rochester quadrajet

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thirdgen

rochester quadrajet

Post by thirdgen » Wed Apr 16, 2014 8:48 pm

i have fitted my quadrajet in place of my holley i had under the holley was a metal plate that does not fit the rochester so i only have the 4 hole gasket under the carb its fairly thick so i left it out car runs ok but do i need one ? does any one know ? can it damage anything ?

i have a elderbrock dual plane i think its called inlet not the pontiac one the cars sounds different with this carb on too exhaust note i mean. but runs well

also i dont have the hot air bit for the choke so i wired it open for now is the electric kit worth getting ? any one have one ? it was coughing a bit earlier today from cold.

just get this done and its leaking water !!!! fooking cars :oldevil:

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bhm1712
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Re: rochester quadrajet

Post by bhm1712 » Wed Apr 16, 2014 10:43 pm

mine has the gasket directly below the carb and then a very thin metal plate the same shape as the gasket below (around 0.5mm thick stainless steel)

The QJ's do sound different because they have the huge secondaries which open at full throttle and it changes the intake and exhaust note = something you dont get with the holley or edelbrock square bore carbs. If you take the shaker off and drive it sounds different again as the shaker kind of funnels the air and changes the note!

As for choke mine doesnt have one and it starts ok from cold and after 2 mins drives fine with no coughing. You may need to set your idle mixtures etc
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thirdgen

Re: rochester quadrajet

Post by thirdgen » Wed Apr 16, 2014 10:52 pm

thanks it started ok just needed to tickle it until it would idle on its own not to long just coughed a but from start up cut out once and was ok after that. i saw the big ones open when i give it the welly on the drive :D
it does sound very different i guess i will get used to it . i might remove the choke bit now. :thumb: it come preset but said it might need tuning to suit.

does run very well even tho i have not driven it yet as its leaking water now.

SUPERCHARGEDGTA

Re: rochester quadrajet

Post by SUPERCHARGEDGTA » Wed Apr 16, 2014 11:53 pm

easy enough to tune just adjust till highest idle then reset idle speed

thirdgen

Re: rochester quadrajet

Post by thirdgen » Thu Apr 17, 2014 8:12 am

thats easy for you to say :D

SUPERCHARGEDGTA

Re: rochester quadrajet

Post by SUPERCHARGEDGTA » Thu Apr 17, 2014 8:31 am

don't forget there are 2 :p

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Re: rochester quadrajet

Post by bhm1712 » Thu Apr 17, 2014 12:21 pm

i wouldnt remove the choke bit, just prevent it from closing and leave it in place.
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Re: rochester quadrajet

Post by carterdj » Thu Apr 17, 2014 4:17 pm

I removed the metal plate when i put my carb back on, but it was going back onto a Edelbrock manifold. Was told it was only needed for the stock manifold. I have put a electirc choke thing on mine which seems wto work fine, as when it was tied open it would stall until warmed up.

thirdgen

Re: rochester quadrajet

Post by thirdgen » Thu Apr 17, 2014 5:15 pm

thanks mine has a elderbrock dual plane on too so thats good to know. :thumb:

Terry-D

Re: rochester quadrajet

Post by Terry-D » Thu Apr 17, 2014 5:42 pm

What was wrong with your old carb Paul :)

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Re: rochester quadrajet

Post by bhm1712 » Thu Apr 17, 2014 5:53 pm

It wasn't a quadrajet! ;)

If you do wire up an electric choke don't forget to put it via a relay for the best operation.
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Re: rochester quadrajet

Post by thirdgen » Thu Apr 17, 2014 8:13 pm

Terry-D wrote:What was wrong with your old carb Paul :)
nothing really except the hot starting problem i read it was a common holley fault it ran well still have it so could refit it again if i dont cure te hot start issue
not any on has reported issues with the quadrajet :pray:

maybe get some more mpg with this one :pray:

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Re: rochester quadrajet

Post by bhm1712 » Thu Apr 17, 2014 9:29 pm

Hot starting problems are rare with QJ. I only know of one who ever had an issue.
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Re: rochester quadrajet

Post by SUPERCHARGEDGTA » Thu Apr 17, 2014 10:06 pm

mine had a problem, but that was the choke coming on too much with a warm engine

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Re: rochester quadrajet

Post by bhm1712 » Fri Apr 18, 2014 6:22 am

Now I know of 2 ;)
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Re: rochester quadrajet

Post by SUPERCHARGEDGTA » Fri Apr 18, 2014 6:38 pm

nothing wedging a screwdriver in the choke flap didn't cure ;)

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Re: rochester quadrajet

Post by bhm1712 » Fri Apr 18, 2014 10:07 pm

Robin tuned my carb not to need a choke and it worked - even on a Minus temp day if i start the car from cold once its fired i just have to pump the gas pedal 3 or 4 times to stop it cutting out straight away, and after that it idles fine and i can drive off pretty much straight away with no coughing or spluttering. Not sure how he did it....
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Re: rochester quadrajet

Post by thirdgen » Fri Apr 18, 2014 10:22 pm

mine aint like that yet

SUPERCHARGEDGTA

Re: rochester quadrajet

Post by SUPERCHARGEDGTA » Fri Apr 18, 2014 11:00 pm

have you set the idle mixture yet?

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Re: rochester quadrajet

Post by bhm1712 » Fri Apr 18, 2014 11:02 pm

thirdgen wrote:mine aint like that yet

Trouble with an off the shelf carb is the jets - may not be 100% right for your engine as well as the idle mixture being off
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Re: rochester quadrajet

Post by SUPERCHARGEDGTA » Fri Apr 18, 2014 11:19 pm

and the actuating rods for the secondary jets may not be set right
and as Ian said, correct jetting is essential

TPI rules :p

thirdgen

Re: rochester quadrajet

Post by thirdgen » Sat Apr 19, 2014 8:34 am

is that technical help :naughty:
tpi rules :oldrolf:
my tpi motor used to have its moments on hot days also. so do not rule. :p

i have driven it goes really well and sounds good i got the gearbox vac pipe on wrong so it would not go up the gears quick enough but soon sorted that out in a minute :thumb:
i have to do the mix still took a plug out yesterday i think they are 400 year old 2 of them just snapped off, got 4 new ones as all thy had get 4 more today. i did have a moment with a hot start still !! but hope he plugs might help as they are very bad.

i asked to match them 4 places oh we dont keep them in !!!! ffs what car is it for !!!!! then a glazed look as they have no idea what a pontiac is lol
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thirdgen

Re: rochester quadrajet

Post by thirdgen » Sat Apr 19, 2014 8:40 am

ngk bpr4fs is what you need for a 400 :thumb:

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Re: rochester quadrajet

Post by bhm1712 » Sat Apr 19, 2014 11:34 am

got a set of 8 off ebay for mine for less than £20

http://www.ebay.co.uk/itm/NGK-Spark-Plu ... 20c12a2258
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Re: rochester quadrajet

Post by bhm1712 » Sat Apr 19, 2014 11:36 am

i set the idle mixture on mine using the higest rev method, but then verified it with an old gunson colour tune in number 1 and number 2 combustion chamber.
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