You can adjust the tension on those. If you installed the MP springs they let the timing all in fast!
Slight acceleration hesitation driving me mad
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Coronet-383
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Ok so I shouldn’t need to replace springs or anything like that? And should I be aware of how i take the distributor off the car? Or specific way to put it back in to make sure the timing isn’t way out of wack? Thanks again for the help, it may be a week till I can get it off the car but I will post updates when I can. Thanks again!
miller
Well-Known Member
I doubt the springs will need to be replaced...unless one is broken. Has happened before, but rarely. Spring kits can be found, but would need to be the right types for the distributor.
Don't worry about the position of it on the motor! There's no magic to it, and the more you learn about it, the better off you'll be. Dropping a distributor in a motor, and timing it, can be as simple, or hard, as you make it.
You just need to find out why, the advance isn't working, understand why, and fix it. If you look in the book, under specs for your distributor, it will tell you how 'much' advance is built into it, via those mentioned slots.
Would be worth your time to research mechanical advances. Via those slots, that limit the amount of advance in degrees, some are fixed, some are adjustable, some get welded up (to shorten the slots), and so on.
The more you know about it, will help you decide which way you want to go. Remember full advance on these Mopars is usually 34-36, and the advance amount in the distributor should work with it. Here's the big BUT. Today's crap gas, not like the gas was back in those days, the car was made.
Initial timing (no advance) that you check with the timing light, with today's gas usually needs more initial timing. To keep full advance in check, yes, the advance amount needs to be adjusted. A fair initial timing set, for today's gas...14-16 degrees. Subtract that, from full advance, gives you the amount of advance degrees you want 'in the slots'.
Coronet-383
Well-Known Member
I’m gonna spend some time researching this like you suggested especially since I prolly won’t be able to pull it off for another week. Thanks again for the help, I’ll keep you guys posted
Mark the housing to the block, remove cap and mark rotor position on housing. Take picture.
Remove the hold down and pull the distributor straight out.
Remove 2 vacuum advance screws and remove.
Remove 2 advance plate screws and remove.
Mechanical advance is below. The plate with the 2 slots should be marked. That number x2 = crank degrees. So if it says 12....12x2=24° mechanical advance so your initial could go to 12 or 13° (24° + 12° = 36° total advance).
The weights can seize/rust so squirt some pb blaster on the pivots and work them loose.
To remove the advance plate, there is a finicky circlip holding it under the felt on the shaft.
The weights are below the plate
Remove the hold down and pull the distributor straight out.
Remove 2 vacuum advance screws and remove.
Remove 2 advance plate screws and remove.
Mechanical advance is below. The plate with the 2 slots should be marked. That number x2 = crank degrees. So if it says 12....12x2=24° mechanical advance so your initial could go to 12 or 13° (24° + 12° = 36° total advance).
The weights can seize/rust so squirt some pb blaster on the pivots and work them loose.
To remove the advance plate, there is a finicky circlip holding it under the felt on the shaft.
The weights are below the plate
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I see ya have two different size springs in there and read this is a thing to do. Was this helpful with your giddeeup?
Not my pic but those are stock. The heavy one has an elongated loop so it doesn't add tension until higher rpms, i.e. comes all in later. In my setup I am using the stock light spring and a light aftermarket spring. Pulls total timing around 2400 rpms.
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FYI...
My Prestolite dual point distributor in the GTX is similar in construction and operation. What I've done is REMOVE the heavy looped spring completely and substituted a lighter spring from a 318 auto trans engine (it fits just fine), the result is all in at 2600 RPM (engine). YES, the total advance is controlled by the length of the slots. The info given previously is spot-on. These are specific to the TYPE of distributor....does NOT interchange with the Prestolite dual point distributor. 34° - 35° TOTAL advance is a good place to start depending on the fuel composition. Everything depends on your circumstances. Just my opinion of course.
Bob Renton
It's curious that the OP said the hesitation started AFTER he rebuilt the carburetor. I'm with Bob that the check valve under the accelerator pump shooter was not put back if it was a ball bearing, or put in upside down if it was a needle. Fix the mechanical advance, but pull the shooter and check that valve!
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Gentlemen,
My original comment re the OEM Holley carb....is it original to the car or you? I believe the original Holley is a model 4160 but some 383 engines came with Carter AVS styles....not "Eddys", but original AVS carbs.
IF its sn original Carter AVS, it will have an inlet ball check valve at the bottom of the accelerator pump well. IF it is an original Holley, it MAY have an redish orange "umbrella" style accelerator pump inlet check valve OR it may have the traditional ball check valve. But both designs use a discharge check valve immediately below the pump discharge nozzles to limit/eliminate the possibility of pull over fuel discharge under high primary air flow. As mentioned previously by others, it only takes a few seconds to check. Also examine the pump's inlet check valve (both types), if not seating properly, part of the initial accelerator pump's volume will be waisted (not delivered) resulting in a possible stumble off idle. The type of fuel being consumed has EVERYTHING to do with the mixture. Ethanol blended fuels have lower heating values (energy) and highet vapor pressure index numbers which may make fuel percolation in the carb more prevalent. Just my opinion of course.
Bob Renton
My original comment re the OEM Holley carb....is it original to the car or you? I believe the original Holley is a model 4160 but some 383 engines came with Carter AVS styles....not "Eddys", but original AVS carbs.
IF its sn original Carter AVS, it will have an inlet ball check valve at the bottom of the accelerator pump well. IF it is an original Holley, it MAY have an redish orange "umbrella" style accelerator pump inlet check valve OR it may have the traditional ball check valve. But both designs use a discharge check valve immediately below the pump discharge nozzles to limit/eliminate the possibility of pull over fuel discharge under high primary air flow. As mentioned previously by others, it only takes a few seconds to check. Also examine the pump's inlet check valve (both types), if not seating properly, part of the initial accelerator pump's volume will be waisted (not delivered) resulting in a possible stumble off idle. The type of fuel being consumed has EVERYTHING to do with the mixture. Ethanol blended fuels have lower heating values (energy) and highet vapor pressure index numbers which may make fuel percolation in the carb more prevalent. Just my opinion of course.
Bob Renton
Thanks - what's happened to me (sorry again for horning in on this post) is after putting in lighter springs and obtaining a functioning vac advance (as it wasn't working) is a friggin floating stumble or miss around 3000-3200rpm. This is right around the rpm I reckon the initial advance is done now with lighter springs. Adjusting timing affects the extent of this; but cannot get it to go away. Seems as though when I disconnect advance and run it stumbling goes away. Have run timing from around 12 to 5 with less stumble at lower advance but no going away. I have electronic ignition and a slightly mod cam. Ran perfect before trying to think I should have a working advance and lighter springs for quicker advance. Ready to nuke the advance and run it like it was before...
Have you verified the vac cannister holds a vacuum? What you think is a stumble could be the vac advance buffeting under vacuum. Or maybe put the stock springs back in and try it out as a baseline.
I have the light springs but I am also running 22 initial /37 total, vac advance on mine has been shimmed. Different cam as well but mine loves it.
Coronet-383
Well-Known Member
It’s an original Holley, says it on the build sheet
Coronet-383
Well-Known Member
it also has the orange umbrella style check valve I replaced it when rebuilding, the flat disk side is under on the spring and diaphragm side, did i install that incorrectly?
Coronet-383
Well-Known Member
This isn’t my carb but how I put it in, is it possible I pulled it through too much?
Coronet-383
Well-Known Member
miller
Well-Known Member
Arrggg. Sometimes, even old farts like me, have off days. Appreciate you guys straightening my act out!
So, like it was mentioned, before you pull the distributor, do this...
Yeah, you can mark the distributor housing/rotor location, to help. Or, pull the coil wire, so it doesn't try to start. Bump the motor over, until you have the timing mark on the dampner, at the timing tab on the timing chain cover. Just don't go past zero.
Then, with the distributor cap off, note the direction the rotor is pointing. It will be towards #1, or #6. Doesn't matter. When you drop the distributor back in, rotor pointing the same direction, it will be in the ballpark. A starting point. Also note the direction the housing is, so when back in, timing is adjustable.
Ron H...might already know this, on the springs. If both springs are the same, you have a single stage advance, or straight line. One light, one heavier, is a two stage advance, making a curve in the advance.
So, like it was mentioned, before you pull the distributor, do this...
Yeah, you can mark the distributor housing/rotor location, to help. Or, pull the coil wire, so it doesn't try to start. Bump the motor over, until you have the timing mark on the dampner, at the timing tab on the timing chain cover. Just don't go past zero.
Then, with the distributor cap off, note the direction the rotor is pointing. It will be towards #1, or #6. Doesn't matter. When you drop the distributor back in, rotor pointing the same direction, it will be in the ballpark. A starting point. Also note the direction the housing is, so when back in, timing is adjustable.
Ron H...might already know this, on the springs. If both springs are the same, you have a single stage advance, or straight line. One light, one heavier, is a two stage advance, making a curve in the advance.
oldbee
Well-Known Member
Looks ok to me.
Coronet-383
Well-Known Member
*update* got the distributor out today, first I hooked the vacuum advance to a vacuum pump to check if it worked also checked it off the car and off the distributor housing and it didn’t work at all. Seems to be dry rotted and frozen. disassembled everything and the advance plate was stuck too. Unfortunately the little nylon end piece that the pin goes through it and the distributor shaft broke when trying to get the pin out. Went to the auto shops in the area and none had the correct vacuum advance for the car and local speed shop couldn’t find the nylon piece so I ordered a remanufactured distributor which should hopefully be in monday. I also finished cleaning, lubed and reassembled the old distributor, hopefully the new one fixes the issue. Does anyone know where I can get the nylon piece that holds the shaft from moving up and down? I’d still like to get this distributor working again. Thanks again for all the help.
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