Gas Pedal Travel

[38convsedan]

Curious about correct amount of gas pedal travel on my 38 CS with 8BA.
Can’t get carb to WOT (only about 2/3).
(EFV8 Bible calls for 10.44” carb arm— mine is more like 9.5”.)
Pictures below show pedal up and then fully depressed.
Doesn’t seem to be enough pedal travel…

[19Fordy]

Would installing a little adjustable turnbuckle (both sides RH threads) that extends the throttle arm to the carb help? See the little aluminum piece in photo. I think I used a 10-32RH die to cut the threads on the throttle rod. Car is a 40 Ford with an 8BA.

[38convsedan]

19Fordy-How much travel do you have on your accelerator pedal?

[19Fordy]

38: Measuring with a combination square from the top surface of the gas pedal to the rubber floor mat the distance between the top of the pedal and the floor mat when the pedal is all the way up is 4 7/8 in. With pedal all the way down that measurement is 1 7/8 in. That gives a travel of 3 in. These measurements will vary according to thickness of floor mat.

The stock 40 gas pedal set up worked fine on the 8BA when using the stock 8BA 2 barrel carb. It worked fine without modifying the linkage. But, when I changed to a Holley 390, I had to add the turnbuckle. You can cut, drill and tap a mild steel bolt to make the turnbuckle.

I am running a 390 Holley 4 barrel on an 8BA and found that I had to modify the linkage using the turnbuckle because the stock length throttle rod would not provide enough "throw" for the Holley to work properly. I did not need to use a return spring on the carb.

Because the throttle rod is mild steel it can easily be welded back together. Or, buy a used one and make a "practice piece" to experiment on.
https://www.ebay.com/itm/1935-39-For...7/391411142838

You can also cut a piece of small dia. rubber hose and secure it in place with tie wraps to find out what length turnbuckle and thread length you need. My alum. turnbuckle is 3/8" OD x 1 3/8 in. long. Use fine threads for better thread contact and finer adjustment.

I would not "mess with" the rod that inserts into the bottom of the gas pedal and attaches to the firewall linkage. Too much chance of badly altering the gas pedal accuating geometry.
Hope this helps. Jim

[al's28/33]

Someone could have replaced the linkage along the way.

I am having a similar issue with my '33 pickup. It was originally a 4-CYL and someone converted to V8 and thus different carb. The "modified" spoon pedal arm is sloppy on the linkage rod connected to the firewall. I'm trying to measure "full upwards" and "full downwards" positions to weld in the pin hole on the rod and drill out a new hole that will give me full range of motion ....... measure 82 times and cut once.

Or it's possible your linkage from firewall to the carb is too long.

[Terry,OH]

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Your pedal should go nearly to the floor. Appears there is something preventing further movement. If you disconnect the Carb from the linkage how far does the pedal depress? Post a photo of the linkage at the Carb.

[38convsedan]

Using 19Fordy’s measuring distance from pedal to floor (see a post #4).
Pedal all the way up-4 3/8”
Pedal fully depressed-3 1/8”
Travel is 1 1/4”
Something is definitely wrong.

[38 coupe]

If you take the pedal loose from the linkage does the carburetor get full travel or not?
Might help diagnose if the problem is pedal, linkage, or both.

[38convsedan]

Carb has full travel with linkage removed and carb arm moved manually.
Lower gas pedal linkage arm is hitting oil line boss on block when depressed, not allowing for further travel.
Is this correct??
I also notice that the two linkage to firewall studs do not seem to protrude equally as there are more threads showing past the nut on the passenger side compared to driver’s side when viewed from interior….not sure if this is a meaningful variable….

[38 coupe]

I don't remember my gas pedal linkage hitting the engine block, that seems wrong.
It sounds like the rod between the gas pedal and firewall linkage may be too long and the rod between the firewall linkage and the carburetor too short. Or maybe just the carburetor rod too short.

[38convsedan]

Removing upper linkage from carb arm does not increase pedal travel.
It appears issue is centered on lower pedal linkage having restricted travel…

[19Fordy]

Originally Posted by 38convsedan

Carb has full travel with linkage removed and carb arm moved manually.
Lower gas pedal linkage arm is hitting oil line boss on block when depressed, not allowing for further travel.
Is this correct??
I also notice that the two linkage to firewall studs do not seem to protrude equally as there are more threads showing past the nut on the passenger side compared to driver’s side when viewed from interior….not sure if this is a meaningful variable….

8/14/23 On the 8BA in my 1940 car the gas pedal linkage does not hit or touch oil line boss at rear of block or anything else on the block. Also, the (round) heads of the firewall studs that attach the big spring loaded accelerator mechanism to the firewall mount tightly against the exterior of the firewall in the engine compartment.

The two threaded fasteners that hold this big spring loaded assembly in place extend through the firewall and pass through the firewall insulator and are held in place with a deep dished steel washer and nut on each. Check and make sure your spring loaded assembly is bolted tight against the firewall. Also, make sure the spring is not broken. The gas pedal should "spring back" by itself.

As a side note, I used an 8RT truck water pump and the stock motor mounts to position my engine. Could your engine be positioned too far back towards the firewall? What set up are you using? I know some folks used 1951 Merc water pumps with Merc "U" shaped spacers.

Just curious, Is the problem you are having new or has it always been a problem?

[38convsedan]

The passenger side linkage mounting stud is in contact with back of engine block.
Previous owner did 8BA engine swap—perhaps engine is mounted too far back.

In a correctly mounted engine and pedal linkage, what provides stop of downward gas pedal travel? In other words, is the downward travel stopped when pedal linkage contacts something or is downward travel stopped by carburetor linkage at WOT?

The threads of the linkage mounting studs do not protrude evenly through the nuts when fully tightened as mentioned earlier. There are more threads showing through on passenger side while threads are flush with nut on driver’s side.

Spring is working correctly.

[19Fordy]

In answer to: "In a correctly mounted engine and pedal linkage, what provides stop of downward gas pedal travel? In other words, is the downward travel stopped when pedal linkage contacts something or is downward travel stopped by carburetor linkage at WOT?"

My downward travel of the gas pedal is stopped by carburetor linkage at WOT. I have adjusted the turn buckle so that the spring loaded cup at the end of the linkage rod just slides over the little ball for attaching the linkage on the carb when the gas pedal is not depressed. Then, when the gas pedal begins to be depressed, the carb linkage begins to move and the primaries on the carb begin to open and the gas squirts out of the carb discharge nozzles into the engine. Gas pedal springs back to its original "none depressed" up position when foot is removed from pedal.

This gas pedal and the carb worked together in this same manner when I was running the 8BA two barrel carb. At that time, I did not need a turnbuckle. But, when I installed the Holley 390, I had to add the turnbuckle to achieve the same operational relationship between the carb, linkage and gas pedal movement.


Look inside your carb and examine the working mechanical relationship of how your linkage works in coordination with the discharge nozzles inside your carb as gas pedal is depressed.

[38convsedan]

Thanks--so it appears the reduced gas pedal travel is a function of the lower half of the accelerator linkage. Something is not correct resulting in reduced pedal travel as the lower linkage is contacting the engine block at the oil line to canister boss.

It doesn't seem possible to remove the linkage with engine installed. The passenger side linkage stud is in contact engine block--no clearance to pull that stud out of the firewall.

Any suggestions on corrective measures with linkage remaining in place?

[19Fordy]

38convsedan: Is there any way you could post a bunch of photos showing what you are dealing with? Here are a few photos that may be helpful to compare with your situation.

1st photo shows dished washer that is used to secure firewall accelerator assembly in place on inside of car against firewall insulation mat. There are 2 of these. The other is hidden by the heater. I covered my OEM insulator with fiberglass cloth years ago.

2nd photo shows pencil point with blue tape resting on top of the head of the special oblong round top fastener bolt on driver side that goes thru firewall and holds accelerator assembly in place. It has a special hollow rounded head through which the accelerator spring arm shaft passes. It is secured in place with nut and dished washer on inside of car.

3rd photo shows pencil point with blue tape resting on top of the head of the special oblong round top fastener bolt on the passenger side that goes thru the firewall and holds accelerator assembly in place.

There is about 2 1/2 inches between the head of the special oblong round top bolt on the driver side and the top edge of the engine block. It looks like it could be loosened from the inside car and removed.

The same bolt on the pass side is about 1/4 inch away from the top edge of the back edge of the engine block. It might be possible to remove it if you first loosen the nut all the way and then tilt and turn the round head so it clears the block. If that doesn't work, my intake manifold would have to be removed.

Four more thoughts. Is you gas pedal bolted in the correct OEM location on the wooden toeboard? Could the accelerator pedal rod be rubbing on the edge of the hole? Are you using the OEM toeboard or a replacement? Is it the correct thickness? I recall when I replaced mine I had to make one edge beveled (like the original)so it would fit like the original and lay flat.

[38convsedan]

I’ll add photos … but I think I’ve found the problem, and it’s also why my horns don’t fit!

The carb requires an amount of arc or free travel to go from idle to WOT.
This is achieved by a corresponding arc or travel by both the upper and lower linkage arms.

There are a couple of hints that something wonky is going on with my car.
First, the carb arm (which attaches to the upper linkage arm/ball) is supposed to be 10.44”. The carb arm on my car was bent down at about 9 3/8” by previous owner. This resulted in carb never fully achieving WOT with pedal fully depressed.
Second hint was pointed out above, which is clearance between linkage studs and engine block. Passenger side stud on my car is in contact with engine block when there should be about 1/2” of clearance.
The 8BA conversion resulted in engine being placed too far back.
That’s why lower linkage arm hits the block preventing correct amount of free travel AND why the carb arm had to be shortened to fit reduced distance AND why the linkage studs are too close to the block.
Reduced distance equals reduced arc or travel of linkage and carb arm: gas pedal stops too soon and so does carb arm.
And THAT’S why my horns didn’t fit when I tried to install them six months ago! The horns didn’t have required clearance from fan belt because the engine is too far back.
(BTW: this all occurred to me at 3:30 this morning…)

[38 coupe]

It is hard to install an 8BA too far back. The transmission mount in the frame dictates where the transmission and engine go front-to-back in the car. If you have the original type transmission, torque tube, and rear axle in place then the engine is pretty much guaranteed to be correctly place front-to-back.
As already said by others earlier in this thread I suspect the front of your engine is too high. Stock 48-52 truck type water pumps with stock 1938 front motor mount hardware should get the front of the engine where it needs to be. What water pumps and motor mounts are in your car?

[38convsedan]

Not sure about water pumps/motor mounts--previous owner did 8BA install.

Hmmm...so it's too high and not too far back?

Given wonky nature of motor placement...any thoughts on how to achieve correct carb/pedal travel??

[19Fordy]

38consedan: At this point it would really be helpful to post photos of your water pump/motor mount set up along with photos that show your present carb linkage configuration. It would be super great if you could post a video describing and showing what you are dealing with.

As to: how to achieve correct carb/pedal travel? I would "start from scratch" and straighten out the bent carb linkage rod to its correct length and work backwards from the carb to see what length rod you need both at WOT and at idle. Take measurements and install various length carb linkage rods to see how it affects gas pedal travel in relation to WOT. You may have to buy a spare carb linkage rod.

You may find you also have to modify the ball location on the carb itself in order for it to operate better. Below are photos of how I repositioned the ball hookup on my 390 carb to accomodate the carb linkage rod with the turnbuckle.

The first photo shows the stock Holley linkage arm. I handmade the little aluminum piece so it could be screwed to the stock Holley linkage arm with the repositioned linkage ball to accomodate the stock Ford linkage arm. Last photo shows final solution hook up when viewed from the firewall.

This was a "trial and error" process to get the travel correct. I know your carb is a 2 barrel but this is just to give you another idea. Look at your carb and see if you could do a similar modification. I would say you are at the experimental prototype stage of your solution. Like I said, it would be super great if you could post a video both verbally describing and showing what you are dealing with.

Now, get back to work, post photos and get more 3:30 AM ideas.

[Zeke3]

Front of the engine too high makes a lot of sense. The nose of the engine being raised would reduce the clearance between the top of the engine and the dash panel, aka firewall. The engine may have been installed with its nose up to improve the clearance with the steering linkage.

[19Fordy]

Zeke makes a very good point. Photo posting time?
It would be interesting to know what modifications were made by the previous owner?
when 8BA was installed.
That's why it's so helpful to keep a written record of what modifications you make to your vehicle and the parts you used.

[38convsedan]

Got it…will post pics this afternoon when I finish my 9-5.
Thanks for all input and insight! I’m so appreciative!!

[19Fordy]

38convsedan: Were any other changes made to your car that would effect engine placement? Does it have stock transmission, drivetrain and rear end?

Does your car have wide belts or narrow belts on the water pumps?

Please post photos of engine showing belt configuration on pumps, crank pulley, generator, fan pulley etc.

Are your fan belts narrow (3/8 in.) or wide (9/16 or 5/8 in.)?

What year 8BA engine do you have?

Be sure to post photos of your entire carb with linkage hookup.

Below are photos of what the 8RT Ford truck water pumps look like and what the 1949 to 1951 Mercury pumps and spacers look like along with the water pump spacers.
The 8RT pumps use wide belts. It would be helpful to see your entire set up.

[38convsedan]

Was told by previous owner it’s a 1950 truck motor..

[19Fordy]

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The 8RT numbers on the pumps and the fact that they are wide belt pumps indicates they are 1950 Ford truck pumps (like mine).
Your engine appears to not be too far back.

It appears that there is some sort of spacer between the ear of the water pump and the top surface of the motor. Is that so?

What happens when you shorten or lengthen the rod with the home made turnbuckle in it?
Does that effect your gas pedal travel? Try and see.

Could you post a photo of the top of the firewall with the throttle, accelerator and carb rod coming thru the firewall?

Right now, I am running out of ideas.

[tubman]

I think it's time to remind everyone that '35-'40 Ford front mounts are lower relative to the rest of the frame than those for '41-'48. The truck water pumps place an 8BA properly when mounted in the later chassis, but the engine will be too low in a '35-'40 chassis. To get the engine at the proper height in the earlier chassis, spacers are required between the mounts and the pumps.

[38convsedan]

Shortening the rod allows carb to open closer to WOT while losing idle setting.
Lengthening the rod results in correct idle while losing WOT. Given current throttle linkage travel, I can’t achieve correct idle and WOT. As stated in post #1, I’m about 2/3 of WOT.

Not sure about any water pump spacer—I included a side view of water pump mounting on block.

Looks like there are several shims under radiator-not sure if that’s normal…

Could an aftermarket pedal/cable throttle assembly be a solution?

[38 coupe]

I have helped install a couple 8BAs in 36-40 Fords. We did not use spacers under the water pump ears. The truck 8BA water pumps have the ear at the same height as the 37-48 water pumps. Spacing the front of the engine up is what is causing the linkage problem. On a recent 8BA install into a 36 we used an electric fan on the radiator, machined the front sheeve off the crank pulley, and "massaged" the oil pan with a torch and hammer to get clearance to the steering (massaging was done with the pan bolted to a scrap block, not on the good engine).

If you remove the spacers you may create new problems. The oil pan may hit your drag link. The front of the crank pulley may be so close to the cross member you can't change a belt. The later fan will probably hit the radiator (I'm amazed to see it in there now).

[tubman]

I guess it's personal choice; I'd rather raise the engine a bit and adjust the throttle linkage than "massage" the oil pan.

But that's just me.

[38 coupe]

Originally Posted by tubman

I guess it's personal choice; I'd rather raise the engine a bit and adjust the throttle linkage than "massage" the oil pan.
But that's just me.

I respect that. We didn't want to affect the clutch linkage, throttle linkage, exhaust pipes, or any of the other stuff that gets fiddly and causes more trouble. The 36 motor was pulled, we dropped in the 8BA, and reassembled. We had one weekend to get it done 200 miles away from home at a friend's place. We got it done.


My personal preference is an original type engine in the car, then no compromises need to be made.

[38convsedan]

So any thoughts on increasing pedal travel in this situation?

[38 coupe]

Can you lower the front of the engine just enough so that the engine clears the throttle linkage, but doesn't cause a bunch of other problems?
Remove that clamp piece in the spliced throttle linkage, use a die to cut threads (maybe shorten one side first), and use a turn buckle to fine tune the length?
This is the trouble with modifications, they lead to other modifications...

[38convsedan]

Oh, in response to an earlier question—car has 1950 truck 8BA with 1938 transmission-torque tube-rear end.

I’m reluctant to lower front of engine as I’m fearful other issues would arise.
Trying to solve pedal travel with least invasive surgery…

Sounds like after market (ie Lokar pedal/cable throttle) might be best (although not cheapest) solution…

Would love to finally experience WOT with the old girl!!

[al's28/33]

Of the linkage from firewall to carb with the turn-buckle, trim the longer rod maybe 1/8" to 1/4" shorter to give the pedal more room to achieve full WOT.... since yours is cut already..... that may be the simplest solution.

[38convsedan]

Shortening linkage from firewall to carb does not affect the limited travel of lower linkage. There is only 1 1/4” of lower linkage (pedal) travel before lower linkage contacts engine near the oil line boss for oil canister. There should be about 3” of pedal travel as pointed out earlier.
The limited lower linkage travel is not allowing the upper linkage to travel enough to go from idle to WOT. The limited travel means I can adjust carb arm length to have either correct idle or WOT, but not both.

I’m thinking that if I somehow moved (bent) lower linkage arm forward (away from fire wall) AND upper linkage arm backward (toward firewall), I could achieve necessary travel.

The only hiccup there is now the pedal would be moved forward from floorboard, necessitating shortening the linkage rod connected to the pedal to bring pedal back to a manageable height from floorboard. The pivot joint in all likelihood would be exposed in the cabin versus being hidden under floorboard…
OR… go aftermarket pedal/cable linkage which I’m beginning to think might just put this issue to bed.

[glennpm]

Late to this thread so I could be missing something.

Would rotating the firewall mounted ball end up 90° or a full 180° solve the interference? I understand that you can't remove the assembly since the engine is right up tight to it.
You could protect parts with a canvas welding blanket and a wet rag around the throttle spring, heat it up and twist the ball end.



Glenn

[38convsedan]

That might work...rotate the ball end so the 10.44" carb arm will fit.

[19Fordy]

Not sure this will provide any help but here is the carb I used on my 8BA when it was in the 1940 Ford.

As a side note, a friend of mine is having a similar problem with the gas pedal in his 1940 Ford. He wants to install a Holley 390 in his 40 that has an 8BA engine with a blower built by Mark Kirby years ago. To achieve this he has ordered the Lokar accelerator kit as the stock gas pedal and linkage would not work for him.

It's not installed yet so I can't provide any photos.

That might be the best and easiest solution.

PS: Unless my eyes are fooling me the base of your 2 barrel carb looks to be a different design than mine. Could this be causing a "misalignment" of your linkage geometry due to the location and height of the carb linkage hook up on the carb itself?

[glennpm]

Originally Posted by 38convsedan

That might work...rotate the ball end so the 10.44" carb arm will fit.

Yes

[19Fordy]

Just in case you want a piece to practice on.
https://www.ebay.com/itm/15549170019...17256d80f900d0

IDEA: What would happen if you shortened the linkage rod that fits into the bottom of the gas pedal and lengthened the rod that attaches to the carb?
A little experimentation may be in order. Just curious----Is your engine running so you can see how much the present linkage needs to be modified?

[38convsedan]

19Fordy—let me know if your friend uses the Lokar pedal/linkage as that’s one I’m considering….
I think shortening the pedal linkage will just move pedal closer to floorboard without increasing travel.
If I lengthen the carb arm I get closer to WOT but lose idle setting as arm returns… there isn’t enough travel in the linkage to reach idle setting (carb lever retracted to idle setting) AND WOT (carb lever fully extended to WOT).

[19Fordy]

OK. I will email my friend and ask him about his Lokar purchase. Will get back to you.
Jim

[38convsedan]

Thank you Jim!

[cadillac512]

If you need more travel at the carb shaft without changing the pedal travel you must either shorten the lever on the carb or lengthen the lever at the firewall. Bending the lever "up" at the firewall to lengthen it is a good idea, and maybe also bending the ball upward at the carb lever to shorten it.


Terry

[glennpm]

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Originally Posted by glennpm

You could protect parts with a canvas welding blanket and a wet rag around the throttle spring, heat it up and twist the ball end.

This would be a great application for an induction heater.

https://tinyurl.com/scpj4suv

Glenn

[glennpm]

Originally Posted by 38convsedan

19Fordy—let me know if your friend uses the Lokar pedal/linkage as that’s one I’m considering….
I think shortening the pedal linkage will just move pedal closer to floorboard without increasing travel.
If I lengthen the carb arm I get closer to WOT but lose idle setting as arm returns… there isn’t enough travel in the linkage to reach idle setting (carb lever retracted to idle setting) AND WOT (carb lever fully extended to WOT).

--so it appears the reduced gas pedal travel is a function of the lower half of the accelerator linkage. Something is not correct resulting in reduced pedal travel as the lower linkage is contacting the engine block at the oil line to canister boss.

Hi 38,

I think you will be better off resolving the interference as I posted above.
https://tinyurl.com/scpj4suv
You could buy an induction heater for probably half the cost of a pricey Lokar setup plus avoid the work and possible hassle to install it. You would also have a nice tool for your collection :-)

The stock throttle assembly mounted to the firewall is a bell crank assembly made to give adequate pull on the throttle rod to the carb. The throttle rod then connected to another lever on the carb which could be extended as Jim has posted clear details for. Changing throttle rod lengths won't fix your problem as you've noted, only interference resolution.

Glenn

[kurt v]

Are you sure you have the correct throttle assembly for your car ?

[glennpm]

BTW, I had to rotate the ball end of the linkage for my 1932 roadster. With two 97s, I had interference with the linkage between the 2 carbs so I cut the outside firewall part of the linkage and welded it such that the ball was 180° rotated.

Stock linkage



Ball end Rotated 180°

[Terry,OH]

There is no need to heat the firewall linkage to bend slightly unless your looking for the very end ball to go vertical. If you slide a long small diameter box wrench over the vertical shaft you can bend it slightly.

[19Fordy]

Originally Posted by 38convsedan

Thank you Jim!

8/19/23: 10 AM I just sent you a PM with the LOKAR info. Go to Lokar.com and look around.
Pedal: XFMG-6098
Cable: TC-1000U36
Bracket: SRK-4000

My friend's 40 is using a Holley 390 and a blower, so the LoKar components he uses might be different from yours. For instance, the cable length. Suggest you first call Lokar and verify what components you need for your situation.

[38convsedan]

Problem solved. I’m fortunate to have an Early Ford V8 expert, Tom Roche, nearby. He stopped by and did several things to achieve full gas pedal travel and idle-to-WOT at the carb.
He massaged (by bending up) bottom of firewall where lower throttle arm passes through. Next, he bent the lower arm over and down so it now misses the block when fully depressed. Finally, we grabbed the lower arm about half way down with vise grips while holding the upper half of lower arm with a bar, and bending the lower half of lower arm down to provide clearance from hitting floor board. All is good now.
I’m so grateful to Tom and the many others who took time to share their expertise and suggestions! This truly is an amazing community!!

[glennpm]

Great, glad you have it sorted out!

So all this was done on the inside of the car?

[19Fordy]

Wow! 38, that's great! So, are we correcting saying that someone had earlier bent that accelerator arm mechanism and floor?

Really glad you had your buddy Tom who could solve the problem. Be sure to take Tom out to a nice lunch or dinner. We need more problem solvers like Tom.

[Angledrive]

The real issue is the engine is raised up in the front a little more than it should be because of oil pan clearance with the tie rods. That is causing the the problem at the firewall. We just tweeked the pedal linkage here and there and made it work. I'll help him with the steering linkage problem later. It is hitting the oil pan at times.

[glennpm]

Good, thanks for the clarification.

Glenn