Gigi rides again - with some issues

[Don Frelier]

Well your cam timing may not be correct if you didn't degree the cam. And 383s aren't real tolerant with a somewhat performance cam.

You're going to need a pretty good initial advance with that set-up and probably a higher stall converter.

Try 20 degrees initial and maybe go higher.
I would also try full manifold vacuum on the advance. But you'll likely need to restrict the mechanical.

You should be able to get it to idle at 650-700 with some tuning.

Do your other tests you mentioned like pulling a plug wire at a time and checking the plugs.
I've seen bad spark plugs right out of the box.

 

[RemCharger]

Agreed^^^ that's a good sized cam for the low compression, will need more advance at idle..and it's a 78 440

 

[subforry]

Ignition advance is in the 18-22 range. I think the mechanical advance springs are weak and kicking in just over 1000rpm (my understanding is 1500rpm or more would be better).

Vac advance is ported, but I can run manifold vac.

Currently no pinging or kick back on hot restart, also pulls well from cruise.

I hope to run more test Friday and Sat. Thanks for the support.

 

[Don Frelier]

Agreed^^^ that's a good sized cam for the low compression, will need more advance at idle..and it's a 78 440

Sorry when I see a picture of that one I immediately associated it with mine.

 

[subforry]

What is up with these spark plugs? This is even bank, 8, 6, 4, 2. I pulled 7 and it looks like other 3. There could have been manifold vacuum leak but wouldn't that make the plug lean? The wire to the distributor could have been loose. What else should I be checking? Again this is a junk yard engine, so a compression test?

These are Autolite 3923. It has Edlebrock heads.

I did pull each plug wire when the engine was running. For me, it was inconclusive.

The float level is 7/16 without the gasket, so a little high.

The even bank valve train looks good. The push rods spin, the throw looks all about the same, the looseness of the rods seems about the same.

My plan is to pull the remaining 3 plugs. Clean plug 4 and swap with another. Lower the floats. Reassemble. Focus on #4 plug wire, maybe swap with a left over wire.

 

[Don Frelier]

I am Not an autolite fan...

 

[subforry]

I am Not an autolite fan...

I am about to buy some new plugs and would be happy for a recommendation.

 

[RedBeard]

I am about to buy some new plugs and would be happy for a recommendation.

Champion

 

[subforry]

I found the #4 plug wire was damaged on the header. Swapped in a replacement. Replaced the plugs. It's idling the best it ever has, kind of fussy to tune. Seems to like a rich idle mixture. Also advanced the ignition time some more. Still stumbles, but I feel like that is more of a cam thing. Tomorrow I will blow out the cobwebs and see how it does.

I still plan to check the torque converter. Also the fuel supply is a little hacked together and I will clean that up.

Thanks for all the help.

 

[67 Mopar]

I suggest you start by checking your "idle circuit tuning" first... This deals with stumble, especially the initial "off idle stumble" under initial acceleration. An important, and often overlooked tuning process for proper initial tuning of an engine.
Hopefully this will help

Read through the instruction below before you start tuning.

To begin, make sure the engine is up to full operating temperature and the choke is completely off. A cold engine requires more fuel than a fully warmed engine even if the choke is off. Remove the air cleaner and connect the tach to the engine, and the vacuum gauge so it reads manifold vacuum.

Before you fire up the engine, slowly turn each idle-mixture screw in until it gently bottoms out and count the number of turns it takes. Do this for each idle-mixture screw and then return them to their original positions. If all the idle-mixture screws are not adjusted the same, do that now. Remember to always adjust both screws the same amount. This will help balance the idle mixture and allow the engine to run as smoothly as possible. If the carburetor is new to the engine, start at 1-½-turns out (counterclockwise) from full in.

Now start the engine and set the idle speed to around 850 - 900 rpm's or so with the curb idle-speed screw. If your engine has a big cam and must idle at a higher speed, that's OK. Note the reading on the vacuum gauge. Next, very slowly turn one idle-mixture screw in ½-turn and note the change on the vacuum gauge. If the vacuum reading increases say, from 14 inches to 14-½ inches, move around to the other side of the carburetor and slowly turn that mixture screw in ½-turn as well. If the engine stumbles or the vacuum drops when initially turning the mixture screw in, turn both screws out about a ½-turn and evaluate the results. On most carburetors, turning the mixture screw in (clockwise) leans the mixture, while counterclockwise (out) enriches the mixture.

The goal of adjusting the idle-mixture screws is to achieve the highest possible idle vacuum at a set idle speed. If the idle speed increases after you adjust the idle-mixture screws (which is likely), be sure to adjust the curb idle speed screw back to the base speed again before moving forward. This is important because a higher idle speed will increase the vacuum reading. Maintaining a standard idle speed will make it easier to evaluate changes to the idle-mixture screws.

 

[subforry]

Well it's been productive. Fixed the leaky gasket at the water neck, swapped temp senders, and lowered the seat.

As for the idle and carb, any restriction on PCV port causes a drop in idle which requires idle speed on the carb to be set too high, thus opening the butterfly past the slots.

The combination that seems to work is breather on the left, PCV on the right which is piped to a tee that runs to the carb PCV port and to the air cleaner.