another H pipe exhaust question

[IBFester]

I checked the board and couldn't find any answers so please chime in,

I run 350 with a rebuilt quadrajet it takes forever to warm up, mechanical choke is in working order but the RPM's won't increase and exhaust just pops at 500RPM's I have to play with the pedal to get it warmed up, after that it runs great.

my Q; would installing an "H" pipe make a difference?

[Steeveedee]

Nope. Maybe set the choke a little tighter. No fast idle, either. Are you sure the choke closes all the way?

[HotWheelsFan]

Quadrajets have several adjustments all around. Manual choke does two things mainly: It closes the butterfly at the top to allow more fuel into the engine and it also has a cam that opens the throttle blade at the bottom of the carb (just as if you were pressing down on the gas pedal), there should be an adjustment screw that contacts the cam or stepped lever that opens the throttle blade with the choke on. Sounds like this should help. It's called fast idle adjustment or choke idle speed and should be on the right side of the carb, choke cable side. You also should have a vacuum pull actuator that opens the choke a little when the engine starts. You can not run the engine with the choke fully closed. As you start the engine the choke blade needs to open up a little bit other wise you get too much fuel.

Bob

[IBFester]

ok, thanks for the info I will takes another look at the choke.
I had a performance shop rebuild the carb because the lower shaft was leaking, they replaced the choke vacuum pod and test / adjust on their shop engine so I assumed they adjusted the choke, guess not...

so about the H pipe - my truck runs great and sounds good, what would be the benefit?

[jimijam00]

Exhaust scavenging that will show benefits on the dyno in the upper band, maybe. I will also change the exhaust note a little. Best thing about it is a lighter wallet.

[RichardJ]

>>they replaced the choke vacuum pod and test / adjust on their shop engine so I assumed they adjusted the choke, guess not...<<

NO carburetor is plug-n-play.

Some adjustments are made on the bench when rebuilt.

Then

Some choke adjustments, idle mixture and idle speed can only be made on the engine it will be used on and with that engine running.

[IBFester]

Originally Posted by jimijam00

Exhaust scavenging that will show benefits on the dyno in the upper band, maybe. I will also change the exhaust note a little. Best thing about it is a lighter wallet.

lighter on the wallet? better gas mileage?

[sfont66]

Regarding the H pipe. I run one not so much for the performance benefit, but for the sound. My exhaust is run out the side in front of the rear tires. It sounded odd before I added the H pipe, because I only heard 1 bank of cylinders. Now I hear a blended tone from both cylinder banks.
This is not so much of an issue on the trucks I have had with exhaust all the way to the back. In that case the exhaust note sounds right to me

[jimijam00]

Originally Posted by IBFester

lighter on the wallet? better gas mileage?

nah. should have worded that differently. your wallet will be lighter.

[LS short box]

In regards to the choke if your intake is original sometimes the heat cross over gets plugged with carbon so the exhaust can't flow thru and warm up the choke coil.

[IBFester]

Originally Posted by LS short box

In regards to the choke if your intake is original sometimes the heat cross over gets plugged with carbon so the exhaust can't flow thru and warm up the choke coil.

if I remove the heat riser will I be able to clear it if it's clogged?

[HO455]

Here is a link to how I adjusted the choke on my truck that may be helpful. Scroll to post 618 to start.

http://67-72chevytrucks.com/vboard/s...698377&page=25

Good luck and please post your findings.

[IBFester]

Originally Posted by HO455

Here is a link to how I adjusted the choke on my truck that may be helpful. Scroll to post 618 to start.

http://67-72chevytrucks.com/vboard/s...698377&page=25

Good luck and please post your findings.

very helpful thanks

[geezer#99]

Originally Posted by IBFester

if I remove the heat riser will I be able to clear it if it's clogged?

You need to remove the intake to check the heat crossover.
Easier to just check the temperature beside the coil with a heat gun.
Compare the temp with the drivers side.

[IBFester]

Originally Posted by geezer#99

You need to remove the intake to check the heat crossover.
Easier to just check the temperature beside the coil with a heat gun.
Compare the temp with the drivers side.

that will save me some tine troubleshooting, thanks