Home 
Home Search search Menu menu Not logged in - Login | Register
> Jensen Healey & Jensen GT Tech > Electrical & Instruments > Pertronix Tachometer "blips"

 Moderated by: Greg Fletcher Page:    1  2  Next Page Last Page  
New Topic Reply Printer Friendly
Pertronix Tachometer "blips"  Rate Topic 
AuthorPost
 Posted: 09-16-2018 07:12 pm
  PM Quote Reply
1st Post
DonBurns
Member
 

Joined: 09-18-2015
Location: Fullerton, California USA
Posts: 75
Status: 
Offline
I am having some issues and was wondering if anybody could shed some light.

This is a "new" 2.2 build with dellortos, Pertronix Flamethrower distributor and Flamethrower coil. "New" being relative because I've been trying to sort out issues for 4 years now.

Anyway - the engine has a slight backfire that I have been assuming was a tuning issue, but now I'm not so sure. When I watch the original tachometer, I have long noticed that there is a slight occasional dip or "blip". As I watch and listen, I am becoming convinced that the mis-fire and little dips in the tach are related. Not exact, because you tend to hear the mis-fire a moment after the tach signal.

In addition, i have an Innovate LM2 02 sensor. If I only hook up the O2 sensor, it works fine, but when I hook up the RPM signal (from the coil) the O2 reading freezes after a short time. I was assuming there was something wrong with the LM2, but am now wondering if the three symptoms are related. Maybe a bad signal from the Pertronix is causing the mis-fire, erratic tach reading and messing up the LM2 computer.

Has anybody experienced anything like this? Any suggestions appreciated.

The brand new Pertronix distributor is also leaking a little oil into the cap. I saw a thread on this a recommendations to get the McMaster-Carr 9505K17 oil seal. Does anybony know if these fit the Pertronics distributor as well as the original? I assume so since the shaft is the same diameter, but not sure about the actual groove for the seal.

-Thanks-

Don

Back To Top PM Quote Reply  

 Posted: 09-17-2018 01:53 pm
  PM Quote Reply
2nd Post
Rick in Miami
Member
 

Joined: 02-17-2015
Location:  
Posts: 31
Status: 
Offline
I’m not suggesting this as the solution for your particular oil leakage problem with your Pertronix distributor but there is a current auction on Ebay offering several used Lucas 41584 distributors (correct for horizontal mounting). At worst they would be good candidates for rebuilding. I have no financial interest in these.

https://www.ebay.com/itm/Lucas-41584-4D84-EL2-EC2-Lotus-Jensen-Healey-Used-Distributor-Points-Vacuum/173533009929?hash=item28675f9809:g:qKEAAOSw8D9bmnRx

Back To Top PM Quote Reply

 Posted: 09-18-2018 02:15 am
  PM Quote Reply
3rd Post
DonBurns
Member
 

Joined: 09-18-2015
Location: Fullerton, California USA
Posts: 75
Status: 
Offline
Thanks- I actually still have the original distributor for rebuild if necessary but am hoping to sort out the Pertronics system as I understood it to be an improvement. Will send in the Lucas for rebuild if that ends up being what it takes. For now trying to understand the issues I am experiencing. The leaking oil doesn't appear to be touching the areas between the rotor and Pertronics sensor (just messy), so I think that is not the issue, but maybe I am wrong?

Back To Top PM Quote Reply  

 Posted: 09-18-2018 08:29 am
  PM Quote Reply
4th Post
Tim Murphy
Member


Joined: 03-22-2005
Location: Huntington Beach , California USA
Posts: 74
Status: 
Offline
I have the same problem, a hiccup when idling. I am going to throw you a couple of curve balls here so be prepared :<) First, in my case, I have given up trying to get everything just right. If the engine starts, runs without overheating and the car stops when I apply the brakes, I am a happy camper. Now, I have an Allison/Crane Cams electronic ignition and ZS's. So maybe it is not in the ignition system. Maybe a sticky valve that takes a fraction of a second too long to close? Or engine vibration causing the carbs to deliver too much/or to little fuel. And my third option, which I favor, is a leaking brake servo causing the 3 and or 4 cylinder to be sucking air from the servo and not through the carbs. That could be tested by when the hiccup is happening, turn off the engine, disconnect the servo and cap the intake tube, then run the engine again. See if the problem continues. My servo is the original and needs to be sent in for a rebuild. How old is yours? I plan on going to the JHPS meeting tomorrow evening, maybe see you there. Take care.

Back To Top PM Quote Reply

 Posted: 09-18-2018 01:53 pm
  PM Quote Reply
5th Post
Rick in Miami
Member
 

Joined: 02-17-2015
Location:  
Posts: 31
Status: 
Offline
Don – I would try taking the taking the JH tachometer out of the equation by bypassing it. Power to the coil goes through it and the RVI just does not play well with electronic ignitions. If that eliminates your miss then you will probably need to convert your RVI (impulse) tach to (or replace with) an RVC tach (current).

When I converted to a Pertronix II my tach would hardly work at all. I tried several wiring alternatives to supply switched 12v to directly the coil while also keeping the RVI tach connected but the best results I could achieve was accuracy up to 3000 RPM. After 3000 it was worthless. I replaced with the RVC and now all is good.

Some background info may be found here https://www.tscusa.org/tech/4_RVI_to_RVC_Tach_Conversion_PhilipMillward_StagNews_2016_Q3_Summer.pdf

I would also recommend making sure the idle circuit on your Dellortos is clean and jetted correctly for your engine upgrades. Are they properly balanced? Are your progression holes properly closed at idle? Are the floats set to the correct height? Mixture screws evenly adjusted?

Some more background info is available here
https://www.mazdabg.com/ftp-uploads/Mazda/RX7/info/carb_book.pdf

Hope this helps.

Rick

Back To Top PM Quote Reply  

 Posted: 09-19-2018 12:58 am
  PM Quote Reply
6th Post
DonBurns
Member
 

Joined: 09-18-2015
Location: Fullerton, California USA
Posts: 75
Status: 
Offline
Rick-

Thanks for the suggestions. I will work through all of those and let you know. As far as Dellorto set up, I've fiddled with them quite a bit and taken to two local "experts" - three if you count the dyno tuner I paid over $10K for rebuild and set up (not including parts). I am not completely happy with the Dellortos. I have balanced as well as I could, but my 02 meter is saying that my ratio is about 10.5 - 11.0 : 1 at idle which seems too rich, with the leanest progression tube 7850.8 and 55 idle jets. But if I change to 50 idle jets it won't run.

I have also asked Pertronics about horizontal mounting of the distributor supplied by Delta Motorsports.


Tim-


I have been wanting to come to a meeting for a long time - afraid to drive this JH further than I can push it at the moment though. Almost talked myself into coming tonight, but the headlight switch chose today to fall apart permanently. It had been held together literally by threads. Ordered a new one today. I will shoot for next month.


I'll test the brake servo idea. I don't think so because I just had that rebuilt, but you never know.

Back To Top PM Quote Reply

 Posted: 09-19-2018 06:35 am
  PM Quote Reply
7th Post
Tom Bradley
Member
 

Joined: 07-15-2013
Location:  
Posts: 121
Status: 
Offline
Don- I would fix the problem with oil inside the distributor first. Engine oil is an electrical insulator, so it could keep the spark from jumping between the rotor and the correct connection on the distributor. Also, if the oil is dirty with tiny metal particles, that could also cause the spark to jump erratically. This could not only cause the misfiring you are seeing, but if the spark is insulated from going anywhere, the power could feed back into the coil primary and cause a voltage spike in the ignition circuitry which could cause problems with sensitive electronic circuitry like the Pertronix and the O2 readout. When you fix the oil problem you should also replace the distributor cap and rotor. If there has been sparks getting redirected inside, the cap could be damaged which will continue to cause problems. The rotor is not likely to be a problem, but they are cheap, so I usually replace it with the cap just to eliminate one possibility.

Note on tachometers: The original JH tach measured the current to the coil and converted that to RPM. With an electronic ignition like the Pertronix, there is more power being delivered to the spark plugs, so there is more current going through the tach. So the tach will read high. Otherwise, the tach should not cause problems unless there is a bad connection somewhere in the system. It is a very robust design internally. If you are still using this tach, you should adjust the idle speed using a separate engine analyzer (which measures RPM by counting voltage pulses) so you are not trying to get a good idle a too low an engine speed. Replacing the original tach with a Spidya conversion, which also effectively counts pulses, will also give you a reasonably accurate RPM measurement. But this is a fairly time-consuming job.

If you did not already know, one of the banes of these cars is bad electrical connections, especially in the engine compartment. A quick way to check for this in the ignition circuit is to put a clip lead between B+ on the battery and the + terminal on the coil. If this gets rid of the erratic firing, then you need to go looking for bad connections.

Sorry for the long post. I hope I did not waste too much of your time with things you already knew. Hope it helped.

Tom

Back To Top PM Quote Reply  

 Posted: 09-19-2018 09:35 am
  PM Quote Reply
8th Post
Tim Murphy
Member


Joined: 03-22-2005
Location: Huntington Beach , California USA
Posts: 74
Status: 
Offline
Don, even if your JH isn't running you can come to a JHPS meeting, just drive another car. There are usually a couple of us there that didn't drive their JHs. If you just had your servo rebuilt, that probably isn't the problem. If it is easy for you to test, give it a try. My guess is that the oil seal o-ring should be the same. I remember I had to put oil on the o-ring and top of the hole to get my distributor back in. It is a very tight fit. I am not sure how oil leaks into the distributor. Does it migrate up the outside of the shaft and then is splattered around by the rotating plates? In any case, I agree with Tom Bradley to fix that problem first.

Tom Bradley-I don't know that much about electronic circuitry but I would be worried if I connected my battery b+ to the coil + that it would put too much amperage into the system and harm the coil or the electronic ignition. Is that an unwarranted fear? Could one run there engine for a long time with that connection? Also, I didn't think your post was too long and was, in fact, very astute and informative.

Take care all.

Back To Top PM Quote Reply

 Posted: 09-19-2018 08:04 pm
  PM Quote Reply
9th Post
Tom Bradley
Member
 

Joined: 07-15-2013
Location:  
Posts: 121
Status: 
Offline
Tim-Your intuition is good. In a standard mechanical points ignition or with Pertronix 1 the hookup should be to the side of the ballast resistor not connected to the coil in order to limit the current so the switch does not burn out. However, the Pertronix 2 has its own current limiting so does not need a ballast resistor. In this case the connection can be straight to the coil. If you look at the schematic for the ignition circuit you will see that it is essentially a long wire going from the battery to the ignition switch, through a bunch of connectors and then to the ballast resistor. Putting a jumper wire straight from the battery to the resistor or coil simply bypasses all this eliminating a bunch of possible failure points. This is how thieves used to "hot wire" a car back before there were things like steering wheel locks. The biggest danger here is that one end of the jumper wire could come loose and short to ground somewhere and cause more problems than you have already. So it is really only useful for quick checks or in an emergency. Back in college I ran my TR4 this way for a week when the ignition switch suddenly got unreliable, but it was not the smartest thing to do.

Back To Top PM Quote Reply  

 Posted: 09-19-2018 11:45 pm
  PM Quote Reply
10th Post
DonBurns
Member
 

Joined: 09-18-2015
Location: Fullerton, California USA
Posts: 75
Status: 
Offline
Here is the response I got from Pertronics about the oil leak. My main question was whether or not their Dist was designed for horizontal placements. Obviously there is oil pressure against the shaft / bushing.


Don,

Oil in the mechanical advance area will would not be a issue. Most of the time oil around the ignitor and it's parts will not cause a problem. In less the oil has start to effect the grounding of the unit through the internal ground wire and plate attachment to distributor housing.

Oil in the distributor could be a bushing issue in the distributor. Or could be because of crankcase pressure causing the oil to push pass the bushing.

If you would like you can send the distributor into for inspection. I can send you a return number if you like to send in for us to inspect.
Your Pertronix Team,
Marvin Grebow Jr.


I have been playing with the car a little today. One strange new thing is that when I turn the key the starter does not immediately turn, but if I hold the key in the start position it will start after 1-2 seconds. I don't remember it doing this before. I verified with my meter that there is that delay before the starter solenoid sees the voltage. With my ohm meter I verified that connection at the ignition switch seems to be instantaneous. Odd, but I am ignoring for now. BTW - I just recently finished installing new wiring harnesses (all three - main, engine, instrument) and went through and checked the relevant connections and added dielectric connector grease.


I learned something new. I went back to basics and attached my Carbtune Pro and fiddled with the idle mixture screws. The Carb Tune readout has not been very sensitive to the screw adjustments. Don't know if that is a sign of an issue. But I started adjusting them by 1/2 turns and happened to look at the O2 meter. This was very sensitive to adjustment. I had been seeing O2 at idle of 11:1. About a 1/2 turn of the screws brought it to about 13:1. That adjustments to the screws would affect O2 ratio should have been obvious - just didn't think of it.


I was adjusting the timing as it seems to hate 10 degrees and below, and I was adjusting to get 12 - 13. The engine very hot at this point and I managed to let the distributor slip out of the mount. Will probably be a couple of days before I get back to it.


Thanks for all of the suggestions and I will work through everything when I can.

Back To Top PM Quote Reply

 Posted: 09-21-2018 05:40 am
  PM Quote Reply
11th Post
answerman
Member
 

Joined: 09-10-2012
Location: Little Chute, Wisconsin USA
Posts: 435
Status: 
Offline
DonBurns wrote:
The brand new Pertronix distributor is also leaking a little oil into the cap. I saw a thread on this a recommendations to get the McMaster-Carr 9505K17 oil seal. Does anybony know if these fit the Pertronics distributor as well as the original? I assume so since the shaft is the same diameter, but not sure about the actual groove for the seal.
Late to the party, but I believe I can answer this for you.

I went through the same thing a few years ago: I was troubleshooting some ignition issues and decided the easiest thing to do was to replace the original Lucas distributor with a Pertronix Flamethrower distributor purchased from Delta. It solved my ignition problems just fine, but started leaking not long after.

I lived with it till last winter and finally called Delta about it. I basically was asking the same question about the seal. Mike from Delta actually chased around at Pertronix until he got an answer, which is that (a) no, there is no seal, and (b) no provision for one.

So, I ended up having an original distributor rebuilt (that's a story in itself) and fitted it with a Pertronix Ignitor II.

Back To Top PM Quote Reply  

 Posted: 09-21-2018 01:07 pm
  PM Quote Reply
12th Post
DonBurns
Member
 

Joined: 09-18-2015
Location: Fullerton, California USA
Posts: 75
Status: 
Offline
Thanks - I ordered a rebuilt Lucas from the club store yesterday. None in stock so will be 2-3 weeks. I went with the new Pertronics originally because new seemed better and they were cheaper than the rebuild- not so much in this case.


Was there a problem with the rebuilt Lucas?

Back To Top PM Quote Reply

 Posted: 09-21-2018 05:10 pm
  PM Quote Reply
13th Post
DonBurns
Member
 

Joined: 09-18-2015
Location: Fullerton, California USA
Posts: 75
Status: 
Offline
So have now ordered rebuilt Smiths 25D which Greg has guaranteed not to leak AND a Spiyda conversion kit to convert the tach to RVC. Will update in a few weeks when I have these done.

Back To Top PM Quote Reply  

 Posted: 09-22-2018 08:07 am
  PM Quote Reply
14th Post
answerman
Member
 

Joined: 09-10-2012
Location: Little Chute, Wisconsin USA
Posts: 435
Status: 
Offline
No, the rebuilt Lucas has been perfect. Problem was that my original distributor, the one that came with the car, was a 45D4, not a 25D4, and Greg was pretty sure it was an MGB distributor. So, I had to scour the group for someone who had an actual JH spec 25D4 that could be rebuilt (thanks Stephen Luckett). That worked out fine once I got the correct one: I still have oil leaks to track down, but not from the distributor.

Last edited on 09-22-2018 08:28 am by answerman

Back To Top PM Quote Reply

 Posted: 09-26-2018 11:47 pm
  PM Quote Reply
15th Post
DonBurns
Member
 

Joined: 09-18-2015
Location: Fullerton, California USA
Posts: 75
Status: 
Offline
While waiting for the distributor and tach conversion, as I said I am going through with relooking at some of the basics. Rebalanced the carbs and tried it from a different direction. Adjusted all of the idle mixture screws to the same turns (ended up at 4 turns) after very small adjustments to the air bleed screws on 1 and 4 to give equal CarbTune readings. Getting to 4 turns was what it took to get an 02/fuel ratio average of just under 14:1. The reading is bouncing around much more than I remember in the past though. Not sure if that means something wrong with the meter. At 3000rpm average is about 12.7 also with a lot of variation, somewhat less. For those with O2 meters are your readings reasonably steady?

Did a compression test, with engine warm.

1- 200
2- 208
3- 184
4- 200


That's a little disturbing. This engine still has very few miles and I did a test when new and they were closer then.

The plug condition seems to indicate that cylinders 1 and 2 have been running rich and 3 and 4 lean. I'll check again to see if these latest adjustments even that out.

Back To Top PM Quote Reply  

 Posted: 09-27-2018 04:05 am
  PM Quote Reply
16th Post
CDA951
Member
 

Joined: 04-16-2018
Location: Santa Barbara, California USA
Posts: 7
Status: 
Offline
DonBurns wrote:
While waiting for the distributor and tach conversion, as I said I am going through with relooking at some of the basics. Rebalanced the carbs and tried it from a different direction. Adjusted all of the idle mixture screws to the same turns (ended up at 4 turns) after very small adjustments to the air bleed screws on 1 and 4 to give equal CarbTune readings. Getting to 4 turns was what it took to get an 02/fuel ratio average of just under 14:1. The reading is bouncing around much more than I remember in the past though. Not sure if that means something wrong with the meter. At 3000rpm average is about 12.7 also with a lot of variation, somewhat less. For those with O2 meters are your readings reasonably steady?

Did a compression test, with engine warm.

1- 200
2- 208
3- 184
4- 200


That's a little disturbing. This engine still has very few miles and I did a test when new and they were closer then.

The plug condition seems to indicate that cylinders 1 and 2 have been running rich and 3 and 4 lean. I'll check again to see if these latest adjustments even that out.


Before freaking out too much about the relatively low compression on cylinder #3, how many miles are on the engine, and have the valves been re-adjusted, and if so, how long ago?

I would do a leakdown test to make sure the cylinder is sealing properly. If so, I would then check the valve clearances (which I know is no small task on the 907 engine). I tend to set the valve clearances on the loose side on an engine with a fresh valve job, because they will tighten up once everything seats in during the break-in process. If the clearances get too tight, the valves are open for a longer duration than normal, and this affects the dynamic compression.

I am currently assembling the engine on our (somewhat) recently acquired '74 Jensen Healey (#19250 for those keeping score), and while this is my first 907 engine, I have a good amount of experience building/breaking in engines as a professional Porsche/BMW technician.

The usual routine at my shop is to install and run the engine with break-in oil, do the initial break-in run (say ~100 miles, and make sure the engine sees some load to seat the piston rings, no babying it!), change oil, re-adjust valves. Then re-adjust the valves and change the oil again at the 1,000 mile mark, and go to normal service intervals after that. Whether Porsche 356, VW Type IV, Porsche 911, or BMW M10/M20/M30, this routine has always worked well.

I did the same on our '81 Alfa GTV6 after a fresh valve job, and the shim-and-bucket intake valves (same concept as a Lotus 907) certainly tightened up after the valves seated in!

Back To Top PM Quote Reply

 Posted: 09-27-2018 04:52 am
  PM Quote Reply
17th Post
DonBurns
Member
 

Joined: 09-18-2015
Location: Fullerton, California USA
Posts: 75
Status: 
Offline
Thanks for the reality check. Essentially no miles on the road. Hours in the garage. I still remember driving a Lamb Miura and being told "it was not a car you should drive further than you can tow it" I hope that is not the case with a JH but not sure yet. This is my second and at over $45K into it and still undrivable. Starting to think that with the engine from my first car - a Ford Pinto - this would be a pretty decent ride. Please don't take this too seriously - just giving voice to the dark place that I suspect many JH owners get to now and then.


BTW - had a '74 Alpha 1750 GTV Iniezione, and a '74 BMW 2002 TII. Hindsight, right?

Back To Top PM Quote Reply  

 Posted: 09-27-2018 05:08 am
  PM Quote Reply
18th Post
CDA951
Member
 

Joined: 04-16-2018
Location: Santa Barbara, California USA
Posts: 7
Status: 
Offline
I also own a '73 BMW 2002tii. Great car, though it is currently awaiting some overdue rust repair . . . .

Another point I wanted to make (somewhat unrelated to the original post and sub-section of this forum) is that while modern wideband O2 sensor controllers can be a great asset for tuning older cars, they are only as good as they are set up to be. Have you properly calibrated your sensor in free air? Are you 100% sure there are no exhaust leaks? It can be easy to obsess over minute changes in A/F ratio and lose sight of the big picture . . . .

Make sure that the mechanical and ignition side of the engine are good, then make sure your wideband setup is properly calibrated and leak-free, then circle back to the fine-tuning.

Last edited on 09-27-2018 05:09 am by CDA951

Back To Top PM Quote Reply

 Posted: 09-29-2018 02:44 am
  PM Quote Reply
19th Post
noomg
Member
 

Joined: 08-02-2018
Location: Long Beach, California USA
Posts: 59
Status: 
Offline
Don,

You have 45 thousand dollars in your J-H, seriously? Not judging, actually I'm impressed, you are truly a man of dedication. Reading your thread it seems to me you may have inadvertently created a witches brew of upgrades and performance parts so when a malfunction occurs it can be difficult to isolate it.
I'd say generally speaking based on my experience the J-H is pretty reliable. I've driven mine from Long Beach to Reno for the air races with a buddy driving his J-H, a distance of 1000mi roundtrip, twice. Both cars ran flawlessly. Aside from Pertronix ignition and an MSD unit my motor is basically stock with 120,000mi on the clock.

Back To Top PM Quote Reply  

 Posted: 09-29-2018 02:48 pm
  PM Quote Reply
20th Post
redracer
Member
 

Joined: 09-10-2012
Location:  
Posts: 187
Status: 
Offline
I agree with noomg: too many variables. The original distributor should be oil free if you replace the internal seal(the very early cars did NOT have a seal but could if one pressed the upper steel bushing down for a seal).
A Petronix ignition system(minus the dizzy) would make for a long reliable system; their distributor with NO seal apparently was not designed to be placed on its side.
As noomg said they're reliable; I have driven my car twice across the U.S. and twice have driven cars back from CA. to Atlanta.

Back To Top PM Quote Reply

Current time is 11:34 pm Page:    1  2  Next Page Last Page    
> Jensen Healey & Jensen GT Tech > Electrical & Instruments > Pertronix Tachometer "blips" Top




UltraBB 1.172 Copyright © 2007-2011 Data 1 Systems