Successful engine swaps need working gas pedals | ...

Step 1:

We had two throttle cables to select from. The Miata cable is a bit beefier, a bit longer, and a bit extra sophisticated on the engine facet than the MGB piece. For the reason that pedal facet of the Miata cable is much like the MGB’s, we determined it might be simpler to adapt the Miata cable to the MGB slightly than the opposite means round.

Step 2:

We began the method by measuring the quantity of journey wanted on the pedal finish of the cable. We hooked the Miata cable to the throttle physique and marked the situation of its base. Then we made two extra marks: one on the throttle-closed place and one at wide-open throttle.

Step 3:

We then put in the MGB cable on the MGB. It feeds by way of the firewall and right into a slot on the pedal. It has a cease swedged on its finish, and a break up pin retains it from shifting out of the pedal’s slot.

Steps 4 & 5:

With the MGB cable we didn’t have to know the bottom location, however we did have to know the size between the throttle-closed and wide-open-throttle positions. We in contrast our markings from the Miata cable and had been happy to see that the size was the identical. If the lengths had been completely different, we’d’ve needed to do some geometry to alter the throttle pedal and get the appropriate size. Generally we get fortunate.

Step 6:

After finishing our first spherical of measurements, we had been able to adapt our throttle cable. We inspected the MGB’s cable mount on the firewall and figured we may make a similar-looking adapter for the Miata’s cable.

Step 7:

We traced the bottom of the MGB adapter onto a bit of 1/8×1-inch cold-rolled delicate metal strap.

Step 8:

We then used some switch punches to mark the facilities of the three holes that we would have liked to drill within the base.

Step 9:

We drilled the holes first, leaving the remainder of the reducing for later.

Step 10:

Earlier than beginning the subsequent a part of the adapter, we took some measurements from our cable. The Miata cable has two plastic catches that snap into place on their ledges.

Step 11:

We realized we may duplicate that characteristic utilizing a bit of 1-inch spherical tube with some “ledges” welded in. We first lower some notches for the ledges with our trusty hacksaw.

Steps 12-14:

After reducing the notches, we may weld some slender strips of metal in place to kind the ledges. We then sanded the welds clean on a mix sander with 80-grit paper.

Steps 15 & 16

Subsequent, it was time for some extra measuring and math to find out how a lot we should always lower down the tube for our adapter. We wanted the cable finish to be 1.25 inches under the firewall ledge to slot in the pedal, as the bottom was 2 inches from the swedged finish. Our base was 0.125 inch, so our tube wanted to be 2 inches minus 1.25 inches minus 0.125 inch. That equals 0.625 inch, or 5/8 inch.

Step 17:

We lower our tube with our hacksaw and welded it to our base.

Step 18:

Earlier than reducing our base all the way down to dimension, we completed one facet on our sander.

Step 19:

We then rough-cut the opposite facet of the bottom with a hacksaw and went again to finish-sand the entire thing to form.

Step 20:

As soon as sanded and completed, our adapter may mount on the MGB similar to the unique one did. It may additionally settle for the snap-in catches of the Miata throttle cable.

Step 21:

We needed to account for one minor element: The swedged finish of the Miata cable is bigger than the outlet within the MGB firewall ledge. A stepped drill bit took care of that situation.

Steps 22 & 23:

With the adapter and the throttle cable put in, we may make our changes. The MGB has an adjustable cease for the throttle to offer simply sufficient free play on the closed place. We want about 3/16 inch of leeway, which permits the engine to idle down however doesn’t make the pedal really feel floppy. Subsequent, we adjusted for wide-open throttle with a threaded sleeve on the throttle-body finish of the cable. 

These two changes are important for a secure, efficient and comfy pedal setup. They’re typically neglected, however we’re all the time very compulsive about making them.

These two changes are important for a secure, efficient and comfy pedal setup. They’re typically neglected, however we’re all the time very compulsive about making them.

Steps 24 & 25:

The Miata cable is sort of lengthy, and we discovered that it was flopping round within the engine bay greater than we appreciated. The cable has grommets that permit helps to maintain it in place, so we shortly fabricated a assist from half-inch-wide, 20-gauge metal. We wrapped the metal round a bar after which used a vise to fold the opposite finish 90 levels. Subsequent, we drilled a mounting gap and hooked up our new assist to the firewall.

Step 26:

It doesn’t seem like something particular, however we all know our throttle cable will serve our swap properly for years to come back.