Post headers install question
 

I recently put some B&Bs on my 86. It's a CIS engine which was making about 320 rwHP before the install. Leask WUR with MSD trigger at 4k and a K&N filter, no diverter valve.

The engine has always started instantly hit or cold and settles down immediately to a nice idle. Still does. But I have noticed now that about 20 minutes into a drive, it stumble and spits some below 2k, but immediately behaves above 2k. Only change is headers. Coincidence or consequence?

Yes I know it's not good to lug the engine, but I also don't like to do a rolling shift into first, and sometimes I get caught out below 2k in second.

Tnx.

I was always told that because headers are more efficent in letting the engine breathe that an adjustment to the fuel mixture may be required, could be your issue

Not enough information about the motor, the way Brian Leaske's gadgets are adjusted, or the muffler that's on the headers so if the ignition is in a good state of tune and nothing else was changed then it's probably running lean where you feel the stumbling.
A good wideband AFR gauge would display that or you can retune Brian Leaskes gadgets and richen up the middle 4mm allen head adjustment on the bottom of the CPR to lower steady cruise control pressure and see if that cures it.

If you have a B&B single out muffler on the headers you're missng around 30 horsepower because it has high backpressure and doesn't flow well unless all the internal baffles, flow directors, and divider panels are cut out. All of them.
Do that and they sound nice and breathe pretty well but are still heavy.

K thanks. Muffler is Borla four outlet, also have a Zork which I run now and again.

1/8 th turn of enrichment and problem fixed. Also, much less popping on deceleration, more of a burble now.

On the fuel head or CPR? I got Brian's headers going on next week so just curious...

tim