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torque converter stall speed ?

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Supervan66
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torque converter stall speed ?

Post #1 by Supervan66 » Fri May 10, 2019 7:33 pm

Hey guys. I got the engine running in my 1966 Econoline.
300 straight 6 bored .060 over
8.9 / 1 compression
Comp 268/268 cam
Clifford headers
Offy manifold with summit 500 carb.

Its running pretty awesome, but I can't get it to idle low and smooth enough . When I put it in gear it tries to jump and lurch on me.
I talked to a few old timers and they seem to think that I'll have to set my idle higher with that camshaft and that I should install a higher stall torque converter.
Any idea what the stock stall speed was ? C4 transmission came from a 1970 fairlane.
What stall speed should I be looking for ?
And does it seem like I'm heading in the right direction?

Max_Effort
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Re: torque converter stall speed ?

Post #2 by Max_Effort » Fri May 10, 2019 9:29 pm

What is your idle speed now?

pmuller9
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Re: torque converter stall speed ?

Post #3 by pmuller9 » Fri May 10, 2019 9:34 pm

Redirected.
Last edited by pmuller9 on Fri May 10, 2019 10:15 pm, edited 1 time in total.

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THE FRENCHTOWN FLYER
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Re: torque converter stall speed ?

Post #4 by THE FRENCHTOWN FLYER » Fri May 10, 2019 9:47 pm

A 2500 RPM stall speed in conjunction w/ 3.50 gears and 31" tires works well in my Willys. I used a 10" converter originally for a 351C Cobra Jet.
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Re: torque converter stall speed ?

Post #5 by pmuller9 » Fri May 10, 2019 10:14 pm

The Comp 268 cam has been used by forum members many, many times and there never has been a problem with running rough at idle.
The converter is not the problem
The Comp 268 cam should have no problem idling at 750 rpm.

First thing to do is a compression check to make sure all the valves are closing on the seat.
The valves may not be adjusted correctly.

Can you tell us how you set the preload on the hydraulic lifters?

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Re: torque converter stall speed ?

Post #6 by xctasy » Fri May 10, 2019 10:33 pm

My post was lost. 2350 rpm is the next step up from 1650 rpm stock.

The issue is lean out due to carb setting, or new lifter preload. It shows up on a vac gauge; the matter shows up if you change the idle needle profile.
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Re: torque converter stall speed ?

Post #7 by Supervan66 » Fri May 10, 2019 11:47 pm

thank you! These questions really got me thinking.
Engine seems to idle best at 850rpm with factory settings on this summit carb. The tuning manual that came with this carb isn’t great. But I’ve had thoughts of trying some different idle restrictor jets.
My engine is pulling 13lbs of vacuum and the needle on my gauge is kind of bouncy.
I studied up a little more on lifter preload and I’m pretty sure I set my preload wrong.
I’m using the stock stud mounted rockers and pushrods and I think I overtightened them.
When I checked lifter preload, I had each cylinder on its TDC and all the pushrods were sitting in the middle of the lifters spring travel.
I’ll check on Monday.

Thanks again, keep them ideas coming !

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Re: torque converter stall speed ?

Post #8 by Max_Effort » Sat May 11, 2019 7:18 am

The converter may have issues, 850 RPM shouldn't make the vehicle jump and lurch.

It does sound as you need to readjust your valves though.


With the vast majority of cams, you can adjust on TDC, the problem is people mistake overlap for TDC.


If you use this method (pmuller9 quote) "adjust the intake valve just as the exhaust valve begins to open BUT you adjust the exhaust valve just as the intake valve CLOSES"
You can't make a mistake.

And (quote from me)
"Just a light touch on the pushrod. Shake it gently while tightening the nut, once the wiggle/looseness is taken up, then 1/2 to 3/4 turn."

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Re: torque converter stall speed ?

Post #9 by old28racer » Sat May 11, 2019 12:12 pm

I second readjusting your lifter preload. If the pushrods looked to be in the middle of the lifter spring travel sounds like the preload is to much. Use pmuller9 method and you can't go wrong.
Convertor stall would be the last thing I would look at, did it work fine with the stock setup? Good luck, let us know what you find.
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Re: torque converter stall speed ?

Post #10 by 68Flareside240 » Sat May 11, 2019 12:43 pm

Looking at the 68 Ford General engine service manual, they state low vacuum (under 18") as loss of power across all cylinders, likely due to late ignition or valve timing, or loss of compression due to ring failure. Intermittent fluctuation they list as ignition defect or sticking valves. I'm going with the valve adjustment. Hope it gets you fixed up.

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Re: torque converter stall speed ?

Post #11 by xctasy » Sat May 11, 2019 6:22 pm

Okay, you have to ensure the hydraulic lifters are correctly preloaded, the cam is properly indexed, and that you have a good ignition curve and spark quality. Ported or Manifold vaccum influences the base advance and advance kick in.

Often, the base idle jet settings for V8 spec 500 to 600 cfm carbs are wrong. Target market is strokers and mild to wild cam intensity V8'S.

Ford USA "four corner idled" the big 600 cfm 4180C/4185/4195 truck carbs to run on itty bitty 175 to 210 hp HO 4V Mustang and Capri 5.0's from 1983 to 1985, and they used a Propane method of setting idle. That picks up leaks.

Propane methoid is this.
http://vb.foureyedpride.com/showthread. ... ost1663147

JACook wrote:The propane enrichment can be done without any special tools, but I will say the tool makes things
a little easier. All you need is a way to repeatably supply a low flow of propane. When I first started
using the propane enrichment method, I modified a regular propane torch by removing the torch bit,
and attaching a hose.

I have altered the factory method just a bit though. Rather than inject the propane into the air cleaner,
I prefer to aim the hose down each individual throat, to make sure I'm getting the same reaction from
all of them. Then I work with progressively lower propane flow rates to fine tune the mixture setting,
while watching both engine RPM and manifold vacuum.

It takes a bit of practice to find the balance, but once you know what feels right, it's much quicker and
more accurate than just using the vacuum gauge.




Ford also used a pull-off Choke, and a very agressive spark advance to warm up the engine to light off the emissions circuits.

Fuel pump delivery pressure and flow can cause huge issues with idle.

Idle problems are not always torque converter problems.

Rope seal drag on newly built engines, high Amp alternators, electric cooling fans running off 130A alternators, and not using a TFi distributor cause a lack of spark intensity, and that can cause idle "matters".


A couple of questions.

Are you using the # 6019 Dual Port 360

https://www.summitracing.com/int/parts/ ... nsanswers/
Image

or

the single plane #5886 360 intake?

Image

Check crgintx and F-250 Restorer.

The issue is that its a Summit 4bbl carb made not of ZincOxide, but another grade, and all those carbs in certian altitudes and climiates often needed a Hot Idle Compensator Valve, its especailly important for our modern ethanol or oxygenated fuels.

Make sure there are no leaks.

Image

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Image


Image


http://www.network54.com/Forum/88781/thread/1029160955/Hot+Idle+Compensator+Valve

The engine needs to be like goldilocks' porridge. Not to cold, not too hot, but just right. The shop manual for my 1963 Thunderbird says the purpose of the hot idle compensator valve is to allow more air into the idle mixture to help control an over-rich mixture when the entering air is very warm. The manual states that the over-rich mixture would result from the fact that the warmer air atomizes the fuel better, thus making less fuel necessary. It is kind of a negative choke, it sounds like. It continues to lean the fuel mixture at idle as the air warms, even after the choke valve is completely open. I suppose that, wherever along the continuum (from full choke to full negative choke) you set the idle, it will be a compromise. The car will be set to idle optimally when the engine is idling at that point on the continuum. But at other points on the continuum, the engine will probably be idle less than optimally. The engineers, by tial and error or by design, presumably determined that the best compromise, overall was achieved by setting the idle to be most efficient when the choke valve was fully open but the hot idle compensator valve was still closed. I don't know what temperature the hot idle compensator valve opens at. But one consideration the engineers may have had in mind is that it may be difficult or time consuming to get a healthy engine idling in a chilly mechanic's shop in the winter with the hood open and the air filter off to run hot enough that the valve will open. Therefore, they designed it so that the best result would be achieved if the idle was set when the hot idle compensator valve was closed



Now, the other method is to recalibrate the transfer slot or Idle Air bleeds.

As stated, they are often not able to be calibrated for 1 to 1-1/2 turns out.

The way to tune them is to contact http://carb-rebuilds-plus.boards.net/

and talk to Mike.

Tell him I sent you. Any time you put a V8 spec carb on an in line six, you have to go back to basics, and on sixes, its answering questions like
Basic baseline tuning which is best done against Fords reference manauals. The big forum posts are not performance, they are always idle, and the stock V8 stuff needs a little bit of a kick in the gutts to work on a street truck.

FoMoCo, they look at lifter pump up specs, valve adjustment, ported vaccum specs which are exclusively hooked into a raft of emission control parts which you've most likely removed. So your off the track, different hymn book.

IMHO, if you go off the Orthodox road, then you have to look at
PCV valve flow and brake booster and modulator valve leaks, which really hurts idle
then carb position,
ignition advance,
current and energy draw from Alternators, auxilary fans, A/C, the dreaded rope seal yadda yadda yadda


Cam duration is the second last to check, and you have to really do that almost last because all the basic stuff needs to be done.

Then carb transfer slots and Idle Air bleeds can correct a lot of stuff.
and a whole bunch of other stuff then doesn't need rechecking.



http://vb.foureyedpride.com/showthread. ... read/page4
http://vb.foureyedpride.com/showthread. ... bfo-needed
Image
XEC Ltd ICBE's Inter Continental Ballistic Engines-
FAZER 6Bi (M112 & EEC5) or FAZER 6Ti (GT3582 & EEC5) 425 HP 4.1L/250 I-6
FAZER 6V0 3x2-BBL Holley 188 HP 3.3L/200 I-6 or 235 HP 4.1L/250 I-6
X-Flow Engine Components Ltd http://www.xecltd.info/?rd=10

Max_Effort
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Re: torque converter stall speed ?

Post #12 by Max_Effort » Sat May 11, 2019 7:30 pm

One thing to add...
After you re-adjust your valves and idle adjustments, if it lurches or stalls going into gear, you could have a torque converter with a seized or binding stator, it will also be very sluggish starting off and accelerating.

Supervan66
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Re: torque converter stall speed ?

Post #13 by Supervan66 » Wed May 15, 2019 12:05 pm

Thanks for the replies folks ! You guys steered me in the right direction.
Yesterday I readjusted my lifter preload with the procedure you outlined. Made all the difference !

Engine is running silky smooth at 700ish RPM , pulling between 17 and 18lbs of vacuum.
It still jumps into gear and I have to hold the brakes to keep the vehicle from moving. Its not terrible, but not right .
The old 240 I had in the van had to idle at 500rpm to keep this from happening, so I might be looking at a new torque converter.

I'm at the end of my adjustment on my Idle speed screw, it idles at 700 rpm with the screw completely backed out. Maybe I'm drawing too much vacuum through the PCV valve, I might clamp that off and see if it makes a difference.

thanks again you guys !

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Re: torque converter stall speed ?

Post #14 by bubba22349 » Wed May 15, 2019 2:06 pm

What happens if you turn the idle mixture screw in (leaning) it out? Base setting after a carb rebuild is 1 1/2 turns out then you adjust the mixture from there. Good luck :thumbup: :nod:
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I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

Supervan66
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Re: torque converter stall speed ?

Post #15 by Supervan66 » Fri May 17, 2019 3:20 pm

I talked to a guy yesterday who said that most PCV valves you buy now days are not meant for any specific engine and generally flow way too much, he recommended putting an orifice in my hose. That helped a lot. Now my idle is sitting at 650rpm and I can adjust it a little lower with my speed screw. Both mixture screws are sitting at 1 and 1/4 turns out.
At 600 rpm my transmission is still trying to go, I'm leaning towards a higher stall torque converter.

Max_Effort
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Re: torque converter stall speed ?

Post #16 by Max_Effort » Fri May 17, 2019 9:36 pm

Supervan66 wrote:I talked to a guy yesterday who said that most PCV valves you buy now days are not meant for any specific engine and generally flow way too much, he recommended putting an orifice in my hose. That helped a lot. Now my idle is sitting at 650rpm and I can adjust it a little lower with my speed screw. Both mixture screws are sitting at 1 and 1/4 turns out.
At 600 rpm my transmission is still trying to go, I'm leaning towards a higher stall torque converter.


Many millions of stock converters with engines idling at 700 RPM, don’t lurch and pull hard when put into gear. Something is up with that converter...

I'll add that I don't think you'd want a higher stall converter in a RV. It's just going to make the trans temp go up and reduce fuel economy. A good, rebuilt stock converter should be all you need.

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