Need Dual Point Assistance

[miller]

I had to reindex the gear in order to be able to get enough movement to set the initial timing, and for it to look normal. If would've run the other way, but then the vacuum advance would've been pushing into my radiator hose.

Understand what your saying. Still shouldn't make any difference. Where #1 plug wire goes in the cap, is not written in stone. Your looking at different engines, the way various parts and pieces are, around the distributor, and go from there. What's shown in the 'books', are simply for factory set-ups. So, otherwise, distributor gets slapped in, as needed, or wanted.
It doesn't matter where the slot is located on the drive gear...installer's choice. So, yep, do which ever way you want, to get the outcome you want. Definitely understand need to turn it, to get time.

 

[miller]

That from the FSM

Yes, sir. 64 factory parts book...(so, Chrysler #s??)

 

[miller]

I bought a cast iron dual point that was supposedly off of a 62 Imperial with a 413. I wonder if that cam will work (and act the same proper way as what mine should be).

Answered that ? digging back through the post. So, you do have two.

Do both have vacuum advance? Just being curious, between the two, does the moveable vacuum advance plate rotate the same direction?

Will the cam and stop plate swap...probably! But, measure the advance slots on both, to compare, both the length and direction.

Understand your frustration. There IS an answer, for what's going on with the vacuum advance...just have to find it.

 

[Dragon Slayer]

Starting over, other then all the previous questions asked are still relevant. Your original Single Point distributor is that Prestolite too? So your cap and wiring has never been changed, your just moving the rotor and cap on to the distributor you have installed? Is that a true statement? If so and when you do this, do you ensure the rotor when placed on the new distributor installed is pointing at the same position as it was when you removed the single point? How are you going about ensuring the sparkplug wires are in correct position of the Dual Point?

If your plugging in the vacuum cannister and the car immediately goes to crap at warmup idle it has to be putting in too much advance or if the breaker plate is too loose as Halifax said is moving the breaker plate such that the gap is closing up even more or adding way too much advance as stated.

 

[miller]

Have 2642899 dist, measured rubb1ng block high to high spot 1.25 low to low .98. Vacuum arm 11. Can't say unmolested for sure bought as a parts dist.

Hey, Fran. 2642899 is the same part number, as 67 GTX has, from re-reading things. Point is, one of them has the wrong cam and stop plate.

Irritating, ain't it!

 

[Fran Blacker]

Do me a favor really cant make out the dist numbers

28?????????
IBS 4006Z 47/6?

The P/N is 2642899 you have the IBS number correct. The lower part of both 9's are partly to mostly dinged. First 9 you can see the leg the second one you can see the upper part of the 9 is the same as the first.
I have 3 cams the 899, middle cam not sure but probably came from a single point Presolite reverse rotation marine distributor and a Super Stock cam on right . Pictures of the bottom of cam is the one that unsure of where came from, marine? Would like to known.
Note the clocking of the rotor flat is different than the other two.
OP earlier said his vacuum advance arm with a 7, mine was stamped with an 11. Was on ebay and found a vacuum advance advertised for a 67 440 HP with an 11 stamped in #133 from Chet's he's up on his stuff. I had to enlarge it 400% and not 100% positive its and 11.

 

[Dragon Slayer]

Hey, Fran. 2642899 is the same part number, as 67 GTX has, from re-reading things. Point is, one of them has the wrong cam and stop plate.

Irritating, ain't it!

I had already pointed that out for him in an earlier post. His cam stop looks like the Max Wedge version based on top letter and orientation of the Rotor Flat on the cam.

They all should work, the only difference is the slot length which drives max mechanical advance, and the Flat for the rotor orientation which would change where rotor points which you have to take into consideration for wire placement. WHICH is why I think it is important to have the distributor drive shaft installed with slot oriented IAW service manual, and engine at TDC for #1 cylinder. At that point when distributor installed with vacuum advance in a position that allows rotation of the distributor, you can look where rotor point and make that #1 wire.

Once you start swapping a cam stop you must verify you have the same clocking of that flat spot. Because in moves rotor to a different position. Those flats are in different location depending on the motor application and distributor characteristics. No vacuum as an example, Mechanical tach drive, Max wedge manifold versus a 440 stock manifold, hemi fuel lines and manifold vice 440 etc.... Otherwise cam dimensions are the same, and slot lengths are pretty close and you can compensate with more or less initial timing. If you read service manual and Chrysler training documents, you can learn that the factory felt some cars needed very specific timing requirements from a standard stock 383 or 440. The max wedge cars with those long manifolds are a good example. Auto versus Man trans is another example.

This why I asked what cap and rotor he is using. It is not hard to get off one position, especially when you swap parts like a Prestolite cam stop. If the same distributor going back in after maintenance, you just need to know where rotor was pointing generally. As long as you do not turn over motor, that ensure your not 180 degree off, and you get back to rough enough initial timing to get the car started and tune it from there. You go with a whole new distributor and all bets are off and you must validate you get number one wire on the correct spot of the distributor.

 

[miller]

Good info coming to light...makes a big dif. Of course, it's been there the whole time, just have to dig deep enough.
At least we're getting educated, or re-educated on Prestolites!

Once I tripped over Mallorys, never looked back.

 

[HALIFAXHOPS]

OK I am coming up with something different on the IBS 4006z number. 426 x2 4bbl, Any one have the mopar number just cant make it out on the tag.

 

[miller]

IBS 4006z

Do you mean the one tag photo in post #146?
From the way the #s read in the parts book...that one IBS 4006z 47 6.
67 GTX's tag IBS 4006z 46 6.

 

[67 GTX]

I will go look for the 62 distributor today and let you guys know what I find from it (PN, etc..)

On my 67 dual point, I changed the vacuum advance that came on it to an NOS one that I bought. I will find out what is stamped on the arm of the one that I didn't use once I find that guy again.

So from reading through everything, the point to point measurement should be 1.025, and not the 1.25? If so, then I believe the cam stop in my 67 dual point should be ok? If so, that removes the need to dissect the 62 dual point that I have for parts.

The distributor that I put back into the gtx was an aluminum bodied distributor (which I believe makes it a Chrysler). Its cam measurements appear to be within spec, so not sure why such a very small gap is giving the proper dwell (which was confirmed with two separate meters).

Just soaking this in a bit. I have some "cam" letters from ones I pulled and rebuilt and slot measurement. Hey here is something none of us touched just had this on a 69 340. The advance plate has ball bearings, well just had one the bearings were worn and the plate was kind of lose so it floated when it advanced on the machine not much but just enough to throw it off., just a thought. I just have to bring my book in from the shop for the measurements no net out there. This is a weird one. I will scan the sun card also no that I have a good number to work with all the settings in one easy to read place. I would kill for a Prestolite reference book on these.

This was something I thought of last night in regards to my vacuum advance issue. If that plate has slop in it, that could be why the car acts up once the vacuum comes into play.

The car ran ok with the vacuum disconnected when I was running the 67 dual point, but not great.

I understand what you guys are saying with re-indexing the distributor. Thank you for the clarification. I just had to wrap my head around it.

One thing I did notice when I put my single pt aluminum bodied distributor back in.
I tested it the same way I tested the 67 dual pt.
I set initial timing to 0*, and rev'd the motor (with vacuum disconnected).
The mechanical advance was less than the 67 dual pt. Now this distributor appears to be working properly, so I don't think the specs for the mechanical advance for the distributor listed in the FSM have to be double to get the reading on the balancer.

Either way, mechanical advance appears to be less than the dual pt. But, the car seems to run better with this one (with the vacuum hooked up, which does have less advance 7.5 vs what is installed (which I think is 10)). That just means with this carb providing carb vacuum, my motor wants the vacuum because it wants more advance (more than the dual pt could give just on its own without vacuum help)). ​

 

[Fran Blacker]

Sorry the screw up on my post have corrected it with a note that it was edited.
Does your cast iron Presolite have 2 light springs or one heavy and one light? Two lights will have full mechanical advance in at around 1000 rpm. Don't know if it would cause a problem if two light springs and the vacuum advance is connected.

 

[Dragon Slayer]

I will go look for the 62 distributor today and let you guys know what I find from it (PN, etc..)

On my 67 dual point, I changed the vacuum advance that came on it to an NOS one that I bought. I will find out what is stamped on the arm of the one that I didn't use once I find that guy again.

So from reading through everything, the point to point measurement should be 1.025, and not the 1.25? If so, then I believe the cam stop in my 67 dual point should be ok? If so, that removes the need to dissect the 62 dual point that I have for parts.

The distributor that I put back into the gtx was an aluminum bodied distributor (which I believe makes it a Chrysler). Its cam measurements appear to be within spec, so not sure why such a very small gap is giving the proper dwell (which was confirmed with two separate meters).

This was something I thought of last night in regards to my vacuum advance issue. If that plate has slop in it, that could be why the car acts up once the vacuum comes into play.

The car ran ok with the vacuum disconnected when I was running the 67 dual point, but not great.

I understand what you guys are saying with re-indexing the distributor. Thank you for the clarification. I just had to wrap my head around it.

One thing I did notice when I put my single pt aluminum bodied distributor back in.
I tested it the same way I tested the 67 dual pt.
I set initial timing to 0*, and rev'd the motor (with vacuum disconnected).
The mechanical advance was less than the 67 dual pt. Now this distributor appears to be working properly, so I don't think the specs for the mechanical advance for the distributor listed in the FSM have to be double to get the reading on the balancer.

Either way, mechanical advance appears to be less than the dual pt. But, the car seems to run better with this one (with the vacuum hooked up, which does have less advance 7.5 vs what is installed (which I think is 10)). That just means with this carb providing carb vacuum, my motor wants the vacuum because it wants more advance (more than the dual pt could give just on its own without vacuum help)). ​

This could be related to your issue. Yes you still have to double distributor advance to match what will show on the balancer. Remember what I said about getting small portion of the mechanical advance at 1500 RPM or so. You do not get full mechanical advance until top RPM around 4500 on a stock advance. That heavy spring prevents it.

So as Fran said, if the DP has light springs on both, or the arm was bent in a lot then you might be getting all your mechanical advance at a lower RPM. Adding the vacuum advance could be causing too much advance. This is where Halifax can help by seeing what the distributor does on the Sun tach machine. Also your SP may have less max vacuum advance. Difference between a 7.5 which gives you 15 total advance. And a 11 which gives 22 especially if your getting too much mechanical advance already at 2 to 2500 RPM can be causing your issue. A stiffer spring and spacers inside the canister will delay and limit the amount of advance for a given vacuum.

Accurate timing measurements with a good tape on the balancer will really help you out. It should be stage mechanical advance per the Service manual chart. The initial advance at lower RPM, and gradual build until all is in around 4500RPM.

 

[HALIFAXHOPS]

Do you mean the one tag photo in post #146?
From the way the #s read in the parts book...that one IBS 4006z 47 6.
67 GTX's tag IBS 4006z 46 6.

Got that the 7 number Chrysler number is what I would like.

 

[HALIFAXHOPS]

I get quite a few in with the MP spring kits in them, they just slam the advance right in.

 

[miller]

The distributor that I put back into the gtx was an aluminum bodied distributor (which I believe makes it a Chrysler). Its cam measurements appear to be within spec, so not sure why such a very small gap is giving the proper dwell (which was confirmed with two separate meters).

Just curious. What point gap on the Chrysler single point?

So from reading through everything, the point to point measurement should be 1.025, and not the 1.25? If so, then I believe the cam stop in my 67 dual point should be ok? If so, that removes the need to dissect the 62 dual point that I have for parts.

Yes, cam measurement okay.

Don't know if there's a chart floating around, that gives the different advance #s for slot sizes. Would help.
Not trying to confuse, but knowing how much mechanical advance on the plate, gives you #s needed to figure out what you have. Difference in #s, slots to the actual rotor. Advance slots are listed for crank speed, showing at the dampner. Rotor degrees (half) are since the distributor is driven by the cam shaft.

Think I'll sit back for a bit, and see what develops.

 

[HALIFAXHOPS]

Believe .017-.023? LOL I just set the dwell on the machine!

 

[miller]

Yeah...sometimes, wish I had one laying around!

 

[67 GTX]

Sorry the screw up on my post have corrected it with a note that it was edited.
Does your cast iron Presolite have 2 light springs or one heavy and one light? Two lights will have full mechanical advance in at around 1000 rpm. Don't know if it would cause a problem if two light springs and the vacuum advance is connected.

I have one light and one stiff spring.

Just curious. What point gap on the Chrysler single point?

Yes, cam measurement okay.

The points gap on my single point was less than .008. So if dwell is closing time (charging time), and the cam is within spec, I don't understand how such a small gap is giving a good dwell (30*).

 

[Dragon Slayer]

Just curious. What point gap on the Chrysler single point?


Yes, cam measurement okay.

Don't know if there's a chart floating around, that gives the different advance #s for slot sizes. Would help.
Not trying to confuse, but knowing how much mechanical advance on the plate, gives you #s needed to figure out what you have. Difference in #s, slots to the actual rotor. Advance slots are listed for crank speed, showing at the dampner. Rotor degrees (half) are since the distributor is driven by the cam shaft.

Think I'll sit back for a bit, and see what develops.

Not for Chrysler. If a Chrysler cam had a 8 stamped on the camstop. It provides 16 degree mechanical advance on crank. If it had 10, it provides 20. Look at the service manual. All values provided as distributor numbers. Degree and RPM. SO you have to double everything if your measuring on the car.

Dwell is typically a more accurate measurement then point gap. To gap points you have to ensure you are directly on the point of the cam. Lower gap works, but spark is different and you risk burning points. Lower gap increase dwell. Manual does state both need to be in spec, as most references and training manual do.