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3.42s work the best with my camshaft I have found - in na form. But the 3.73s are the most comfortable for me when I use a 200-4r at hiway cruise.
I had a breakthrough moment last night when a thought on boost referencing the power system popped into my head from nowhere. Amazing how you can just let things sit in your mind awhile and they get sorted out sometimes. This 7043244 core doesnt have the best setup for access to the base of the power piston but it is doable.
Sounds great! Yeah I went 3.42 to go withthe th400, and yes with an overdrive the 3.73 is great!
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Big improvement today.....
I was looking again at the Qjet as a whole system, wondering and contemplating the fueling problems I have had. Made a couple small changes, the Qjet is just RIGHT if you know what I mean. should be faring better in my estimation.
I reinstall it on the car and look at the operation of the throttle blades. THE SECONDARIES ARE ONLY OPENING 1/2 TO 3/4 OPEN AT WOT
Its the stupid things that get you. Its been like this all along because I used a 2 barrel cable bracket and didnt check to be sure the cable opened the blades 100%.
I mean, Ive been thru thaat a million times before. Youd think I would remember.
Anyhow the carb (and turbo) is acting much better after a swap to a 4 barrel bracket!
Todays test drive shows boost comes in 500rpm sooner, now at 2500rpm! Turbo must be spinning harder.
Boost came up to a steady 8psi, higher than I wanted but its rock steady. (I had modified a 12 psi spring - may do so again)
WOT fuel is a dream until I empty the Qjet - I may need to work on increasing fuel bowl capacity soon.
Ran it all the way through 3 gears.
One of the changes I made to the carb leaned out the part throttle power mix to 13:1 which causes a stumble under boost and out of the secondaries. Easily remedied.
I also have a mild lean condition midway in the secondaries. I think a rod change gets me there.
I cant wait to get another run in the car after the next changes. Trying hard to get ready for the raceday at Lebanon Valley.
You can use as large as 0.160" for the seat, that would help your fuel starvation issue.
You can also add capacity to the carb by removing some of the material from the bottom areas of the black plastic spacer block that sits over the float in the carb there.
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I think I am at .150 seat right now. And yea I was thinking of maxxing float setting and cutting down the block for more room. Ill have to take a look at places where I might be able to shave the casting a bit too.
I am wondering if it is possible to have some sort of remote supplemental fuel bowl to increase the capacity. Just an idea, not sure if it is feasible or not...
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Wow that is thinking outside the box Sean! I like it!
I will see what I can accomplish with what Ive got, but that idea is going in the "remember to try this" file.
Thinking just quickly about it, I am certain it is possible and even do-able.
BPG Member
I have modified the WG spring again - heating, relaxing a coil and cutting it off - and now it hold max boost at about 5-6psi.
I think this is perfect for the initial tuning and testing of the system. The WG has a provision so I can add a bolt and pushplate to increase the spring preload to achieve more boost later. I am thinking I will get it tuned at 5-6psi and get some track time, then adjust to 8psi and retune...then get track times to compare.
I need to get a strip tuning kit for Qjets. I have used up all the standard sizes of jets and rods that I have. Now I need some jets that are right inbetween drill sizes. I cant make what I need - going to have to buy some.
edging ever closer to a good tune. 10 minutes at a time.
I did modify the baffle block and raise the float to max to get more fuel bowl capacity.
Thanks for the update, great work!
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looks like I have the primaries dialed in. finally. nice lean 14.5:1 cruise, good smooth power. about 12.5-12.75:1 power mode comes in at 10 in Hg and below.
Secondaries are great at WOT. but right now the transition is needing some work. Kind of stumbles a bit. I think its goin lean as the secondaries start to open up. Last part of the puzzle here.
Its just going to take some trial and error. each revision gets closer.
Hooray!!!
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well I got the transition to secondaries just right - but now I go lean or rich at WOT, depending on the rods I use.
You know what is a real pain in the butt? The lack of availability of secondary rod sizes. I have about everything available and I need things right in between.
Tired of messing with it atm. need a break. but Im almost there.
What I may do is go with the good transition and 2nd rods a little too rich at WOT, and just bump the boost up a little to try to get rid of the WOT stumble. I need to add the adjustability to the WG anyhow.
I agree, go to the max boost you plan to run then do the fine tuning... Otherwise you will go through this again when you up the boost and you know you will... Maybe 12 PSI?
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hehheh yea but Sean I want to keep the boost low so I dont blow the thing up or melt a piston or something while I am tuning it!!!!! It makes some baaad noises when it goes lean. Besides which my fuel system can certainly keep up with 5psi. Not so sure about 8psi, so it eliminates a variable at this time .
The adjustability preload bolt works well. It is at its minimum setting 5psi right now.
I am learning a lot about how the carb reacts to boost. It seems you can stay a lot leaner than I would have expected with the rods and jets. at heavy part throttle (low vacuum) situations the boost in the hat starts squeezing more fuel from the carb.....sort of progressive enrichment.
I am finding that a 12.5 mix is great at WOT full boost but 13:1ish performs better under most other circumstances including transition.
I need a break. Getting tired of messing with it.
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Oh man I finally got it.
Lots of test n tune, change and try....but it was worth it.
Primaries deliver nice smooth power, nice lean cruise around town. Transition to secondaries is flawless - cant even tell except by the sound. WOT power is VERY nice.
I produce 6psi right now and when on the boost, the car "feels" like it did when it had the nitrous. I would hope to run equivalent to the 50 shot times I had run....13.5 or thereabouts. But I really dont know. We will see at Lebanon Valley May 25th!
There is still some "fine" tuning to be done to squeeze more out of the current arrangement. But tonight was the 1st time I ran it from a dead stop through the gears with no issues of fuel delivery. So pleased with that. Boost stays in thru the gearshifts - it shifts HARD and goes!
On a downshift from cruise, it takes about a second for the turbo to spool up and then WHAM the power hits.
I do think spooling is inhibited a little bit by the 3.08 ratio gears I am running but its whats in there right now.
You really can hear the difference in the engine when its on the boost. It just sounds sooooo much happier. That giant magnaflow doesnt hurt either.
definitely put smiles on my face tonight! Time for a few beers!!!!!
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