Help Please

[pete0186]

Hi I'm new to quadrajets and pulling my hair out
I have bought off Ebay a 17059553 and fitted it to a 69 corvette. Things went relatively well except it ran very rich and leaked fuel from the air horn gasket. When I took it apart I found the body and air horn warped which I was able to straighten otherwise in very good condition. The jets were a miss-match of 71 and 70 with home ground needles. So I bought Cliffs book and set to work
I found the specs of the carburettor (best as I could measure) matched Cliffs recipe 1 except for the jets and needles and the description of the engine in Cliff's recipe was spot on for what's in the corvette. I set the ATP screw as per Lar's quickie method due to the home ground screws and installed the below needles and jets.  Things going well right, not so much.
 It backfires through the carb and lack performance. I set ATP for the best I could get the car to run which seems to be a long way out from the starting point. Could someone advise if I'm even close with jets and rods or will this type of carb ever work   
What I installed
prim rod 50
Jets 73
sec rod CK
Hanger K
Engine
350CID  mild cam, headers, 300Hp iron manifold, auto trans, standard converter, standard gears

Any help will be greatly appreciated       

[pete0186]

one other thing sea level, if it make a difference 

[Cliff Ruggles]

Tell me more about the 1969 Corvette' engine, CID, compression ratio, head castings, camshaft, etc, etc?

BIG flags go up from an Ebay purchase then finding it's a crap shoot internally.

IF you plan on using that carb I'd call us at the shop and provide all the engine details and we can set you us with a custom kit and tuning parts to nail down the calibration w/o having to pull your hair out.......Cliff

[pete0186]

Hi Cliff,
Thanks for getting back to me. Do you ship to Australia?
Engine details
350cid
Heads 3998993
69 cast intake
Compression unknown expect 8.5 to 9
Cam unknown mild bit of overlap
Headers
Just had a look and found atp screw wind nearly all the way out to stop back fireing through the carb very little travel left in the piston
Pete

[Cliff Ruggles]

I ship overseas daily, and to anywhere.

993 heads are excellent, compression would be really low unless a flat top piston were used and shim type .020" head gasket.

Most SBC builds don't get flat tops or tight quench due to the thickness of the aftermarket replacement gaskets.  This lowers compression .4 alone and if the pistons are factory dished it would be under 8 to 1 in that scenario.

So you can basically build the same engine with flat tops, tight quench (around .025-.035"), 993 heads and come up to well over 9 to 1 compression.

Makes a BIG difference when choosing camshafts and tuning parts for the carburetor.

The 17059553 is CA emission calibrated and very lean, but a good carb and I can set you up with what is needed to get it to work on that engine.......Cliff

[pete0186]

Thanks Cliff
I will give you a call early next week when I work out the time difference
Pete

[Cliff Ruggles]

Sounds great.  We can also correspond by email:

cliffshp@embarqmail.com

[pete0186]

Hi Cliff,
Email sent
Thanks
Pete