Kennymonster

Response is very crisp with current setup, I've only observed mid range rich condition at dyno setup where I was just dumping the pedal to WOT, which probably is contributed a bit from the cam profile as well. Overall I'm happy with the setup, but then you occasionally see 'those other' l28 dyno charts with a perfectly flat afr which makes you want to tinkle more, it's a disease I swear.

Yeah I'm just nit picking on the last 500 band I'm working on getting a 4.11 in there soon so probably going to spend more time up there. As for the accel pump, during the pulls I was careful to start around 3k and gradually tip in to minimize the effect, I guess the afr's pretty close to optimal for my setup except for the rich cruise, which I'll back down to 60's once my car is off the jack stands.

Was doing some googling and came up on this thread again, so I thought I might as well post my updated NA setup/jetting notes for reference (the blow through turbo setup has been sold as of earlier this year, ring went bad on my old block and decided to back to the loud but slow route ) Now running: N42 / e88 combo, .480 / 276 cam, Mikuni 44's, .45 pump with 34mm venturis Right when I had cranked the car up after the fresh motor swap running on open header (back in July?), I retained my previous NA jetting which was 62.5 pilot 140 main 190 air With no exhaust, this netted ~13 afr in 4th gear up top, which was great. I haven't bothered with tuning for a while, but it seems after I had finished all the exhaust and new final drive setup, I noticed it had dropped a point or so to 11 to 12 afr under WOT in 4th. Thus the tinkering again last few weekends; After few different combos, I had 130 main and 180 air for a bit, which was reasonably flat except for a spike of 13.5 to 13.8 around 5 to 5.5k, seemed little bit too lean for comfort so I'm currently running 62.5 135 main 190 air This setup nets 12/13 AFR from 3k to 6k, and dips down to 12 afr at 6.5k. At this time, I'm tempted to try 200 air to see if I can lean out the 6.5k to 7k range... however from my experience the air jets seldom had predictable effect on the actual curve of the AFR (verified on dyno), often times a very slight change if at all. From what I've gathered going to 37mm will net me that extra 500 rpm but at a sacrifice of low band, and probably will have to rejet everything again. I could also try going back to 130 mains and smaller air (maybe 170's) to try to address that spike, but thinking maybe slightly conservative tune is safer being 9.5:1 now for CR, and running California 91 octane most of the time in racing conditions. My cruise AFR is still a bit rich with the big pilots, it was around 12/13 with the 130 mains, and 11/12 with the 135 mains - I'll be trying 60 pilots later on for the cruise/low range.

Just reporting back for purpose of search results in the future: I got it to run well using the proper marks. I did take some measures though to ensure an accurate reading, even with a barebone timing light I think the multiple sparks from the MSD have a way of fudging the reading. - Swapped in a separate wire (of different brand just to rule out the existing wires as issue), routed it away from all the others to prevent any interference - Bolted on the L28 tab with multiple scale marks to double confirm the TDC mark, offset mark, and total advance mark - Set the total advance to ~35, it was a bit more touchy to adjust with the precautions taken above, I can only guess the previously seen '35' was off by few degrees Still getting some exhaust popping but that might just be pilot jet settings, definitely less than before however. The reading I checked before the adjustment showed 2.5 degrees at idle (which would mean only ~20 degrees full advance), to my surprise ran reasonably well but it did struggle at the top end occasionally. Now with the newly set timing, it's pulling strong past 6k in fourth, and I'm a happy man.

I also have one sitting in my garage if you want moar maxima heads On a stock dished block with less than average compression, and a very mild cam, I put down 150rwhp which wasn't too bad for not doing any headwork.

Thanks for the feedback, actually was attempting the dial back light method last night at a buddy's, and his craftsman tool conveniently died. I agree with your overall assessment, though on a CR of only 9.5 : 1, 91 octane, and a .480 lift cam (all supposed numbers from PO), I would think it would just dog at only 10 degrees total advance. Currently the power feels similar to my previous 8.7 : 1 with nowhere near as built motor, which ran on 36 or so total advance as typically done. Fuel/induction hasn't changed, 44phh mikunis, fuel psi is right at 3.5 psi as it should. I guess I don't really have any other ideas besides confirming with another dial back light, or maybe using the black numbers & slightly increasing the timing by 10 degrees or so to see if the power immediately drops off or gains.

I've had no problem in the past setting the ignition timing on few different L6 motors, various 240z/280z style timing marks, etc. so I'm kind of stumped on what's happening. Quick overview: this motor was actually built by another owner, I bought it and had it crated over, dropped it in to replace my dead blow through set up. I was told the specs for it, complete bottom rebuild/head/cam setup to my liking. Crank pulley that came with the motor is a single groove, I can't tell if it's the euro version (the ring portion looks different), and doesn't seem to match any aftermarket pulleys either, so confused here as well. There are multiple grooves / timing marks on the pulley, which look like this: - Big gaps are increments of 10 degrees (verified with 280z timing scale tab), smaller gaps are increments of 5 degrees - I checked for TDC via spark plug on #1 on compression stroke, it was the highest at the black "0" mark on the pulley, farthest to the left if looking from the front - When I go to set the total advance timing at 3k+ rpm, it looks like the above pic.... which shows the supposed 35 degree offset mark based on the established TDC, way off from the timing marker/pointer, it's reading almost 10 degrees full advance which is not correct. Note at this setting, the motor runs very healthy. - I've tried adjusting to the referenced black 35 mark to coincide with the black 0 TDC mark at full advance: loss of power and heard detonation. - The red numbers are what makes more sense to me, as I think the total advance is already correct, but that doesn't jive with what I saw to be TDC (the #1 piston was higher on the stroke on the black 0, vs red 0 mark) I'm just running it as is right now, but would like to find out once and for all what's really going on here.. any feedback is appreciated. Power level is great, also getting a lot of exhaust popping when I let off (though the afr is fine) which I'm not sure is related to the ignition timing or not. Pic of the crank pulley:

Got the 155 main / 170 air combo in today, took care of the transition problem for high load @ 3rd / 4th gear The smaller air corrector seems to have done the trick, mains kick in lot earlier and the 'lean spike' doesn't go past 12, at WOT it's at 11.2 to 11.3 under 4th gear pull to 6000. Car feels happy with the nice fat mixture.

Yeah the 160's were an experiment to see how it behaved under super rich condition, under load, that gave me an insight for pilot to main transition under high gear / boost. Been just informed that Mikuni air jets only come in 10's, not 5 increments??? Bah, I'll try the 155's with both 170/180 airs I guess. I think my AEM unit does a self calibrating routine at start, or it seems like. Next time you're out here on the West coast, holler and we'll go for a drive!

Going to do some jetting this weekend.. at 150 main /180 air, 1st/2nd gear is dead on 11.5 but after getting hot (as in after 8 laps), it's leaning out too much in transition in any high load / high gears, 3rd/4th/5th. I threw in 160's last night for the hell of it, pulled like a mother in 3rd/4th without leaning but saw the AFR dip down to 9's when main's kicked in and settled in 10's at WOT. I'm thinking of going back to 150 main, but trying 170 air to see how much effect it would have, hoping for lot earlier transition than the 180's to keep everything smooth. Edit: Got impatient and just went out for a 4th gear pull with 150 fuel / 170 air... transition was ok with WOT at 4th around 12 AFR at 6000, this was 8 pm in the evening though. I'm sure it'll lean out in the day when it gets hotter. The 20 gap between main and air seems to be the trick? Just ordered 155 main and 175 air's from Todd, hoping for rock solid 11 AFR

^You're only couple of hours from me, how long are you sticking around in so cal / any plans to attend ZCon next week? The San Diego Z club folks are going nuts getting everything set up, I'll be volunteering at the zcon AutoX on the 9th also.

^I have not, but will soon. I always go to the same place so it should show a pretty accurate before/after comparison, I put down 150/150 as NA, expecting low 200's with the boost.

^Yup detonation kills motors, not boost. I had the wastegate hooked up incorrectly on one run, accidentally hit 16 - 20 psi few times, but with the afr/ignition in check, it pulled like a space shuttle. If I can get this to work after many frustrated nights, I know you can figure out your issue Steve Will be waiting on updates!

Sure thing' date=' I'll try to be as brief & concise as I can, and attempt to avoid turning the thread about me / my setup. I figure some of this will be useful information for anyone going this route anyway, hybridZ has some scattered info on blow-through's but nothing comprehensive, I should really put my notes together and post the build log. Current Mikuni settings, with 10 psi on the t3/t04b turbo that came with the Cartech kit (sorry not much details on the turbo itself, had it rebuilt due to it destroying itself during tuning) Mikuni 44's 34mm venturis 150 main 180 air 62.5 pilot 45 pump For those not familiar, the kit is basically an 80's Corky Bell / Bell Engineering creation, not too many around these days. I came across it randomly when someone offered it to me out of the blue, at a bad time to resist since I had a local friend/competitor who was about to turbo his Miata. If you do a search for this online, you'll probably see a handful having ran it in the past, but switched over to EFI, as well as a bunch talking about wanting or running it, and never following through (in typical internet fashion of easier said than done). There are also tuning concerns stated, or the lack there of. I have to admit that I didn't know much about it, but still wanted the challenge based on the assumption that if the kit was being made and sold at some point, it had to have worked. It took some time to really get it to run decent, not because of the jetting, but more to do with providing adequate fuel delivery and addressing the plethora of issues that came with pressurizing the carbs, against their intended purpose. Here's a quick cliff notes to save headaches for those researching this route: - Get an EFI fuel pump + bypass style regulator with boost reference + run a bigger return line. This will maintain 3.5 needed for the carbs, and with the fuel regulator upping the psi of fuel 1:1 ratio with the boost applied, it'll ensure that the float bowls stay full. i.e. Fuel pressure needs to be at 13.5 to have 3.5 psi at the carbs + 10 psi of compressed air coming in. - Ignition timing, I think this was one of the advantages of trying this set up in 2014, as opposed to 1985. With the MSD 6AL unit, I was able to get an additional MSD module that connects to it, a 'boost timing master.' With the boost reference, it will retard the ignition timing between (1 to 3 degrees, adjustable), per each pound of boost, and you can also choose at what point the retarding kicks in, between 1 to 5 psi. This allows me to maintain 15 degrees base timing at idle, mid 30's at cruise when off boost, and total advance back down to 20 at full boost. The kit out of Corky Bell's literature: [img']http://i47.photobucket.com/albums/f180/Kennymonsterious/11cgqbp.jpg Replaced that ridiculous 80's wastegate on the left with a newer model, same brand: 3 port Mallory regulator with boost reference: it actually has total of 4 ports for inlet/outlet, and the return which comes out the bottom. This worked out nicely for the triples, since I have 1 port as feed, the 3 remaining outlets have dedicated lines going into each carb to prevent any starvation. Shot of my engine bay as of today, since there's no ECU, everything has to be referenced the old fashioned way, with vacuum/boost. Using a short runner Mikuni intake manifold, I'm using 4 out of 6 vac ports which most NA setups will retain the hex plugs/not use. Fuel pressure and ignition timing is referenced at the plenum, to achieve earlier and simultaneous signal for each. Only mods to the carbs at this point, are changes to the jetting above, and making slightly thicker gaskets out of cork material for the jet covers, to make sure there's no pressure leak under boost (could probably order new sets from Todd... but I'm afraid they'll be something like 20 bucks each)

^If the compression on the cylinders check out, I guess check the valve clearance? I feel like these carbs are pretty stout and hard to believe they'll start fouling all of a sudden for no reason, I wonder if your lashes went out of adjustment. As for me, I have a set of 65 pilots but afraid that'll just enrich my cruise more than it already is, basically at a level of compromise at this point. I wonder if all that intercooler piping and whatnot is impeding off boost air flow and making my afr richer than it would be at cruise, i.e. compared to just open velocity stacks sucking in. My buddy just ordered a set of rebuilt 40's from Todd for his L24 on a smallish cam, and he received 62.5 and 65 for baseline, apparently that's where the starting point should be anyways. I have 170 to 220 for air and mains ranging from 120's (don't ask ) to 165, I see that you're a frequent shopper with Todd as well haha. My current tune right now at 150 main /180 air / 62.5 pilot is actually pretty good at 10psi, I'll probably leave it unless I run into issues, haven't really done too many pulls at 4th gear yet since it hits 3 digits pretty quick now ;p