Line pressure after shift kit

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indirect_connection

indirect_connection

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I installed a basic shift kit during my 904 overhaul. It came with a stiffer regulator spring. The instructions stated to install the spring with the aduster all the way out, and if you wanted firmer shifts to go back and adust it in up to .260.

When I installed the trans and checked line pressure, it was 75psi and 100 psi with the throttle lever all the way back. I had to pull the trans back out before driving it, and I was thinking of increasing the pressure a bit more why it's out. I guess I'm used to more modern transmissions where 100-150 would be the higher limit (but they also have electronic pressure control).

That got me thinking, what is a maximum pressure that one could run before causing issues? I've searched all over the web, but most specifications I can find are just the stock ones listed in the service manual.

Other than the risk of making the shifts too harsh, what are the hazards of cranking up line pressure? Shift timing? 2-3 overlap?

The only mods done during the shift kit install are the stiffer line pressure and converter valve control springs. 3rd apply seperator plate hole was drilled to .140, and 2nd apply to .98. I was supposed to drill out the 2/3 timing port, but on my seperator it was already way larger than the size they suggested. I'm not sure if that makes the 3rd shift take longer or less time.
 
I'll tell you what i did; I drilled and tapped a hole in the case, in line with the adjuster. Problem solved. There is not a lot of pressure change available, so crank it to the max, and then when it turns out to be too harsh......pop the plug and dial it down. I tapped it for a pipe-plug with an Allen Socket.

EDIT
mine was a 904
 
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On a 727 or a 904? I saw that mentioned before, but the spring adjuster sits behind a compound curve on the case of my trans. Did not seem like any good place to tap.
 
indirect_connection said:
On a 727 or a 904? I saw that mentioned before, but the spring adjuster sits behind a compound curve on the case of my trans. Did not seem like any good place to tap.
Click to expand...

If I had a 727, I would try to figure out a way to do it, even if I had to weld a blob of aluminum on there.
If I had not put the port on my 904trans, I would have been way too lazy to drop the pan, as many times as I cranked on the that adjuster.
For me, it was a learning experience. I mean there are three pressure systems in the TF, and only the Throttle Pressure is easily adjustable; it's just not fair.lol. Getting all three to play nice together is a bit of a PITA, but well worth it in the end.
It would have been much easier if the governor hadn't been buried.
 
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Reinstalling the stock converter fixed the problem. Factory drain plug allowed me to flush out the clutch deposits. The shifts don't seem that much firmer, but I was not able to really get on it as I was just cruising around on Memphis side streets. Don't really want to go wide open from a standstill either. I want the 7 1/4 to survive until the 8.8 is built. I would be interested in comparing the mods done on a Tf2 kit, but I haven't seen the instructions posted anywhere.
 
The pressure range is controlled by the spring you install. and the adjuster fine-tunes it in that range. The springs are color coded.

Cranking up the pressure , in my experience, has not harmed my 904; I tied the lever all the way back for a while and road tested it like that. Other than Part-Throttle Bang-shifts it showed me that I needed a different Throttle-pressure spring. So after I installed it, the pressure at PT was of course way too high, and the Governor fell asleep. So the first thing I had to do was adjust the governor to work with the new Line Pressure , and then fine tune the KD system, then fine tune the line-pressure again.
Along the way, I discovered that the 1-2 shift, and the 2-3 shift were not synchronized; one was occurring much sooner than the other, soooooo Off came the VB again. By the end of the summer, it was all working fairly well, so the following winter I took it apart and freshened it up, mapping all the springs and things so I could build a clone.
Well that never happened, as I sold that whole powertrain to my son, and it was gone.
and I have no idea where I put the map.
 
When I installed the valvebody for the second time, I had the blue spring cranked down maybe .115. The instructions said to install the blue spring for the Heavy Duty tune, and add no preload to the spring. I followed those instructions the first time and got the 75psi-100psi I noted above. I did not recheck pressures after pulling the valvebody and increasing the tension.

The test drive showed that my shifts were still pretty early and fairly soft. Now to be fair, I only have a 20 minute test drive in traffic, so it's hard to gauge.

I'm going to add some more miles and try and get a full accessment.
 
The higher you crank the line pressure the later your automatic upshifts will be. More throttle pressure will delay the upshift even further.
To get the governor back in sync for daily driving, the governor pressure has to be increased.
If you want neck-snapping shifts, your engine has to have some decent bottom-end torque,or
you need a higher stall to slingshot the rpm up to where the torque is.
To have lots of bottom end torque, the cylinder pressure has to be, oh IDK say 155 psi or more with iron heads,
At 135, forget it.
I'll guess 145/150 is the minimum I would tolerate before I'm taking the engine apart.
And at 160/165 with tight-Q it will be very snappy.
With alloys, the pressure needs to be at least 15%more, which, to get your money's worth, the psi needs to be greater than what you can squeeze out of iron. Some guys here on FABO are running close to or a tic over 200psi with alloys, still on pump gas. I myself have run 185psi still on 87E10, with no problems
You can get away with less pressure, if you have skinny tires that slip right away, or with hi-performance gears.
If you are not interested in tirespin, but are interested in snappy shifts, then you need to be particularly precise in your stall selection, or downsize the carb, or improve your traction.I think I got that right.
The bigger the engine, (within reason, like stock strokes) the easier it is to get this all synchronized.
It's really hard with a low-compression 318, with even a modest cam, cuz the pressure is so low to start with. Installing a bigger cam into a 318with no increase in Scr/Dcr, just makes it IMO, intolerably soft on the bottom.
And finally the higher your elevation the softer the hit will be.

The point is this;
IDK a doggone thing about your engine, so before you spend the entire summer playing with the trans, you sorta need to make sure your engine has the goods, and your TC wants to co-operate. To that end I highly recommend a compression test, and a flash-stall test..

For myself, on the street, with a stock 318LA, I like the hit of a 2800 with 3.23s or less; it's like soft,soft, soft, then, at 2800; WHAM! 318s have pretty good torque at 2800, and the hiway gears keep the engine in the high-torque range for a long time. It will never be quick, set up like that, but the hit is hilarious, and you will have a ton of fun. Ok, I had a ton of fun,lol.
A stock 340 has a very similar bottom end, if a lil more torquey, but needs gears to spool it up in a hurry.
I have not run my 360 with an auto, but it has a chitload of bottom-end,lol.
If you have a stroker, I know chit about strokers,lol, except that for me, I see no point in having one ,because I don't have the money to spend trying to get it to hook, on the street. I gave up at 325/50-15 BFG DRs, trying to get my 360 to hook, so concentrated on turning it into a drifter, now with 295/50-15s, sliding safely around as many corners a day as opportunities present themselves..... which it turns out, is a lotta fun.
 
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I'm not going to fool with it much until I change the rear end because I'm sure the ratio change will change the shift speeds as well.

I have not done a compression test yet, but I expect it's up there. Reringed 5.9, edelbrock/MP heads with 58cc chambers, 212/220 @.050 cam. Idles with 18" HG.

If the early shift bother me too much, I may just swap the column shift for floor shift. Easy shifting for cruising, manual shifts for fun. The shifts did seem firmer when I shifted manually at a higher rpm. That may point to the "stock" torque converter being a little loose.
 
indirect_connection said:
I'm not going to fool with it much until I change the rear end because I'm sure the ratio change will change the shift speeds as well.
Click to expand...

Absolutely yes it will change the shift speeds, to even earlier. With a given governor, increasing the driveshaft rpm by gearing is the same as driving faster with a smaller gear. The governor still shifts according to the driveshaft rpm, but now with a bigger number gear, this happens sooner.
So swapping from say 3.23s to 3.91s, the driveshaft rpm will increase by 3.91/3.23= plus 21%, at any given roadspeed. This is a lot, and this will require a different governor weight.
From the factory, there are only a few combinations of governor parts that I have seen, namely
2 slugs, three valves, and several valves. There may be more, I lust haven't seen them.
The pressure these combinations of parts will make, are made to fit the applications thru manipulation of line-pressure and fine-tuned with throttle pressure adjustments.
A&A Transmissions has whatever governor you might need.
 
indirect_connection said:
I have not done a compression test yet, but I expect it's up there. Reringed 5.9, edelbrock/MP heads with 58cc chambers, 212/220 @.050 cam. Idles with 18" HG.
Click to expand...
Yeah that combo should make reasonable torque.
However, alloy heads will suck a lotta heat out of the chambers at low to mid rpms, So when swapping to alloys for a streeter, the Scr needs to be bumped up at least a half a point; say from 9.2 to 9.7, just to compensate for the heat loss. I found mine needed a full point from 9 to 10, and then needed more compensation for the bigger cam I chose. And then I found out that alloys run pretty good at 10.5 to 11.5 depending on the resulting pressure. Mine still burn 87E10 at 180psi. And you ain't seen torque until you get to 180 psi,lol.
Once you get her wound up, there is less time to get rid of the heat, and that is when the alloy heads start to shine.
I painted my Eddies in an effort to keep the heat in.
 
Good read, but
Did you put their numbers thru the wringer.
When I read Scr of 10.88 and 185 psi came up, with a 250@.050 cam; that instantly raised a BIG red flag.
So I went to the Wallace calculator, and sure enough, the Wallace spits out just 155psi, even by adding enough ramps to gross up that 250@.050 to 292 advertised, and with an Ica of 79*/ elevation of 0 ft.
The only way the Wallace will spit out 185psi with an Ica of 79* is if I sink that thing to 5000 ft below sealevel.
To get to 185psi@ sealevel, the Ica needs to be around 64*....... just like mine, which points to a cam of just 230@.050.......... So IDK what's up with that.
Now, not many people are gonna try to argue that alloy heads are gonna make more power than iron at the same pressure. In fact, many studies have proven the opposite. And so
once again, this HRM test proves nothing useful to a streeter, because
No streeter will ever build a 185 psi iron-headed street engine because we know that it will have the death rattle below 3000 rpm, at which they (HRM) conveniently didn't test.
But we also know than many many 185psi and higher alloy headed beasts are out there with long 6.123 rods even, that you can floor at idle, with a 4 speed even, that exhibit no detonation.
So, IMO, they (HRM) do a pretty good dance, with their numbers, but also IMO, it ain't all that helpful to a streeter.
And you know what I always say; the proof is in the trapspeed.

My lil 367 for instance, goes 93 in the Eighth at 3467 pounds and at 900 ft elevation. The Wallace says to do that, takes 433 hp. Here's the rub; my 367 is running a wee small cam of 230/237/110@.050 but with OOTB Eddies adjusted to about 180psi. And it did this while shifting at 7000; well actually, she came out of the starter box at 7000 and just stayed there thru 4 gears, for the whole trip, spinning continuously.
It's pretty obvious to me that my combo should NOT be making 433 hp. And so it was at the track. I even went to visit the guy in the other lane who confirmed that his numbers looked correct on that ET slip. I then went to the tower and complained that their timer must be wrong, but they replied that no one else had complained lol.
So, my trapspeed of 93 must stand. And that means the 433 has to stand.
Now, if their 250* cam power peaked at 6100, You can bet that at 7000, I was way over-speeding my 230* Cammed engine. In all likelyhood mine power-peaks at 5500, or less; I figured 5300 with an onboard " accelerometer".
Now consider that in the HR article; they have a 388 cuber with 20 more cam degrees than mine; that's 3 cam-sizes!
and their engine made 483@6100 @185*F, also with aluminum, also at a claimed 185 psi.
You can see that on a dyno, my engine would make more than 433hp at the proper rpm.

All in all it's all bogus, cuz the trapspeed cannot lie, 433 hp it is.. Maybe I'm rambling, IDK
But there is no way, on the street, that I'd run iron heads at 185psi and at 110*F
Don't call him crazy but the only guy I know of who wants to try it is @yellow rose , who is willing to try 170 psi and iron, but with 4.56 gears,lol.
From 170 to 185 is a very loooooooong way.

IMO, on the racetrack, where the engine will never be loaded below maybe 3500stall, Maybe a guy could get away with 185 psi and iron. IDK, I know nothing about racing.
But on the street, some very high percentage of the time, your engine will be spent between idle and say 3500rpm, and very very few guys will run 4.56s or 3500 stalls, am I right? So then there is no chance anyone would deliberately try to run 185psi with iron heads, especially not at 110*F.
I call BS on the bs test.
BTW-1
I have been running a rock-solid Engine cooling system temp of 205 to 207*F, since about year 2000. And yeah, she went 93 at that temp. Just imagine how much faster she wouldda gone at 110*F ,lol. that would be like, according to HRM, about 20 plus horsepower; I don't think so tim.......... Again, that's racetrack stuff.
BTW-2
My 367 is set up at 10.95Scr and pumps 180psi with a 230*cam and Ica of 64*, and a LeakDown of less than 4%
So that is Why I got alerted tom the HR article using a 250*@.050 cam. The only way to get to 185 with an Ica of 79* is to enter minus 5000 ft in the elevation box, lol.
BTW-3
the allloy heads do not suck heat out of the water ...... exactly. If they do/did, the thermostat would just compensate for that. But
IMO the alloy heads suck heat out of the combustion chambers, the same way we use aluminum in heat sinks to suck heat out of things that would otherwise run too hot. And ............ the proof is that, to make the same low-speed torque wit alloys to match iron..... you have to boost the SCR at least a half a point they say..... because at lower rpms the alloys have plenty of time to transfer combustion chamber heat to anywhere its colder than in the chamber; so hyup the cooling system, hyup the underhood air, and hyup even into the oilpan. You won't see it on the temp gauge because the stat will keep it all at the minimum cooling system temperature, continuously....
But when you floor it for a few seconds, the chamber heat cannot get away fast enough and BADABOOM! we are making power! Now do you see what I'm saying about my little 367? It really comes alive at the top of the track after being at 7000 for 7 or so seconds,lol.
BTW-3
The test I would like to see, is to see an iron-headed SBM, set up for street, running the max pressure for 91 gas and no detonation below 3000 rpm; run the Eighth with that and optimize the gears to trap right yet be streetable.
Then
Pull the iron heads and install same design Alloys but run the pressure up to the max again for 91 gas. Then record the Trapspeed change, and if it needs to be regeared, well just do it. Then compare the two. See
Now that would put the controversy to rest once and for all.
After that, I want to see the alloy headed version strangled with gearing until it traps as slow as the iron. I wanna bet you can take out 10 to 15% gearing, exactly what a streeter needs; 3.23s versus 3.91s But I'm just spitballing.....
As for me, I'm never going back to iron heads in my Barracuda. 433 is a nice fat, alloy-headed, 230*-cam sporting, power-number, lol; on about 33* ignition timing and 87E10 even, lol. Hyup, 32/34* at 3200/3400 and same all the way to 7000plus.
 
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