seeholmes

1961 Dynaflow drivability

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I have a 61 LeSabre with a 364 and Dynaflow transmission. This is my first Buick so I feel like I'm still getting the hang of the Dynaflow. As long as I keep the fluid level on full it drives really nice. Lots of pickup and smooth as can be. The one exception if that when I go up a big hill (there is one in particular on my way to work, on the freeway) it seems to loose its guts a bit. I usually hit it at 70 mph and to maintain 70-75 I have to get really into the throttle. As the hill levels off at the top (while maintaining a fixed throttle position with my foot) It pulls like I hit the turbo switch. It almost feels like its loosing pressure or something. At first I thought it was carb related but I've been through carb, ignition, etc. So I'm 99% sure its the Dynaflow.

 

I'm going to drop the pan this weekend and have a look at the screen. I may try to do the pressure test procedure per the manual. Any other suggestions. This in no way is stopping me from driving and If this is just how it is so be it. I can work around this but If there is a way to increase performance I'm all ears.

 

Thanks,


Craig

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Is this a 2 bbl carb?  Or 4 bbl?  And when you say "

5 hours ago, seeholmes said:

As the hill levels off at the top (while maintaining a fixed throttle position with my foot) It pulls like I hit the turbo switch."

 

And then you say " 

5 hours ago, seeholmes said:

It almost feels like its loosing pressure or something.

 

I am wondering if you could explain this better?

 

On one hand hitting the turbo switch could mean the car picks up in performance,  while losing pressure seems to indicate the trans is slipping.  Of course hitting the Turbo switch could mean turning the turbo off, while I presume you mean the stator in the torque converter is switching pitch out of the power position?

 

 

 

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Details on "the hill" . . . length from the base to the top AND elevation change?  How much extra throttle is needed to maintain road speed, as if it was on "cruise control"?  What is the time duration of the bottom-to-crest event?  At what general elevation is the base terrain in that area, above sea level?

 

Presuming you have a "modern car", how does it act in the same situation?  If you have the cruise control set to the 70mph road speed, keeping your foot on the accel pedal, what happens when you reach the crest of the hill, at that same throttle position?

 

In general, at that road speed, the torque converter should be "tight", but determining where the ":kickdown" (i.e., switch-pitch" in the torque converter) happens might need a factory service manual to determine.

 

How would the car respond if, on level ground, you applied the same amount of throttle, at the starting road speed, over the same distance?

 

While you have the car on the lift/jack stands for the atf change, DO take that opportunity to check the rubber in the fuel lines . . . tank to carb.  IF they have not ever been changed, still having a pre-1992 set of rubber lines, then change ALL of those, too!  Put new, ethanol-resistant rubber fuel lines in their place.  Also tap on the muffler and exhaust system, looking for any difference in the sound, which might indicate any loose baffles in the muffler or any pipes which might be internally collapsed . . . just to see what's there, more than anything else.

 

While the NailHead Buick V-8 has a very strong torque output, you are also dealing with a 300cfm 2bbl carb on an engine that's running close to or at the rated torque peak.  I mention that as a point of reference issue more than anything else.

 

What did the spark plugs you removed look like?  Color of the ceramic insulator, in particular?  White-to-light tan colored or sooty and darker?  How many miles/month has the car been driven lately?  Just curious.

 

My suspicion is that what you're experiencing COULD be completely normal, but do make sure everything is operating "to spec".  IF a friction material (clutches or band) was slipping, the atf would probably be darker red and have a "cooked"/burnt smell to it.  IF the atf fluid level is checked when the car has been run for at least 10 miles at highway speed, then again after "the hill", does it change much?  Fluid heated by internal slippage would expand and cause a higher level on the trans dipstick, usually.  But if there might be some internal seals which have worn, then that might be indicated by "lazy" engagement or similar?

 

Please advise,

NTX5467

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Sounds like my Dynaflow and my modern Nissan with a CVT transmission.  They both need gas to get up the hills around here.

In my Nissan I can watch the tach and the engine goes from 2,000 RPM to almost 4,000 on one of the hills. This is on cruise, on an interstate going 75 or so.

Same experience with my 60 Electra.

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My only thought is transmission fluid bunching up at the rear of the transmission on a very long grade possibly starving the pump a little bit.   My other thought is it is just a darn big hill and some umph will be needed to crest it eventually. 

 

Did this just start or was this always how the Buick performed on this hill?     

 

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50 minutes ago, avgwarhawk said:

My only thought is transmission fluid bunching up at the rear of the transmission on a very long grade possibly starving the pump a little bit.   My other thought is it is just a darn big hill and some umph will be needed to crest it eventually. 

 

Did this just start or was this always how the Buick performed on this hill?     

 

Put a tachometer on temporarily.  You should see very little RPM change unless the switch pitch is engaged.

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12 hours ago, NTX5467 said:

Details on "the hill" . . . length from the base to the top AND elevation change?  How much extra throttle is needed to maintain road speed, as if it was on "cruise control"?  What is the time duration of the bottom-to-crest event?  At what general elevation is the base terrain in that area, above sea level? (I checked this morning and the base of the hill is 140 ft above see level and the crest is 340 ft. The length of the hill is about 2 miles. Tofday I started at 70 and maintained my speed with little extra throttle input. Where I struggled was trying to increase speed or maintain say 80. Its probably just a little more than the dynaflow can handle and Im of with that.

 

Presuming you have a "modern car", how does it act in the same situation?  If you have the cruise control set to the 70mph road speed, keeping your foot on the accel pedal, what happens when you reach the crest of the hill, at that same throttle position? (My 2013 F150 is twin turbo and very powerful so it can handle increase load very easily. This "baseline" probably hurts me with respect to the Buick. I likely need to re-calibrate my driving style a bit)

 

In general, at that road speed, the torque converter should be "tight", but determining where the ":kickdown" (i.e., switch-pitch" in the torque converter) happens might need a factory service manual to determine.

 

How would the car respond if, on level ground, you applied the same amount of throttle, at the starting road speed, over the same distance? (On level ground the Buick is amazing. It can pull very hard from 70 to 90. It also pulls hard from 20-60. I did a lot of tuning to get the best drive-ability  across a wide range of conditions. That "tuning" likely has me sensitive to "the hill". 

 

While you have the car on the lift/jack stands for the atf change, DO take that opportunity to check the rubber in the fuel lines . . . tank to carb.  IF they have not ever been changed, still having a pre-1992 set of rubber lines, then change ALL of those, too!  Put new, ethanol-resistant rubber fuel lines in their place.  Also tap on the muffler and exhaust system, looking for any difference in the sound, which might indicate any loose baffles in the muffler or any pipes which might be internally collapsed . . . just to see what's there, more than anything else. (All great points and will be checked)

 

While the NailHead Buick V-8 has a very strong torque output, you are also dealing with a 300cfm 2bbl carb on an engine that's running close to or at the rated torque peak.  I mention that as a point of reference issue more than anything else. (So my carburetor situation is unconventional. I ended up installing a 4bbl manifold and use an edelbrock 750 carb with the secondaries disconnected. Its square bore so should flow around 375 the way its hooked up. I tuned all circuits with an o2 sensor to be sure I was in the ideal A/F ratio. This setup performs much better than when the secondaries were hooked up. Im 12* BTDC at idle for timing (32* total). Vacuum advance is hooked to the timed port on the carb.

 

What did the spark plugs you removed look like?  Color of the ceramic insulator, in particular?  White-to-light tan colored or sooty and darker?  How many miles/month has the car been driven lately?  Just curious. (With AC 45 plugs they were reading a bit too "clean" ceramic was white and no sign of damage to electrode. I just switched to some new AC 43s I had in the garage. It runs great however I havent pulled a plug yet to have a look. I forgot to last night as I just revived an AC car fan shroud so was eager to throw that on. No temp issues by the way, I just recored the radiator to high efficiency 4 row. My old 3 row was 75% blocked resulting in higher than desired temperature. (up to 220 on a hot day). Not It stays at 170 on the freeway, 190 in town (180 t-stat)

 

My suspicion is that what you're experiencing COULD be completely normal, but do make sure everything is operating "to spec".  IF a friction material (clutches or band) was slipping, the atf would probably be darker red and have a "cooked"/burnt smell to it.  IF the atf fluid level is checked when the car has been run for at least 10 miles at highway speed, then again after "the hill", does it change much?  Fluid heated by internal slippage would expand and cause a higher level on the trans dipstick, usually.  But if there might be some internal seals which have worn, then that might be indicated by "lazy" engagement or similar? (I think you may be right. I will have a closer look this weekend to see how it looks under the pan. I will also check the other things you mentioned. The exhaust looks factory, I cant say what fuel line up to the pump. THe fuel pump. regulator, lines, filter, on the carb side are all new.

 

Thanks for your input. Greatly appreciated!

 

Please advise,

NTX5467

 

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13 hours ago, JohnD1956 said:

s this a 2 bbl carb?  Or 4 bbl?  And when you say " I am running a 750 cfm carb with the secondaries disconnected. I have found this setup to give the best power across the widest range of conditions. I tuned it with an o2 sensor to make sure all the circuits were responding properly (i.e. not too lean or rich for the given load)

  19 hours ago, seeholmes said:

As the hill levels off at the top (while maintaining a fixed throttle position with my foot) It pulls like I hit the turbo switch."

What I meant by that is if Im pulling up the hill with my foot in a fixed position, when the hill levels off I begin to accelerate rapidly. This is expected I suppose as the load decreased substantially. 

And then you say " 

  19 hours ago, seeholmes said:

It almost feels like its loosing pressure or something.

 

I am wondering if you could explain this better? (I don't feel it slip or it doesn't seem like the RPM is increasing (although my car is very quiet so not so easy to tell sometimes). What I'm feeling may be the fluid drive feel of a dynaflow where its slightly disconnected feeling where you apply extra throttle but don't immediately get a response or feedback . On level ground or slightly down hill the feedback is pretty responsive)

 

On one hand hitting the turbo switch could mean the car picks up in performance,  (This is what I meant) while losing pressure seems to indicate the trans is slipping.  Of course hitting the Turbo switch could mean turning the turbo off, while I presume you mean the stator in the torque converter is switching pitch out of the power position?

 

 

 

 

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2 hours ago, Bill Stoneberg said:

Sounds like my Dynaflow and my modern Nissan with a CVT transmission.  They both need gas to get up the hills around here.

In my Nissan I can watch the tach and the engine goes from 2,000 RPM to almost 4,000 on one of the hills. This is on cruise, on an interstate going 75 or so.

Same experience with my 60 Electra.

I think you are probably right. Ive been spending a lot of time tuning the carb, ignition, plugs, etc. and Im likely just over-analyzing every condition. 

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1 hour ago, avgwarhawk said:

My only thought is transmission fluid bunching up at the rear of the transmission on a very long grade possibly starving the pump a little bit.   My other thought is it is just a darn big hill and some umph will be needed to crest it eventually. 

 

Did this just start or was this always how the Buick performed on this hill?     

 

I will pull the pan to make sure the screen looks clean and change fluid etc. Today I took the hill at 70 with minimal effort, meaning hardly any additional throttle input. In reality there is no reason I need to blast 80 up that hill anyway. In some ways this is a unintended consequence of COVID-19 as my commute is usually slammed with traffic and I take that hill at 40mph. Now with no traffic Im scratching my head wondering why I cant take it at 80-85. The plus side is my 70 minute commute now takes 25 :) 

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16 minutes ago, seeholmes said:

I will pull the pan to make sure the screen looks clean and change fluid etc. Today I took the hill at 70 with minimal effort, meaning hardly any additional throttle input. In reality there is no reason I need to blast 80 up that hill anyway. In some ways this is a unintended consequence of COVID-19 as my commute is usually slammed with traffic and I take that hill at 40mph. Now with no traffic Im scratching my head wondering why I cant take it at 80-85. The plus side is my 70 minute commute now takes 25 :) 

 

Generally it is best to take the hill at the posted speed limit.  At 80-85 one is ready for the cuffs.   At any rate,  taking the hill today without issue and another day with issue, what is the weather like on either of these days?   Weather, mass air pressure and ambient temps do affect performance.      

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16 minutes ago, avgwarhawk said:

 

Generally it is best to take the hill at the posted speed limit.  At 80-85 one is ready for the cuffs.   At any rate,  taking the hill today without issue and another day with issue, what is the weather like on either of these days?   Weather, mass air pressure and ambient temps do affect performance.      

Today I took it at 70 which is likely why it was fine. Previous days I was trying to go faster. Good point on the cuffs :) 

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Sounds like the hill coming into Allentown PA that my Enclave struggled with. I would compare the design of of a proper 4GC or AFB with a half disconnected 750, especially how the power valve operates. I just have this quirky thing about stuff that ain't hooked up right.

 

I crest a hill with my '60 Electra fast with my left foot hovering over the brake pedal.

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6 minutes ago, 60FlatTop said:

Sounds like the hill coming into Allentown PA that my Enclave struggled with. I would compare the design of of a proper 4GC or AFB with a half disconnected 750, especially how the power valve operates. I just have this quirky thing about stuff that ain't hooked up right.

 

I crest a hill with my '60 Electra fast with my left foot hovering over the brake pedal.

Im generally the same as you when it comes to stuff not being hooked up right. I struggled with the carb for a long time and could never get it to operate properly when the secondaries would come in. I tried adjusting the air valve to slow dons, speed up , jetting at all different levels. It just seemed to loose velocity in the intake when the secondaries opened up and I couldn't tune it out. That coupled with the fact that it runs so good with just the primaries and in reality I cant see my setup needing more than 375 CF< (heavy car, dynaflow, older engine, etc. 

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2 hours ago, seeholmes said:

Im generally the same as you when it comes to stuff not being hooked up right. I struggled with the carb for a long time and could never get it to operate properly when the secondaries would come in. I tried adjusting the air valve to slow dons, speed up , jetting at all different levels. It just seemed to loose velocity in the intake when the secondaries opened up and I couldn't tune it out. That coupled with the fact that it runs so good with just the primaries and in reality I cant see my setup needing more than 375 CF< (heavy car, dynaflow, older engine, etc. 

it is possible that the car is looking for the extra from the secondaries when under that kind of load 

375 cfm is small, Nailheads like carb i understand your thinking but you might be defeating yourself

in that situation a 2bbl would probably be wide open so why not let the secondaries help out

just another way to look at it 

 

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The clone carburetor you have is probably calibrated for a high performance 350 Chevy.

 

The fuel distribution curves on a 364 Buick and a 350 Chevy are as different as the personalities of Attila the Hun and Nelson Mandela.

 

If you are happy with the clone, then I will say no more.

 

If you are not happy with the clone, then two suggestions (either of which will run better on a Buick 364 than the clone).

(1) The original Stromberg 2-barrel 7-114 or Rochester 2-barrel 7019042.

(2) The original optional Carter AFB 3089s or the superseding 3578s

 

Any of the above would be specifically calibrated for a 364; however, I do not know what engine characteristics (camshaft profile, compression, etc.) that may have been changed when the optional 4-barrel was installed on the engine. Stromberg specified the 7-114 specifically for the dynaflow. The others do not specify transmission other than automatic.

 

Jon.

 

 

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35 minutes ago, carbking said:

The clone carburetor you have is probably calibrated for a high performance 350 Chevy.

 

The fuel distribution curves on a 364 Buick and a 350 Chevy are as different as the personalities of Attila the Hun and Nelson Mandela.

 

If you are happy with the clone, then I will say no more.

 

If you are not happy with the clone, then two suggestions (either of which will run better on a Buick 364 than the clone).

(1) The original Stromberg 2-barrel 7-114 or Rochester 2-barrel 7019042.

(2) The original optional Carter AFB 3089s or the superseding 3578s

 

Any of the above would be specifically calibrated for a 364; however, I do not know what engine characteristics (camshaft profile, compression, etc.) that may have been changed when the optional 4-barrel was installed on the engine. Stromberg specified the 7-114 specifically for the dynaflow. The others do not specify transmission other than automatic.

 

Jon.

 

 

Great info Jon! Any idea what the CFM ratings are for those carbs? Just curious. The best I can get my carb 2 run is by detaching the secondaries and essentailly running it as a 2 barrel.. That along with changing jets, rods, squirter size, etc. It does run  well now but its a pretty hokey setup :) 

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Now that we know you have a 1/2 AFB rather than the OEM 2bbl, is the exhaust system still the OEM-spec single exhaust?

 

No, your F-140 EcoBoost is not a good "baseline" for comparison between how it acts and how the Buick acts on the same road or road speed.

 

I don't know that there are any real issues with the DynaFlow.  With the carb change, how did you alter the trans linkage from the carb?  Is it now adjusted/configured as it would have been on an OEM 364 AFB?  Perhaps, rather than a 750cfm AFB, it needs something more like the 500cfm model instead.

 

NTX5467

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41 minutes ago, NTX5467 said:

Now that we know you have a 1/2 AFB rather than the OEM 2bbl, is the exhaust system still the OEM-spec single exhaust?

 

No, your F-140 EcoBoost is not a good "baseline" for comparison between how it acts and how the Buick acts on the same road or road speed.

 

I don't know that there are any real issues with the DynaFlow.  With the carb change, how did you alter the trans linkage from the carb?  Is it now adjusted/configured as it would have been on an OEM 364 AFB?  Perhaps, rather than a 750cfm AFB, it needs something more like the 500cfm model instead.

 

NTX5467

The exhaust is still the OEM single. Funny you should mention it, Im considering doing a new dual exhaust system this weekend (at a local exhaust shop). As far as the trans linkage goes, the switch pitch is hooked up to engage per the user manual. The rod starts moving at about 70% throttle and is full range at 100% throttle.  I think I would have been much better off had I selected a 500cfm but I keep hearing that nailheads love big carbs. In some respect Im sure thats true but with a giant car and a dynaflow maxing out at about 4300 rpm I doubt a huge carb is doing me any favors.  On my 31 Model A I have a 1957 270hp 283 from a corvette. All original down to the dual WCFB carbs. No issues with carb size there. My point being its an entirely different application with a 1700lb car, 4 speed, nice gear ratios in transmission and rear end. (3.50 1st gear x 33.6 ring and pinion)... Redline is about 6500...

All and all I absolutely love this Buick. My first one and I cant get enough!! 

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2 hours ago, seeholmes said:

Great info Jon! Any idea what the CFM ratings are for those carbs? Just curious. The best I can get my carb 2 run is by detaching the secondaries and essentailly running it as a 2 barrel.. That along with changing jets, rods, squirter size, etc. It does run  well now but its a pretty hokey setup :) 

 

The CFM is nowhere near as important as the applicability of the fuel curve.

 

As far as the clone running well, a wise man with a sense of humor once stated that if one has not tasted steak, baloney is pretty good! ;)

 

ALL engines like big carburetors, if the engine is installed in a trailered race car! ;) I used to run two 500 CFM two-barrels on a 121 CID 4-banger. And it ran like a scalded dog.............from about 4,000 to 10,000 RPM.

 

Jon

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Just to circle back on this issue and what I've found/done to address. While inspecting the exhaust for damage I started wondering how well the single exhaust can perform with my 364. The exhaust had 1.75" Y pipe to 2.25" intermediate pipe to an OEM style muffler. This should be a maximum of 400 CFM. That seemed close to the 375 CFM intake I was getting from my "primary only" carb arrangement. I decided to do a 2" dual system with higher performance mufflers (still fairly quiet).  The difference in power is astounding! I immediately hooked up the secondary side of the carb, re-tuned metering rods and jets. The butt dyno says I added 50-75 horsepower. The "hill" that I was struggling on (hard to go faster than 75mph full throttle) can now me taken at 80+ with less than 50% throttle position. Thanks for all the input. It certainly helped to vet this issue with you guys.

 

Craig

 

PS the 750 Edelbrock performer carb ended up with the power stage of the metering rods 1 stage leaner than factory, the secondary jet ended up 1 stage rich. The accelerator pump arm was moved to the lowest position (biggest shot). It truly drives like a different car.

 

I also realized while working on the car that my driver side motor mount is shot. This weekends activities are:

Replace both motor mounts

R&R oil pan and gassket

R&R tran pan and gasket

new high and low accumulator seals

New front wheel bearings (inspect brakes and service if needed)

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