78 Spider Issues

[sbuck]

Let me first start by saying I have been reading up quite a bit and this forum is priceless!!! Hopefully I will soon be worth some of your collective knowledge and be able to pass on the learned to someone else.
Alright I have just bought a 78 spider 1800 5 speed with the stock 2bbl carb manual choke with a couple of issues.
First it had been sitting a while and started and idles just fine but upon throttle increase or acceleration in gear it has a popping/crackle coming from one of the barrels on the carb. Once the idle is or throttle is steady it purrs. It's only when a sudden increase occurs that it makes the noise.
Second there is no brake pedal it goes right to the floor with only the spring as resistance. I don't see any fluid leakage. The car just has no brakes, just the e-brake works. With that being said when I pump the brake pedal at idle the idle increases. Then it goes back to normal. I'll pump the pedal a few times then the idle increases then goes back to normal once again. HELP HELP!!!
Any assistance would be greatly appreciated.

[Weelan]

I suspect someone that may know better than me will also reply, but I think it sounds like you have a leak in the brake booster. The popping coming from being really lean. Do you hear a hissing sound when you press the brakes?

[sbuck]

Do you think a leak in the brake booster would cause the idle to change when the brake is pumped?
Also I will check on the hissing sound and adjust the mixture. Thanks Scott

[Weelan]

I do, but others may say otherwise.

The brake booster is connected to the engine in order to either create a vacuum or fill it with air, I forget which way that works. You could unhook the brake booster hose and plug it and see if the idle and when you rev the engine evens out and stops popping. I had a backfire issue like this, but it was caused by the intake manifold not being seated and letting air in.

[ScotcH]

I can confirm that a leaking brake booster will cause idle issues when pressing the pedal, and backfires ... it's pulling in air from the leak, so the mixture is wrong. I just unhooked the booster vac line and plugged it until I can change the booster. However be aware that the brakes require significat force when driving without the booste.

[4uall]

Did the same, not that bad to apply the brake

[sbuck]

I appreciate all the advice. Unfortunately I have not had a chance to dig into the car yet. I will try the suggestions as soon as the weekend is over. Does anyone know where the mixture screw is located to adjust the carb richer on the two barrel stock Weber?

[majicwrench]

If it idles fine idle mix OK.
Brake booster will affect it mostly at ilde. So again, if it idles fine, booster is OK.
Keith

[So Cal Mark]

uh, wrong. The booster has no effect until the pedal is depressed. If your car is a 78, it should have a water choke not a manual choke