first run at track

[LanceB]

My brother took his 77 to the track over weekend (for the first time ever), and he said his engine sputtered at about 5000 rpm about when it was shifting. It is an automatic and he said he felt like he had to really let off on the gas to get it to shift also. The car ran great on the way home, sounds like something with the carb, but I don't know. I thought maybe the mixture was too rich when he floored it. he has never had this problem before, and after talking to him, the only thing different was he put high octane gas in it. What do you guys think?

 

[Altered]

Could be valve springs are weak causing valve float about that rpm.

Coil could be breaking down causing loss of spark.

Timing could be off. Too much slack in timing chain, worn cam or distributor gear. or a loose dist. hold down allowing the timing to move can cause this.

What distributor are you running? Should be a HEI but if its a points type the points could need replacing or reset.

Other possibilities are
- old plug wires breaking down.
- spark plugs needing replaced
- air leaks usually close to the carb or air intake to the plenum

I'm sure I have forgotten some things but these usually cover something like this.

 

[LanceB]

Looks like process of elimination. I know he hasn't changed the plugs or wires since he purchased it over 5 years ago, so that would be a good place to start regardless. I am not overly familar with distibutors, so I need to inspect it and see what kind it is. Thanks for the advice. It was a 1/8 mile track, and his best run was 9.8 with a horrible reaction time and the sputtering, so I think we could be knocking on low 9's if we get this fixed and he learns how to race.

 

[Altered]

IMHO always diagnose the problem before purchasing parts. Unless of course you just want the new part or have money to blow. Plugs and wires are easy to check so I agree thats a good place to start. Hope it is a easy fix.

 

[LanceB]

I want to diagnose first, I just know the plugs haven't been changed in a LONG time....so even if they aren't broke wouldn't hurt anything. Of course, diagnosing the problem is the hard part....