1977 400 gets a 4-barrel

[Dan Szwarc]

I hooked up a vacuum gage and this car sucks 20-21 inches coasting, 16.5 in gear with the brake on, and 17-18 while cruising.
All vacuum readings are rock solid and stable. I changed the power mode spring to the heaviest (8" compared to 4" which is stock), and I got slightly better part-throttle response. I'm going to install an adjustable modulator as Larry suggested because the tranny is upshifting so quickly, it barely has a chance to use the lower gears, even in mildly aggressive driving.

I have the timing set for +12 which should be 8 degrees BTDC when I account for the 4 degree advance that I added to the cam timing (since the spark is set off the cam, but defined as degrees BTDC which is crank timing. I may have to retard it a tad more because I do get "rattling" (as Barry calls it), but it is engine knock or pinging. The car has always pinged, but I will try to reduce that. I still have to mess with the vacuum advance.

[Dan Szwarc]

I pulled the plugs (which I plan on replacing with new ones) and they are a nice tan color. That means the previous 2-barrel, as weak as it was, was ideally tuned.

Today I am topping off the tank and starting my mileage tracking on the new carb. Unfortunately, the weather is going to suck ass this week. I don't know if I will be able to report back quickly on any improvement.

[pepsi2185]

Im looking forward to your findings. Only an engineer would enjoy doing a mod and evaluation of mileage for fun, even on your days off crunching numbers . . . . . .

[Dan Szwarc]

I have been driving a little and playing a little. I'm going on an Easter drive today to my sisters, but it's not very far or mostly freeway.

I purchased a TCI adjustable modulator because the tranny upshifts so early, the car is not taking advantage of the HP it can generate now.

The timing was mis-set at about +10 degrees and I adjusted it back down to +8. No more knocking at acceleration.

I give this upgrade a 9 so far (out of 10). Noticeable improvement in drivability and off-the-line get up and go. The mileage is yet to be seen.

One thing odd is the car does not idle steadily. It has a slight surging at any RPM. What could this be?

Oh, and I installed the MSD unit. It works. Don't know if it is or will make any difference.

[Barry Wolk]

What does your vacuum gauge say at low idle? Steady, or does it jump all over?

That sound like mine at low idle. Try torquing the intake bolts and the carb bolts now that it's been heated up and run it. You might have a vacuum leak.

[Dan Szwarc]

I'll double-check the intake torque.

The vacuum gage is steady as a rock.

[Mad Scientist]

My first guess wound be something with the fuel delivery. But with the MSD are you using the old wires? They’re might not be up to carrying the voltage that the MSD can put out. They and or the cap and rotor could be arcing. This evening after the sun is turned off for the day open hood and see if by chance there is a “light show” going on.

[Mad Scientist]

Im looking forward to your findings. Only an engineer would enjoy doing a mod and evaluation of mileage for fun, even on your days off crunching numbers . . . . . .

What you mean that there are other things one can do for enjoyment? Oh I suppose I could take the family and go on a tour of the local junk yard.

[Kuripiiritus]

did the edelbrock carb had any kind of media with it? Holley has a nice dvd. which has a lots of troubleshooting and tuning tips, related to the carb, and other main reasons that can be causing problems instead of the carb. It's too big to upload though almost 4GB. I'll take a look when i can(not near the dvd at the moment), too see whats there about rough idle and surging.. Also i can upload it, if there is a place with enough space.

[CurtC]

Edelbrock also supplies a DVD with their carbs. It's excellent and thoroughly covers installation as well as tuning and typical troubleshooting issues.

[Dan Szwarc]

I watched the DVD. Not useful. Very general info.

[AndyMarkV]

How did you set you idle mixture?
If the idle is lean, sometimes it will surge like that.
I ususally set mine by highest vacuum.
I do something close to this....
http://www.chevyhiperformance.com/howto ... index.html

Good call on the adjustable modulator. I'll be curious to see how it and see how it reacts. A good shift pattern makes these cars much more fun!
I had to chase down some issues with my modulator before it worked right. .
First I had to find a good vacuum source that wasn't affected by anything else. I also found the rod that the modulator pushes was too short to achieve the adjustment I was looking for. I would adjust it until it wouldn't shift without finding the shift pattern I wanted. A rod .075 longer really helped.

I learned this from a guy on 460ford.com:
You can also cut a piece of heavy coat hanger or a small drill bit to make a little longer modulator pin,the stock ones come in different lengths and a longer one will make the shifts a little later and firmer.Make a new pin about .075 longer than the one that is in there now and see if that helps it,if it's a little better make one a little longer and keep trying,if you get it too long it won't upshift and then you will know to grind it down a little until it shifts again.Hope this helps..

[Dan Szwarc]

How did you set you idle mixture?

I followed the instructions for the carb: set idle speed, adjust one screw to max RPM, leanest setting, reset speed, adjust other screw to max RPM, leanest setting, reset speed, adjust screw for 20 RPM reduction.

The car was always bouncing at idle. I don't know if it did it BEFORE I installed the MSD system.

If the idle is lean, sometimes it will surge like that.

It did it no matter what the idle mixture screws were set at,

I ususally set mine by highest vacuum.

I'll double-check vacuum readings, but I got a rock solid reading the last time.

I learned this from a guy on 460ford.com:
You can also cut a piece of heavy coat hanger or a small drill bit to make a little longer modulator pin,the stock ones come in different lengths and a longer one will make the shifts a little later and firmer.Make a new pin about .075 longer than the one that is in there now and see if that helps it,if it's a little better make one a little longer and keep trying,if you get it too long it won't upshift and then you will know to grind it down a little until it shifts again.

Good tip. I'll keep it in mind. I have plenty of bad drill bits.

The weather has not been cooperating. Three days straight of rain. I might be able to drive the car to work tomorrow, but not play with it afterwards (too much other work to do).

I have the whole summer ahead of me. I hope to drive the car a lot more than usual.

[lincolnlarry]

Dan I can not wait to hear your mileage resaults

My motor has 70,000 your saying you chain was lose at 90,000 I have not put
a new chain in yet because of that now you make me think I should do it right
away but this is all high way from AZ to Wisconsin I wonder

Just be sure your plugs are running tan color and your good

My carb was used and sitting on the shelf here the stock meter spring had a boog
just off idle so I went to the highest spring and it turned my plugs black now
I am just 1 step up and it works fine think it was just a litle dirt but I did
clean and replace the needles and seats befor install

If you run into this you will need to buy the 5 spring set auto zone has them
I am thinking it was my carb not the spring rate also I have the accel pump
in the lowest shot

I try to get to the board as mush as I can but I am always so busy that is why you
see my posts so late at night.

And just think I retirered in 2001 but I still own the shop I have been trying to get
the boys to buy it but they don't seam to want to the building is only like 5 years
old all my tools there go with it Oh well they will get it anyway when I go to
the next world you see its a brother and 2 nephwes and 2 others that work there

I may just investigate the leak I have by the thermo housing and just take it
for a ride tomorrow but the lic is expired thinking about colector plates I never
drive it anyway in the snow coverd salty roads for me it would be ok because
there is a restriction I think from may 1st to nov 1st in this state on collector
plates you buy them once and never pay again, I have thenm on my other cars
but don't remember the dates of operation

The car has to be 25 years old for the plates and can not be used for a daily driver

[lincolnlarry]

Dan,

One thing you might want to check is the floats they may be off just remove the
meter rods the linkage and pull the top the gasket will be ok just be carefull

I cant remember the size drill you use but check the floats even eldebrock says
some times they are not set the same and that could very well be your serge at
idle

I checked mine when I put the new needles and seats in and sure enough they
were not the same

I also went to the highest spring but than droped back to the #5 just 1 step
above the stock #4

You will find the drill size in the instructions or on the eldebrock website I would
check the floats and play with the springs befor changing the rods or jets
also the accelerater pump position I have mine at the lowest

On the vac modulator find a short small screw driver I had to grind the sides on
one of my craftsmans to get it to fit in the vac tube also I think it would be easier
to turn it in a few turns and back off rather than turning it in under the car
that was a pain my exhaust was close and got a small burn after going under
4 times to get it where I wanted it light throttle 1600rpm

You can as someone else also mentioned get a longer rod .050 at a time any
machine shop can make these up for you its not a hardened pin and has very
little pressure on it

Also the TCI nickle chrome pan with a drain plug is just under $30 I put one on
so I could change the fluid without removing the pan to do it and it makes the
job a lot less of a mess just a thought and a good price on the pan

With the plugs just go to walmart $0.99 each a set of autolites get them tan
and than go to your plug of choice I am running the E3 3.40 another excellent
choice would be the NGK Vpower a great plug for $2.25 ea the e3 are like
$6ea

We have been using the Vpower in a lot of vehicles and people notice more
power gas mileage and smother running, we see gains from 1 to 3mpg with the
Vpower and the customers are very happy with them

We just got over a foot of snow here lost the electricity for a day so my
lincoln that I planed on getting out is now delayed.

Oh well I have to put the new fuel pump on it is dripping oil out the weap hole
I have never seen a pump do that befor I got a carter from napa for $27 I also
got a new water neck solid steel the org alm the 2 tabs by the bolt holes
has deteriated so bad its seaping coolent the neck was $10 and weighs about
5lbs there is some of the weight you removed if you want to put some back LOL

Once you get your carb working properly you will be even more plesed I see you
already gave the upgrade a 9 out of 10 that is a very high opinion of the
upgrade, I knew you would be pleased but you sound very very happy thats
what makes doing the upgrade all worth while

My base timing is 16 degrees have it at 18 the timming is related to piston
position having the came advanced 4 degrees does not effect this relationship
of how many degrees from TDC the piston is

Also the retard the factory put in is in the gear and the aftermarket chains
0 is 0 so your 4 degrees advanced this will give you more low end and may be
why you have the flat spot but play with the springs accel pump and check the
floats befor changing the rods and if you do have to change the rods go 1 step
up at a time and when you change the rods you may have to also change
the spring rate again

Take your time use the cheap plugs and get it right than Il bet you will go to
a 9 1/2 9 3/4 rating on the upgrades I see a lot of people get carried away
when jetting a carb .005 .010 makes a big diff they go nuts and end up to
rich and than say the setup is crap but its not as with any changes to any
motor it takes time to get the carb jetted just right that is where the best
power and gas mileage will be