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72Z/28
01-04-2007, 11:52 AM
I have been having a hard time to register my car and pass the stupid inspection which is mandatory where I live...

The engine is 350 which is built as a 383 stroker with long tube headers. In order to pass the emission test, I had to put a catalytic converter on each side. The converters were taken off from a mustang, apparently from a newer model as per the muffler shop guy.

I also had to just adjust the air-fuel ratio in order to lower the CO and HC rates. Last but by no means least, I have flowmasters on each side, and I had to adjust the RPM in order to make it sound more quiet at idling. AT idling, the RPM is at 520 or sometimes less.

Sorry for the long story, but I had to go through all that crap in order to pass the emission test..

My concern is this:

If I keep the catalytic converters on, will it affect the engine as far as the higher back pressure goes.

I appreciate sharing your knowledge with me guys..

paul67
01-04-2007, 04:10 PM
Theres a good chance no because they are off a late model ,early 1s would have said yes. They used to say about 10%. If you think you need them go larger pipes, where are the flow masters as mine are fitted just by the rear axle, the pipes run out the back of the car ,it was to quite so I put 2 more pipes on so I have 4 out the back to get that v8 burble

RobM
01-04-2007, 05:58 PM
what year is the car? is it a 72 like your name says? if so you shouldnt need cats....

by the way there are some high flow cats out there that have very little back pressure and on a mild motor can actualy help performance some.

72Z/28
01-05-2007, 03:36 AM
what year is the car? is it a 72 like your name says? if so you shouldnt need cats....

by the way there are some high flow cats out there that have very little back pressure and on a mild motor can actualy help performance some.

I know for a fact that 70-75 year camaros did not come with cats. I had to put them just to pass this stupid emission test..

So you think it would be better to take them off because the car finally did pass the emission test..

Steve68
01-11-2007, 08:51 AM
Where do you live??

you could leave the cats

Fuelie Fan
01-11-2007, 09:53 AM
Is it carb'd or EFI? If you're not running closed loop, a 3-way cat will be pretty ineffective away from stoich, so it'd be worthless to leave them in place. If you ARE running closed loop, i'd leave em. I'll be putting cats on my 69 nova next month. There's no excuse not to, when you consider the power that brand new cars with full emissions equipment are making, the whole "cats are a restriction" argument is bunk.

TD509EFI
01-11-2007, 12:51 PM
I agree with Fuelie Fan, if you're running closed loop EFI there's no reason to take them off.

If you're running a stock non feedback Qjet, leave them on if there are just two way cats and the fuel curve is close to stock. Three ways cats need closer control of the A/F mixture to keep them effective and away from overheating.

John