Freeway On ramp "testing" with Th400
Thread Starter
Melting Slicks
Joined: Sep 2002
Posts: 2,631
Likes: 0
From: Union City CA
Freeway On ramp "testing" with Th400
With the freeway meter on, I waited my turn and got on it hard, I powerlaunched it at maybe 1100 or 1200rpm's and it went okay. But the problem is it shifted at around 3100-3600rpm I couldnt tell that well I still have the stock insturment cluster.
I want it to shift later on in the power band without making it unstreetable when Im just cruising around town. Is that possible with a Th400 or is it preset to shift at that rpm? :confused:
I want it to shift later on in the power band without making it unstreetable when Im just cruising around town. Is that possible with a Th400 or is it preset to shift at that rpm? :confused:
Racer
Joined: Sep 2001
Posts: 354
Likes: 0
From: Prineville Oregon
Re: Freeway On ramp "testing" with Th400 (Light84vette)
If it was shifting that low at full-throttle then something is not right. Is your vacuum modulator hooked up?
To change your shift points you can start by installing a "shift-kit", some kits come with an adjustable modulator that you can adjust from underneath the car with a small screw-driver. The shift-kit also makes the gear-change firmer/quicker. You can also just purchase the adjustable modulator from Summit or Jegs for around $20
For very high shift points the next step up is a B&M Govenor recalibration Kit which sells for $29 from Jegs. By changing springs and weights you can get the tranny to shift upwards of 5000-6000 RPM at full throttle. This is a little more complicated and messier as you need to remove the govenor cover and drain 1-2 qts. fluid every time you make a change.
For ultimate shift control put in a reverse pattern manual valve body (will also need new shifter). You can shift at any RPM at anytime but it's then just like a stick...you'll need to always shift at every gear-change.
Deen
To change your shift points you can start by installing a "shift-kit", some kits come with an adjustable modulator that you can adjust from underneath the car with a small screw-driver. The shift-kit also makes the gear-change firmer/quicker. You can also just purchase the adjustable modulator from Summit or Jegs for around $20
For very high shift points the next step up is a B&M Govenor recalibration Kit which sells for $29 from Jegs. By changing springs and weights you can get the tranny to shift upwards of 5000-6000 RPM at full throttle. This is a little more complicated and messier as you need to remove the govenor cover and drain 1-2 qts. fluid every time you make a change.
For ultimate shift control put in a reverse pattern manual valve body (will also need new shifter). You can shift at any RPM at anytime but it's then just like a stick...you'll need to always shift at every gear-change.
Deen
Melting Slicks
Joined: Dec 2001
Posts: 2,025
Likes: 1
From: Billings MT
Re: Freeway On ramp "testing" with Th400 (Light84vette)
You should be able to the majority of your adjustment through an adjustable vacuum modulator. Mine shifts at 6000rpm, and that is without modifying the govenor.
:cheers:
:cheers:
Thread Starter
Melting Slicks
Joined: Sep 2002
Posts: 2,631
Likes: 0
From: Union City CA
Re: Freeway On ramp "testing" with Th400 (VETDRMS)
Thanks for the info, Im going to have to get started on that tomorrow.
Plus since this is the engine mod forum, I have a 406 with unknown heads ( engine rebuilt by a shop and they used chevy heads of somekind) with a 750cfm holley carb and an air gap intake. With this setup it really pulls on 1/4 and 1/2 throttle pulls at slow speed but full throttle doesnt really have that much a difference and it doesnt seem to revv up that great. Could the heads be holding me back from all the power b/c all it does is pull really hard below 15-30mph but not above or from a roll or a stop. :confused:
Plus since this is the engine mod forum, I have a 406 with unknown heads ( engine rebuilt by a shop and they used chevy heads of somekind) with a 750cfm holley carb and an air gap intake. With this setup it really pulls on 1/4 and 1/2 throttle pulls at slow speed but full throttle doesnt really have that much a difference and it doesnt seem to revv up that great. Could the heads be holding me back from all the power b/c all it does is pull really hard below 15-30mph but not above or from a roll or a stop. :confused:
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Freeway On ramp "testing" with Th400 (Light84vette)
I don't think there are any heads that would choke it off THAT badly. I would find out what they are if I were you. Is there a severe blockage in the exhaust? A cat maybe? Are the secondaries on the carb opening?
Thread Starter
Melting Slicks
Joined: Sep 2002
Posts: 2,631
Likes: 0
From: Union City CA
Re: Freeway On ramp "testing" with Th400 (CFI-EFI)
Couldnt be the exhaust, I have super comp headers and a full 3inch dual exhaust with dynomax mufflers. How could I find out if the secondaries are opening at all? The carburator is fairly new but When I tried starting it the first few times when I just built it and had everything together, it back fired and the carb had a little fire a few times.
Timming couldnt be off too much either b/c temps never go over 189 on a hot day. Could it be the th400 or maybe the tq convertor whos slipping under power maybe? Its a B & M version that locks up by itself, Speed shop told me that it would lock up later in the rpm range if engine made more power.
Timming couldnt be off too much either b/c temps never go over 189 on a hot day. Could it be the th400 or maybe the tq convertor whos slipping under power maybe? Its a B & M version that locks up by itself, Speed shop told me that it would lock up later in the rpm range if engine made more power.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Freeway On ramp "testing" with Th400 (Light84vette)
Could it be the th400 or maybe the tq convertor whos slipping under power maybe? Its a B & M version that locks up by itself, Speed shop told me that it would lock up later in the rpm range if engine made more power.
With this setup it really pulls on 1/4 and 1/2 throttle pulls at slow speed but full throttle doesnt really have that much a difference and it doesnt seem to revv up that great. Could the heads be holding me back from all the power b/c all it does is pull really hard below 15-30mph but not above or from a roll or a stop.
Safety Car
Joined: Aug 2001
Posts: 3,681
Likes: 200
From: Waterford Mi
Re: Freeway On ramp "testing" with Th400 (CFI-EFI)
You might want to look at the rear gear ratio and torque covertor. It may be that they won't let the motor get to the power curve fast enough, keeping it from the proper rpm range.
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Drifting
Joined: Aug 2000
Posts: 1,316
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From: Houston, TX
Re: Freeway On ramp "testing" with Th400 (redwingvette)
what type of fuel pump are you running and do you have any type of pressure regulator? Do you have a fuel pressure gauge that you can check pressure while running and WOT?
Thread Starter
Melting Slicks
Joined: Sep 2002
Posts: 2,631
Likes: 0
From: Union City CA
Re: Freeway On ramp "testing" with Th400 (HWoods)
I have the stock fuel pump with a holley pressure regulator to 7-8psi but the guage is under the hood, I dont have a meter in the cockpit. I still have the stock guage cluster but I plan on changing that in a couple of months.
