73 corvette 454 with a 17057216 and a spare 17080205

[leroy]

Hello fellow quadrajet lovers

First the car 3500lb 454 781 heads 2 1/8" side pipes 1 7/8" straight thru's 16" vac@650rpm 38 degress all in by 2800rpm, ported advance. Intake has no branding I can see but is a duel plane ali job. Guessing stock compression and cam unknown, starts  to fall over at  5400rpm.  4 speed 3.55 rear 27" tall tyres.

Bought this car in Australia and had only been in the country 4 months , appears to of had a frame off rebuild looking at it but can not tell your much more about the motor.   

Now the carb. Hurts me to tell you this but it is a remanufactured  one from somewhere( the air bypass was blocked off with lead plugs could not see numbers on jets, primary rods looked like 41B (was there an E?eyes not as good as used to be) , 110 inlet, DP secondary rods and one of the full vac ports was missing a tube and not blocked off)

Anyway dived in everything looks nice and clean, blocked off the vac leak checked throttle plates sealing off properly when closed, did the secondary lock off at 90 trick and confirmed apt screw was operational (this one in the throttle plate)

Drilled the mixture screws out to 90 thou air bypass closed up and set to 50 thou from the spare put in the needle and seat  being a 130 put the 72 jets and 51M rods and DR rods

Anyway smooth idle and nice transition to primary and happy with the secondary side but still need to sort the primary side i reckon it is still too rich usind tip in method

soo want to buy cliffs primary rods and DA rods but what jet s , oh the air bleed is 55thou

[Cliff Ruggles]

"M" series metering rods would not be correct for an early style carburetor with the APT in the baseplate.  They are too short, and the tips are too fat.

The "M" series metering rods were used in the later single main airbleeds carburetors, with the APT just in front of the power piston.....Cliff

[leroy]

Thanks for the reply Cliff

Guess I will put the 41B that I have back in then

Given what you have said looks like I will not be able to use your 44 rods then

Was thinking since it was a 170 series carb the M would be ok but glad you sored me out

What are your thoughts on jet/rod combo would work given the car its in

Thanks again

[Cliff Ruggles]

If the APT system is in the baseplate, they use longer metering rods, with .026" tips.  They made Chevy truck and Marine carburetors with 1705XXXX numbering that were still the old divorced style units that used longer primary metering rods.

The later single main airbleed models with the APT in front of the PP, used "M" series metering rods.

They can also be set up with our "44" metering rods and smaller main jets.

We sell the correct length rods for the early carburetors.....Cliff

[leroy]

Yep the apt is definately in the base but looks to me that it has the single main air bleed

Does that sound right or has the airhorn been mismatched to the body . I know the number on the air horn is different to the body

Righto so a set of primary rods to suit from cliff but what jets just wondering if I need to go smaller than the 71 in recipe 1 or maybe just a softer PP spring.

When I floor it it does stumble a bit and then up and away but  it does leaves two puffs of black smoke behind me and is not the tyres any advice is appreciated

Cheers

Leroy

[Cliff Ruggles]

Rochester made some single main airbleed divorced choke models in the later 1970's, right before going to the later style q-jets in truck applications.

They are nice carburetors, and easier to tune than the huge MAN divorced choke models from the same period.

The stumbling going to full throttle probably isn't related in any way to the primary jet/rod/pp spring set-up.....Cliff

[leroy]

Hi Cliff

I want to order a SR carb kit for the 17057216 from you along with rods  jets and power piston springs

given the details in the first post can you reccommend the rods and jets  to order and which colour spring to use

Do you know what this carb was originally on and is it normal to have a different code number on the airhorn to the body  just curious

Cheers

Leroy

[firefox3]

Here's a link to a vacuum break someone on Ebay is selling for your model carb.

http://www.ebay.com/itm/77-CHEVY-TRUCK-BLAZER-PICKUP-4WD-CARB-VACUUM-BREAK-/360347282835#ht_500wt_949

The seller lists the application for your model and some models with similar numbers.

[leroy]

Thanks for the reply firefox so now I know what it used to sit on now

If I had read cliffs comment before would of seen he had mentioned chev trucks but now I know it was on a 350/400 cube motor as well thanks

My vacuum break works fine I reckon has about a bit more than 2 second delay

I think the stumble is on the primary because it happens low in the rev range say between 1500=2500rpm range and after can feel when the secondaries kick in nice and smooth but I have also set the hanger hieght to a G hieght since but when the m rods where in the stumble was not there

think the best thing i could do is maybe only adjust one thing at a time and test

another thing the float hieght is measured from 3/16th in from the toe of float to top of carb body right?

the reason for the question is when I set it at 1/4" hieght before the carb was flooding when turned off so have dropped it a bit to stop that maybe my float has absorbed some fuel anyway get a kit and re try I guess
 enjoying having  a good at getting it right

[Cliff Ruggles]

I would get one of our kits, it will have a new float, correct high flow viton needle/seat assembly, and the upgraded accellerator pump assembly.  We can supply the correct tuning parts for what you are doing.

BTW, we sell the same choke pull-off for $25, with the straight inlet.....Cliff

[leroy]

Righto Cliff will fill out your form and get some goodies Cheers

Once I have it done will give it a run and tell a story

[Cliff Ruggles]

Lee, you didn't put an email address in the email that you sent, so I have no way to respond to it......Cliff

[leroy]

oops sorry cliff have sent quote request with just an email thanks

[leroy]

Hi Cliff do you want me to resend a quote request form or you just really busy at the moment

Cheers

Leroy

[Cliff Ruggles]

Your email must be in the request or I can't respond to it.

You can also send a message directly to:

cliffshp@embarqmail.com