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360 really doesn't want to idle in gear

Smokinnjokin

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Mid 70's smog engine swap in a '67 satellite with a 727. Engine has headers, edelbrock performer 500cfm carb and otherwise stock.

I am having a really tough time getting it to idle properly in gear while holding the car with brakes. As soon as I shift into D, it starts idling very erratically. Same when I start slowing down at a stop sign, once the car slows to 5mph or so the idle gets very rough and erratic. It is nice and smooth when in P or N.

I am reasonably sure the car does not have the correct TQ for my rearend gear ratio (3.23) because such a high idle is required to keep the car from stalling in gear while holding at a stop. Regardless, i feel that the poor idle quality in gear is a separate issue.

I have gone through the Edelbrock carb to set lean idle air screws and electric choke. Car has points but seem to work fine, starts right up instantly and vac advance is working. Timing pointer is missing so tough to check timing, Any other ideas?
 
check for vacuum leaks using a gauge or spray test,
you should not need a high idle to run in gear.
check for carb being Too lean with gauge.
have the mixture screws at least 2-1/2 turns out to start with.

and check to make sure that you put a 360 convertor in that 727.
360 is weighted on the vertor,318 is neutral balance.
did the 727 come with the coronet or the mid 70s 360??
almost sounds like a locked up vertor?

you say car starts up instantly,so? sounds like the timing is close,
i would try adjusting it a few degrees at a time/turn the dis Barely and try to restart the car.
if it gets easier to start,tighten the dis,
then get in the car and listen Carefully while do do the powerbrake test.
hold brakes put car in gear and bring engine up in rpm you will hear a rattle if the timing is too advanced.
loosen the dis and bring it Back a few degrees.
do Not drive the car till you get the timing close to where it should be.

also,i am curious,what motor mounts and brackets did you use to get the 360 in the coronet?
 
Sounds like a vacuum leak somewhere. Are you running power brakes or manual? Plugs will also show weakness when under a load. I always start with the simple possibilities first and go from there. I agree though if it fires right up timing is pretty close.
 
check for vacuum leaks using a gauge or spray test,
you should not need a high idle to run in gear.
check for carb being Too lean with gauge.
have the mixture screws at least 2-1/2 turns out to start with.

and check to make sure that you put a 360 convertor in that 727.
360 is weighted on the vertor,318 is neutral balance.
did the 727 come with the coronet or the mid 70s 360??
almost sounds like a locked up vertor?

you say car starts up instantly,so? sounds like the timing is close,
i would try adjusting it a few degrees at a time/turn the dis Barely and try to restart the car.
if it gets easier to start,tighten the dis,
then get in the car and listen Carefully while do do the powerbrake test.
hold brakes put car in gear and bring engine up in rpm you will hear a rattle if the timing is too advanced.
loosen the dis and bring it Back a few degrees.
do Not drive the car till you get the timing close to where it should be.

also,i am curious,what motor mounts and brackets did you use to get the 360 in the coronet?

I did not do the swap, but I have been in the bellhousing and seen that it is an externally-balanced 360 convertor. Not sure what mounts were used.

Counted turns on the airscrews and took them both out to 2-1/2, one was considerably farther in, that helped a lot. Wish edelbrock had that bit of info in the manual, possibly I overlooked it. Now I have a rattle under light acceleration so I'm guessing the timing may be a bit too advanced. Going to play with that today.
 
Sounds like a vacuum leak somewhere. Are you running power brakes or manual? Plugs will also show weakness when under a load. I always start with the simple possibilities first and go from there. I agree though if it fires right up timing is pretty close.
Manual drum brakes, manual steering. No evidence of vac leaks.
 
I am curious if my vacuum advance is set up correctly. I read on FABO thread that the vac advance hose needs to go to the ported vac line on edelbrock carbs (#50 on diagram) not the full-time vac port (#51). I just checked mine and it is hooked to the full-time port. Is this causing too much advance too soon? Would that cause the detonation at part-throttle acceleration?
 
I don’t have a diagram in front of me to know which number your referring to. But it’s the tiny port on the front passenger side I believe. But yeah a full vacuum port would be pulling vacuum to soon. I always plug the vacuum hose from the distributor to set the base timing. Then hook it up and go from there.
 
I forgot this is a mid 70's motor in a '67 car, and that the timing marks are hiding under the water pump cast into the cover. So I was able to get a timing light on it.

Ok so i switched the vac advance to the correct port, bumped timing from 5btdc to 12, car feels good holding it using brakes. Now just need to test drive to see if my rattle went away. No indication of it reving up to mid-range holding car with brakes. Starts right up and idles nicely. Returns to idle with no problems.

Test drive results coming later today!
 
I am curious if my vacuum advance is set up correctly. I read on FABO thread that the vac advance hose needs to go to the ported vac line on edelbrock carbs (#50 on diagram) not the full-time vac port (#51). I just checked mine and it is hooked to the full-time port. Is this causing too much advance too soon? Would that cause the detonation at part-throttle acceleration?

I'm not sure what the diagram looks like. Move the vac hose to the other one and see what happens.
 
Ok, so car is running good with latest settings. Timing set to 12 btdc static, vac advance working properly hooked to ported vacuum.

I still have a rattling sound though during acceleration, i don't think it is detonation or lifter noise. Through changes to timing and carb settings the sound has not changed at all. Motor feels great, revs well and feels like plenty of power (for stock smog 360 anyway).

Timing mark is wobbly at higher rev ranges, i'm thinking this means my oem timing chain/gear is not doing great? There is a flapping noise from the front of the engine when i rev it, I think thats what sounds like rattling from inside the car while accelerating. It's not terrible, a minor annoyance really but the exhaust is so quiet i can definately hear it with the windows down.
 
Put a new chain on it, make sure to get one that allows for a couple of degree adjustments. If it's stock then set it at 0 or slightly advanced.
It will run even better.
 
Put a new chain on it, make sure to get one that allows for a couple of degree adjustments. If it's stock then set it at 0 or slightly advanced.
It will run even better.

So timing should be closer to 0 for a low-compression smog motor? Only mods are edelbrock carb and full TTI headers/exhaust system. Running 87 octane. No vacuum accessories. I only ask because it seemed to run stronger when I bumped the timing from 5btdc to 12btdc.
 
Cam valve timing, not ignition timing. Mechanical not electrical.
I suggest you do some reading on how to set up a timing chain before you install one.
 
I’d definitely put a chain on it if you can hear it. Don’t want it to slip and possibly bend valves and such. Or do what my duster did once and leave you stranded away from home.
Glad to hear you got it running good though. That’s a good feeling!
 
Cam valve timing, not ignition timing. Mechanical not electrical.
Yeah I definately have no experience with cam swaps. Don't want to crack the motor open until I 100% understand whats involved. Is it possible to swap timing chain/gears without removing the cam?
 
Yeah I definately have no experience with cam swaps. Don't want to crack the motor open until I 100% understand whats involved. Is it possible to swap timing chain/gears without removing the cam?
Yeah totally. Bottom sprocket slides over crankshaft, top sprocket bolts to the front of the cam. Just make sure you have top dead center and all that jazz in order.
 
I do have a plunger dial indicator I use for TDC on motorcycles, I will have to take a look and see if I have the correct adapters to thread it into the #1 spark plug hole.
Any recommendations for a cheap/strong timing set that is appropriate for a mostly stock motor? I can upgrade to something heavy duty later when I do a cam swap. Right now, i just want reliable.
 
An inexpensive timing set won't necessarily fail. But I had a fair to good quality one that was 3.5 degrees retarded right out of the box. If you plan to upgrade the cam later then just throw something in. I'll bet it will run better than it does today.
Melling or Sealed Power will be fine.
 
Ok, so to double check that I understand how this works, I can't necessarily trust that my factory cam+ whatever timing chain I buy will be mechanically accurate?

So I install my new chain at 0degrees, set my dist at 0 static and verify that the #1 piston is actually at TDC. If it is off, I write that # down and from then on, I will have to add it when reading my timing marks and timing with a light (or add it to the light if it has that option?) to get the true value. Is that about the gist of it?
 
To really understand this stuff I suggest you find a good engine building book and study it.
To just put a chain on you are pretty close. But to understand valve timing is more complicated.
To do it properly and understand the relationship between the valve opening/closing relative to the piston position you need a degree wheel on the crank.
A dead stop for the piston and a dial indicator on the intake valve.
To just replace the chain with what you have you really don't need to go through this procedure.
Your cam is retarded right now because the chain is stretched.
Guarantee it.
 
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