$$ to spend on 2F (1 Viewer)

[Rochfort]

My tricked-out 2F, in a theoretical world where all of this could be made available:
1. Aftermarket / custom aluminum connecting rods - for increased redline
2. A combo of tight bearing clearances, for the camshaft, crankshaft, and low-tension piston rings (because viscous tractor oil is more volatile, increases parasitic loss, and its specific-heat is not ideal for engine cooling)
3. Gapless piston rings - this is where two rings sit in the same land, overlapping each other, reducing blow-by and increasing compression
4. Factory exhaust manifold - the 2F needs not the direct heat riser, but, some indirect heat thru a dividing shield, but, the whole fuel-atomization topic is mainly a condition of temperature, the plenum was designed for a naturally-aspirated application (carb) and it was more than capable when the system was in a factory configuration. I tend to think that headers make the number one cylinder run lean when winter circulates thru the engine bay, and the original carb set-up had a wax thermo valve that could direct hot air off of the exhaust manifold, so it could work better regardless of temperature. Both of my '75, and '82 air cleaner assemblies have non-functioning wax thermo valves, so with headers, and likely damaged / missing parts, I'll probably never know what the original start-up was like, but, the cold-driving is the only time it feels like a farm impliment.
5. A vacuum-operated choke breaker on the non-USA carb - making it novice-proof for start-up, as long as you remember to use the choke.

Most of the slowness is related to shifting the 2F with the H42 and 4.11s. If feels slow because I'm driving next to cars with

^^^^This^^^^

The bottom end can only spin as fast as the top end can feed it. It needs to breathe.

automatics. 4Runners, FJ Cruisers, Tacomas. The rest of the time, the suspension, steering, and reasonable braking distance (no abs) is keeping the throttle from opening.

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^^^^This^^^^

The bottom end can only spin as fast as the top end can feed it. It needs to breathe.

Yeah exactly.
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[Grayscale]

I'm borrowing knowledge here. But, a '75 USA carb is the ultimate Aisan carb. Why, because the accelerator pump is not enough to keep the driver from leaning-out the engine in some situations. Yes, the '75 'smogerator' is the choice carb in this situation.

On a factory '75 USA carb there is an Auxiliary Accelerator Pump, and a Power Valve controlled by the emissions switching valve. So, in theory, the carb could enrich itself two ways. The power valve will enrich the main circuit, Venturis, providing more emulsified fuel via vacuum-actuated demand. The auxiliary accelerator pump adds to the non-emulsified charge, the accelerator's squirt in the primary barrel. Traditionally, the two barbs on the carb would be routed to manifold vacuum, and I'm silently crediting all the innovators on Mud who shared this with me. However, I'd follow a Nissan-vacuum-spaghetti trick that I learned, insert an orifice in the vac line - like a Weber carb main jet, so you can fine-tune just how much throttle pedal stomp it takes to enrich your souped-up, cammed-up, bored-out 2F. Start small and drill the jet to fine-tuen it for how much manifold vacumm loss you get from stomping on the gas. I'd cut-out the auxililary accelerator pump enrichment during cold water temps with a thermostatic vac switch probed into the thermostat housing. This engine does poor with liquid fuel when it is cold, and it isn't like the '76 or later carbs had this feature, avoid the carbon deposit and oil contamination with liquid fuel if you can. However, it would be ideal when the engine is at regular running temps.

 

[Rochfort]

I built my 2F about as much as I can. Bored, balanced, top-shelf domed pistons and rings, RV cam, wide-runner intake, headers, Late F head, Chevy valves, port matched and polished. It's still not fast but it does go slow better.

Gg

I'm borrowing knowledge here. But, a '75 USA carb is the ultimate Aisan carb. Why, because the accelerator pump is not enough to keep the driver from leaning-out the engine in some situations. Yes, the '75 'smogerator' is the choice carb in this situation.

View attachment 3852881

On a factory '75 USA carb there is an Auxiliary Accelerator Pump, and a Power Valve controlled by the emissions switching valve. So, in theory, the carb could enrich itself two ways. The power valve will enrich the main circuit, Venturis, providing more emulsified fuel via vacuum-actuated demand. The auxiliary accelerator pump adds to the non-emulsified charge, the accelerator's squirt in the primary barrel. Traditionally, the two barbs on the carb would be routed to manifold vacuum, and I'm silently crediting all the innovators on Mud who shared this with me. However, I'd follow a Nissan-vacuum-spaghetti trick that I learned, insert an orifice in the vac line - like a Weber carb main jet, so you can fine-tune just how much throttle pedal stomp it takes to enrich your souped-up, cammed-up, bored-out 2F. Start small and drill the jet to fine-tuen it for how much manifold vacumm loss you get from stomping on the gas. I'd cut-out the auxililary accelerator pump enrichment during cold water temps with a thermostatic vac switch probed into the thermostat housing. This engine does poor with liquid fuel when it is cold, and it isn't like the '76 or later carbs had this feature, avoid the carbon deposit and oil contamination with liquid fuel if you can. However, it would be ideal when the engine is at regular running temps.

.

 

[Rochfort]

I'm borrowing knowledge here. But, a '75 USA carb is the ultimate Aisan carb. Why, because the accelerator pump is not enough to keep the driver from leaning-out the engine in some situations. Yes, the '75 'smogerator' is the choice carb in this situation.

View attachment 3852881

On a factory '75 USA carb there is an Auxiliary Accelerator Pump, and a Power Valve controlled by the emissions switching valve. So, in theory, the carb could enrich itself two ways. The power valve will enrich the main circuit, Venturis, providing more emulsified fuel via vacuum-actuated demand. The auxiliary accelerator pump adds to the non-emulsified charge, the accelerator's squirt in the primary barrel. Traditionally, the two barbs on the carb would be routed to manifold vacuum, and I'm silently crediting all the innovators on Mud who shared this with me. However, I'd follow a Nissan-vacuum-spaghetti trick that I learned, insert an orifice in the vac line - like a Weber carb main jet, so you can fine-tune just how much throttle pedal stomp it takes to enrich your souped-up, cammed-up, bored-out 2F. Start small and drill the jet to fine-tuen it for how much manifold vacumm loss you get from stomping on the gas. I'd cut-out the auxililary accelerator pump enrichment during cold water temps with a thermostatic vac switch probed into the thermostat housing. This engine does poor with liquid fuel when it is cold, and it isn't like the '76 or later carbs had this feature, avoid the carbon deposit and oil contamination with liquid fuel if you can. However, it would be ideal when the engine is at regular running temps.

My carb's boggy at low RPMs. Here's a pic from Mud, where's the aux pump?

I'm borrowing knowledge here. But, a '75 USA carb is the ultimate Aisan carb. Why, because the accelerator pump is not enough to keep the driver from leaning-out the engine in some situations. Yes, the '75 'smogerator' is the choice carb in this situation.

View attachment 3852881

On a factory '75 USA carb there is an Auxiliary Accelerator Pump, and a Power Valve controlled by the emissions switching valve. So, in theory, the carb could enrich itself two ways. The power valve will enrich the main circuit, Venturis, providing more emulsified fuel via vacuum-actuated demand. The auxiliary accelerator pump adds to the non-emulsified charge, the accelerator's squirt in the primary barrel. Traditionally, the two barbs on the carb would be routed to manifold vacuum, and I'm silently crediting all the innovators on Mud who shared this with me. However, I'd follow a Nissan-vacuum-spaghetti trick that I learned, insert an orifice in the vac line - like a Weber carb main jet, so you can fine-tune just how much throttle pedal stomp it takes to enrich your souped-up, cammed-up, bored-out 2F. Start small and drill the jet to fine-tuen it for how much manifold vacumm loss you get from stomping on the gas. I'd cut-out the auxililary accelerator pump enrichment during cold water temps with a thermostatic vac switch probed into the thermostat housing. This engine does poor with liquid fuel when it is cold, and it isn't like the '76 or later carbs had this feature, avoid the carbon deposit and oil contamination with liquid fuel if you can. However, it would be ideal when the engine is at regular running temps.

Tell me about it, mine's boggy at low rpm's. An aux accellerator pump carb is the fix?

 

[Grayscale]

Auxiliary Accelerator Pump

 

[Rochfort]

Auxiliary Accelerator Pump

View attachment 3852963

Damn i want one ...

 

[Grayscale]

I think it was Weber idle jets, not main jets, that will attenuate a vacuum signal when inserted into a usual vac line.

The Auxiliary Accelerator Pump feature is cast on 2F carb bowls, but only a few have holes drilled, and a diaphragm housing on it.

A '76 USA carb, and others, only have the externally-controlled power valve, which isn't bad, perhaps an attractive option - like for doing a sustained sprint to merge into traffic. ascend a hill...

The USA Aisan carb had a bit more richness to the fuel mix, with jets bigger than my current late, generic market spec Aisan. They probably had smog carbs run rich because that allowed the retarded timing and smog pump to make a cleaner exhaust, removing CO with an afterburner. I wonder about using smaller jets in the USA-spec 2F Aisan carbs? Like using a china carb for a parts donor?