1967 Side exhaust

[Jeremy H.]

I have a 67/435hp that we are just getting back together. It has original side exhaust pipes on the car. NOS. I haven't done a NOS pipe car in a while. It is popping when we rev tnhe rpm's up. As the rpm's come down it is popping a little. Normal or not? Is there anything I can do to get it to stop? Completely rebuilt motor to original specs. Car also has A.I.R.

Thanks

Jeremy Hedges

[Tom H.]

Re: 1967 Side exhaust

Jeremy, we might need a little info. There could be ignition or fuel issues we need to look into. A little pop on decel is not real unusual, but I wouldn't think the popping would be normal on accelleration. Does the car seem to run well, or do you feel a hesitation or miss. You say the pipes are NOS. Are the baffles good ?? Just exploring some possibilites.


Tom

[Joe C.]

Re: 1967 Side exhaust

Since your engine has an air pump:

1. Replace malfunctioning A.I.R. diverter valve

If that doesn't cure it, then:

2. Fuel mixture too rich.

[Jeremy H.]

Re: 1967 Side exhaust

car runs great. I think I will check diverter valve. How do I know if it any good?

[Joe C.]

Re: 1967 Side exhaust

car runs great. I think I will check diverter valve. How do I know if it any good?

Plug the vac line to the valve and remove the A.I.R. pump belt.

[Kenneth B.]

Re: 1967 Side exhaust

I have a 67/435hp that we are just getting back together. It has original side exhaust pipes on the car. NOS. I haven't done a NOS pipe car in a while. It is popping when we rev tnhe rpm's up. As the rpm's come down it is popping a little. Normal or not? Is there anything I can do to get it to stop? Completely rebuilt motor to original specs. Car also has A.I.R.

Thanks

Jeremy Hedges

What gas are you using ? If the compression is 11:1 it will not like unleaded premium all that well. Try racing gas or octane booster. Dose it quit after the motor warms up?
KEN

[John H.]

Re: 1967 Side exhaust

car runs great. I think I will check diverter valve. How do I know if it any good?

See the procedure for checking the Mixture Control Valve on page 6T-3 of the '67 Chassis Service Manual; the function of the Mixture Control Valve on 67's is totally different than the diverter valve used on later engines with A.I.R.

[Douglas L.]

Re: 1967 Side exhaust

Jeremy,

Remove the mixture control valve. You should be able to blow air into it from one direction only. If air goes in from both outlets, the valve is not working properly. One outlet should take air unrestricted, the other should not. If both outlets are taking air, clean the valve thoroughly with lacquer thinner. Then try the air test again. If one side will not take air, that's good. Now hook a Mity Vac up to the vacuum port on the valve. Then force air into the side that won't take air and squeeze the mighty vac. If you hear a sudden rush of air, the valve is working properly.

An a 66 - 67 AIR motor, the popping in the exhaust is most likely caused by a too rich fuel mixture getting to the exhaust valves when you let off the gas. The mixture control valve should open in deceleration allowing a burst of air from the pump to be diverted into the base of the carb leaning out the fuel mixture.

[Dale C.]

Re: 1967 Side exhaust

Jeremy I had the same problem with my 435 side exhaust 67. I had to rebuild the heads and bought a generic intake manifold gasket set from the speed shop. I should have known better when he told me that 435's didn't use 2 1/2" exhaust or donuts. You new to get a intake manifold gasket set that doesn't have the crossover that goes under the center carb blocked. When I realized that I went back to a style that didn't block it and it was great. Popping gone. Good Luck Dale