Bought my 63 a couple of years ago, and up until now have had no issues at all. When starting cold, I hit the gas and the choke closes. It starts and runs, but runs rough like it is loading up. Not a smooth fast idle. Once it is warmed up it seems to run better, but lately it seems that it still doesn't idle as smoothly as it used to. When I look down the carb, I'm not seeing gas pouring into the intake. Recently I've also noticed a little hesitation/dead spot when going around corners....feather the pedal a little and It's ok. I'm not a carb guy by a long shot...just looking for some things to look for. BTW, it's a Holley 4160. I did search the forum....just not sure where to start looking. I'd appreciate any help.
TIA
Danno

 

May just need a little cleaning. Go to NAPA and get some Seafoam.

 

yeah, seafoam ROCKS. mix some with your gas as directed AND pour 1/3 bottle slowly down the carb of a running warm engine. shut the engine off for 5 min and start it up and watch all the junk it disolves. read the directions. Its good stuff.

 

It may be time to put a rebuild kit in it.

Dan

 

Thanks you guys...I'll give the seafoam a shot. One thing I didn't mention was that it seems like the problem started soon after I bought some HT gas at BP. Previous to that, I had ALWAYS bought gas at a WalMart gas place because they were the only place that had 93. Last time I went to get gas there, all pumps had 91 octane stickers...no more 93. The attendant on duty swore up and down it was the same gas....she couldn't tell me why the pumps now have the 91 octane stickers. So anyway, I passed and went to the local BP and got the next best thing...92. Not sure if it's just coincidence, or not....but car has run like crap ever since....worse when cold. Choke appears to working correctly. Guess I'll try some new gas and buy some seaport.
Stay tuned.

BTW...Dan, I don't think the carb is that old. I'll check through previous owners old receipts.

 

Could be that the additives in the new fuel have dislodged some crud somewhere in your fuel system, making its way unintendedly to a passage or seat in your carb.

I'd give the Sea Foam a chance before switching fuels

 

Tried the seafoam...no change. Went to take her out for a spin tonight, hit the gas a couple of times, didn't hear the choke set. Started right up, but idled real rough. Pulled off the air filter after a couple of minutes and the choke was about 1/3 open. Put air filter back on and took it out for a long 1 hr drive. Every time I came to a stop it about died....had to put it in neutral to keep it running. Noticed a slight hesitation/stumble on moderate acceleration...but not always. Idles at just under 500rpm in gear...and like I said before barely stays running. What's the best way to set the idle up? Adjusting the set screw on the throttle or idle mixture screw. Any tps would be greatly appreciated. BTW...327/300, PG, Holley 4160.

Danno

 

FWIW, I would opine that the infamous "Bubba" has been messing with your engine at one or more points in the last 43 years.

The "Holley 4160" is a clue being as how the OE carb was a Carter AFB.

Chances are Bubba installed a high overlap cam.

Taking a vacuum and total idle timing reading at idle in Drive could be a clue. Please state idle vacuum in Drive as "xx Hg. @ xxx RPM" if you wish to respond.

Is the vacuum advance control signaled by full manifold vacuum or "ported" manifold vacuum? What is the ID code stamped on the VAC bracket? At what vacuum level does the VAC begin to advance and what is the full advance @ manifold vacuum reading?

What is the initial advance, and what is the centrifugal advance curve?

The answers are usually in the details, not in a bottle or can.

I responded because you finally gave us a clue in your last post about the configuration - 300 HP PG - which is a good place to start when seeking advise on an engine driveabililty problem.

Duke

 

Reminds me of what an instructor used to tell us in trade school.

"Basics, Basics, Basics."

Check or change the fuel filter, check float level, take a peek in the tank is there rust?

The idle seems a little slow to me. Although I think the factory manual say's around 475 for automatic trans.

As Duke pointed out the carb is not OEM. Which a lot of times means the car is over carbuerated.

 

Thanks for the replies....I'll get some more info and post later. FWIW, I've owned the car for 2 years....it ran and idled perfectly up until a few weeks ago, so don't think it's over-carbed. The idle was never lumpy, so I think the cam is probably stock or close to it. I do know that the engine was rebuilt in the mid 70's...just not sure what it invloved.Seems like I checked the casting numbers on the intake, and it was a 65 vette intake. No issues with the tank as it was replaced by a previous owner.....looks very clean. My gut tells me it's running rich and loading up...but who knows.

Thanks again!

Danno

 

Check all vacuum hoses and components for leaks.

Duke

 

Thanks, Duke. I've eyeballed vacuum lines and didn't see anything obvious. I'll look closer tonight after work.

 

Pull the plugs. Bet they are carboned up (black) and time for a change!

 

I decided to pull a plug to take a look....pretty black. Went ahead and installed a new set of AC R45's per some past forum threads....it had R43's. Thought for sure it would run better...same thing. Pulled off the shielding...there is no can on distibutor. Previous owner installed Pertronix... See pic...



With engine barely idling vacuum reading was 10g @ 400 rpm



Timing at idle was at the top of the plate (18 degrees ?)

OK, Duke beat me up.....

 

what kind of distributor is that??

anyway, I'm definitely no expert but if I recall properly 10hg @ idle on a 327/300 is way low. In fact that's lower than the vacuum on my L76 with the 30-30 cam! i'd guess somebody changed out the cam to something much different than stock.

I'd also strongly consider swapping out the distributor to a correct one with a vacuum can. Running vacuum advance typically gives you better throttle response, better idle characteristics, and a cooler running motor.

 

Pic of the old plugs...

 

Looks like some kind of aftemarket distributor with no vacuum advance. That's part of the problem. Start looking for a tach drive single point. Virtually any will do. Set it up with a 12" vacuum can. Measure the centrifugal and establish the initial timing to achieve 34-38 total WOT advance, and this should yield low to mid 20s total idle timing.

Try advancing the initial to about 24 at idle, as you advance you will have to adjust the idle speed down to maintain about 450 to 500. Take a vacuum reading. If it's less than about 15" it probably doesn't have the OE cam.

You should also research the list number of the carb and determine what application it was originally for. Chances are the idle/off idle is not set up for your engine configuration.

Bubba had definitely been working on your engine.

Duke

 

"I've owned the car for 2 years....it ran and idled perfectly up until a few weeks ago, so don't think it's over-carbed. The idle was never lumpy"


A couple of comments:

You said the car ran well and then at some point in time it started to run crappy. So rule out the constants.

In spite of the fact that they're not original to your car, the distributor, the and the Holley, just because of what they are can be ruled out. I am curious about that gas stain on the manifold below the float bowl plug. I can't see a fuel filter so I don't know if you're running one. You should be. You may have a piece of junk lodged in the needle valve. Why not take a look?

The plugs look like they are too cold and maybe gas fouled. 43's are too cold. 45's are okay.

I've never seen a pcv laying in the horizontal like yours. I doubt it's causing your problem.

The distributor? I'd check the points condition and dwell. It may have changed. If it's pointless, I can't help you.

The intake manifold looks like a factory Holley manifold although maybe not for your particular year car.

Don't get sidetracked by people saying your car has been "Bubbaized" and automatically start throwing money at changing parts to make it "correct". Your basic setup was in the ballpark at one time. Just something changed, like the gas. I also doubt the gas is your problem. It's something simple.

 

Appreciate the replies everyone. I'm still convinced this carb is loading up...so I'm going to look into that before I even think about considering ignition/timing. What I do know is that it ran flawlessly for 2 years with the current setup. I'm with Mike...it's probably something simple....i.e. vacuum leak, sticky float, etc..
I'll let you guys know what I find.

Danno

BTW, Mike...The gas stain you see is actually a cleaner I sprayed the carb with. No gas leaks.

 

When you get the carb apart, check the power valve diaphragm for leakage. It may be blown.