madkaw

Not a Mikuni expert -BY FAR, but you didn't mention if this fuel pressure problem is affecting the engine performance? Could you just have a guage problem?

Okay, but what about gasket matching! Only kidding:)

Okay, I understand the logic behind the reversion better now, but again I was suprised of the size difference. And when refer to overlap, are you refering to a cam that has an overlap grind? Does my stage 2 270/270 with 480 lift qualify that statement? Also, does the fact that this is a Mikuni short manifold change the effective velocity as compared to a long manifold? In other words do changes as far as the possible negative effect of gasket matching to velocity lessen, because of the less distance for the charge to travel? Lastly( I hear a sigh of relief from the crowd), when using this manifold later on for ITBs, would this be a mute point as far as fuel injection? Would gasket matching be a better course at that point? I hope someone else is getting something out of all these questions!!!!!!

TonyD, thanks for the response, but confused about this line I'd not screw with it, port matching will gain you nothing if the manifold is smaller than the intake port I think you meant that I don't want the intake manifold port larger then my head port-which I understand that. My E-88 head is modified with the larger valves, mild porting, unshrouding of the chamber area and a stage 2 cam. I was just taken back by the size difference in comparison to the gasket-as in the photo. If there was some opening up to do I wanted to do this before I mounted these up. This is all a learning curve for me and I just ASSumed that gasket matching was prudent, but worth while effort towards performance. I have no proof, but I believe my SU's are choking my engine performance in their stock form. With my humble head improvements and dual 50mm exhausts it seems my engine needs to 'breathe more', but I might be just talking out my a$$. I will probably just bolt on as they come for now, and see how the improvement goes. These 40's came off of a car running a L24. I believe the brochure for the Mikunis stated that this was a 23% hp increase!

Are the new ones rubber or urethane? If they are urethane then drop them in some boiling water for a couple minutes before installing and they should form into place easier.

I saw some of your posts and pictures when doing the research. This blow thru set-up is very cool, but I think I will be over my head. I think I will stick to my original plan to go from SU's, to Mikuni's, then EFI TBI's and then maybe turbo charge that!!!! I think with the advantages of wide band O2 set-ups and edis you could maybe help the blow-thru set-up work better without a lot of guessing on your afr's. This doesn't change the fact that the Cartech box is too small or the set-up is not as driver friendly as what I want for a semi-daily driver. Tony would say-go efi is the better way to go-and I agree. The money spent on this set-up would be much more cost effective to buying a wideband/O2 and EDIS and getting the optimum tune on my SU L24 now and slowly work towards a MS controlled EFI.

This is the problem when considering this set-up, there is not much info out there for the non-expert mechanic. I read that this Cartech set-up puts boost out like an on/off switch which cause lean issues. This might be a waayyy cooolll set-up in it's time, but it might be more expensive and time consuming then just going from carbs to EFI. Yes there are threads about the Cartech, but no specific instructions.

Thanks Tim, I'm not really interested in doing any "porting " as much as doing gasket matching. Looks like you went beyond gasket matching, but your intake ports might be enlarged. I only enlarged my e-88 ports to match the stock gasket and SU manifold.

Thanks Sam ,and as Shane said, he sent me that info. I wish it was for the Mikuni set-up. Sam , you said the Mikunis are for the cartech set-up specifically-do you know if the jetting is set-up for the blow thru and does they have different floats?

I know this is a long shot, but does anyone have any info on the Cartech mikuni blow thru set-up. I would love to find a copy of the installation of this set-up. I have contacted cartech and they said all that stuff was destroyed when they moved offices.

Mikuni

Okay, I was told this kit(came in a mikuni box) was for the 240z specifically. So they intentionally make the runners small to apply to all the L6 motors? I noticed quite a lip behind the mounting flange area- in the runner, so gasket matching shouldn't take it beyond the actual runner diameter?

I broke out my Mikunis to look them over for the future install on my Z. I wanted to check out jet sizes and such to get my base line for future tweeks. I went thru great trouble to gasket match my SU's to my e88 before install and thought I would do the same for the Mikuni set-up. But WOW, i couldn't believe what I saw when I layed an extra intake gasket against the manifold. Am I missing something here or is this right? That is a huge difference-not sure what to do here guys, I just seem baffled over this. These are 40phhs by the way. Comments please.....

Yeh, I realize that, that is why I am anxious to get a wideband on this car and stop guessing as to what I'm doing. I didn't just bolt on parts---well I did-but I do realize it's about tuning them all together. The car seemed lethargic revving out in 3rd gear. It was like I was watching the tach in slow-mo. Somethings a miss there, so I need to know what's going on----back to the O2 sensor.

I am kind of where your at right now-lot's of work and not happy with the end results. I agree with the above statements that a more precise tune will get better results. I need to get a wideband also, so I am not just guessing about what's going on. I believe I have an engine that wants to breathe, but my SU's are not providing enough air to the engine, but can't prove that without the O2 sensor. Your engine sounds good-don't give up on the L6 yet, it has the way-cool factor going for it!!!

Well a totally disappointing trip to the dragstrip. Though the car held together great, my times sucked, The best i could muster was a 15.6, I have a lot of time and money in this car for 15.6. I'm hoping the triple Mikunis will wake up this motor. I will be getting a wideband shortly to verify what I think is a lean top-end.

I believe it is a rare breed anymore that hangs out and walks and talks cars and also be someone you can count on.First off it is hard to get anyone you can count on. A person that rememebers that favor or that knows that you will always reciprocate a good deed.I have a good friend for 30 years now and the basis of our friendship is cars. He just lives across town, but It might as well be 100 miles away before we ever get together becuase our schedules are so full. I'm lucky to get time to step out in my garage that's 10 feet away between work and family stuff and spending time with my wife-who works full time. It's a different era! My son doesn't want anything to do with working on a car and that's fine, but I believe it is the younger part of your life that you get the time to hang out with car buddies-on a regular basis. Ahhhhh--for the good ol days again!!

Pull off the valve cover and look at #4 valves. Especially the where the rocker rides on top of the valve, it might have turned sideways with a sticky valve!

Well I've tried to set the timing back to 10 btdc and keeping the vacuum advance, but I still get detonation at the vacuum and mechanical overlap point-around 2800rpm. Though it doesn't last that long going thru the gears, and it is only prevelant at a slow acceleration rate, I'm pulling the plug on the vacuum advance until I get something better. one big reason is that I smelled coolant today inside my car, but couldn't find any source for the smell. Wasn't using the heat either. Looked around my heater core and everything looked dry. So paranoia set in--BLOWN HG. No white smoke, no visible leaks outside the engine, plugs looked alright. I took the cap of the radiator and started the car and saw some bubbles, but I think the thermostat just opened so maybe the rush of coolant caused the bubbles???? I just went back out there again after the motor cooled and simulated the same thing and bubbles right after the thermostat opened, but couldn't see anymore after that. Don't have the capabilty or time to do a leakdown right now-anything else I should check? Motor seems to run pretty smoothly though I have been messing with mixtures on the SU so it wasn't perfect. I'm kind of dislexic(and a bad speller) when it comes to certain things, but now that the weather has turned cooler and dryer the mixture probably leaned out right? So if I leaned out the SU's on top of that, have I gone to lean and would that enhance detonation? I'm gonna research this right now so don't flame me I want to take the car to the dragstrip this coming tuesday, but want to make sure there isn't anything wrong with the motor first.

For that price I think would spend my money somewhere else. 1600$ just for the plenum-ouch! I would think that kind of money would allow you to modify those Mikuni intakes anyway you want and you would have something really different---BLING!!!!

Looks like that MSD only changes the final amount of advance, which is helpful, but not what I'm looking to do. I think better results can be obtained by modifying the Nissan dizzy, but not as easy as turning a knob. Getting that vacuum advance to work with a power curve is the challenge. My car is awesome at 21 intial and 36 total, but I can't use the vacuum advance for economy. My next dyno run will be at the quarter mile at indianapolis, and I plan to run the car at the same timing setting as I did at zcon, then I am going to go for a pure power run with the vacuum advance plugged. Then I will work for something in between. I am kind of anxious to see the difference in the first two runs. My butt dyno says it will be considerable. I do have to keep in mind that i made a BIG float adjustment since the dyno run and I have gained at top-end for that effort. This is the most workable approach since Tony is hiding his top-secret dizzy somewhere is his toybox.

I also wonder what he did with that dizzy if your running 8 initial and still getting 36 total! You might find some reshaping of the mechanical weights or springs or slots for the advance-you better hold on to that dizzy. I think I will try and find another e12-80 dizzy and experiment with it and keep my original stock.

If you won't sell it, can you just take it apart and make an outline of the weights on a clean sheet of paper for a templet From what little I've read of dialing in the dizzy, the reshaping of the weights is much better at controlling the mechanical input then messing with springs. My car ran so great at 10 intial with full advance, now I just need to find the secret combination to get the full advance to come in at the right time. This is going to take some serious R&D and many trips to ORP raceway-darn! I will probably find a nice set-up and then I will be mounting the Mikunis--- to start all over again.

I'm suprised that you could just "plug in" your advance when running 34 total, but I have no idea how much advance your dizzy vacuum pulls. What's you intial set at then. Bottom line is that if you can do that and not detonate and keep all that top advance and good mileage your doing great! I believe I have one of the early electronic dizzys, I will have to look to see how much vacuum advance it has. I think you are running higher compression, but you must have some overlap with that cam. Just curious-what kind of pressure do you get doing a compression test? If I didn't mention it earlier, this dizzy is all in at 2500rpm. The vacuum advance is 17 degrees. So at 2500 rpm at a cruise/slight loading(going thru the neighborhood at slow cruise thru the gears) I had 10+17+17= 44 which from what I have read is not out of the norm, but at that 2500 mark is where I would here a slight ping.

I would like to use the mechanical advance, but this e12-80 needs to be tuned to my engine. The e12-80 pulls too much advance at the wrong time for my application and causes detonation and does not optimize power. Why run 27 degrees total when you can run 35.I did look at the idea of slotting the pull rod, but I don't think there is enough rod to do that-but I'm still working at something to that fact. As far as being a long day at the dyno-if I have my ducks in a row and have several options to try during my dyno time, I can make effecient use of my time. 30 ounce, I think I am experiencing what you have now. I have suffered mpg for power, but I haven't really given up any drivability. The power is good everywhere and very smooth and predictable, just needs to be more effecient. I would like to cut the vacuum advance in half and see how close I can get to 36 degrees total without detonating. If I was able to make the vacuum advance somewhat adjustable it would give me several options at the dyno in a quick period of time. I would just be curious to see the numbers comparing what I ran at zcon(10 degree intial-27 total) compared to where i am now(21 initial-36 total approx.) Fuel injection is great, but for performance you need to be ready to spend$$$. I would like to go with a edis set-up and install a megasquirt and do the timing curve right, but for now it's going to be tweeking the e12-80.