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Jul 19, 2021 16:44:50 GMT
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to create a denser inlet charge ,and so make more power , and economy . a bit of heat can be providential , a lot of heat ,detrimental . i would have the heat off all together,and a cold air inlet , as long as external temps were above 20c , and try without it lower down until it became a mixture maldistribution problem . the density of your inlet air at the temperature it is is probably the equivalent of 5000 feet above sea level  i suppose you could pop a thermocouple on a wire in the inlet to see. It would probably make a difference given that it does run better in winter, but it's so marginal that I'm not going to worry. The air intake is behind the radiator, which has incoming air at 30°C on average in summer, warms that to 50-60°C on top of the engine heat baking the manifold... |
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Got fed up with a hot breeze blowing up from the engine bay, all the way up my trouser leg. In this hot weather it's not overly nice so I took a sheet of high density sticky backed foam, cut a hole in the middle and slapped it down onto the floor with the rod sticking through. A much smaller orifice (previously a hole about 2" in diameter) should prevent the majority of the air from coming in. The cabin is warm enough as it is.
I'll see how that is next time I'm out in it.
Phil
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to create a denser inlet charge ,and so make more power , and economy . a bit of heat can be providential , a lot of heat ,detrimental . i would have the heat off all together,and a cold air inlet , as long as external temps were above 20c , and try without it lower down until it became a mixture maldistribution problem . the density of your inlet air at the temperature it is is probably the equivalent of 5000 feet above sea level i suppose you could pop a thermocouple on a wire in the inlet to see. It would probably make a difference given that it does run better in winter, but it's so marginal that I'm not going to worry. The air intake is behind the radiator, which has incoming air at 30°C on average in summer, warms that to 50-60°C on top of the engine heat baking the manifold... Turbo intercooler fitted to the end of the air inlet? |
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Turbo intercooler fitted to the end of the air inlet? Cool air intake from the front of the car would likely be as effective, given how tortuous the intake path is... After having done about 50 miles in it today, doing the valves makes the most noticeable difference to the running. At 45 (pretty much bang on 2000 rpm) it's near silent and progression is made deftly. In other news I'm now pretty sure I've got something sticking in the throttle modulator circuit on the gearbox to cause the gears to act weird. Mind you, twice today it changed gears perfectly, through all 4 from a standing start. The throttle modulator is meant to do 2 things: First it modulates the line pressure going to the servos and clutches, making a full throttle gear change much more violent and positive than one at light throttle. That is a simple bleed valve that's opened. Second it changes the road speed at which the gears change, by putting part of the bleed pressure behind 3 pistons that boost the gear change springs. So, a catch up on that- the governor spins with road speed, and increases pressure behind the 3 main gear change pistons. Each has a spring (or springs) which are each harder to compress than the last, meaning as road speed increases, pressure against the springs rises, the weak spring is overcome and the valve shuttles, causing the gears to change to 2nd. Then again to 3rd as the second valve shuttles, and then finally 4th. The valves are prevented from shuttling also by the pistons which have force in proportion to gas pedal position behind them meaning a higher road speed pressure is required to shuttle them if the gas pedal is pressed down. So, the incorrect behavior is thus: First gear will hold until 3rd gear engages, often missing 2nd or engaging it very briefly. 4th then will not engage until high road speed is achieved. Sometimes releasing the gas pedal makes it shift, other times not and it'll hang in 3rd. As road speed decreases, it'll sometimes go 4-3-1 and then suddenly to 2 with quite a jerk. Reverse often engages the parking pawl with the engine running. Things to bear in mind, the throttle modulator piston is not sprung. It is only returned by hydraulic pressure against the lever arm that actuates it. There's a secondary shuttle for the line pressure modulator. Either one of the pistons that push against the gear change valves is sticking open and preventing correct movement or the throttle modulator valve is acting janky. The throttle modulator valve has been recipient of minimal attention because it's in the top half of the valve block. I think I'll start there, so perhaps this weekend if the weather allows I'll drop the oil and pull the valve block off again and check the modulator valve assembly in great detail. It's proven it can change smoothly and correctly. It just needs to do it more often! Phil |
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Last Edit: Jul 21, 2021 5:21:21 GMT by PhilA
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Jul 21, 2021 12:46:03 GMT
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Is there a possibility that the spring for 2nd gear is too strong, or been swapped with 3rd, thus causing it to be bypassed?
No clue what the innards look like, just going off your description of operation.
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Jul 21, 2021 13:56:26 GMT
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when the governor was sticking on my range rover 4hp22 Ashcrofts suggested I try red lubegard, it fixed it and it's never done it again. The dodgy spelling would indicate it originates from your neck of the woods as well.
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Jul 21, 2021 14:37:37 GMT
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when the governor was sticking on my range rover 4hp22 Ashcrofts suggested I try red lubegard, it fixed it and it's never done it again. The dodgy spelling would indicate it originates from your neck of the woods as well. I did have issues with the governor sticking and lucked out massively by funding a brand new old stock governor to put in. That did help but it's not what's going wrong. I'll keep the lubegard in mind though. |
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Jul 21, 2021 14:38:49 GMT
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Is there a possibility that the spring for 2nd gear is too strong, or been swapped with 3rd, thus causing it to be bypassed? No clue what the innards look like, just going off your description of operation. No, because this is an intermittent fault. When it works correctly it's as smooth and seamless as any new automatic. Just... that's not very often. I'll find what's sticking, it's just there's a lot of things in the balance that affect each other. Phil |
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Someone asked me how the vacuum screen wash pump works.
There you go
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Jul 24, 2021 18:35:01 GMT
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Summertime.  Today started fairly cool then got hot quickly.  Drained the oil from the last time I pulled the valve body and having had time to settle, the precipitate in the oil is visible. That's 2-3 gearchange right there, where it drags both gears for a moment. Drained it out again and pulled the valve body off. Again.  I focused on the top half of the assembly and dumped it in the ultrasonic bath for a while, polished the shuttles and made sure they move freely. Reassembled and road tested, it's better. It doesn't engage the parking pawl when out into reverse with the engine running now, it doesn't do the 4-3-1 thing when decelerating. Occasionally 1st will stick but it was persuaded in all events to resume normal operation by tapping the throttle. Better. Imperfect but better. Phil |
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glenanderson
Club Retro Rides Member
Posts: 4,359
Club RR Member Number: 64
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1951 Pontiac Chieftainglenanderson
@glenanderson
Club Retro Rides Member 64
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Jul 24, 2021 20:33:30 GMT
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I feel your pain. I hate having to revisit stuff that I thought I’d put to bed.
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My worst worry about dying is my wife selling my stuff for what I told her it cost...
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Jul 24, 2021 21:16:01 GMT
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Arrrgghhh.
Sorry to see that.
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It got more warm.  Even worse in the sun- laying under the car to take the thing to pieces my legs were in the shade. Putting it together again they were being baked.  Dexided to see how it would behave with an oil thickener in. Seems to have helped a little so I went for a quick drive to test. Stopped to get an old fashioned cherry coke (with chunks of cherries in!) on the way back. I had expected to have trouble with the valve block, to be honest. The throttle valve shuttle was sticky so I freed that up; having resolved 2 of the 3 issues isn't too bad- unfortunately the primary one is still partially with us. I think that's down to it being plain worn out. You figure, the 1-2 gear change is the one that the box does the most. I'll keep my eye open. There was a brand new old stock Dual-Range Hydra-Matic valve block came up for sale before Christmas but I didn't have the money for it- also I would've had to change the column assembly (well, technically not but the stops wouldn't have lined up, as mine currently has N Dr Lo R, the dual range valve block has N D-hi D-lo Lo R) and it turns the gearbox body into the 53-54 model with the option to do 1-2 only, 1-2-3 only, 1-2-3-4, Reverse and Neutral. Mine only has 1-2 only and 1-2-3-4. I'll keep my eye open for a replacement. They don't come up that often but even one with 50,000 miles on would be likely better than mine in terms of wear. The rest of the gearbox is good. Just the controls. It also behaves a lot better when the weather is cooler... Phil |
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Last Edit: Jul 25, 2021 0:23:45 GMT by PhilA
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that b and m trick shift stuff made a big diff to the c4 in the tvr ,which had no cooler phil ,
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It's been doing a little better as it's been driven, though expensive fluid might help.  I haven't been doing anything other than drive it though. It's filthy, covered in squashed insects on the front. Needs an oil change. Phil |
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Road trip  35 mile round trip to Tractor Supply, because they have cheap 30W diesel oil with zddp and other vitamins and minerals. Followed a beige diesel Volkswagen with a truckman top home.  Got stuck behind some dawdling guy in a Tahoe who couldn't decide if he wanted to do 40, 45 or 50. When you're being honked to hold speed and then get passed up by a 70 year old car something's wrong. He got passed up by Volkswagen (slowly and with a lot of clag). Oil change pending, hot the pressure is a bit mediocre at idle.  10-15psi. Granted, the book says anything over 5psi is fine but it's done 1200 miles and is black as midnight. Phil |
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glenanderson
Club Retro Rides Member
Posts: 4,359
Club RR Member Number: 64
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1951 Pontiac Chieftainglenanderson
@glenanderson
Club Retro Rides Member 64
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I work on a similar principle; that if you get overtaken by a sixty year old Land-Rover, you need to have a good think about yourself and whether hanging up your keys is the right thing to do. 🤣
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My worst worry about dying is my wife selling my stuff for what I told her it cost...
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jamesd1972
Club Retro Rides Member
Posts: 2,921 
Club RR Member Number: 40
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1951 Pontiac Chieftainjamesd1972
@jamesd1972
Club Retro Rides Member 40
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I work on a similar principle; that if you get overtaken by a sixty year old Land-Rover, you need to have a good think about yourself and whether hanging up your keys is the right thing to do. 🤣 I’m hearing you both 😬 going up Bristol hill on the A39 in the LR used to be very challenging - with the old tired engine the steep bit was 30mph max. With the new engine I can do 40 but am probably held up one time in 4 by somebody who chugs up in a modern thing in too high a gear. Completely does my head in- they are using the same amount of fuel with their foot to the floor anyway. Can’t safely overtake and they usually do 50-60 once over the brow. Tahoe owner was probably complaining about mad hot rodders zooming about😁 James |
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I still like that you can flick your turbo on with a flick of a switch on the dash.
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I still like that you can flick your turbo on with a flick of a switch on the dash. Very Mad Max, I agree. |
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