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Discussion Starter #21 (Edited)
Thanks My427. Yeah, I'm not able to log with this handheld. There is aa "IRM count" that logs in the system info to evaluate electrical interference. With the Pertronix system (post 12) I consistently got an IRM count of 5 or higher, sometimes in the 20's. That was with the distributor and coil feed pairs twisted and shielded with a tinned copper mesh shield on each pair grounded on one end. With the current MSD (post 13) my IRM counts are always zero.

See the videos linked from post 12 and 13 for the rotor phasing issue. Pertronix has a problem, MSD does not. I have the MSD adjustable rotor in my parts box but don't need it.

On my current setup I timed the ignition to 8 degrees BTDC with the MSD distributor alone (no box) and the vacuum advance disconnected. Adding in the vacuum from the manifold gives me 20 degrees total at idle. Mechanical adds another 18 starting at 1500 rpm and all in at 3500. Car ran fine like that; smoother than before, just not perfect.

I then added the MSD box and took the post 13 video. Then I changed out the cap and test drove. Again, smoother than without the box yet not perfect. I should also add that I was able to reduce the idle speed from 750 to 700, and increase the idle AF from 13.8 to 14.2.

Then a day later, cold start, I drove the car and got a bad misfire on light acceleration off the line. Once warmed up the problem went away. So I went to re-time the ignition- but the MSD box causes the RPM reading on my timing light to basically double. So I timed it for apparent 16 degrees instead of 8. Drove the car like that, the misfire was gone.

Next day, same issue with misfire on cold. So I timed the ignition old school, kept the vacuum advance connected, advanced slowly at idle until maximum vacuum then set it there. Idle surging slightly until highest vacuum. Not sure where it's at, I'm guessing just a little bit higher than 8; maybe 10 or 12. Car ran well like that. I also set a new tune on the EFI and will test it again today.

I have a 30 amp 4PDT switch on order to wire the system and enable me to switch between distributor only (inductive) to full multi-spark capacitive.

By "not perfect", the engine isn't smooth at cruise. But I think I've isolated the EFI and ignition out of this equation. Maybe it's the cam that I'm feeling. Maybe my engine balancer didn't do his job well enough.
 

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Discussion Starter #22
Last week I found a slight leak at the cylinder head to header connection at cylinder 4. I'm certain it wasn't there when they were installed, as I recall inspecting the job after it was done (I was super busy at that time so farmed the job out to my buddies at Classic Metal in Mocksville, NC). But last week after smoothing out the ignition I heard a slight noise, put my hand near to feel it and sure enough, a slight leak.

I have a pair of Sanderson headers on the car and the manufacturer recommends no gaskets, just a smear of RTV copper on the joint. After a time it must have given out and I had a pinhole size leak. Every exhaust pulse sends a high pressure wave down the tube and this is followed by a vacuum, so a leak out means fresh air and oxygen gets into the system. When that additional O2 goes past the O2 sensor, the ECU interprets that as a false lean. This explains why my fuel mileage has been so poor, about 12 mpg, and I should be getting at least 15.

For anyone interested, here is a short tutorial on tuning EFI, and it covers why leaks in your exhaust system can really mess you up. Watch all four.


I re-sealed the header, set a new tune and the car runs terrific now. I'm still running AF at 14.7 at cruise but had to richen a bit to 13.8 to get a smooth idle. Was also able to reduce idle speed to 650.
 

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Discussion Starter #23
I tried really hard to keep my original air cleaner but the MSD distributor being so tall contacted the bottom of it. I had tweaked the metal as much as I could but the cleaner was still pressed down on top of the two back wires. To tweak the cleaner more required more work than my talent alone can handle, so instead of cutting the old part then paying my body man to shape and weld a patch I found this nice looking unit from Billet Specialties.

The "Classic" theme goes with the build quite well. Intake air temperatures have been reduced by about 15 degrees F, which surprised me over the OE snorkel. I ran the car last night and it seems to run very smooth, indicating that I have eliminated electrical interference from the close metal contact.
 

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Discussion Starter #24
New cast badge on the air cleaner provides just the right amount of bling.
 

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Yadkin, a touch off base, but how did your Sanderson header install go? How about the sound and any adjustments to the rest of the system?
 

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Discussion Starter #27
Yadkin, a touch off base, but how did your Sanderson header install go? How about the sound and any adjustments to the rest of the system?
The headers fit the engine nicely, but I literally have only about 1/8" clearance on both sides of the chassis. The driver's side makes contact with the steering box and I have to address that issue soon.

Also, Sanderson did not recommend any gasket, just a smear of RTV copper sealer at the head connection. I used more than a smear, and still had two tiny leaks on the passenger side. No amount of tightening took care of it. I finally pushed more RTV in at the two locations and obtained a seal- I don't expect it to last. "Hot Stuff" brush-on manifold dressing was suggested to me by an experienced hot-rodder, and I have a small jar on my shelf, along with new 12 point ARP header bolts, for when the RTV gives way.

As with any header installation, expect to have custom exhaust work to plumb the rest of the system.
 

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Discussion Starter #28
When that additional O2 goes past the O2 sensor, the ECU interprets that as a false lean. This explains why my fuel mileage has been so poor, about 12 mpg, and I should be getting at least 15.
On my last two tanks of gas I have been able to achieve 14.0, then 14.2 mpg. This includes mountain driving.
 

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Discussion Starter #29
After more tuning I've got my distributor set as follows:
• At idle 15 degrees initial + 19 vacuum = 34 total
• At 4000 RPM WOT 15 initial + 18 centrifugal + 6 vacuum = 39 total
• at 3400 RPM cruise 15 initial + 18 centrifugal + vacuum = 41-45 total

My last tankful, a good mix of highway, two lane and some city driving, I achieved 15.6 mpg.
 
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