Spark Plug, Compression, Gearing, and Power Feedback

[Chickenman]

The plug you want is NGK BPR6ES.   Do NOT get BPR6ES-11 . The 11 actually stand for 1.1mm , which is a pre-gap of .041". In NGK numbering, no suffice on the end ( Like 11 ) designates a standard gap of .031". The 1.1 mm plugs should not be gapped down to .030". It puts a weird angle of the side electrode and causes faster wear on the side electrode tip. 

You always want resistor plugs on any Modern car. Less EMI  and they will foul less than non-resistor plugs.

Lastly, the MSD Blaster 2 coil is not a great choice for a non-CDI ignition. Without getting too technical, it just isn't a good match in electrical specifications to your Unilite or any early Generation electronic ignition boxs. It is designed to be used with CDI boxes or high powered Modern Inductive boxes.

Inductive ignitions are very sensitive to the coil used. They require a higher Primary resistance than a CDI coil and a different turns ratio. 

I had an MSD Blaster 2 coil on my 1976 280Z for a while. And the stock Nissan 280Z coil actually put out a better spark. Why? Because it was a better match to the factory ignition box. 

 

 

 

[Chickenman]

I now have a Crane HI-6S MultiSpark inductive box combined with the MSD Blaster 2 coil. Spark output is much better. However, I will be switching the MSD Blaster coil to a Crane LX91 E-core. That is the recommended coil for the Crane HI-6S and is a much better match spec wise. Spark output with the LX91 coil should be much higher. than with the MSD coil 

I also have a Crane Fireball CDI box with a PS92 Race coil. That will REALLY fry your wienies in a hurry. It's over kill on my 10.3 CR NA engine. The HI-6s inductive box is more that strong enough.

I may sell the CDI setup to one of my Turbo buddies. It would be perfect for a High Boost Turbo application.  

[Mike W]

When I had the unilite installed (along with the MSD ignition box) I also used the recommended Mallory coil - part number 29440. It was a part of their ProMaster line of coils.   I have not had any issues with this coil and contiue to use it with my 123 dizzy and the MSD box.  Seems to be a pretty good combination.

Given that MSD has now acquired Mallory, I do not believe this coil is available any longer. However, I do have a spare so if Jeff gets to a point where he wants to try a different coil I would be happy to lend him the spare that I have.

Mike.

[madkaw]

I would think your compression readings would be a bit higher for that combo. 2.9 block and small chamber head . Those look like stock L28 numbers . 

[7tooZ]

No one has mentioned the valve settings. Don’t they play a part of the overall success of tuning?


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[Zed Head]

1 hour ago, 7tooZ said:

No one has mentioned the valve settings. Don’t they play a part of the overall success of tuning?
 

Good point.  A full tune-up would be the way to go.  Piece mealing won't be very fulfilling.

Beside that, I don't think that you can get to 2.9 liters on an L24 block without swapping the crankshaft.  An overbore alone doesn't get you there.  Kind of looking like a run-of-the-mill L24 engine that needs a few mods and a tuneup.

[EuroDat]

One thing I do when making any "improvements" is record a simple baseline performace to compare later.

Easy to do. Go for a drive and do an acceleration test in 3rd, 4th or 5th gear, depending on your final gearing. Start the test at around 1500rpm full throttle to the maximum rpm you are happy with. Record how many seconds it takes to get to 2000rpm, 2500rpm, 3000rpm etc. After your improvements are done do the test again and note the difference.

A friend of mine put tripple webers on his Zed and it sounded great, but when we tested it it was actually slower up to 2500rpm. Took a dyno tech 4 hours rejetting, and then playing with the timing and cam timing to make a big difference.

[EuroDat]

8 minutes ago, Zed Head said:

Beside that, I don't think that you can get to 2.9 liters on an L24 block without swapping the crankshaft.  An overbore alone doesn't get you there.  Kind of looking like a run-of-the-mill L24 engine that needs a few mods and a tuneup.

Hardway is using a L28 N42 block in his 240Z, but still 2.9L shouldn't be a problem if the rest of the engine components are for a L28.

That was my point on the E88. "E88 with stock cam" is not going to work as well as a N42 or even a N47 with the bigger inlet valve. Thats is assuming it's of a L26. The L24 had smaller inlet and exhaust valves. Not enough info on what has been done to the head.

Edited February 2, 2018 by EuroDat

[Zed Head]

Oops, it's right there in the first post isn't it.  My mistake.

So, back to a full tuneup and a little more detective work.  Maybe some minor modifications.

[EuroDat]

51 minutes ago, Zed Head said:

Oops, it's right there in the first post isn't it.  My mistake.

So, back to a full tuneup and a little more detective work.  Maybe some minor modifications.

No worries, its Friday.

I agree with the tuneup. The engine has a 20% increase in capacity over the L24 so everything working right you should have a noticable increase in power.

 

[240260280]

Ignition timing has to be set correctly.  Triples like lots of timing in the lower rpm's.

[Hardway]

I had some time to mess with the car today.  Before I did anything I replaced the leaky valve cover gasket and cleaned up the spark plug side of the head.  That alone took an hour+ since the current gasket had been glued to the valve cover with a generous amount of adhesive.  Once cleaned I installed the NGK BR6ES-11 #7131 spark plugs, gapped at .033 and hooked everything back up.

Using an external tachometer and timing gun I had 12 degrees adv. at idle which was 1,000 RPM.  I could not get the car to idle smoothly below that so I ran with it.  I observed the advance maxing out at 32 degrees at 3,000 RPM.  I did not make any adjustments to the distributor.  A quick test drive did not yield any change in driving impressions.

With the valve cover off I noticed some dual parallel scoring from the timing chain on the inside.  During a previous valve adjustment I noticed quite a bit of slack on the driving side of the timing chain so the scoring on the valve cover confirms its not right.  At this point, for many reasons I am parking the car and will not drive it until I fix the timing chain.  I fear it could slip or break causing severe damage to the engine.  On that note I am thinking of pulling the engine so I can re-seal it, clean it, and paint it.  At the same time I can decide what I would like to do about painting the engine bay as it is currently three different colors, black, red, and silver.

I appreciate all of the help and feedback regarding this issue and will keep you posted on my progress.  Thank you everyone!