New member with a circle track dirt car

Good day everyone. I came here to try to find a touch more power and learn the common problems with the motor in my circle track dirt race car. I am unsure if it is a 4AC or a 4ACL, but from looking around here, it looks identical to what y'all have.

It is a 1987 Chevy Nova sedan, unfourtunately it is an automatic. It has been a circle track dirt race car for at least a year or two, racing in the Twister class (stock front wheel drive cars). It has completely gutted interior. There's not even a dash in the car. It does have a complete roll cage (not a roll bar) in the car which adds a lot more weight. But seeing how there is no window glass in the car, the door panels are completely gutted out as well (just the outside sheet metal is there and the doors are riveted in place) it should be pretty light.

So when my race team and I got the car, it had a blown head gasket letting water get in the oil as well as a blowout between cylinders 3 and 4 causing a miss. We just got the cylinder head resurfaced and put the motor back together again with new gaskets. It has no A/C, no power steering, and all the emmissions/vacuum hoses have been removed or capped accept for the hose leading to the dizzy for the vacuum advance.

So, I am here to learn more about this motor, find easy ways to increase power a bit utilizing stock (looking?) parts and to find the weak points and things to watch out for.

To update this thread, I raced this weekend. On Friday night, I started off dead last in the field being my first time to race dirt track. That was 22nd place on a 15 lap race. By lap 10, only 10 cars remained on the track! It was a serious bash fest but luckily, I remained in tact and not a scratch on the car. I ended up in 9th place, having passed one car at the checkered flag.


So before the race, I weighed the car. With me in the car, it weighed 2030 pounds. That means that without me in the car, it only weighs 1860 pounds!! Talk about a light weight! If the 6 point roll cage were to be removed, it would probably take a good 150 more pounds out of the car, but that roll cage will save my hind end should anything bad happen so it's staying put!

It's hard to add power while still look stock. Look into a 7AFE bottom end with some higher compression pistons, also a camshaft regrind can add power as well. A 7AFE bottom end is 1.8L so that will bump your torque up, and a new cam will raise power.

EricsFreeAE86 wrote:

It's hard to add power while still look stock. Look into a 7AFE bottom end with some higher compression pistons, also a camshaft regrind can add power as well. A 7AFE bottom end is 1.8L so that will bump your torque up, and a new cam will raise power.

I had found some write ups that talked about a 7AFE bottom end. Would that still bolt up to the stock auto transmission?


I am hesitant about adding an aftermarket cam to it as you could hear that in the exhaust note.

Tranny should bolt up to the engine since it's an A block, but you might have adaptability issues with the flex plate. Still though, a 4A powered dirt track car sounds boss.

You could do the spring flip in your secondary diaphragm to got a little more power. No one would possibly notice that.

jjstabs wrote:

Tranny should bolt up to the engine since it's an A block, but you might have adaptability issues with the flex plate. Still though, a 4A powered dirt track car sounds boss.

You could do the spring flip in your secondary diaphragm to got a little more power. No one would possibly notice that.

Do you have any more information on the diaphragm flip?


When I ran the car over the weekend, it did not like being cold. After it warmed up a bit it ran better. At low speeds it would hesitate a bit coming out of the turns in 2nd gear, but if I kept the speeds up it did great. I was able to keep up with higher hp cars on the straights, but most of the cars would leave me behind in the corners. I need to work on that as it is more of me not knowing fully how to turn the car on dirt vs. the car's lack of capability.

At the start, I would put the car in 1st gear and shift to 2nd gear at 6k rpm. With how light this car is it pulled really good up to about 5500, then the power started to fall off. I was hitting about 5k rpm in 2nd gear at the end of the straights. I have no speedometer so I have no clue as to the speeds I was going. My only instrumentation is a tach and a coolant temp gauge.

I posted a video of the spring flip in the "FREE POWER" thread under engines. If it's hesitating coming out of corners, your float is probably off. 6k is pretty high for these engines, not because they won't rev, but because the power band is long gone by then. You're probably making most of your torque between 3300 and 5000.

jjstabs wrote:

I posted a video of the spring flip in the "FREE POWER" thread under engines. If it's hesitating coming out of corners, your float is probably off. 6k is pretty high for these engines, not because they won't rev, but because the power band is long gone by then. You're probably making most of your torque between 3300 and 5000.

Yes, I do agree that this engine is past it's peak power by 6k, however when I shift it into 2nd gear, it is in the meat of the power band which then gives a good pull on the front straight. If I shift into 2nd gear sooner, it does not pull as hard as quickly.


The only time the car hesitates coming out of corners is if the RPMs drop below about 3200.


The spring flip looks to be VERY easy to do so I'll give it a shot and see what happens!!