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Crashtd420

A 521 in Massachusetts

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One of my tests that every vehicle I build has to pass is what I call the "valet test". If you can hand your keys to any valet without having to warn them of anything, it passes.

 

Dumping the clutch to stall the motor does not pass the valet test.

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Well I don't like it when it diesels so I'll spend the time making sure it doesnt....

So far I have been successful..

 

Speaking about tuning I just installed F7 emulsion tube, with 130 mains and 180 air correctors ( 175s got stuck in other tube) and what difference that made to the transition circuit....  even from I lower rpm I can dump the throttle now and It just goes with no hesitation.. no more easing into it needed...

 

Its amazing the difference from baseline running to being tuned properly.... after I drive it a bit I'll probably make a couple slight adjustments with the new tubes, plus I still need to see how it does on the highway, but around town was a blast and air fuel numbers looked good..... 

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Also after all the discussion about the ac idle I figured out a couple things.....

 

First no body seems to make a solenoid that can actually increase the idle without a touch of the throttle, unless as thisismatt and stroffgren were talking I could lessen the spring tension, but I'm not going through all that....

 

2nd was the solenoid cycling with the compressor...

 

Last, Locations I got options... 

 

So end decisions is buy a better quality solenoid, to give me the best chance for success and I'm ok with having to tap the throttle once when I turn the ac on to set the idle....

 

Screenshot-20190911-172351-Chrome.jpg

 

I think I can get it cheaper, that listing includes brackets I dont need....

 

I figured out If I wire it to the dash unit fans the solenoid will be activated when ever I turn the ac on, so no cycling with the compressor...  the wires are accessible behind the unit.. 

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My solution does *not* require you to modify the spring tension for the pedal return.  That's the point.  You make a disconnect between the butterfly valve and the throttle linkage, allowing the solenoid to only act on the butterfly valve without affecting the pedal linkage.

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9 hours ago, thisismatt said:

My solution does *not* require you to modify the spring tension for the pedal return.  That's the point.  You make a disconnect between the butterfly valve and the throttle linkage, allowing the solenoid to only act on the butterfly valve without affecting the pedal linkage.

However you word it your still trying to eliminate the effects of the springs on the solenoid,  I'm still not going to do it... 

Edited by Crashtd420
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2 minutes ago, thisismatt said:

🤦‍♂️

It will be ok..... 

 

Regardless I had to order a solenoid to see how things react to my setup before I even think about trying to do a mod like your talking... I'd rather keep this as simple as possible....

 

So the one I decided on goes for around $50 or $60 without the bracket, and i  managed to find a new one on ebay discounted to $25, so I bought that.... 

 

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Have you de carboned your 521 engine lately?

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5 hours ago, Charlie69 said:

Have you de carboned your 521 engine lately?

Never really thought about that?

Why do you ask?

 

It only has 4300 miles since rebuild....

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Carbon builds up from running rich and can causes dieseling.

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7 minutes ago, Charlie69 said:

Carbon builds up from running rich and can causes dieseling.

Ah I see.... I dont really run rich from what my air/fuel gauge tells me, plugs are always clean and the right color....

If I have the idle set properly it doesnt diesel...

 

Shouldn't it keep its self clean like the spark plugs if tuned properly?

Or will it happen regardless being carburated?

 

I suppose it cant hurt to decarbon the engine either way..

are you talking about misting water from  a spray bottle down the carburator while running?

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 I doubt it's carbon as all L20Bs and up diesel on shut off if without an idle cut solenoid. It's a combination of 120 timing, 8.5 and up compression, engine temperatures in the high 180s and idle fuel from a crburetor engine. Nissan couldn't/didn't solve this and added an idle cut solenoid. Only EFI got rid of it.

 

"Clutch dumping" is unfair and misleading. It's loading the engine against the brakes by gently slipping the clutch and turning the ignition off. It's easy to learn in 4-5 tries, (probably less) becomes a natural part of the turning off process, just like pulling the e brake on.... and doesn't cost a cent. 

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weber makes a DGV_IC version of their 32/36 and has a bigger idle jet holder for the electric selinoid.

 

Sometimes pushing the gas down as it shuts off will kill the dieseling as it looses vacuum cause the main butterfly open using the main jet thus bypassing the idle jet..

 

I run water thru them sometimes to help dicarbon the motor on hot days.Gentry dripple gas in there.

 

I bet water injection during shut off might work.. I always thought of hooking up a water line to the vacuum port to suck water in thru that to do a drive to help dicarbon up the motor

Edited by banzai510(hainz)
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RE clutch dumping - And it should be done anyway, but it still doesn't pass my test.

 

Remember, some guys here are searching to remove the idiosyncrasies of ancient technology.

Edited by Stoffregen Motorsports
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The only time I dump the clutch Is to do a burn out..... 

 

Clutch dumping, water injection or any other trick to stop dieseling is not a fix... its just poor tuning....

 

I could be wrong, but I feel the reason Nissan couldnt stop it is due to the fact that these vehicles get sold everywhere.... how do you produce one setup to work under all conditions, height about sea level, temperature, etc.... what works for me here might not work in so cal or up in Oregon..

 

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I never seen or heard of this.

Most sidedrafts wont have this run on issie as there isn't enough vaccum to draw thru unlike a single carb with all 4 clyinders going thru the idle port so there would be more vaccuum

 

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8 hours ago, banzai510(hainz) said:

I never seen or heard of this.

Most sidedrafts wont have this run on issie as there isn't enough vaccum to draw thru unlike a single carb with all 4 clyinders going thru the idle port so there would be more vaccuum

 

 

SU’s will diesel. Common problem on roadsters if the tuning is wrong.

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I have had my dual SUs tuned to where the plugs were tan and it still dieseled like crazy.

They just diesel because that is what they do, as already mentioned in this thread even Nissan could not stop dieseling so they put in cutoff valves to stop it.

Personally I just don't see why anyone has to put their manual transmission vehicle in neutral to shut it off, it seems like a waste of time to me, if it was an automatic I would understand, but were not talking about an automatic here.

I don't have any vehicle on my property in neutral, when I shut it off it is in gear, this was never an issue 30/40 years ago, people just put their foot on the brake, turned the key off and let out the clutch at the same time, the vehicle doesn't even jump when you do it everyday, I guess it is becoming a lost art, like paying attention to ones driving when one drives. 

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Dieseling is just like the name implies. The heat of compression added is just enough to push the idle air mix above the auto ignition temperature. So remove any of the four... air, fuel, compression (motion) or heat and it stops.

 

Air.... a solenoid to hold the idle speed screw against. Engine off the throttle plate(s) close... no air.

Fuel... a fuel cut solenoid. Ignition off no fuel. Maybe tuning the idle mix on the lean side. Doesn't have to be 14.7 it will run well above this. Mine says 17-19 sometimes. Keep idle as low as possible.

Heat... A 'cold air intake' rather than warm air from behind the rad. Heat shields for the intake and carburetor(s). Insulate the fuel line or connect a return line to supply cooler fuel. Run colder range of spark plug if possible. Avoid carbon build up from poking around town or short trips with choke on. Carbon from using the choke is unavoidable so shut the choke off as soon as you get moving and can do so. Take out for a hard drive every now and then to clean it out.

 

Compression (motion)..... Use clutch to load and stall the engine. If you just can't reduce/ eliminate by the above steps Christ learn to stall with the clutch. With foot on brake you put a slight load on the engine with the clutch and turn the engine off, wait till fully stopped and let the clutch up the rest of the way. This is NOT clutch 'dumping'. This is so easy and natural no one will even know you are doing it. If an automatic, shut off in drive (it stalls instantly) then put in park. Easy as pissing in the shower. This is how it was done in the day. 

 

 

 

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Well Solenoid showed up and as expected not strong enough to open the throttle on it's own but once its extended it stays out ..... 

It has more than enough strength at that point, once active I was able to push on the throttle to wot without the solenoid returning.... 

 

So yes I will have blip the throttle once when activating the ac, but the idle will stay up till I shut it off so I dont thing that will be do bad to deal with.....

 

Next step deciding which place to mount it....

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I wonder if it could burn out if you forget to blip the throttle. I know I have seen line lock solenoids burn out.

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6 minutes ago, Stoffregen Motorsports said:

I wonder if it could burn out if you forget to blip the throttle. I know I have seen line lock solenoids burn out.

I haven't tested it that way yet.... eventually you have to touch the throttle, I am assuming it would kick out once you do.. ..... 

I'll try it later.... 

I'll energize it closed, then see if it extends when I move the throttle... it should extend and stay extended ... 

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