Qjet specs for a close to stock pontiac 400

[Marx3]

Hi, the 17058272 I have on my freshly rebuilt 400 is not working properly.
Engine is stock except the heads have been milled for 8.4:1 CR and a Crower 60240 cam ( 210/222adv. 112 lsa  )The engine never ran good with it, even after I gave it an overhaul with new idle tubes and cleaning up all holes and passages with compressed air, etc.

Engine idles ok smooth, even down to about 500 rpm, but it dies when I put it in gear, even at 900 rpm idle.
Car has horrible take-off and feels like it is missing half the cylinders when cruising. It drives and handles allrigth, but it feels very very tame.
Heck, it wont even spin the tires on a wet road.

Also, the carb tends to drip from the venturis. This carb is coming off asap. It is old and molested from previous owners.
I have plenty of M4M's lying around, also 800 cfm units. I am going to rebuild the cleanest one I can find, but want to know what specs I should shoot for.
I am thinking this:
.080 bypass
.045 dcr
.036 tube
mixturescrew holes about .090
Acc.pump holes about .025

MAB's both .070 ( or about .140 combined )
have plenty of secondary rods to try. Will go testing with my wideband to hit 12.5-12.8:1
Have 76 jets and 50 M rods in there right now, and it is running 15:1 afr at cruise, but the MAB's are pretty large as I recall, so I think I will start out at 73 jets and 44 rods.

My previous car was a Cadillac with a 500 and a Qjet I built for it and that engine ran like it was fuel injected. I want the same results here...
What do you think of these specs ?

[Marx3]

Found a clean 17080270 from a 301 and did the following:
mixtureholes .085
idle bypass air .077
tubes .034
DCR stock .039
upper idle bleed body .070
lower idle bleed .070
discharge holes .027

upper MAB .070
lower MAB .070
jets 73
rods 44

secondary rods are from the previous carb. Havent adjusted that part yet.
float height is juuust under 1/4, fuel pump is stock mechanical.

timing is about 35 degrees in idle with vacuum, and about 35 total without vcauum at 3000 rpm.

installed solid nozzles, adjusted the airflap opening distance and grind the flaps for secondary pull-over enrichment.

The idle wants to roll a bit, and the engine wants to stall when I put it in gear when the idle is at 800.
Off idle response is still not impressive at all.
I haven't finetuned the afr with my wideband yet.

Also, with the idle at 1000 rpm I have nozzle drip.

I must admit, though I have build many carbs and also customized quite a few, I have gone blind to these problems!. Especially now that I KNOW the carb is "about" as close as it should be...

Or is it???

[Cliff Ruggles]

A low compression 400 with that cam is going to want/need a LOT more idle fuel, about what a 10 to 1 CR 400 would need with a 230 @ .050" cam in it.

I'd go more with bypass air, at least .100", .038" idle tubes, and .055 if not .059 DCR's.

Main jets 73 or even 74's with 44 full tapered rods.   You could also use 41-43K metering rods and it would be pretty close.  Keep the "M" series primary rods away from those units, they will not work well with them.......Cliff

[Marx3]

aha! you dont say. Oh boy am I glad there is an obvious reason for it not running good off idle.
I am  these values right away!
You recommended this cam for me... right ? ( ehh...  )

I will finetune AFR's once I get this car running good. I have your rods in there right now and plentey of both K and M rods available.
As far as I know K rods are stepped and M rods are tapered like the rods you supply. Why do you recommend K rods over M rods in these units, then?

[Marx3]

got the tube up at .038, the DCR up at .058 and the by-pass up to .0100, next drillbit was .0110, thought that might be too much.

Idle is massively improved... I guess, since the cam doesn't make a whole lot of vacuum i can not expect it be able to handle 600 rpm idle without strugglin a little not to stall...  ( stock converter )

My rear tires are doomed now... that's for sure :-)

This just made my whole rebuild worth the effort!
Thanks as always!

[Frank400]

installed solid nozzles

  What do you mean by that ? 
Frank.

[Marx3]

the secondary fuel nozzles has holes in them on certain units... Actually I am not sure eactly why this it not good in a "performance" application, but Cliff recommends to get rid of them and put solid ones in there.

[Cliff Ruggles]

The cross drilled holes are only their on models with limited airflap opening.  With the airdoor opening all the way up we want all the fuel to come down on the far side of the divider plate for improved distribution/atomization, etc.......Cliff