I have just purchased a 1987 firebird formula to run a few lapdays at our local track.

It has a 305 and it looks as though it was caburated origionally based on the vacuum diagram under the hood.
So, nothing strange yet....however....
It has a been messed with so I need some advice...
Here is my list of strangeness.

It has a Holley 7005-1 marine 500cfm 2 barrel on it.
I guess I need to know if it wll run OK on the track?

It has the small distributor on it with no vacuum on it, and yet there is a plugged vacuum line laying beside it.
Is it possible that this distributor has only mechanical advance?

The car seems to run, but it does have some hesitation midrange.

Any advice woudl be great.

 

As for the distributor it sounds like it may be a computer controlled unit. If so then it will need to be changed out. Lift the cap off and check if it has a small rotor that is just pushed on, if so then almost no advance at all (there is some built in).

The only small GM distributors I know of are either points or electronic computer controlled. If it is aftermarket it could be anything. Can also check the advance with a timing light and slowing increasing the RPM while looking at the marks.

I'll move this to the carb's board for additional help.

RBob.

 

With the car being an 87 (valve covers with center bolts) I assume that I have the roller cam...
What cars could I get a disrtibutor from?

 

The cam doesn't really affect the distributor selection for factory rollers. Besides, you can remove the driven gear from the factory distributor and put it on the vacuum/mechanical advance unit you get.

For the track, you could go ahead and use the computer controlled distributor. Just set the timing at high RPMs, where you don't see any additional advance (there is a little "limp-home" default advance built into the distributor control module), set it for about 36 degrees advance. This assumes you spend most of the time above ~2500 RPMs at the track. It also assumes you have a dial-back timing light or timing tape on the balancer.

 

Good advice.
I cranked up the distributor advance...
It runs rich at low RPM, but there seems to be lots of power when it is full throttle.

It there any risk of hurting the engine doing this...
The disrtibutor I mean, not the full throttle.

I guess I will see at teh lapping day at the track.

 

Does anyone have any comments on the 500cfm 2 barrel for track use.
A freind of mine will loan me a Holley 650 double pumper, however, I am not sure that I will see much difference on a soloII track.

 

The distributor could care less where you have the timing set. It's the engine that cares. And, it's not surprising it runs rich at low RPMs, because that's where you'll be lacking needed advance.

2 bbl carbs are flow rated at a higher vacuum (really delta-pressure) than 4 bbls. So, a 500 CFM 2 bbl will not flow as much as a 500 CFM 4 bbl - quite a bit less. But, it may be adequate for a mild 305.