Ok you have me thinking In a good way i hope Cheers...I think i know where the issue is..I will fit my msd coil to it,open the gaps in the plugs a little,leave the boost and start dropping the numbers out of it,I think the weak spark is being compensated by more advance....see what happens

cheers anthony

I forgot to mention TopGear used colder plugs and avgas for his setup which is drawthrough rather than blowthrough so completely different beast to yours.
However ignition with e85 seems more complicated for idle, midrange and top end. For the link I put up the smaller motor setups use more ignition down low and decrease as the rpm increase. Maybe doesnt hurt to index the sparkplugs to the inlets as well?. Maybe only a possible gain of 1-2hp but it all counts.

Also what do you think is the deal with leaner 2 and 3 as I thought the equal length manifold design would compensate here unless the boosted charge is doing something funky and spreading out to the outer parts of the manifold runners therefore 1 and 4 getting more somehow. Maybe you need to use a square box over the carb rather than the hose straight on the throat as there could be some kind of bias in the flow pressure that spreads it more to 1 and 4.

From this info making the gaps larger might not be the right way to improve your setup as it recommends smaller gaps and 3 colder ranges for the plugs when using e85 and 7.25:1 air/fuel ratio.

Quote:

CarCraft article

I have already dropped my plugs from 5's to 7's,this is my theory my first theory was heading in the wrong direction
Im going to put a stronger coil in today,drop the timing leave the boost at 11 and open the plugs a little and check the plugs if it goes rich which it should because everthing is late in the combustion cycle i will start dropping jet sizes.
The std coil wouldn't fire the plugs without a gap size on or under 0.022 it was just being blown out coming on too boost...The leaness of 2-3 has me stumped you 100% correct in equal runners and i can't see any reason for the Air entering the carb to be biass,I was wondering about pulsing in the manifold at first due to the firing order but cant see how that will happen ,so im wondering if these two run hotter sharing there exhaust port....?
the other problem with E85 is its power doesnt drop off that much running really rich unlike 98...but the issue is too rich and it wash's your oil of the cylinder walls yet E85 makes its peak power right on the max rich side!

My next question was going to be could the 2/3 shared exhaust cause some hotter reversion in these cylinders than 1 and 4. If this is the culprit maybe going by Jmacs previous posts it seems the cheapest solution if so is to enlarge the ports on the exhaust manifold 1mm so there is a step from the exhaust ports on the head and the reversion is reduced.

On some more threads it seems a tip top ignition setup along with the 3 stages lower colder plugs with smaller gaps is the key as the e85 flame front is more erratic but is offset with the richer but cooling qualities once the correct ignition/boost balance is sorted.

ok Im running MSD coil in it now,it required an 8ohm MSD ballast resistor but i read here that datsuns run 7 ohms standard so i put it in as is...
dropped the the timing down to 6deg locked with vac in at 20 deg....what this has done is im making 16 pounds of boost with out touching the turbo settings and the car feels weak compared to before,on top of this my mixtures are now lean midrange id expect this is from the extra boost,
so im tipping my hat towards the burns happening later into the cycle and into the exhaust creatining hotter exhaust which is spooling the turbo harder but doing nothing for my exhaust valves!

Just another note Im using petrol a/f ratio Not E85 a/f but if i were im running between.7.1472-7.3134 on the E85 scale Or 10.75-11...
I have the distributor locked at 18 deg and it's know starting to pick up a lot more torque boost is still 15 but the motor felt stronger on 11psi with 25deg.
cheers anthony

I like the work on this classic build. Great job indeed!

Thats great Anth keep up the notes as its easily forgotten.
what are the plug gaps?

I thought i would share as much as i could,there are other with more knowledge the me and im hoping at some point they may chime in....But That has changed today running 28 thou gap in the plugs i went for 23 ,drove to the servo to get more E85 it now goes alot better,....BUT whilst on the main road i decided to safely wind it out...No good Im running out of fuel...not in the sense the mixtures are leaning out,but the std fuel pump cant fill the bowl quick enough....
So for those that want to run around 14 psi on 98 with a stock pump it can be done and will handle it without any issues You must Boost reference the base as I did this will save on electric fuel pump,and rising rate reg...The mechanical fuel pump probably would handle low boost levels on E85
Here is another picture of my setup

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  rsz_anths120y.jpg (189.61 KB)

whats the turbo and what rpm is it coming on song? If you can get your car to Sykine in Ballarat for a dyno tune he could sort you out but maybe you are just toying for the fun of it at this stage.