As part of your troubleshooting you might want to confirm what size jets are installed in your HD8 carbs - easy enough to check . I believe the HD8s, depending on application, could have .090", .100" or .125" jets (E-Type triple SUs are .125" with UM needles). I recall a number of years ago swapping the stock Strombergs on an Series II XJ6 over to a pair of HS8 carbs and they needed to be re-jetted from .100" to .125" jets. No doubt a set of undersized jets would cause fuel starvation. Good luck.
I tend to agree with the view that it is a fuel problem, now that we know that it is a non-standard 2 x HD8 configuration. Maybe someone here has a similar setup and can recommend appropriate needles etc. I suspect that the ignition problems from using the incorrect distributor wonāt make themselves obvious until the basic mixture problem has been correctedā¦ There is a lesson here for all of us. If your setup isnāt stock, and you are looking for help/advice, please identify all the variations from stock in your first post.
I had a similar setup with similar symptoms the only difference being that it was an xj6 instead of an e type. I provided the solution that solved the problem for me as well as a simple 10 minute modification to test if the modification will help. If it does not it is only 10 more minutes to return it to where it was and look elsewhere.
Yes. The specs for the hd8 carbs used with a double carb setup in the xj6 call for a different spring than the triple carb e type or mark 10 setup. They all call for the um needle. The stronger spring acts to keep the piston depressed a bit more which richens the mixture. A bit of weight on the piston will crudely do the same thing. It may seem counterintuitive but it works on the same principle as the oil in the damper slowing the rise of the piston on acceleration to richen the mixture. It worked for me. It may or may not work for Pat but it is simple to try.
Yes, a lesson for me at least, when asking for help give all the information in the first post, valid point thanks.
I have an update and will answer some questions. I am using velocity stacks for the two carbs, not the Hover set up (which I still have) and the stock exhaust system.
Now the update: I installed the correct dist, no change. I then installed the good old contact points.
My wiring diagram clearly shows a green and white wire from fuse #7 going to the dist. And a white wire from the dist feeding power to the coil - is this correct? Anyway, my local buddy said that seemed odd and suggested I by pass that wire for a test, so I hot wired the coil from the battery and disconnected the white wire of course. Took it out on a road test and it was much improved but still a bit crappy on acceleration. So I stopped and advanced the timing a bit, it improved a bit more. Itās still not in itās happy place on the upper end of acceleration, but I think a more comprehensive timing with a light may dial it in. Iām not very good at timing a car, never have been so will get help with that.
Once I get it to accelerate as it should, with the hot wire, I will re try the white power in wire from the dist. But Iām afraid the rain has hit for a few days so Iāll have to wait ;(
I will also look at the oil in the dampers of the carbs, I used ATF, is/was this correct and if not what do you suggest?
You might change the ATF to 20/50 simply to mimic a change to a Stiffer spring, without having to buy one and wait for arrival. If it shows improvement, then you have a direction to go and the 20/50 can easily be dumped out and replaced
Since itās an SAE20 oil many recommend using 3-in-1(blue container) in the dampers - available at your local hardware store or Crappy Tire! Iāve also used engine oil but IMHO it would be helpful in your situation to try to reduce the number of variables in order to track this issue down.
The issue is/was when the car is sitting still, but that has changed once I hot wired the coil. I need to do more testing when the roads dry out and Iāll report back.
Since you have the points back in can you not just time it statically per the manual ? Back when my cars had points this is how I timed them and was not hard. Here is video to show one method.
Electronic points sytems including Pertronix are VERY sensitive to voltage. If car runs OK with old style points this indicates a voltage drop between battery and distributor. Easily tested by running power direct from battery to distributor, bypassing the ignition switch as you have done. Most āfuel problemsā turn out to be electrical in my experience. Donāt leave the āhot wireā in place too long without the engine running to avoid damage to the Pertronix and/or coil.
Hi Bill, sometimes the simplest of answers is the best, but Iām afraid that it is. I even changed the order by one just to see what the affect would be.
FYI to all, I have reduced the issue by 80% by using a hot wire to the coil and not the correct wire from the tach. My next step is to try the thicker oil in the carbs, hopefully today if the roads stay dry.
Pat
Sorry Mitch, I donāt understand what you mean that the wires are switched? FYI, I have never restored an E type, heck I have never even driven a Jag until this one so I have not got a lot of knowledge on them except what I have learned along the way.
Could you explain about the wire wires please? I have a white in to the three way plug, and a white out, one goes to the fuse and one to coil - thatās all I know.
Problem solved! It was fuel relatedā¦ running way to lean on the higher RPM. Changed the UM needles to UI (pretty sure thats what they are, too lazy to run out to the shop) and off it went!
Pat
There is a lesson here for all of us. If your setup isnāt stock, and you are looking for help/advice, please identify all the variations from stock in your first post.
