'64 230 running overly rich

[Improbcat]

The 230 in my '64 is running really rich, so badly so that it backfires when I'm coasting in gear on the highway.

I've rebuilt the carb & replaced the float. This was only the 2nd carb I have ever rebuilt, so no guarantees I got it right. It didn't seem to make any difference though.

I tried hooking up a vacuum gauge to the vac line off the carb, but I get zero vacuum at idle, and more the more I accelerate, which doesn't seem entirely right.

I have not set the timing as I don't have any idea what the correct timing is, but I tried doing it by ear and just as it start getting to the smoothest spot the distributor hits the block.

Is there a way to adjust the fuel mix on the carb? Is the vacuum right or do I have an issue there? Is the distributor stabbed in wrong?

Help?

[Sharps40]

If it starts the dizzy is probably stabbed in okay, maybe out of adjustment but....


On points factory timeing is 4 degrees BTDC. A good engine on points may handle 6 to 8 BTDC w/o pinging. Set timeing with vacuum advance disconnected and the hose from the carb plugged.

Dwell, from memory is about 32 to 36 degrees. Set it low and let it advance up as the rubbing block wears down. Points gap should be between 16 and 19 thousands.

Spark gap with points about 35 thousands.

Take your dizzy vacuum from ported vacuum if its a stock cam. Put a draw on your dizzy vacuum can to make sure its woking/not stuck.

Make sure your carbs lower butterfly is open a crack at zero pedal and/or as indicated in your carb rebuild kit...sometimes you set this on the rebuild and your linkage from the firewall is out of tollerance and opens it even further when you hook it up...so setting the throttle opening is two part....a specified opening by adjusting the carb linkage at rebuild, ensuring your linkage from the firewall is tweaked so as not to change that setting when you hook it up.

Your manual choke should be adjusted so it properly opens/closes the top butterfly when you push pull it.

Turn your idle mixture screw in to closed and open it 2 to 2.5 turns. (your idle speed screw should be set as described in the carb rebuild.)

Now, start the motor, stay with the gas pedal 10 minutes till its fully warmed up. If it stalls hot, lightly increase the idle speed till it runs.

Once running, hook a tach to the coil. As long as your idleing from 400 to 700 rpm hot you should be good to start adjustments...It may idle rough as a cob, thats okay as long as it keeps running so you can lean over the fender and tweek the settings.

1 - turn the mixture screw in by 1/4 turn increments till the idle drops and the engine gets rough/misses....or even stalls. - Here you are too lean.

2 - with the motor running (in case it stalled at step 1) turn the mixuture screw out by 1/4 turn increments, it should increase RPM and become smoother...keep going in slow 1/4 turn increments till RPM stops increasing and the motor either gets no smoother or begins to roll. Here you are too Rich.

3 - Turn the mixture screw in by 1/4 turn increments till you get highest (lean) idle on the meter, very smooth. Listen, your lean miss should occur once ever 10 seconds or so, no more.

4 - Turn the mixture screw out (rich) 1/4 turn from best/highest/smoothest lean idle...done with baseline mixture adjustments. Here you are very close...time assume the mixture is good enough and to tweak something else.....

5 - Adjust idle screw to preferred idle speed. Try to keep it 750 or less to keep it out of vacuum advance at idle and to reduce wear on brakes/clutch, etc.

6 - Make sure accelerator pump linkage is set per carb rebuild directions, shut down the motor. Cycle the throttle while looking into the carb to see the squirt from the accelerator pump....

7 - if all is well, button up the air cleaner, reconnect PORTED vacuum to the dizzy and go test drive.

At this point, if you have a good engine and did the carb right, your motor should be working pretty well and this hot start should be easy.

Expect to do some refinements of the ignition, fuel mixture, idle speed and accelerator pump for best mileage and performance, do your test drives from idle to WOT. Make sure you pull some hills in 2nd from 10 mph and try for continuous acceleration up the hill to gauge ping/power, responsiveness, etc..

Second test drive is cold engine the next morning. Hows the cold start and cold idle, hot idle, driveabilty while choked, recheck the performance while hot...come back and as you desire, make very small changes to mixture and/or idle and/or ignition advance each time and retest till yer happy. Just change one thing at a time and go drive...plan for 10 to 20 test drives till yer happy.

Always use a tach when tuneing the carb and your ear...searching for highest smoothest lean idle then go check the engine for power and pinging...

Let us know how it goes.

[Improbcat]

Thank you for all that info, it will be a huge help.

Another question though, I only seem to have one source of vacuum on the carb, it is on the baseplate and has a hard line running from it to near the dizzy. Is that the correct setup?

[Sharps40]

If its a 64 with a Rochester B it has ported vacuum connection, for a hard line with a compression fitting, located inbetween the lower and upper butterflys. It should be on the side that faces the valve cover.

Use ported vacuum to the Dizzy for stock engine/cam.

You "May" require manifold vacuum to the Dizzy for performance engines/cams.

[Sharps40]

If useing a vacuum gage to tune, take it from manifold vacuum....

If you hook a vacuum gage to ported vacuum you will read zero or close to it at idle...that is proper function for ported vacuum. Its why a dizzy on a stock cam motor is hooked up to ported vacuum so the vacuum advance only functions in the driving range, not at idle.

If you have a radical cam, still read your vacuum from the manifold but for proper vacuum advance when driving above idle, you may have to hook the dizzy to manifold vacuum....since radical cams make less useable vacuum in the standard rpm ranges where you will spend mosta yer time.

[Sharps40]

As long as that vacuum port on the carb, you described, is ABOVE the lower throttle butterfly, it is Ported Vacuum and is the proper place to hook up yer dizzy on a factory motor.

There were many editions of the B and Monojets, vacuum ports coulda moved up and down over the years but...

Ported Vacuum is always above the lower butterfly

Manifold vacuum is always below the lower butterfly.

[Sharps40]

Another ear tune...while driving, as you reduce deceleration pop and burble yer gettin closer to the right settings. As a general rule of thumb, deceleration pop from the exhaust (decelerating in 2nd, say 20 mph down to 10 mph) indicates yer prolly outside of the best settings for carb and ignition. I find deceleration pop and burbling to be more prevalent when the settings are too lean but can occure when too rich too.

[66Submarine]

I'll throw in that I tune idle mixture by leaning it out until it starts to run rough, then enriching it until it just smooths out. Or slightly lean of max vacuum/engine speed, say maybe a 1/8-1/4 turn. All while hot, of course. I'd try something like that and see how you like it.

Some other diagnostics: How do the plugs look, black and sooty? How's it start cold, and hot? What kind of fuel mileage are you getting? (Mine was getting 18MPG or so tuned like I describe) Does it load up and idle down when idling after it's warmed up?

I'll also throw in I'm running 10º initial timing. Chevrolet calls for very little but It really liked the additional timing.

Hope this helps!

[gofastnut]

Lots of great info! I know I've still got some tuning to do.

[Sharps40]

A good engine and a good points dizzy may well go to 10 degrees BTDC w/o ping and still have good hot/cold starts. A worn engine or worn dizzy, not so much. I do basic tune at 4 BTDC...get it as good as it'll run and then play with kicking the advance around and fine tuning the carb with it as you go. When you hit detonation/ping on hard acceleration, back off the timing till the noise in the motor quits, reset the carb and you have adjusted your motor combination for max power and efficiency with that grade of gas/your driving style.

[66Submarine]

Actually, the engine I was referring to leaked down 65% on one cylinder (only checked a couple) and will roll a thick cloud of blue smoke as long as you hold it at 2,500! Tired old thing.

[Sharps40]

Might need the extra advance then just to have long enough to start the extra oil burnin!

[66Submarine]

That's about the truth!

Also, to the OP/others, one thing no one has mentioned yet is total advance. Dyno tuning is best, obviously, but lacking that you should try to end up at 36 degrees or so total.

For instance, my C-30's 195HP 283 is set to 12 or 14 initial right now. Factory curve is pretty lazy, 10 @ 1,500, 15 @ 2,000, and 28 @ 4,200 by my book. So spinning it to 3,100 should be around 22 mech advance, + the 14 initial = 36 total. Now, if I were to spin it all the way to 4,200 that would result in 42 degrees total.

[Sharps40]

I did a total mechanical advance check recently. You can do it using your factory 12 degree timing tab and a silver sharpie. See the thread attached at post #175 and #181 for details.

http://67-72chevytrucks.com/vboard/s...d.php?t=571916

[geezer#99]

Originally Posted by Sharps40

As long as that vacuum port on the carb, you described, is ABOVE the lower throttle butterfly, it is Ported Vacuum and is the proper place to hook up yer dizzy on a factory motor.

There were many editions of the B and Monojets, vacuum ports coulda moved up and down over the years but...

Ported Vacuum is always above the lower butterfly

Manifold vacuum is always below the lower butterfly.

Sorta true!!
Manifold vac ports can be found at the top of a carb. Look at the choke pull-off pot on the front of a quadrajet for example.
Only way to be sure is pull off the hose, stick your finger over it or attach a vac gauge.

[gofastnut]

Running super rich when warmed up! I will check my points, ignition timing and plugs, then move to idle mixture screw.

[rideblue00]

good info here guys, thanks

suscribed!

[gofastnut]

OK, so I looked at the points....about .012 gap . I replaced points & condenser, cap, rotor & plug wires. Also found and replaced bad vac hose to dizzy. It starts right up now, but my $400 Snap-on timing light broke!
So...I'll get it "fixed", then try to get it timed and set dwell.
Thanks for all the info Sharps40!

[Sharps40]

Yer welcome.

I use the 25 dollar actron timeing light from Advance...works good and its drop proof. When ya drop it ya get another and another and another. Ya can get 16 for the price of a snapon!!!!

[gofastnut]

Well, the Snap-Off I bought when I had money. I'm probly gonna borrow a cheapie to use. I love the light I have, just don't like the cheap way they anchored the circuit board under the buttons.
Oh yeah, also found the fuel pump indicating a leak out the "leak indicator hole", badly!
Gonna try to get it replaced on my lunch, adjust timing and see how it runs so I can drive it in the local parade.

[Sharps40]

Very cool. Luck!!!!

Leak indicator hole? I never heard of that one before. Are ya sure ya didn't accidentally discharge yer pistol into it in a fit of tuners frustration?

[Sharps40]

Oh hell, yer CA. Ya'll ain't got no guns or gun rights or even self defense rights. Sorry, I forgot, Peoples Public Of and all...bout like NJ anymore. Glad I'm here in the Great South....God, Guns and Trucks! Present Administration not withstanding!

[gofastnut]

Sharps,
I live in an Ag community, and God, Guns and trucks are still VERY popular. If I had discharged a firearm into it, I would have KILLED the whole engine, not just that weasily little fuel pump. The pump was not original, but some of them from 20 or so years ago had a weep hole, that would, well, weep when the diaphragm started leaking. A visual and olefactory alert, if you will This one did, and was shooting fuel out of the pump about a foot! Not to mention having about 3 gallons of gas/oil in the crankcase.
Got the pump changed out and checked timing...about 40 degrees retarded!!! I changed the oil/filter, put timing at 6 advanced and she runs great! well, not as bad anyways

[gofastnut]

So it runs pretty well. I have to adjust/fine tune the carb a little, but, it's WAAAAY better than it was! Oh, and only 1.5 turns out on idle mixture is what she likes.
Thanks for all the info, you guys are great!

[Sharps40]

I'm glad this worked out. Ya got it tuned, didn't shoot the truck and seem happy.

Mostly, I'm glad ya didn't shoot the truck!

Now, pack up yer stuff and move to Gods Country, the Great State of NC or any part of the South. Bring yer guns and trucks and stuff, we're hunkerin down fer the Obamaclips and gonna see it thru!!!!

Enjoy that CA Sunshine, go ride now!