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engine guy question about 383

Posted By: 3wracing

engine guy question about 383 - 07/20/14 02:43 PM

checked the compression on my #s 69 roadrunner. compression #s warm were 148 to 159.Is this in tolerance? The motor is stock never out of the car.The stock heat riser is still on the car.Oil preessure is fine doesnt smoke runs and drives like it should.The only problem is when you rev the motor up the rpms are slow to come back down . I am getting ready to pull motor to do engine bay and would like to address any problems at that time i do not want to hurt #s motor any help ? thanks
Posted By: BSB67

Re: engine guy question about 383 - 07/20/14 02:52 PM

Quote:

checked the compression on my #s 69 roadrunner. compression #s warm were 148 to 159.Is this in tolerance? The motor is stock never out of the car.The stock heat riser is still on the car.Oil preessure is fine doesnt smoke runs and drives like it should.The only problem is when you rev the motor up the rpms are slow to come back down . I am getting ready to pull motor to do engine bay and would like to address any problems at that time i do not want to hurt #s motor any help ? thanks



Compression is fine.

The problem is likely not in the motor.

Give more detail on exactly what it is doing
Posted By: 68LAR

Re: engine guy question about 383 - 07/20/14 02:58 PM

Those numbers are normal. Back then, the engines weren't making the compression that they were rated at. My original 383 had the same numbers you are getting.
Posted By: 3wracing

Re: engine guy question about 383 - 07/20/14 06:56 PM

when you rev the motor up to say 2 grand it seems it takes a longer than normal for the rpms to settle back down to normal. Or when driving it say you shift to second the rpms stay up between shifts. I have a good return spring the carb plates are going closed . Not that it matters but the carb is a 68 -383 4spd carb that the original owner says was on it since new . . vacume is around 10" with the timing around tdc which i think is somewhat low .
Posted By: 68LAR

Re: engine guy question about 383 - 07/20/14 07:23 PM

If it's a completely stock 383, 10" is too low. You should be around 12" or a little higher. If the idle doesn't settle after higher rpms, you may have a vacuum leak somewhere or the carb throttle blades are hanging up. Next time you try it, try taping side to side with a very small hammer, on the carb throttle shaft(primary side),just to see if the idle drops back to normal. If it does then you know it's the carb, if it doesn't, then you know it's a vacuum leak or maybe timing. With 10", I'm leaning toward a vacuum leak, or retarded timing. 0* @TDC, with a stick car is normal with the vacuum line off of the distributor.
Posted By: HemiRick

Re: engine guy question about 383 - 07/20/14 09:34 PM

Vacuum will be low at TDC timing as it should be about 10 degrees Before TDC, advance the timing some and the vacuum will come up to where it should be.....
Posted By: ademon

Re: engine guy question about 383 - 07/20/14 10:11 PM

if its a completely original untouched 4 speed car and carb, you should have a dashpot that looks like the one on my 68, you set that dashpot to touch the lever at 2K if i remember correctly from the FSM and it will drop to idle slower than cars without the dashpot. It should drop about 1 to 2 seconds slower than a normal carb. if you dont have the dashpot then maybe timing or throttle blades open to far???

Attached picture 8214519-68RR3834-speed(7)(640x480).jpg
Posted By: ademon

Re: engine guy question about 383 - 07/20/14 10:12 PM

one more pic

Attached picture 8214521-68RR3834-speed(12).jpg
Posted By: 68LAR

Re: engine guy question about 383 - 07/20/14 10:42 PM

I forgot about the dashpot.
Back in 68 & 69 stick car timing was TDC. Auto's were 2* BTC for 383's.
Posted By: 3wracing

Re: engine guy question about 383 - 07/21/14 12:09 AM

this is the carb on my 69. Sorry its dark its an n96 car also

Attached picture 8214601-Jul20197.JPG
Posted By: ademon

Re: engine guy question about 383 - 07/21/14 12:22 AM

With the motor off have someone hold the Pedal to the floor, you should see the dashpot plunger extend out, then you should be able with your finger to depress it in and it should have some resistance once in let go and it should extend out smoothly. They do go bad often
Posted By: johnedod

Re: engine guy question about 383 - 07/21/14 12:37 AM

Check the secondary throttle plates and make sure they're not sticking as well.
Posted By: 383man

Re: engine guy question about 383 - 07/21/14 03:22 AM

I could be wrong but from what I remember dashpots were mostly only on auto trans cars. They were used to help catch the idle on auto cars so if you let off the gas real quick in gear it would bring the idle down slow so it would not stall. But I only remember them on auto cars as stick cars did not really need them. But it looks like your carb in the picture has the dashpot on it. Ron
Posted By: dogdays

Re: engine guy question about 383 - 07/21/14 05:55 PM

I wasn't doing Mopars back then, but on GM cars the slow closers on the throttle were mostly on stick cars. The reason being that during emissions testing, dropping the throttle closed quickly increased the unburned HC and CO. Stick cars had many more times of throttle-off, throttle-on because of shifting.

R.
Posted By: ademon

Re: engine guy question about 383 - 07/22/14 12:17 AM

That's what I hear also, plus smoother shifting.
Posted By: JohnRR

Re: engine guy question about 383 - 07/22/14 12:35 AM

69 would have a dashpot and it's a 4speed thing.
Posted By: Pynzo

Re: engine guy question about 383 - 07/22/14 12:58 AM

Carter 4615S is the stock carb for '69 383 manuals and will have the dashpot. It does slow the return to idle from 2000+RPM. Keeps the vacuum advance raised while dropping throttle while speed shifting, reducing emissions. 4426S for '68 carb and it too will have the dashpot.
http://www.tocmp.com/manuals/Carbs/Carter/Chrysler/1965-1979/pdf/Chrysler121-173.pdf
Scroll down to Form 5526C for '68 AVS parts list
and Form 5534A for '69 parts list. There is a difference in primary rods and secondary jets.
Posted By: Pynzo

Re: engine guy question about 383 - 07/22/14 01:53 AM

You say this motor has never been out of the car. You MUST check if you have the stock single roller aluminum w/ nylon teeth cam gear as it will cause your low vacuum issue as well as cylinder pressure issues due to retarded cam timing. If it's still in there get rid of it. Check this way: pull the distributor cap and watch the rotor as you grab the fan belt on both sides of crank pulley. Pull the belt so's crank spins in reverse direction of normal rotation. If you spin the crank more than 5 degrees without the distributor rotor moving- you've found your problem.
Posted By: 3wracing

Re: engine guy question about 383 - 07/22/14 11:38 PM

yes thier is slop the way you describe in the timing chain. Yes it made me nervous . With the timing light it doesnt jump around the way some do . Thanks for all the help guys!
Posted By: Pynzo

Re: engine guy question about 383 - 07/22/14 11:49 PM

Put in a decent double roller before you pull the engine and redo your tests. It can be done with gasket kit for under $100.
Posted By: 383man

Re: engine guy question about 383 - 07/23/14 03:05 AM

Quote:

I wasn't doing Mopars back then, but on GM cars the slow closers on the throttle were mostly on stick cars. The reason being that during emissions testing, dropping the throttle closed quickly increased the unburned HC and CO. Stick cars had many more times of throttle-off, throttle-on because of shifting.

R.



Dont want to start a debate here but that is wrong. The dashpots are used mostly on auto cars. I just read it again in one of my auto training manuals from years ago just to be sure my memory was still working. Ron
Posted By: ademon

Re: engine guy question about 383 - 07/23/14 03:28 AM

Don't know much about other makes but mopars used dashpots mainly in stick cars and idle solenoids in the autos, at least 69 and earlier after 70 or so I see mostly solenoids. Ford I think was big on dashpots for autos
Posted By: 383man

Re: engine guy question about 383 - 07/23/14 05:18 AM

I am not saying stick cars did not get dashpots as I know many did. But the auto books I have read over the years in my training always says they were used mostly on auto cars for all brands according to most auto books I have read thru the years in my training. I know that does not mean its gospel but most I have seen were always auto's but as you have said many stick cars seem to have them also. Ron
Posted By: JohnRR

Re: engine guy question about 383 - 07/23/14 03:23 PM

Quote:

Quote:

I wasn't doing Mopars back then, but on GM cars the slow closers on the throttle were mostly on stick cars. The reason being that during emissions testing, dropping the throttle closed quickly increased the unburned HC and CO. Stick cars had many more times of throttle-off, throttle-on because of shifting.

R.



Dont want to start a debate here but that is wrong. The dashpots are used mostly on auto cars. I just read it again in one of my auto training manuals from years ago just to be sure my memory was still working. Ron



Ron , sorry but you are wrong , my 69 383 4 speed bee and dart both have dashpots , as far as mopars are concerned it's a 4 speed thing.

The electric solenoids are used to set idle speed, some engines had a run on issue and the way around it was to set the throttle blades completely closed and use an electric solenoid to set and maintain idle speed.
Posted By: 383man

Re: engine guy question about 383 - 07/23/14 05:52 PM

Quote:

Quote:

Quote:

I wasn't doing Mopars back then, but on GM cars the slow closers on the throttle were mostly on stick cars. The reason being that during emissions testing, dropping the throttle closed quickly increased the unburned HC and CO. Stick cars had many more times of throttle-off, throttle-on because of shifting.

R.



Dont want to start a debate here but that is wrong. The dashpots are used mostly on auto cars. I just read it again in one of my auto training manuals from years ago just to be sure my memory was still working. Ron



Ron , sorry but you are wrong , my 69 383 4 speed bee and dart both have dashpots , as far as mopars are concerned it's a 4 speed thing.

The electric solenoids are used to set idle speed, some engines had a run on issue and the way around it was to set the throttle blades completely closed and use an electric solenoid to set and maintain idle speed.



Mopar may have used them on stick cars but I am not wrong as I have been told by instructors and read it many times that they were used on auto cars. Heck I can post the page from one of the books I was given over the years in training. Ron
Posted By: 383man

Re: engine guy question about 383 - 07/23/14 06:39 PM

Quote:

Quote:

Quote:

I wasn't doing Mopars back then, but on GM cars the slow closers on the throttle were mostly on stick cars. The reason being that during emissions testing, dropping the throttle closed quickly increased the unburned HC and CO. Stick cars had many more times of throttle-off, throttle-on because of shifting.

R.



Dont want to start a debate here but that is wrong. The dashpots are used mostly on auto cars. I just read it again in one of my auto training manuals from years ago just to be sure my memory was still working. Ron



Ron , sorry but you are wrong , my 69 383 4 speed bee and dart both have dashpots , as far as mopars are concerned it's a 4 speed thing.

The electric solenoids are used to set idle speed, some engines had a run on issue and the way around it was to set the throttle blades completely closed and use an electric solenoid to set and maintain idle speed.



Ok John it looks like we are both right. Here is a page from one of my auto books I got over the years and it says they use them on auto's.



Then I decided to pull out my 68 Dodge service manual and it says its used on manual trans. So can we both be right ?? Why not ?

And here is the page from the Dodge 68 service manual. I was surprised to see this as all of my books I got over the last 35 years in my tech training seemed to always say auto cars have them but I was wrong to doubt some on here who were also right. Ron

Posted By: JohnRR

Re: engine guy question about 383 - 07/23/14 07:56 PM

Quote:

Quote:

Quote:

Quote:

I wasn't doing Mopars back then, but on GM cars the slow closers on the throttle were mostly on stick cars. The reason being that during emissions testing, dropping the throttle closed quickly increased the unburned HC and CO. Stick cars had many more times of throttle-off, throttle-on because of shifting.

R.



Dont want to start a debate here but that is wrong. The dashpots are used mostly on auto cars. I just read it again in one of my auto training manuals from years ago just to be sure my memory was still working. Ron



Ron , sorry but you are wrong , my 69 383 4 speed bee and dart both have dashpots , as far as mopars are concerned it's a 4 speed thing.

The electric solenoids are used to set idle speed, some engines had a run on issue and the way around it was to set the throttle blades completely closed and use an electric solenoid to set and maintain idle speed.



Mopar may have used them on stick cars but I am not wrong as I have been told by instructors and read it many times that they were used on auto cars. Heck I can post the page from one of the books I was given over the years in training. Ron




But we aren't talking about brand X cars here on Moparts , or this particular subject car.

But thanks for posting up those pages ...
Posted By: 383man

Re: engine guy question about 383 - 07/23/14 09:12 PM

You are right as I realize we are talking Mopars here its just when ever I read or was told by an instructor they never specified any brand as the way I took it it was talking about all brands. But I admit I learned something here as I was just taught that mostly auto cars use them. I appoligize if I ofended anyone. And all my years around Mopars I never really looked into it on just Mopars until now. We learn something everyday is what they say. Ron
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