FJ40 1976 Sluggish/Strained Starts Hot Engine 2F…Exploring Heat Shields, Carb Cooling Fan. (1 Viewer)

Ackcruisers

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I have a 1976 South American FJ40 with 2F Engine running a Chinese made H3662 aftermarket 21100-61012 carb. No smog. I’m exploring my options to eliminate the sluggish/strained starting when hot in preparation for summer driving. My SA FJ40 was built in 4/76 and has original rebuilt engine. I’m considering adding the following:
  • Carb cooling fan 16362-61020 Fan No. 2 (California Spec) click here
  • Carb heat shield 21912-61012 (shield for mechanical linkage) click here
  • Exhaust Manifold Insulator Heat Shield NO. 1 17167-61010 click here
  • Exhaust Manifold Insulator Heat Shield NO. 2 17168-61010 click here
  • Exhaust Manifold Insulator NO. 3 17169-61011 (still available from Toyota click here )
I‘ve not fully researched this yet but wondering:

A) why these SA trucks had no exhaust shields or cooling fans?

B) will just the shields be enough to help with hot starts?

Below are the shields I need and shots of my carb set up.

3B065F1F-4AEB-40C5-93C2-A3A57D943532.jpeg

005225E9-EF73-44D3-9CD9-DE4AF8402E56.jpeg
 

GA Architect

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Here was my solution for a carb cooling fan installion into a rig that didn't come with one. -> click here <-

I've since installed the Holley Sniper EFI and removed the carb cooling fan I installed.
 
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B) will just the shields be enough to help with hot starts?

In my opinion (and 30 years of farting around with hot starts), they will do nothing to stop hot soak or vapor lock. The rear-most manifold shield is to stop heat from getting to the firewall. The front manifold shield is the heat stove for winter starting. The shields between the the ex and intake are part of the heater riser system for cold starting.

I took apart my manifolds and had 1" of metal milled off the bottom of the intake manifold, and made a 5/16" steel plate to seal off the exhaust manifold. This large air gap between the manifolds prevents some of the exhaust heat from cooking your intake. I also switched to TBI fuel injection, which was the real cure to endless hot starting issues.

The OEM design of having the exhaust manifold directly below the carb. will always create heat problems on summer days. A carb fan (I still have and use mine) is a good idea. Our crap gasoline (with Ethanol or not) is designed to control emissions, not to allow 50 year old trucks to run well. I added EFI (AFI TBI) to my truck so that I could drive it on hot days without a near-death experience every time I pulled out of a gas station or after parking the truck for a few minutes on a hot day.

Steve
 

Ackcruisers

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Here was my solution for a carb cooling fan installion into a rig that didn't come with one. -> click here <-

I've since installed the Holley Sniper EFI and removed the carb cooling fan I installed.
Thank you. Did you sell your carb cooling fan setup? I’m going to defer the EFI set up until after I try the cooling fan route.
 

Ackcruisers

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If you’re financially set to add the EFI set up, that’s probably the best remedy no doubt...... BUT I will say that once I got my cooling fan running, it did help with the hot starts!

Good Luck :cheers:
Thanks. Appreciate it. I’ll go with cooling fan for this season. Now I need to source brackets etc...
 

Ackcruisers

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If anyone has pictures of the Insulator Exhaust Manifold Heat, NO.2 and NO.1 as shown in schematic, I would be very appreciative. I’m not clear on which ones will fit my set-up.
0E1684F1-CFCB-4B34-957A-45FB42DF039D.jpeg
 
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Unobtanium parts. Several guys here fabbed/hacked replacements. I recently discovered this because I was looking for the forward insulator and learned they’re unobtainable.
 

Ackcruisers

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Unobtanium parts. Several guys here fabbed/hacked replacements. I recently discovered this because I was looking for the forward insulator and learned they’re unobtainable.
Thanks for letting me know. I think the one most useful for me is the rear manifold. I will have to get resourceful creative.
  • Exhaust Manifold Insulator Heat Shield NO. 2 17168-61010 click here
 

Ackcruisers

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Can someone verify this 17168-61010 will fit my 1976 FJ40?
I'm not exactly sure where it will go.
The product number matches what I need but the shield appears to be different than in schematic.

1617970339317.png
 

Dizzy

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I'd consider the fuel return line, as well. Because your air horn doesn't accommodate it, then consider a stock air horn. If you can't fit a stock air horn on the aftermarket carb, then it might be possible to fabricate one in the fuel inlet line (I also know where you might source one from a scrap yard). An electric fuel pump might deal with an empty bowl better than the stock pump.

The factory manual says that a slightly open throttle plate will lean-out your hot start, and fire up the engine faster. You have tried that right? I'm personally going to install a hand-throttle, soon, which I feel would work for winter conditions, was standard for factory PTO, and might dial-in a hot start with minimal accelerator pump plunger.

Because City Racer (and Fuji-Japan clone carbs) is closed for a bit, I might just buy your same carb, try on a spare factory air horn, fiddle with rebuild compatibility etc.
 

Dizzy

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The stock set-up is too hot, in my opinion, blowing exhaust directly on the intake manifold. Maybe this cools it down?

"In/Ex Manifold Heat Riser Block-Off Plates" (a bit after 1/8th of the way down the page)

 
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Does your engine have problems idling when hot? I had a similar problem, rough idle and hard start once I had been driving for a while, specially pushing the engine a bit. Water temp was fine. Mine had low vacuum, but no vacuum leaks. How's you vacuum? Ended up being the valves needed adjusting in my case. Solve my hard starting when hot issue and improved the power by quite a bit.
 

MadMace

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Might be a little too simple but I had trouble with hot starts and have significantly reduced them doing a couple of things. First, try ethanol free gas, if you have access to it. Second and more importantly, when doing a hot start depress the gas pedal all the way to the floor and hold it there while starting the truck. As soon as it starts, release the gas pedal. A fuel return line will also help.
 

Ackcruisers

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I'd consider the fuel return line, as well. Because your air horn doesn't accommodate it, then consider a stock air horn. If you can't fit a stock air horn on the aftermarket carb, then it might be possible to fabricate one in the fuel inlet line (I also know where you might source one from a scrap yard). An electric fuel pump might deal with an empty bowl better than the stock pump.

The factory manual says that a slightly open throttle plate will lean-out your hot start, and fire up the engine faster. You have tried that right? I'm personally going to install a hand-throttle, soon, which I feel would work for winter conditions, was standard for factory PTO, and might dial-in a hot start with minimal accelerator pump plunger.

Because City Racer (and Fuji-Japan clone carbs) is closed for a bit, I might just buy your same carb, try on a spare factory air horn, fiddle with rebuild compatibility etc.
I have not tried the lean-out method for hot start. I will try it. Overall, the truck starts fine but struggles just a bit when hot. Just trying to optimize the system and wanted to investigate heat shields and carb cooling fan. Thanks for the suggestions.
 

Ackcruisers

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Does your engine have problems idling when hot? I had a similar problem, rough idle and hard start once I had been driving for a while, specially pushing the engine a bit. Water temp was fine. Mine had low vacuum, but no vacuum leaks. How's you vacuum? Ended up being the valves needed adjusting in my case. Solve my hard starting when hot issue and improved the power by quite a bit.
Here is a video of my engine after adjusting valves, lean drop carb adjustment and timing click here. Overall the engine runs very well with good power.
 

hobbes

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It’s been mentioned a couple times above, what do you have for a fuel return setup?
 

Dizzy

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It’s been mentioned a couple times above, what do you have for a fuel return setup?
Those carbs don't easily accommodate it. I don't know that a 2F needs it, but, I don't know why USA 2Fs came with it, either. Even if gas gets hot, the fuel pump and bowl float should keep up with the vapor lock (the bowls are vented internally into the air horn).
 

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