is too much advance a good sign of a engine not wanting to start cold? my engine is a bear to start when shes cold and latley ive been having one tunning prob after the next. so i was screwing with the timing and now she takes alot of crankin to start. i want to have it set so my timing is 25 about at idle and 35 at wot but how could i do this without going over advance? could i just take out my mechanical and leave in my vacum? would it still start.

stock dist

 

i just run the machincal advance on my 406 25 degrees idle 36 total.it starts fine hot and cold

 

so no vacum just mechanical. what type of spring curve kit do you have in it?

 

its got accel springs and weights...but its been so long thati cant remember what springs i used...yeah no vaccum advance i unhooked it was pulling way too much time.it runs a hell of alot better now

 

So you can just block off the vac. advance and set the mech. to about 25 or 26???? I have the light springs and stock weights in my car... is that a good drag racing trick or street?? I may try that next Wed at the track..... What do you think?

-Terry-

 

yeah just plug off the vaccum port on the carb and set your timing so it pulls 35 or 36 whatever your engine likes best.i drive around everyday like that,its worth a try.most race cars dont have any type if advance, the distrubter is welded where the weights go on and they run there total advance all the time.

 

i havent tried it yet but i always thought the advance at idle will make hard starts.

 

it does make hard starts with full advance at idle ,25 degres isnt so bad.some people with full advance all the time have a swith to get the engine rolling and another to put power to the distrubter once it is rolling or they just buy some kind of start rertartfor there ingition.id like to try that but its too much crap to go through on a street car

 

You're talking high compression, high lift/overlap cam stuff. For a street driver, keep the initial advance reasonable (allow more mechanical advance in the distributor), and set for total with the engine RPMs high enough for full mechanical with the vacuum disconnected - you need either a timing light with dial-in advance capability, or timing tape on the damper. Connect the vacuum advance back up for good idle and cruise behaviour.

FWIW, excessive initial advance usually causes more problems with hot starts (kicking back into the starter) than with cold starts. If the "not wanting to start" you're talking about is cranking and cranking before it fires, that most likely has absolutely nothing to do with ignition advance.

 

Having to crank and crank the motor over to start when cold sounds more like a dry fuel bowl in the carb than a
advance problem.
Edelbrock carbs have a tendency for this because the fuel bowl is internal where a holleys fuel bowl is on the side of the crb.(front and back).
When the car is shut off hot after a good run, the fuel in the bowl tends to evaporate making for a longer start the next day or next week.
More so than say a holley.
Nothing really to worry about. Just give 'er a few good pumps of the gas pedal before starting (to get some fuel in the intake manifold) close the throttle and it will start almost immediately. In the modern era of Electronic Fuel Injection we forget that a carbed motor needs a little priming of fuel in the morning to start quick. This is pretty normal.
You could try a wooden carb spacer under the carb to reduce the heat soak.
Your timing ( 25 initial and 35 total sounds about right for a hi performance advance curve with a cam like you have. You want to retain the vacuum advance for efficient part throttle cruising. Not need to disconnect it.

 

so how could i get that little amount of advance with the vac hooked up?



thats a good possibility.my fuel feed system is lame as well so im sure its not helping any. i have a efi in tank pump with a 3 port regulator that sends one line back to the tank and one to the carb. it was only temporary untill i went lt1 injected but i have yet to aquire the parts.maybee it syphons the fuel out of the bowl some how.

 

Siphoning is an impossibility since the needle/seat is well above the fuel level.

 

"so how could i get that little amount of advance with the vac hooked up? "

If you hook the vacuum advance to the "ported vacuum" source on the front of the carb, there will be no vacuum signal at curb idle speed. therefore no vacuum advance at idle. When you open the throttle part way (like while cruising down the road, there will be vacuum at that port and vacuum advance during cruise.
Set your initial timing and total mechanical timing with a timing light with the vacuum advance hose disconnected and the idle speed set as low as possible. then reconnect the vacuum advance to ported vacuum. Then readjust the idle speed to about 700 in gear.

You will always have problems with a carbed motor if you use a EFI fuel pump. If you could replace the fuel pump with a nice 6PSI high flow pump and get rid of the regulator you'd have less problems. You will still likely need to pump the throttle a few times in the morning to
prime the intake with fuel thou. Just part of the joys of running a carburator. Get used to it.

 

i still dont understand how i could only get like 10* of advance. most mechanical advance mechanisms advance over that amout just by itself than adding vacuum on top would be way over advance. i only need like 10*

i guess i dont understand how i could use both.

 

HELLO!!!!

Ya want 25 intial base timing. you want it to mechanically advance varying with RPM to 32-36 degrees at high rpm. (with the weights at maximum travel)
If the mechanical advance travels more than this, limit its travel. (change the weights to ones with a different shape, change the centerpiece, add a bushing to the advance pin, weld up the advance travel slot that the pin rides in.)
You then want to add an additional 10 to 20degrees of further vacuum advance while cruising down the highway at part throttle. Therefore your total advance at cruise on the highway will be like 46 to 56 degrees BTDC. ........25(I) +11(M) +10(V) = 46.....

Setup the vacuum advance to achieve this. (10 to 20degrees)
get an adjustable vacuum advance (Crane Cams) ... You can adjust the rate of advance per inch of vacuum applied By adjusting the diaphram spring.
and you can limit the travel of the advance linkage to set the amount of vacuum *advance travel*. (This is independent from the rate of advance.)

Get someone that knows distributors to help you.