[Formulajones]

Yep, depending on the length of the tips and the hanger used.

Or just put a holley on it

[ta man]

In this case it isn't a quadrajet....

[Formulajones]

Yeah I know, meant to be a joke for someone here. Man, tough crowd, no sense of humor with this bunch.

[gtofreek]

Originally Posted by ta man

In this case it isn't a quadrajet....

Wonder why I thought it had a Q-jet?

[77 TRASHCAN]

Chad
Is your dyno tuning done?

Would be nice to get that beast leaned out a little, not just to see the power output.
Since it's a street car for all around drive-ability...

[Cliff R]

"Too me, putting larger tipped rear metering rods in would, essentially, change the secondary jetting. No?"

Paul, it really depends on the length of the tips, taper of the upper section and included angle between the tips and the upper section. The hanger will have an impact here as well, as will how far the air door is opening. So in basic terms, you can install smaller rods and actually go leaner, or bigger rods and go richer, depending on what rod was replaced and it's height (hanger used) in the secondary jet holes.

This isn't a Q-jet thread, but I will say since we're talking A/F on the dyno that there is NOT 50hp left on the table here with jetting. Could be that much for something like secondary throttle plates not coming all the way up to 90 degrees, no spacer used on a single plane intake, etc, in combinations with jetting, but jetting alone going from "pig" rich to just a tad lean isn't going to leave that much power out of the dyno run.....IMHO......Cliff

[Chadmokc]

I have like 50 dyno sheets (each pull had like 5 sheets of paper he printed with all the parameters on them) printed up in a folder and I pulled what I thought was the most current but they are out of order. Monday when I go pick up the engine, I will take a flash drive and get all the data on it and I can find the last run and see if it still needs some tuning done. I took a pic of those sheets and graph and posted them because it gave a good idea of the power it made. I will also do some more tuning once the engine is in the car and has a load on it.

[gtofreek]

Originally Posted by Cliff R

"Too me, putting larger tipped rear metering rods in would, essentially, change the secondary jetting. No?"

Paul, it really depends on the length of the tips, taper of the upper section and included angle between the tips and the upper section. The hanger will have an impact here as well, as will how far the air door is opening. So in basic terms, you can install smaller rods and actually go leaner, or bigger rods and go richer, depending on what rod was replaced and it's height (hanger used) in the secondary jet holes.

This isn't a Q-jet thread, but I will say since we're talking A/F on the dyno that there is NOT 50hp left on the table here with jetting. Could be that much for something like secondary throttle plates not coming all the way up to 90 degrees, no spacer used on a single plane intake, etc, in combinations with jetting, but jetting alone going from "pig" rich to just a tad lean isn't going to leave that much power out of the dyno run.....IMHO......Cliff

That's why your the Q-jet modifier, and I'm not! I just rebuild them.

[ta man]

Originally Posted by Chadmokc

I have like 50 dyno sheets (each pull had like 5 sheets of paper he printed with all the parameters on them) printed up in a folder and I pulled what I thought was the most current but they are out of order. Monday when I go pick up the engine, I will take a flash drive and get all the data on it and I can find the last run and see if it still needs some tuning done. I took a pic of those sheets and graph and posted them because it gave a good idea of the power it made. I will also do some more tuning once the engine is in the car and has a load on it.

That's when the real tuning and fun begins...good build...and you know the engine is ready to rock!

[mchell]

Originally Posted by Chadmokc

I will also do some more tuning once the engine is in the car and has a load on it.

good idea.........every time I tuned my engine for optimum results on the dyno(chasis or engine dyno), it did not translate to optimum performance at the track...things change dramatically when the car is actually moving..

[Formulajones]

Yep, there will always be some tuning once in the car. Usually leaning it a tad for the reasons I mentioned earlier are pretty common. Not sure who said 50 HP, but there is certainly another 10-15 to be found with that AFR you saw on the dyno, it will generally run a smidge richer installed in the car as well. Besides, track tuning is always a great time anyway.

[blueghoast]

If you have one or can borrow one put a 2-inch OPEN CARB SPACER on it.
That should help lean it out some and should give you another instant 20 HP.
It did on mine. Problem was it wouldn't fit under the hood of my 64-Tempest.
I was amazed of the instant hp it made though. Try it.

GT.

[shaker455]

Originally Posted by Chadmokc

We ran the timing up to 30 played with the jetting, air bleeds and emulsions. We switched to my headers that are larger primaries but shorter length compared to the dyno headers, played around with timing, plugs and jetting some more and this is where she's happy. The #'s are a tad lower than expected but I also built this as street car with more room to grow later if need be and believe it will still be a handful with this power level

No disappointment here, this thing sounds like an animal and I grin childishly every time it fires up.

We did run it up to 5400 and hp holds strong from about 4900-5100 then starts dropping off.
With brakes left to do, a little rewiring and getting driveshaft cut down, I'm guessing she'll be back on the road in about 2-3 weeks. Busy at work and a baby may slow that down though

Which QF Q-850 you got?

There is 11 to choose from.

I'm not clear why your dyno guy did not get the AFR's to 12.5 WOT?

Was his dyno wideband off?

[Cliff R]

Power production is what;s important. Unless the dyno operator was completely clueless he would have jetting up/down in conjunction with advancing/retarding timing to get the best power numbers.

I NEVER trust any monitoring equipment with this sort of thing. A few years back when we had my engine on the dyno for testing and the resulting magazine articles in Popular Hot Rodding and HPP Magazine we did some carb testing after all the pulls were completed and best power numbers recorded.

Installing an 850 Holley to replace my q-jet resulted in LESS power on the very next pull, but the fuel curve looked a little cleaner/smoother with better BSFC numbers. Not sure how that can happens and the dyno operator noted it.

When the engine was re-installed in the car and we did the private track rental we also did back to back carb swaps just like we did on the dyno, and the big Holley a tad slower than the Q-jet, almost EXACTLY what the differences on the dyno would have accounted for....FWIW.....Cliff

[shaker455]

Originally Posted by Chadmokc

Long day at the dyno and only 2 short pulls. Water leak at the crossover due to me not getting the valley pan sucked down enough and it holding the intake up a hair. Got that fixed then had rough idle and distributor issues, cylinders 5 & 6 plugs were black. Replaced cap and rotor and fixed that. Then had no spark, found a loose connection and fixed that. Whew... Got a 3000-4500 rpm pull in to check carb and timing and it made 519tq at 3800 and 414hp at 4500. Changed some jetting around and picked up a few. Not as much as I hoped but still a lot of tuning to do. Tomorrow he will fine tune and run it up around 5k rpm to see the final numbers she nets. I also will have him run with my 1 3/4" headers for a final pull because the headers he's running with the sensors on them are tiny, I'm talking like 1 1/4" tiny. That's what they look like anyways. Hoping that is restricting power a little.
We will see...

Chad,
Where did you guy's end up for timing, jetting, etc?
Jeff

[Chadmokc]

Here are a couple more pulls from earlier. Both these are at 28 degrees timing but the first is with dyno headers and the second with my headers. The earlier dyno sheet I posted is when we had just bumped it up to 30 degrees timing and ran it to see where we were at. There was more tuning done after that and a couple more pulls up to 5400 but then we ran into heat soak. He also worked Saturday and I was busy at my buddy's working on my car. So there may have been even more fine tuning done.

Q850 drag carb
76 fronts 84 rear
Last I knew. May have changed since then. Started with 33 air bleeds and swapped those but may have went back. I honestly, am just learning this carb stuff so I left it to him.
He loves the tuning ability built into these quickfuels. I will find out where the a/f and that stuff ended up.

[shaker455]

Very good & let us know.

Last sheet posted is in the 11's