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MG MGB GT V8 Factory Originals Technical - Tuning the Carter 400

I've been running the Carter 400 for several years now and have never had to make any changes to it. However, I've made a few changes to the car and now have developed a lean surge at cruise. About 2000rpm.
Are the metering rods that same for the Carter/Edelbrock 500 series?
The first change from a Rover 3.5 to a 4.0 was a straight swap. No adjustments needed. I just changed from a 3.9 axle to a 3.07 and that's when I developed the surge. I guess it wasn't noticed before because I was always running at higher rpms.

Thanks,

Kelly C
Kelly Combes

Do your ign first, timing. Advance initial timing 2 or 3 degrees first and see what happens. If that helps then check your centrifugal advance.

The only way to know if you are running lean is to read the plugs or use a fuel ratio meter.

The rods are the same.
Bill Guzman

Rods, jets, and springs are interchangeable between the the 9400 series Carter 400 and the Edelbrock 500's. Wide band O2 sensor really makes things easy to tune.

Dan Jones
Dan Jones

Thanks, I'll do the basics first. I did richen it up a 1/4 turn and it helped a bit. This weekend I'm going through the full tune procedure. I'm currently running Bosch platinum plugs and wanted to change them to Champion standard plugs anyway. Not sure if I can find anyone with an CO meter though.
Kelly
Kelly Combes

Three letters for ya, Kelly:

N G K
Carl Floyd

One more time NGK If you like Champions then the
Black Champion made for trucks.
Bill Guzman

Okay, NGK seems to be the brand. I can always take the others back. I think I'm going to order a Lucas sports coil too. I'm running a standard Lucas coil from who knows what that I pulled off the shelf. That should help too.
Kelly Combes

What NGK P.N. works in the Buick 215?
Jim Miller

If you have high compression use on step cooler plug from stock. Cross reference the Ac, champion # to NGK
If you have electronic ign then a MSD blaster coil is the ticket. $36 US
Bill Guzman

Jim,

A stock 215 uses NGK BPR5HS (remove the R for non-resistor plug). For the reasons Bill stated plus extended high RPM use, I prefer the BPR6HS.

For Kelly, the late Rovers have a longer reach (3/4" vs 1/2" reach of the 215) so they use either BPR5ES or BPR6ES. I'll be using the BPR6ES in my 3.9.

Decoding NGK spark plug numbers:

http://www.ngksparkplugs.com/docs/tech/design_symbols_plugs.pdf
Carl Floyd

I'm still running a points type distributor from my 73 Rover engine. Kind of old school, but that's okay for me.
I traded in the Champions for a set of NGK BPR6ES plugs.
I'll let you know if that does the trick.
Kelly Combes

Kelly,

I would consider that to be an early Rover. They changed considerably around 1980. Double check the thread reach. You may need the BPR6HS plug for that engine.
Carl Floyd

Carl, the 4.0 is from a 98 Disco. That's what I bought the plugs for. The distributor is from my old 73 3.5 Rover. I reused the front cover, oil pan and "stuff". Allthough, come to think of it, I had 3.9 heads on the 3.5 so the plugs where the same anyway. It's fun to mix and match parts, but you can never tell what the result may be.

Kelly
Kelly Combes

This thread was discussed between 11/05/2007 and 18/05/2007

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