wire can start a fire. 

Are the fuel filter, fuel pump, etc. good and not starving the carb for fuel at high speeds?

[Bob & Sue 110]

After closer inspection 4 & 7 seem to be the leanest 3 & 8 look good under a large magnifier. I've changed the fuel filter & put new plugs in, have the carb off will tear it apart today or tomorrow. Checked for vacuum leaks with water spray just before pulling carb off no leaks. Did re-torque manifold 3 bolts were about 15 ft/lbs torqued all to 20 ft/lbs, 2 of them were on the drivers side with block off plate in the center of the manifold. Added another can of Seafoam to the tank with 8 gallons of fresh non-ethanol gas. 

 

[barnett468 418]

the spacer is not causing your problem.

if you want to remove water from the gas you should be using heet as was mentioned on your thread on the vintage mustang forum yesterday instead of foamy sea juice.

[Bob & Sue 110]

1 hour ago, barnett468 said:

the spacer is not causing your problem.

if you want to remove water from the gas you should be using heet as was mentioned on your thread on the vintage mustang forum yesterday instead of foamy sea juice.

This is s subject you can debate all day long, after boating for over 40 yrs I know a lot about water in fuel & ethanol separation. Iso-heet & heet are both just methanol or a blend of methanol & isopropanol good for frozen fuel lines, stabilizes water in fuel but does nothing for fuel separation. Valvtect is what I put in it with the Seafoam, Valvtect encapsulates the water so it can be burned through the engine & the Seafoam lubes all engine components & removes any built up varnish particles.  

[barnett468 418]

You did not say you put valvtec in it.

[Bob & Sue 110]

It was in another post on additives I ran out of ValvTect and went tp Foss Harbor Marina & picked up 6 more bottles sorry for any inconvenience this has caused anyone I guess I'm not perfect.

quote:

I add a can of SeaFoam or ValvTect every other time I buy ethanol gas I usually put 1 can for 8-10 gallons as stated above Startron is another good product they both do the same thing it encapsulates the water separation that starts within a week from the time he ethanol is added. I learned the hard way after having to have 50-80 gallons at $4.79 a gallon plus $500 pump out & disposal fee of old dirty marine gas pumped out of our boat.

This is different than the way products like Stabil work. Ethanol will add about 8-10 octane to the gas after about 2 months the octane drops gradually 92 octane after 2-3 months will equal 82-84 octane gas. 

I usually get non-ethanol gas when I can and fill it up with that.

ValvTect - Valvtect Marine Gasoline

https://seafoamsales.com/auto/

[barnett468 418]

So are you saying it runs perfectly and now the only "problem" is that the rear 4 plugs are darker than the front 4?

If it runs perfectly you do not have a plugged circuit, nor will water plug a circuit.

If the float level is below the inspection hole or near the bottom of the sight glass id possibly just leave it for now. Maybe put some new plugs in after all the sea foam and stabalizer and this and that is gone from the gas then check them again later.

[Bob & Sue 110]

Plugs 3 & 7 are lean all the rest are normal. Maybe it's the design of the manifold I'm going to make my own gasket next time to fit the manifolds carb profile.

I pulled the carb apart cleaned, blew out all the circuits out & double checked everything, new plugs, fuel filter. Started right up sounds good need to lower secondary float & idle speed circuit today. Ran out of time wanted to watch the Dawgs trounce the Beavers & it started raining.

If it quits raining today I'll take it for a ride hopefully it's run all the water out of it. I drained about a pint of gas out yesterday it's all gas no water separation.

 

[barnett468 418]

What intake is that?

Why are you running that intake with a mild cam?

Yes, different manifolds can cause slightly different plug colors. On a dual plane intake, the plugs fed by one side can be darker or lighter than the other and in some cases, it is helpful to stagger the jetting by using one size different jet on one bank. This often evens them out enough.

 

 

[Bob & Sue 110]

It's an older Holley Street Dominator the new Dominators are square bore.

It came on the care & will work on EFI so I'm not changing it.

[barnett468 418]

That's a rare intake.

[1969_Mach1 333]

Those are  rare intake manifolds these days.  My older brother use to run one on a mild 351W.  It made a lot of low and mid range torque.  Most people shy away from a single plane intake but the single plane Holley Street Dominator works great on a street driver.

[Bob & Sue 110]

On 9/29/2017 at 12:07 PM, 1969_Mach1 said:

I've never used water spray to check for leaks.  How does that work?

I've always used something like carburetor cleaner.  Spray it along gaskets etc.

Water spray does the same thing all your doing is a temporary sealing of the leak plus it's non-flammable & cheap.

I missed this question earlier. 

[LoneWolf2U 136]

On 10/1/2017 at 8:53 AM, Bob & Sue said:

It's an older Holley Street Dominator the new Dominators are square bore.

It came on the care & will work on EFI so I'm not changing it.

And it has been polished and modified some from the pic you posted.

The use of a 4 hole spacer will greatly improve your throttle response and low end grunt.

Not saying you need it (for those who wish to refute it) just saying try a 20.00 test for your self as see the difference as I have done.