When installing a Texas T Distributor, here is what three generations of Model T'ers found when installing this distributor:
1. Out of the box, the points were set open.
2. We reset the points to .030"
3. After getting everything connected, we found open terminals on 2 and 4 , 1 and 3 were live.
4. A cap and rotor replacement did NOT correct the problem.
5. Resetting the points to .012", all four cap terminals were live.
Visual of the cam lobes revealed the following:
Lobes on 1 and 3 were higher were higher than 2 and 4 .
We are limited to .012" to make the engine run, which it does, but only .012" will work.
So our question is this: What is the proper point gap setting for this application ?
We are concerned that the cam lobes are not symmetrical, should they not be all the same ?
A close-up lobe picture will be uploaded shortly.
Any replies would be appreciated.
I just did a quick google search for point gaps as .030 sounded like a lot. I see Ford 302 says .017-.020. For a VW beetle it seems that.016 is correct. So .012 seems a little small but not rediculous.
While I would hope the lobes would be the same height, the truly IMPORTANT thing is that they open exactly 90 DEGREES apart. Now you may be able to test for this as follows;
Connect a light bulb supplied by power with the other side completing the circuit to ground through the points. As you turn the engine the bulb should turn on and off!!
OK, so now carefully and slowly crank the engine by hand and watch for the bulb turn OFF !!
Without moving the crank now make a mark on the pulley relative to something on the front cover. Or perhaps also measure the location of the crank relative to the ground.
Now turn some more and try to establish where the next point opening happens. And so on.
Another option is to look down the first two cylinders and measure the piston location (the piston should be at about the top of one of the cylinders for each point event should be about exactly the same relative location for them)
Assuming my test establishes that all four point events happen as I've described then you should be OK
Points should be 016-020 it s a vw 009 distributor head
Les, thank you for your comments. You make a good observation. Obviously, we set the point gap incorrectly to start with. Having said that, my disappointment is that the distributor cam is machined so grossly that cam lobes 1/3 are visibly shorter that lobs 2/4. Our point setting is therefore predicated to the shorter 2/4 lobe. This is telling me that 1/3 would fire before 2/4. That being said it could be that the timing difference is so insignificant that it has no real effect. But, this is a reflection of the quality of the distributor itself. Not sure if the lobe is replaceable or should the distributor itself be replaced or just leave it as is and move on. My dentist son is a master at taking pictures of some very small objects and he did a lobe shot. We'll see if he can enhance the lighting to the point he can post. I just think the lobe machining is gross. Jerry
Jerry - Seems like the quickest and easiest way to initially determine accuracy of cam lobes would be to just turn the engine over slowly with spark plugs out (easier with no compression) and just check point gap with feeler gage.
I should have specified to check accuracy of HEIGHT of cam lobes ONLY. Use Les's method to check timing.
I also should have said to check point gap with feeler gauge with point rubbing block on each of the individual four cam lobes making sure they are all the same. Sheash,....I'll get it all said yet! Sorry,.....harold
We know there is a significant difference between the depth of lobes 1/3 AND 2/4.
That has been established beyond question. The difference is greater than .015". We measured it. So my question to all who have had distributor experience is "is this acceptable". I would think a lobe with this much differentiation between lobe cuts would be out of tolerance. Harold, this is what we did and how we found the different measurement. So where do I go from here? Live with it or return it to the supplier and ask for a replacement?
No, this quality escape is not acceptable. The Texas T Part distributors have lackluster quality coils and condensers too. I would return it and ask for a refund.
I would certainly contact them. Obviously they probably just buy the distributor from some other supplier, so it is not like they actually made it badly themselves. Non the less they should supply you with better quality than you received in my opinion
If it is an 009 it will have one lobe that will have a slightly different profile than the other three lobes. This was done to address a heating issue on the original VW engine it was designed for. I could go on and speak about that; however, I will not. Long story short, that issue does not significantly impact the use of the 009 when used on a model T engine for several reasons such as RPM and the fact we use a manual advance during various driving conditions. From what you have described, this may or may not be the problem you have described. Pictures go a long way to describe what you are encountering. Post a few and we can go from there.
Hi, I am Jerry Davis's son who took a few pictures of the cam lobe, I thank Mark Chaffin from Corona CA who apparently identified the fact that the VW had a similar asymmetrical cam lobe arrangement, that is what we see in these pictures.
ALL of us did not follow the Texas T Distributor directions in setting the point gaps, it plainly states: .016-.020". One of these days........
At .012" point gap, it runs well, but as wear occurs, the gap closes, right ? We will reset to .016 and see what happens next driving session.
Here are the pics of our asymmetrical cam lobe. It would be good of Texas T Parts to at least mention this feature if indeed the cam lobe was built that way as Mark Chaffin from CA pointed out.
Thanks for your input !
Have you ever tried a timer and four coils?
I have high quality jpeg pictures, they were way too big of a file size to post here, I had to figure out a way to "dumb them down."
So here we are, showing the asymmetrical cam lobe configuration. I was unable to get a shot of all four lobes, the radiator was in the way of my macro lens/ringflash set up.
I agree with Mark Chaffin, this cam lobe was built this way, not a defect.
Gentlemen, I have some high quality macro pictures that are apparently way too good to upload. This picture is obviously not useful. I can email the picture , but that is probably not for public consumption on the forum.
I apologize for this picture, the original jpeg was remarkably detailed.
I will keep trying....
Stick a degree wheel on the front or back of a T engine-----with the head off put a dial measuring TDC of a firing order on each cylinder----stick an ohm meter connected to each side of the closed point when the number one point is ready to open---then check the rest in order----with each at TDC with the dial-----the degree wheel will show how far each is off or on.
The number 3 lobe on the dist. is retarded a few degrees for VW because that cyl runs hotter. The gap on the points is the same on all cyls.
Gentlemen, here is a link to a hi quality resized image showing the asymmetrical cam lobe on the Texas T distributor.
I think I have this image thing figured out now.
Onward through the fog...
Jerry and Brooks
Upon reflection I have heard about this quirk of the VW distributor before. Certainly the timing variation mentioned is I'm quite sure less than the timing variation that occurs on most T's with the stock ignition. So I wouldn't be particularly concerned about that on the average T
I see no issue with the point cam that would bother me if it was my car
I hope this helps
"Visual of the cam lobes revealed the following:
Lobes on 1 and 3 were higher were higher than 2 and 4 .
That's a huge problem if true.
I agree with Royce. But to my fairly trained eye, what I see in the picture looks very consistent for height
I agree also with Les' observations. Follow the instructions, set it and go bro!
Allrighty now, Les Schubert and Mark Chaffin.....
Thank you both. I had a 1972 Super Beetle back in my college days, I recognized this Texas T distributor as a Bosch/VW unit, just didn't remember (or never had to ) the asymmetrical cam lobes. I agree guys, we are good, we are going to set the cam lobe gap per instructions to .020" and go tighter if necessary. It runs now, so we are good. Thank you both !
Suggest adding a separate ground wire when using the Texas T distributor. I put in the Pertronix kit which eliminates any asymmetrical cam lobe issues. The Pertronix unit has been in use for over 10 yrs, with no issues. I like it! Also, I carry a spare module in case it fails....just like the coil guys who carry a spare coil.
Les, I agree. It's on to better things. Jerry.