79 DL idle problem

[HawaiiBrat]

1979 Subaru DL - EA71 - Stock Hitachi

It does not idle on it's own until it's been warmed up. I can start the car easily but I have to rev it lightly for quite some time until it's able to idle on it's own. When it's finally warmed up I can drive somewhat fine but while coasting at low speeds there is some sort of surge/hesitation. This happens when I let my foot off the gas but only at very low speeds and never happens if my foot is constantly on the gas. Has anyone experienced this or perhaps know what I should look at? Everyone I have spoken to so far has mentioned the carburetor which I have rebuilt already. Perhaps I didn't do a great job at doing so? I appreciate any help provided to me. Thank you

[travelvw]

Rebuilding an old carburetor rarely works out unless you are meticulous and know what you are doing.

Sounds like the carburetor. Choke not adjusted properly (cold idle), clogged jets or any of the many, tiny passages in a carburetor, improper tuning, etc.

If its legal there, I'd put a new Weber conversion on the car.

K

[Subasaurus]

it's the choke as previously mentioned, your choke isn't opening up all the way, and when the engine is "cold", it needs your foot constantly on it to open the choke alittle bit till it warms up (choke finally opens enough) and when it's completely warmed up you mentioned it's sluggish at low speeds, either it's too far opened (maybe the auto choke is worn or not reading engine temp correctly) when warmed up or not opened enough when fully warmed up.

i've never had luck with auto chokes, i've tried 3 times on 3 different cars, so everytime i see one i immediately pull it and replace with a manual mechanical cable choke.

chokes are super sensitive when cold and after it just ran across the city and then sits for 30min (partial warm up), those are the hardest for a vehicle to start, even modern cars with worn sensors.

 

also if it still has the original hitachi carb on there, i would say it sounds like it's working better than intended.

Edited August 25, 2020 by Subasaurus

[HawaiiBrat]

9 hours ago, Subasaurus said:

it's the choke as previously mentioned, your choke isn't opening up all the way, and when the engine is "cold", it needs your foot constantly on it to open the choke alittle bit till it warms up (choke finally opens enough) and when it's completely warmed up you mentioned it's sluggish at low speeds, either it's too far opened (maybe the auto choke is worn or not reading engine temp correctly) when warmed up or not opened enough when fully warmed up.

i've never had luck with auto chokes, i've tried 3 times on 3 different cars, so everytime i see one i immediately pull it and replace with a manual mechanical cable choke.

chokes are super sensitive when cold and after it just ran across the city and then sits for 30min (partial warm up), those are the hardest for a vehicle to start, even modern cars with worn sensors.

 

also if it still has the original hitachi carb on there, i would say it sounds like it's working better than intended.

Adjusted the choke and she seems way better now! Appreciate you both!

Edited August 26, 2020 by HawaiiBrat

[HawaiiBrat]

On 8/24/2020 at 10:12 AM, travelvw said:

Rebuilding an old carburetor rarely works out unless you are meticulous and know what you are doing.

Sounds like the carburetor. Choke not adjusted properly (cold idle), clogged jets or any of the many, tiny passages in a carburetor, improper tuning, etc.

If its legal there, I'd put a new Weber conversion on the car.

K

Adjusted the choke and she's running way better now! Appreciate it! Would you still go with the weber conversion anyway? It's legal here.

[Subasaurus]

15 hours ago, HawaiiBrat said:

Adjusted the choke and she's running way better now! Appreciate it! Would you still go with the weber conversion anyway? It's legal here.

i did, engine roars now, it's so weird how different the sound it makes now that it's not being restricted by the Hitachi, MPG is 21-23 if that matters to you at all.

 

>i should note, i got a ripoff branded one, here's the link on ebay for it, i couldn't spend $400 for the Webber branded one at the time since i wasn't working.

there's a version with an auto choke on this ripoff branded one too if you decide to go the cheap route.

https://www.ebay.com/itm/SUBARU-76-89-EA-71-81-32-36-DGV-CARBURETOR-CONVERSION-MANUAL-CHOKE-K730-M-ECON/361450089325?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

it was $200 back in 2017, i see it's gone up in price lol.

Edited August 26, 2020 by Subasaurus

[HawaiiBrat]

1 hour ago, Subasaurus said:

i did, engine roars now, it's so weird how different the sound it makes now that it's not being restricted by the Hitachi, MPG is 21-23 if that matters to you at all.

 

>i should note, i got a ripoff branded one, here's the link on ebay for it, i couldn't spend $400 for the Webber branded one at the time since i wasn't working.

there's a version with an auto choke on this ripoff branded one too if you decide to go the cheap route.

https://www.ebay.com/itm/SUBARU-76-89-EA-71-81-32-36-DGV-CARBURETOR-CONVERSION-MANUAL-CHOKE-K730-M-ECON/361450089325?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

it was $200 back in 2017, i see it's gone up in price lol.

I got one with a bunch of parts a while back. I just don’t know if it’s all I need though. Looks to be barely used. There’s a weber, adapter plate and the air filter. Do I need to go and purchase something else? Unfortunately looking it up online the model that I have is an auto choke redline weber. 

[travelvw]

If the original runs great, leave it be (unlikely).

Most folks like the convenience of the auto (electric) choke, but it's finicky to set perfectly and generally ends up on the rich side to run well under most circumstances. I too personally like the manual choke since you only use what you need, which shouldn't be much unless its really cold (not Hawaii). I've run many carbs without a choke and had no issue other than having to hold it for a bit after pumping to fire it up. Manual choke is the best of both worlds IMO.

Weber offers a conversion kit for auto choke carbs, and its cheap. An auto choke carb can be converted to manual but a manual cannot be converted to an auto. I would personally sell or give away the used who knows what carbs and buy a genuine Spanish Redline Weber if you want your Brat to be reliable and fun to drive... the cheap stuff is Chinese knock off and its absolute garbage; it will not last. A quality carburetor is worth every bit of $3-400; it is your entire fuel/air management system and that is dirt cheap.

K 730 or K 730-M

K

Edited August 26, 2020 by travelvw

[HawaiiBrat]

3 hours ago, travelvw said:

If the original runs great, leave it be (unlikely).

Most folks like the convenience of the auto (electric) choke, but it's finicky to set perfectly and generally ends up on the rich side to run well under most circumstances. I too personally like the manual choke since you only use what you need, which shouldn't be much unless its really cold (not Hawaii). I've run many carbs without a choke and had no issue other than having to hold it for a bit after pumping to fire it up. Manual choke is the best of both worlds IMO.

Weber offers a conversion kit for auto choke carbs, and its cheap. An auto choke carb can be converted to manual but a manual cannot be converted to an auto. I would personally sell or give away the used who knows what carbs and buy a genuine Spanish Redline Weber if you want your Brat to be reliable and fun to drive... the cheap stuff is Chinese knock off and its absolute garbage; it will not last. A quality carburetor is worth every bit of $3-400; it is your entire fuel/air management system and that is dirt cheap.

K 730 or K 730-M

K

Perhaps I will be going the weber route. Thought she was good to go but I guess not. Upon initial start up it will idle (It never did before) It starts off low then shoots up quite high out of no where? 

Edited August 27, 2020 by HawaiiBrat

[travelvw]

Sounds like maybe too much choke now and your idle speed is set too low. You need to find someone who knows how to tune a carb.

K

[Subasaurus]

tuning a carb is not rocket science, set your timing and idle first, every flywheel is different on these EA71's, they were all welded by hand, mine is at 8degrees with idle being 850rpm due to having electric fans and needing a bit more rpm for the battery to catch up to the power draw, also make sure the engine is warmed up before tuning. more timing=more power but more HEAT, be conservative about your timing and how much power you want to push out of your lawnmower of an engine. then make sure there's no vacuum leaks! and hook up a vacuum gauge, you can get these for $12 at harbor freight, your goal is 18 inches of mercury by playing with the mixer screw, you want it as far opened as possible before the gauge begins to dance and ultimately heading back down the gauge (less suction) which means less stable which means engine may randomly shut off on you, (start at turn and a half out) once you're right at when the needle wants to dance and start loosing suction on the manifold, back off away from that area 1/4turn-1/2turn, this will help when weather changes, although i'm not sure how much the weather changes in Hawaii. if your car can achieve anything more than 18 inches, that is spectacular and uncommon, you can get away with 15inches of pressure, but next time the weather changes, expect issues.

-forgot to mention, vacuum gauge hooks up where the distributor advance would hook up to, you go based on non advanced timing, also don't throttle the engine without the advancer hooked up, you're asking for fire to shoot out of the carb. a cool way to know if the vacuum advance is working and the bladder inside isn't shot is to suck on the vacuum advance with your mouth, it should increase idle a bit when you do this.

another thing to note, timing, idle, and mixerscrew all mess with each other, it's a 3 plot graph, you mess with 1, you gotta mess with the other 2, your goal is to get all 3 lines to meet up as close as possible, make sure to mess with your idle again once you've tuned everything, and then review your timing again, i usually repeat 3 times and call it good enough till a cold front hits.

Edited August 27, 2020 by Subasaurus