Idle Issues

[canonball]

Disclaimer: Carbs are not my forte.

I'm slowly learning how to work on these things, I've got a '63 with original V6 and a brand new 2 barrel Holly that replaced the tired, old stromberg. At first it was running and idling great (last week), now the idle is throwing a tantrum. It's rough, doesn't want to stay running when it's cold, once the engine is proper warm it will usually stay running but it's still rough and periodically backfires up through the intake. But when the light turns green and you're giving it gas and moving through the gears it runs beautifully.

I'm going to take a look at it tomorrow and see if I can't figure out whats going on with it. My guess is either the idle mixture screws need to be adjusted or the idle jet might have debris clogging it up. The old fuel filter (I think it was original) was the little glass cup the fuel would flow through, not sure how well it filtered out debris since it didn't actually have a filter. Anyway, I was planning on getting an in-line I just haven't gotten there yet. But I figure with the old gas tank it would probably be pretty easy for something to float it's way into the carb and plug it up somewhere.

Given the issues, do those sound like feasible causes?

[WOLFMANmike]

Originally Posted by canonball

Disclaimer: Carbs are not my forte.

I'm slowly learning how to work on these things, I've got a '63 with original V6 and a brand new 2 barrel Holly that replaced the tired, old stromberg. At first it was running and idling great (last week), now the idle is throwing a tantrum. It's rough, doesn't want to stay running when it's cold, once the engine is proper warm it will usually stay running but it's still rough and periodically backfires up through the intake. But when the light turns green and you're giving it gas and moving through the gears it runs beautifully.

I'm going to take a look at it tomorrow and see if I can't figure out whats going on with it. My guess is either the idle mixture screws need to be adjusted or the idle jet might have debris clogging it up. The old fuel filter (I think it was original) was the little glass cup the fuel would flow through, not sure how well it filtered out debris since it didn't actually have a filter. Anyway, I was planning on getting an in-line I just haven't gotten there yet. But I figure with the old gas tank it would probably be pretty easy for something to float it's way into the carb and plug it up somewhere.

Given the issues, do those sound like feasible causes?

yes very ..... you most surely want to put a good inline filter in ... next and most likely you have junk in your needle ans seat causing havoc and hate and discontent ... but if the carb does not have the blue reusable gaskets then you could be looking at buying new ones to get the junk out of the needle and seat . i don't really think its the mixture screws as it was running fine before ... but just in case after you get the junk out most Holley carbs like 2 and a half turns out hope this helps ya Happy Truckin

[geezer#99]

X2 on the need for a filter but leave the carb alone for now.
What's your initial timing?

[TJ's Chevy]

Originally Posted by canonball

Disclaimer: Carbs are not my forte.

I'm slowly learning how to work on these things, I've got a '63 with original V6 and a brand new 2 barrel Holly that replaced the tired, old stromberg. At first it was running and idling great (last week), now the idle is throwing a tantrum. It's rough, doesn't want to stay running when it's cold, once the engine is proper warm it will usually stay running but it's still rough and periodically backfires up through the intake. But when the light turns green and you're giving it gas and moving through the gears it runs beautifully.

I'm going to take a look at it tomorrow and see if I can't figure out whats going on with it. My guess is either the idle mixture screws need to be adjusted or the idle jet might have debris clogging it up. The old fuel filter (I think it was original) was the little glass cup the fuel would flow through, not sure how well it filtered out debris since it didn't actually have a filter. Anyway, I was planning on getting an in-line I just haven't gotten there yet. But I figure with the old gas tank it would probably be pretty easy for something to float it's way into the carb and plug it up somewhere.

Given the issues, do those sound like feasible causes?

The 2 barrel should perform fine on that engine out of the box. The 1st problem that comes to mind is the old fuel filter being left on. ANY time you install a new carb on an engine you should put a new filter in. A metal filter from Napa will work just fine, or even the clear plastic filter so you can see how clean the fuel is or isn't. I would bet fuel issue since it was running fine before. Geezer mention timing, but that probably isn't the issue as the engine WAS running Just fine. But for your info the factory initial timing was 4-6 degrees advanced. Lot of times you can bump the timing up and the engine will perform even better. I have a 305E with a 4 barrel and dual exhaust. Timing is set at 10 degrees with the vacuum advance on Ported timing. Engine is very responsive and has much better pull to it. Try a new filter and run it for awhile, richen up the idle mixture screws to see if that helps, but if the carb has crap in it...your gonna have to take it apart and clean it or it'll never perform its best. While your at it I'd do a valve adjustment to. These engines HATE tight valve lash, and will throw idle tantrums with tight valves as well. .012 for the intake and .018 for the exhaust. Run the engine until it comes up to full operating temp and you can adjust the valves with the engine on or off. I did mine running and had them done in a few minutes. Keep us posted.

[WOLFMANmike]

Originally Posted by TJ's Chevy

The 2 barrel should perform fine on that engine out of the box. The 1st problem that comes to mind is the old fuel filter being left on. ANY time you install a new carb on an engine you should put a new filter in. A metal filter from Napa will work just fine, or even the clear plastic filter so you can see how clean the fuel is or isn't. I would bet fuel issue since it was running fine before. Geezer mention timing, but that probably isn't the issue as the engine WAS running Just fine. But for your info the factory initial timing was 4-6 degrees advanced. Lot of times you can bump the timing up and the engine will perform even better. I have a 305E with a 4 barrel and dual exhaust. Timing is set at 10 degrees with the vacuum advance on Ported timing. Engine is very responsive and has much better pull to it. Try a new filter and run it for awhile, richen up the idle mixture screws to see if that helps, but if the carb has crap in it...your gonna have to take it apart and clean it or it'll never perform its best. While your at it I'd do a valve adjustment to. These engines HATE tight valve lash, and will throw idle tantrums with tight valves as well. .012 for the intake and .018 for the exhaust. Run the engine until it comes up to full operating temp and you can adjust the valves with the engine on or off. I did mine running and had them done in a few minutes. Keep us posted.

thats why i didn't mention timing as it was running good before ... unless the chain is so old it jumped a tooth and threw out the timing . but this is very unlikely

[TJ's Chevy]

Originally Posted by WOLFMANmike

thats why i didn't mention timing as it was running good before ... unless the chain is so old it jumped a tooth and threw out the timing . but this is very unlikely

These engines have lasted as much as 500,000 so yes....very unlikely a tooth jumped. Especially Right when carbs were swapped. lol

[cadillac_al]

I always blame the points and condenser first unless they are new. Running dirty gas through a new carb isn't the best move either. I would still blame the points unless they are new.

[WOLFMANmike]

Originally Posted by cadillac_al

I always blame the points and condenser first unless they are new. Running dirty gas through a new carb isn't the best move either. I would still blame the points unless they are new.

Good point I just assumed it was a HEI. .. well you know what they say about assuming lol.

[TJ's Chevy]

Originally Posted by WOLFMANmike

Good point I just assumed it was a HEI. .. well you know what they say about assuming lol.

Unfortunately these never came from the factory with an HEI. Sucks cause they make a nice improvement. Though there is a guy who makes a direct swap one on ebay. Spendy though, but nothing but good reviews.

[canonball]

Wow, been busy the last few days and haven't had a chance to check in here. Thanks for the info guys! So I richened the fuel mixture a little a few days ago and that helped, it's still a little rough, mostly while it's getting warmed up, but it holds an idle and still runs great when driving up and down through the gears. On fuel filters, I'm guessing I'm going to need someone to help me cut and flare the fuel lines in order to fit the fuel filter right? Any recommendations on fuel filters? I'm used to the clear plastic filters used on bikes, I like being able to monitor the fuel going through there.

[TJ's Chevy]

I've used clear plastic filters several times. Since I know my system is clean I've now gone to the metal type. Feels safer. lol You can cut your line and use rubber hose and a filter.

[cadillac_al]

Fram makes clear automotive fuel filters.

[canonball]

She's running better now, in nosing around under the hood I also found a bad fuel line, don't know how I missed it before. The rubber hose that runs from the metal line underneath the engine up to the fuel pump. It was deteriorating to the point that it looked like one of those soaker hoses you buy for the garden. That's replaced with some brand new hose. Where would you guys recommend fitting the fuel filter? It would be easy to put it in the middle of that hose I just got, is it better to have it after the fuel pump though?

[TJ's Chevy]

Since you have a stock pump it doesn't really matter. Anywhere that keeps the filter far enough from the exhaust manifolds.