recurving distributor

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Bad Sport said:
Wouldn't the solder kinda "wear" being soft and all?
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If it were a bearing maybe.... As a travel stop cushioned by springs you might gain a degree 10 years or so down the road. But as I said "while you are dialing it in". Once you find the setting you want you can measure the lead, if it bothers you then sweat it out and weld to the dimension you measured. You can also add material to the inside rather than the outside if you want to add tension and slow down the curve or correct a unstable timing at idle situation. Sometimes the springs you have are the correct rate but just a tad too long and this will fix that.
 
well i talked to them thru e mails,,im guessing from not gettign a direct answer,,,there plate wont get me the adjustment i need,,not sure why but he said to run my vacuum,advance off the full vacuum port,,on the carb not on the timed port,,im thinking they missed my question of what im trying to do,,,,according to hot hemi heads a 241 C,I need 8 degrees inital and 30 degrees total timing,, im thinking a mopar performance dizzy has too much advance built in for this motor,,,
 
fstfish66 said:
well i talked to them thru e mails,,im guessing from not gettign a direct answer,,,there plate wont get me the adjustment i need,,not sure why but he said to run my vacuum,advance off the full vacuum port,,on the carb not on the timed port,,im thinking they missed my question of what im trying to do,,,,according to hot hemi heads a 241 C,I need 8 degrees inital and 30 degrees total timing,, im thinking a mopar performance dizzy has too much advance built in for this motor,,,
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What you are describing is a 20* -21-22 "crank degrees" curve which is pretty common. Nothing spectacular about that
 
67Dart273 said:
What you are describing is a 20* -21-22 "crank degrees" curve which is pretty common. Nothing spectacular about that
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ok im sure you are correct,, but how do i limit the total timing to 30 degrees with a mopar performance dizzy ?? im not so versed in fine tuning,,,thanks
 
Sir, you will find that the Hemi will stand a LOT more than 8* initial.

Looking at it from a design standpoint, it has everything working against it for detonation. No quench. A domed piston that interferes with flame travel. But, somehow it defied what the engineers "thought" it would do and actually is detonation resistant. That means you can probably run a good bit more initial timing than you think. Something you will want to experiment with for sure.
 
fstfish66 said:
ok im sure you are correct,, but how do i limit the total timing to 30 degrees with a mopar performance dizzy ?? im not so versed in fine tuning,,,thanks
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It depends on WHICH MP you have. Some of them made "later" actually had an adjustable advance, similar to Mallory. The way I see it your options are...(not necessarily in order)

1.....Find out if your MP is adjustable, or find out if the FOB plate will fit.

2.....If not consider recurving (welding up the slots) your MP distributor or doing the same with an OEM distributor

3.....Or buy an adjustable dist. such as MSD, Mallory, etc

Here's a thread on the adjustable MP. Not all of them are / were

http://www.forabodiesonly.com/mopar/showthread.php?t=67882

and

http://www.forabodiesonly.com/mopar/showpost.php?p=869899&postcount=16
 
67Dart273 said:
It depends on WHICH MP you have. Some of them made "later" actually had an adjustable advance, similar to Mallory. The way I see it your options are...(not necessarily in order)

1.....Find out if your MP is adjustable, or find out if the FOB plate will fit.

2.....If not consider recurving (welding up the slots) your MP distributor or doing the same with an OEM distributor

3.....Or buy an adjustable dist. such as MSD, Mallory, etc

Here's a thread on the adjustable MP. Not all of them are / were

http://www.forabodiesonly.com/mopar/showthread.php?t=67882

and

http://www.forabodiesonly.com/mopar/showpost.php?p=869899&postcount=16
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THANKS for the link to this posting,,it explained what i was missing,,,and shows a few ways to get where i need to be,,,thanks a ton
 
RustyRatRod said:
Here is the Allpar article that discusses the Hemi combustion chamber efficiency. About 1/4 the way down or so......but the whole article is worth the read.

http://www.allpar.com/mopar/hemi/chrysler-hemi.html
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ok thanks ill read it,, but remember im not tuning a ground pounder 426 i have a 241 CI,, 7.1 compression small valve motor that didnt even come with a 4bbl,,,and produced a whopping 180 HP back in 1953,,,now with a reground to big of a grind cam,,not my doing,,, headers,,,4bbl,,,trying to squeeze a little out of it but at least make it run as good as it can for what it is,,,,its in a street rod,,
 

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That's really cool. BUT, remember, the two reasons you listed, cam too big and compression too low are two huge reasons to advance initial timing. I plan on running around 20 initial on mine with 12-16 mechanical. A "real" hot rod engine will take less timing because of the high compression. Lots of timing is not needed there. The reverse is true of low compression engines. They need lots of timing. Just food for thought.
 
ok thanks for the info,,,,this is an area i have always been week in,,, dizzy tuning,,, im just going by what hot heads had told me,,and thinking the mopar performance dizzy may have too much total timing,, its currently tuned by the old trusty vacuum gauge,,knowing im not going to get much more if any out of it,, just trying to learn a little more about tuning it,,next i have to look in to what the rpm range of this motor should be,, seems 4000 is about it,,,seems strange to me for a low deck motor,,,thanks again,,
 
RustyRatRod said:
BUT, remember, the two reasons you listed, cam too big and compression too low are two huge reasons to advance initial timing. Just food for thought.
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THIS! This! THIS!! And not just here, ALL over FABO engine projects. People offer others a "glove fit" timing suggestion, when indeed somebody can pick up huge hp and drop some serious E.T. with this advice! I've ran on some mild small blocks around 44-46* full advance timing on the street with no issue and the E.T. slip 100% backed it up (so did the butt dyno), and ran other mild small blocks around 36* fully advanced. Let the engine tell you, and not a "one size fits all" article or adviser.
 
318willrun said:
THIS! This! THIS!! And not just here, ALL over FABO engine projects. People offer others a "glove fit" timing suggestion, when indeed somebody can pick up huge hp and drop some serious E.T. with this advice! I've ran on some mild small blocks around 44-46* full advance timing on the street with no issue and the E.T. slip 100% backed it up (so did the butt dyno), and ran other mild small blocks around 36* fully advanced. Let the engine tell you, and not a "one size fits all" article or adviser.
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Meanwhile I was absolutely astounded to learn that 3G hemis don't want any more than 22 ? or so total
 
Now, do you guys use the Mechanical advance exclusively, or use mechanical and vacuum together?

I have been trying to figure out how to set up my ignition. Maybe I'm reading too much and not actually trying it for myself. I want to figure out my carburetion and ignition pretty soon, though.
 
Jay_340 said:
Now, do you guys use the Mechanical advance exclusively, or use mechanical and vacuum together?

I have been trying to figure out how to set up my ignition. Maybe I'm reading too much and not actually trying it for myself. I want to figure out my carburetion and ignition pretty soon, though.
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For street cars that see highway miles is makes sense to take advantage of the vacuum advance. It will improve the mileage in almost every application.
 
mguner said:
For street cars that see highway miles is makes sense to take advantage of the vacuum advance. It will improve the mileage in almost every application.
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Okay, that makes sense. I'll probably have to do some experimentation when the time comes.
 
Unless you are running what "is really" a race car on the street you should seriously consider vacuum advance. It adds MILES to the mpg figure. "In some cases" they can be a PITA. On a few engines, they can over advance too quickly, causing part throttle ping. Only time I remember this was when I ran a Quadrajet on my 340. The characteristics of the carb vacuum port gave too much vacuum too fast.
 
In your experience, what works better, on the timed port or the manifold port on the carb? I suppose I need to experiment, but where do you typically put yours?
 
fstfish66 said:
ok thanks for the info,,,,this is an area i have always been week in,,, dizzy tuning,,, im just going by what hot heads had told me,,and thinking the mopar performance dizzy may have too much total timing,, its currently tuned by the old trusty vacuum gauge,,knowing im not going to get much more if any out of it,, just trying to learn a little more about tuning it,,next i have to look in to what the rpm range of this motor should be,, seems 4000 is about it,,,seems strange to me for a low deck motor,,,thanks again,,
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Be open minded.....but keep what Hot Heads told you in the back of your mind. I have spoken with Bob Walker a good bit during my Hemi build. He is far from stupid. He really knows his stuff. Your specific timing will be something to experiment around with. It's all dependent on your specific combination as to where the optimal timing will be. I am just "assuming" they respond like every other engine. I could well be wrong. I know I am going to start mine off with 16 initial and 18 mechanical and go from there. Mine is only 9.1:1 static compression, which is relatively low for an early Hemi, so it will probably end up with more........but then again maybe not.
 
You will probably want to try it both ways. Everyone's setup has variables. Depending on what your throttle position is at cruise the ported vacuum may or may not be best suited to your application. Manifold vacuum will apply the advance at idle which may cause too fast of an idle or some other issue. The timing also retards as you open the throttle on manifold vacuum which could cause a driveability issue if your accelerator pump is marginal.... The vacuum advance will also drop out on ported when you open the throttle but this occurs at a higher RPM. Lots of things to consider. Some people use the manifold vacuum so they can run less mechanical initial and get a good clean shut off on cars that like to "run on" or "diesel" when hot.
 
The cam and distributor turn at the same speed and degrees right? They both turn at half the speed and degrees as the crankshaft. I was taught that you had to double distributor degrees to get crank degrees, timing wise. The factory distributor advance limiter plate was marked in distributor degrees because that was where it was installed so it had to be doubled to get crank degrees of timing. Then it was added to initial advance which is measured at the crank to get total advance. Or am I reading all this wrong?
 
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