Can someone help me I just got a 1975 280z and it is back fireing bad it will run good for a little while and I think it is runing rich to

[collective groan]

Good morning, and welcome (assuming you're new to the club).

Someone is going to give you this advice sooner or later- download the FSM (factory service manual) for your year/model.

Use the "Search" feature and take notes and apply the troubleshooting info you find.

There are very knowledgable, skilled owners here- who are very helpful and will advise and guide you just based on your plea.

Equally, there are many who would prefer that you educate yourself, apply your new knowledge and request help for the things you don't understand or if you have reached a dead end.

What's really fair and will serve you better is to demonstrate that you are willing to invest in more than a car and that you have done your homework first.

"Teach 'em to fish and they can feed themselves..."