Changed gears poor track results

[rfoll]

You said the car lost 1 mph, but I didn't see anything about et or 60' time. Where I race it's not uncommon to see nearly 2 mph changes in mph just from atmospheric changes when the sun goes down, or from one weekend to the next.

[1980RS]

You said the car lost 1 mph, but I didn't see anything about et or 60' time. Where I race it's not uncommon to see nearly 2 mph changes in mph just from atmospheric changes when the sun goes down, or from one weekend to the next.

The best 60ft was on the 1st pass and it was a 1.46, I ran a 6.59@103mph but when I got going to about 1000ft. the car was starting to bust up so let off of it and coasted to the end, didn't want to break anything. Most of the other 1/8 were worse as the track went away quick for me. I have the 406 out now and put my 358 pump gas SBC in it with a tighter converter for my last weekend of racing. Last pass on that engine was an 11.29@118mph but I have since switched out the 300-25 for my Air Gap with the divider cut out for a test. Not sure what it will do with a steeper gear.

[steve cowan]

You said the car lost 1 mph, but I didn't see anything about et or 60' time. Where I race it's not uncommon to see nearly 2 mph changes in mph just from atmospheric changes when the sun goes down, or from one weekend to the next.

The best 60ft was on the 1st pass and it was a 1.46, I ran a 6.59@103mph but when I got going to about 1000ft. the car was starting to bust up so let off of it and coasted to the end, didn't want to break anything. Most of the other 1/8 were worse as the track went away quick for me. I have the 406 out now and put my 358 pump gas SBC in it with a tighter converter for my last weekend of racing. Last pass on that engine was an 11.29@118mph but I have since switched out the 300-25 for my Air Gap with the divider cut out for a test. Not sure what it will do with a steeper gear.

Do you think it might of been valve float at the big end??
After every meeting I always remove rocker assembly and check valve tips.
Speeding up the valve via rocker ratio can change the game above 7000 rpm .

[1980RS]

You said the car lost 1 mph, but I didn't see anything about et or 60' time. Where I race it's not uncommon to see nearly 2 mph changes in mph just from atmospheric changes when the sun goes down, or from one weekend to the next.

The best 60ft was on the 1st pass and it was a 1.46, I ran a 6.59@103mph but when I got going to about 1000ft. the car was starting to bust up so let off of it and coasted to the end, didn't want to break anything. Most of the other 1/8 were worse as the track went away quick for me. I have the 406 out now and put my 358 pump gas SBC in it with a tighter converter for my last weekend of racing. Last pass on that engine was an 11.29@118mph but I have since switched out the 300-25 for my Air Gap with the divider cut out for a test. Not sure what it will do with a steeper gear.

Do you think it might of been valve float at the big end??
After every meeting I always remove rocker assembly and check valve tips.
Speeding up the valve via rocker ratio can change the game above 7000 rpm .

Doesn't seem like valve float as the last 2 passes of the day the 406 would go up to 7K without a problem after the spark plug change. I did find one thing that is quite interesting though, I swapped all the rockers, pushrods and stud girdle to the 358 and all looked good there but when I went to change the jets I drained the front bowl fine but the rear bowl was dry and there is no signs of leaks. I was puzzled by this so I replaced the rear fuel bowl and added a new needle and seat, not sure if there was a problem on the runs last week but who knows.

[steve cowan]

The best 60ft was on the 1st pass and it was a 1.46, I ran a 6.59@103mph but when I got going to about 1000ft. the car was starting to bust up so let off of it and coasted to the end, didn't want to break anything. Most of the other 1/8 were worse as the track went away quick for me. I have the 406 out now and put my 358 pump gas SBC in it with a tighter converter for my last weekend of racing. Last pass on that engine was an 11.29@118mph but I have since switched out the 300-25 for my Air Gap with the divider cut out for a test. Not sure what it will do with a steeper gear.

Do you think it might of been valve float at the big end??
After every meeting I always remove rocker assembly and check valve tips.
Speeding up the valve via rocker ratio can change the game above 7000 rpm .

Doesn't seem like valve float as the last 2 passes of the day the 406 would go up to 7K without a problem after the spark plug change. I did find one thing that is quite interesting though, I swapped all the rockers, pushrods and stud girdle to the 358 and all looked good there but when I went to change the jets I drained the front bowl fine but the rear bowl was dry and there is no signs of leaks. I was puzzled by this so I replaced the rear fuel bowl and added a new needle and seat, not sure if there was a problem on the runs last week but who knows.

at least you found something
best of luck this weekend

[Monza355]

You said the car lost 1 mph, but I didn't see anything about et or 60' time. Where I race it's not uncommon to see nearly 2 mph changes in mph just from atmospheric changes when the sun goes down, or from one weekend to the next.

The best 60ft was on the 1st pass and it was a 1.46, I ran a 6.59@103mph but when I got going to about 1000ft. the car was starting to bust up so let off of it and coasted to the end, didn't want to break anything. Most of the other 1/8 were worse as the track went away quick for me. I have the 406 out now and put my 358 pump gas SBC in it with a tighter converter for my last weekend of racing. Last pass on that engine was an 11.29@118mph but I have since switched out the 300-25 for my Air Gap with the divider cut out for a test. Not sure what it will do with a steeper gear.

You mentioned tighter converter ! Did you install another converter than the previous 8” Tci with the 350 engine ?

[1980RS]

You said the car lost 1 mph, but I didn't see anything about et or 60' time. Where I race it's not uncommon to see nearly 2 mph changes in mph just from atmospheric changes when the sun goes down, or from one weekend to the next.

The best 60ft was on the 1st pass and it was a 1.46, I ran a 6.59@103mph but when I got going to about 1000ft. the car was starting to bust up so let off of it and coasted to the end, didn't want to break anything. Most of the other 1/8 were worse as the track went away quick for me. I have the 406 out now and put my 358 pump gas SBC in it with a tighter converter for my last weekend of racing. Last pass on that engine was an 11.29@118mph but I have since switched out the 300-25 for my Air Gap with the divider cut out for a test. Not sure what it will do with a steeper gear.

You mentioned tighter converter ! Did you install another converter than the previous 8” Tci with the 350 engine ?

Yes I have run this 10" converter with my 358 in the past and it worked quite well so it will be interesting to see how it works with the 4.88's. I am interested to see how cutting the divider out of the Air Gap works, as I have some data from using it with the divider still in.

[1980RS]

Got the news today, my 8" converter is bad. Now I know why it slowed down.

[steve cowan]

Got the news today, my 8" converter is bad. Now I know why it slowed down.

Glad you wont be chasing your tail since you found the problem.
Track testing and especially trying to do A-B-A collecting data is a crap shoot at best everything is against you lol.
I am really interested in results of rear gear change .

[Monza355]

Got the news today, my 8" converter is bad. Now I know why it slowed down.

Did you have it cut open ? If so, what was wrong with it ?

[77cruiser]

Got the news today, my 8" converter is bad. Now I know why it slowed down.

Did you check the trans pan for debris?

[1980RS]

Got the news today, my 8" converter is bad. Now I know why it slowed down.

Did you check the trans pan for debris?

Yep, nothing much in there, even the fluid was nice and clean, gonna run it Sunday if it don't rain.

[1980RS]

Got the news today, my 8" converter is bad. Now I know why it slowed down.

Did you have it cut open ? If so, what was wrong with it ?

Trans guy said the part that's only supposed to turn one way is broken don't remember what he called it. That was the same thing that happened on my tow vehicle years ago when I was swapping in the new turbo 400 back then. Took that one in and the same thing was wrong. Funny thing is it seemed to work great out of the hole it just seems like it was slipping a lot more than it used to and the mph was down. The car seemed to RPM really well at the stripe and sounded better than the prior test day but it was done. Did the same thing on the last pass with the old 4.10's also.

[Monza355]

Yes. That’s a common failure. It’s called a sprag, it’s inside the stator. Often times when it fails the converter will be completely locked or there about with no stall at all.

[77cruiser]

Yes. That’s a common failure. It’s called a sprag, it’s inside the stator. Often times when it fails the converter will be completely locked or there about with no stall at all.

That's what happened to my $80 Vega conv. 42 years ago. Car lost 3-4 mph & 3/10 sec. slower.