timing / tuning question

[Capt Dan]

Got my '66 started this past weekend after 3 years in hibernation.

Runs OK, but I am having trouble getting the idle down. What RPM should it be ideling at? I know need to time the ignition and tune the carb. What order should I work in? What should my inital advance be (At idle) and what total advance should I be shooting for? I assume with the new cam etc. I will not be at factory specs. Should I disconnect the vacuum kickdown on the trans. before I set the carb?

I also have an intermittant miss on one side that I only notice at idle. I am going to check the plugs and wires. Anything else that could be causing this?

Thanks in advance.

 

[Kriek]

Similar question, so I'll just listen in.

 

[grego37]

Is the gas in the tank 3 years old too??

Is this a new rebuild?

If its new, Were the cam / lifters broken in properly?

I dont know what to reccomend on the timing specs, you may want to wait until someone chimes in with that. You may Need to post more info on your engine. cam specs, carb, compression ratio etc..

FOR INITIAL TIMING:
you need to disconnect the vacuum hose that hooks to your distributer, and plug the hose.
FOR TOTAL TIMING:
you need to hook that hose back up.

You need to lock in timing first,
then adjust the carb

 

[69Rcode_Mach1]

Yes as stated above always do the timing first then tune the carb. So long as the car stays running you should be fine. Here is my general order: Timing, set the idle, adjust the valves, and then all the rest of the carb (jetting, accelerator pumps, power valve).

 

[Capt Dan]

Engine was rebuilt a little over 3 years ago. Didn't drive it much because I had some reliability/driveability problems that I thought at the time may be caused by an old fuel system and the A/C. Had to put it away and now I am trying again. I broke the cam in as was directed at the time. (forget what that was now) Engine probably has less than 1-2000 miles on it.

New Gas. New Tank. New fuel line to pump. Cleaned a relatively new Carter HP fuel pump. New line from the pump to carb w/ new filter. Cleaned relatively new Edelbrock Carb and replaced gaskets. Car starts easily, but it just seems to want to idle around 1000 rpm so that it doesn't stall when I put it into gear. Seems a bit fast to me seems like it is hard on the tranny to pop it into gear that fast. I bought an idle compensator solenoid to help with the A/C this time around, but I haven't got that far yet.

Cam specs? Edelbrock performer cam
Carb? Edelbrock Performer 600CFM 4V
Heads? Stock - Had them re-built with the engine, but nothing drastic.
Don't believe there was much done to the engine beyond stock replacements to effect compression.
Headers? Yes - Hedman or Hooker, I believe. They have been on the car long before the rebuild.
Mechanical advance distributor. (Mallory Unilight)

As far as the miss goes I can just hear it out of the exhaust when standing in the back. Random intervals and only on one side. Probably need to check my wires again and clean and regap my plugs. this is minor and may work itself out after it has a chance to see the road. EDIT: I had the valves adjusted once I got it running the first time. Maybe I should do it again? How often should they need to be adjusted right after a rebuild? Maybe something slipped in one cyl. causing a miss?

 

[grego37]

ok.
Im no expert, but start here see how it goes.
Nevermind my dis-connect vacuum advance line comment, I thought you had a different distributer.

Set initial timing 10-12*
adjust air/fuel mixture screws until highest idle is heard (or highest vacuum using a vacuum gauge )
Then adjust your main idle adjustment, see if you can get it to idle around 700rpm.

Then check total timing:
have someone hold the rpms around 3000 , read the timing , and see what you get. hopefully its around 34-36*

Test drive , see if you like it.
You can repeat if needed , adding 2* to the initial (you should re-adjust carb if you change your initial timing)

 

[krash kendall]

Have you checked for any vacuum leaks? I run my car at 10* advance on the full vacuum port (driver's side) and idle at about 700 RPM. After that is done adjust your idle mixture screws using a vacuum guage hooked up to the tee at the back of your manifold. Start with the idle mixture screws at 1 1/2 turns out. Adjust one screw by turning out while compensating for RPM changes with the idle stop screw untill you reach the highest vacuum reading. Turn it back to the point to where it drops again to make sure then back to the highest point. Move to the other screw and do the same, then recheck the first screw.

 

[Kriek]

I found this guide helpful. (dont mind the website)

 

[Capt Dan]

On my Edelbrock carb I have three vacuum ports on the front of the carb. Two small on either side of a larger one. The larger one is connected to the PCV valve. Are both of the smaller ones manifold vacuum? I checked it on the drivers side and am pulling close to 15"

I did time and adjust it last night. Runs much better and idles around 800-850 and no longer dies when I put it in gear. Thanks.

Next problem.... the miss I thought was just one one side is really just the engine bogging at idle. with the timing light it looks like it jumps the advance 10+ deg. and then returns. Could this be a vacuum leak in the intake? I have a mech. advance distributor.

 

[krash kendall]

The port on the driver's side is full vacuum, the passenger side one is timed vacuum for cars with emmissions control. USE WHATEVER ONE WORKS BEST FOR YOU. I'M NOT OPENING UP THIS CAN OF WORMS! I use full vacuum and have the other one plugged as it allows the car to idle better at stops.

 

[krash kendall]

Oh, and close to 15 lbs is good. I get about 14.5 lbs. But you should be adjusting those idle screws with whichever vacuum port (again, I use full) hooked up to your advance. Your auto trans vacuum tee at the back of the manifold should have a small port blocked off that you can use for your vacuum guage.

 

[grego37]

Maybe your wires,cap ,or rotor

 

[krash kendall]

Try a higher grade of gas to smooth things out.