Hacking a Hemi
- Thread starter OUTLAWD
- Start date
Will do. I don't have a good place to run it by me to test. I hit 38mph with the stock engine and governor, I am shooting for 50mph in the 1/8, but to be honest I have no idea. The gearing calc says I should be able to hit 52mph at 7k rpm
A temporary tank should have arrived today, as I am not getting a good gravity feed with the stock tank and Chikuni.
Ill be on a stretched DB
A temporary tank should have arrived today, as I am not getting a good gravity feed with the stock tank and Chikuni.
Ill be on a stretched DB
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Is it ok to resurrect your own zombie thread? It’s been a while, but bought a house in the meantime that has needed quite a bit of attention.
Made it to the track with the rebuilt combo last night. I don’t have a place to really test, so I have to figure everything out at the track.
Cruising around the pits it was pig rich and wouldnt pull above 5000, I went down to a 115 main in my 24mm OKO, this seemed better.
My first pass was made with 12/54 gearing, ~2800 stall and 7” driven with stock spring in middle hole. The engine would not pull above 5400rpm. My 15x6.5 tire measures 14” static, but grows some at speed. The engine just couldn’t pull the gear. Ran a couple 12.68 @ 49 mph.
I was going to leave it alone, for the bracket race later in the night, but swapped to 10/54 gearing. Also went down to a 110 main. This worked well and went 12.3 @ 51 going through the traps at 6400. It was still pulling, but slowly.
The TAV is shifting too fast. It gets out of the hole very good with me rolling on the throttle, 2.4-2.5 60’ and will power wheelie from 5 mph roll, but it’s done shifting between 60-100’, if not sooner.
I have the aluminum weights and pink springs in the primary. This seems far less consistent than the stock zinc/blue combo. Sometimes it would want to grab at 1800 rpm, other times it wouldn’t move until 2800rpm. This made it very hard to launch consistently, I red lit in the second round of eliminations and ran it out the back to 12.09 @ 52.5.
I have a yellow driven spring to try, but I might also play with the garter springs to make it Stall higher and hopefully gain consistency.
Made it to the track with the rebuilt combo last night. I don’t have a place to really test, so I have to figure everything out at the track.
Cruising around the pits it was pig rich and wouldnt pull above 5000, I went down to a 115 main in my 24mm OKO, this seemed better.
My first pass was made with 12/54 gearing, ~2800 stall and 7” driven with stock spring in middle hole. The engine would not pull above 5400rpm. My 15x6.5 tire measures 14” static, but grows some at speed. The engine just couldn’t pull the gear. Ran a couple 12.68 @ 49 mph.
I was going to leave it alone, for the bracket race later in the night, but swapped to 10/54 gearing. Also went down to a 110 main. This worked well and went 12.3 @ 51 going through the traps at 6400. It was still pulling, but slowly.
The TAV is shifting too fast. It gets out of the hole very good with me rolling on the throttle, 2.4-2.5 60’ and will power wheelie from 5 mph roll, but it’s done shifting between 60-100’, if not sooner.
I have the aluminum weights and pink springs in the primary. This seems far less consistent than the stock zinc/blue combo. Sometimes it would want to grab at 1800 rpm, other times it wouldn’t move until 2800rpm. This made it very hard to launch consistently, I red lit in the second round of eliminations and ran it out the back to 12.09 @ 52.5.
I have a yellow driven spring to try, but I might also play with the garter springs to make it Stall higher and hopefully gain consistency.
Even with stock engagement RPM it would wheelie. Its on a ~50" wheelbase DB30, no wheelie bar. So I roll on the throttle instead of whacking it open at the launch to keep it civilized.
With the 12/54 gearing it it would launch, shift, then sit at 5400RPM for the rest of the run, went 49 MPH.
I went to 10/54 gearing and it would launch very well, then it would fall on its face and slowly pick up speed, as you said. Could only hit ~6400 and 52MPH by the 1/8 mile. If I had more room, I feel I could rev it out to 7-7500.
I forgot to bring snap ring pliers, so I couldn't swap the driven spring at the track. I have since went to the yellow spring, but haven't tested it yet.
A few guys had cameras, but no one uploaded anything yet.
I am half tempted to pick up a clutch to see what it will do, but for general putting around the TAV is great.
With the 12/54 gearing it it would launch, shift, then sit at 5400RPM for the rest of the run, went 49 MPH.
I went to 10/54 gearing and it would launch very well, then it would fall on its face and slowly pick up speed, as you said. Could only hit ~6400 and 52MPH by the 1/8 mile. If I had more room, I feel I could rev it out to 7-7500.
I forgot to bring snap ring pliers, so I couldn't swap the driven spring at the track. I have since went to the yellow spring, but haven't tested it yet.
A few guys had cameras, but no one uploaded anything yet.
I am half tempted to pick up a clutch to see what it will do, but for general putting around the TAV is great.
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It falls on its face because when the TC shifted out, it pulled the engine down out of its power band. If you tighten the yellow spring to its strongest setting, that should help hold the rpm up so when it shifts you are In the power band.
A race type clutch might give you better top end results but you will loose your out of the hole grunt. You'll probably have to use your feet to push along until the engine makes enough power to do its job. You'll just have to try it and see.
If racing an 1/8 mile, you need to gear it to run top rpm at finish line. Do you have any bigger rear sprockets to try ?
A race type clutch might give you better top end results but you will loose your out of the hole grunt. You'll probably have to use your feet to push along until the engine makes enough power to do its job. You'll just have to try it and see.
If racing an 1/8 mile, you need to gear it to run top rpm at finish line. Do you have any bigger rear sprockets to try ?
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