Carb return spring question ??

Moderator: Larry Jowdy

Carb return spring question ??

Postby RandyM » Sun Feb 18, 2018 10:06 am

Hey guys,

I'm still planning the heim joint conversion (just waiting on warmer weather to get back out in the garage) but in the interim have a quick question regarding carb return springs......should I have one?

I noticed on my carbs there are no springs? On my 1968 912 it has a return spring on each carb, I know this is not a 912 but should my 550 have one...or two? Could this be a reason my throttle pedal/cable is so touchy.

Here's a picture of the 550 carb, there is a hole for a spring but no where to attach on opposite mounting area.

Thoughts?

ImageIMG_4185 by Randy Mally, on FlickrImageIMG_4186 by Randy Mally, on Flickr
Randy
RandyM
$$Donating Member$$
$$Donating Member$$
 
Posts: 40
Joined: Tue Oct 23, 2012 4:23 am

Re: Carb return spring question ??

Postby RS-60 mark » Sun Feb 18, 2018 12:17 pm

It looks to me like you already have a return spring, as shown in the picture. If the return spring you already have is not broken and is properly installed, your carb should SNAP closed with no-doubt-about-it authority from any open position of the throttle. If it doesn't (and it absolutely must) then there is a bind somewhere that needs attention -- not more spring pressure.

I'm not sure where you are referring to when you say "there is a hole for a spring but no where to attach on opposite mounting area".

On a similar subject, many of us have a "fail-safe" spring somewhere on our linkage. In my case, I have a relatively weak coil spring spanning between my throttle cable attachment arm on the hexbar and a little bracket screwed to my fan shroud. It is not there to assist closing the carbs. Instead, it is there primarily hold the hexbar linkage in tension against the idle stops on the carbs when there is some slack in the throttle cable, and as a fail-safe in case the throttle return springs on the carbs break (which could be a bummer at WOT).
Last edited by RS-60 mark on Mon Feb 19, 2018 10:56 am, edited 1 time in total.
User avatar
RS-60 mark
$$Donating Member$$
$$Donating Member$$
 
Posts: 2920
Joined: Wed Jan 23, 2002 12:00 am
Location: Windsor, California

Re: Carb return spring question ??

Postby Mtflyr » Sun Feb 18, 2018 4:10 pm

Hey Randy,
Here's pic's of my carb springs. I made little tabs and secured them to the underside of each carb plate drilling a small hole and taping it. I bent the right side up slightly to add a little more tension. Originally both springs were just hung over the bottom carb plate lip which is right above the tabs that worked fine but didn't look so good. My cars in the garage and a little millscale rust shows on the throttle bar to carb screws.

Pete
Attachments
IMG_1358.JPG
IMG_1355.JPG
User avatar
Mtflyr
$$Donating Member$$
$$Donating Member$$
 
Posts: 153
Joined: Tue Jul 14, 2015 6:42 pm
Location: Northern Virginia

Re: Carb return spring question ??

Postby RandyM » Sun Feb 18, 2018 4:40 pm

Thanks guys,

I just noticed the spring behind the linkage....I must be blind!

I am so used to springs like on Pete's car (and on the 912) I simply missed the coiled spring behind the linkage. Here's a picture of the 912, It has return springs and I assumed the 550 should as well.

Pete, I noticed you also have the coil spring behind the linkage and the other spring going to the plate. Do I need to add some springs?

Thanks,
Randy

ImageIMG_3634 by Randy Mally, on Flickr
Randy
RandyM
$$Donating Member$$
$$Donating Member$$
 
Posts: 40
Joined: Tue Oct 23, 2012 4:23 am

Re: Carb return spring question ??

Postby Mtflyr » Sun Feb 18, 2018 6:39 pm

Maybe just depress the throttle pedal and watch what happens if both return back to the stops as soon as you release the pedal it should be good. I agree with RS-60 if all snaps shut you should be good if not there may be a bind.
Pete
User avatar
Mtflyr
$$Donating Member$$
$$Donating Member$$
 
Posts: 153
Joined: Tue Jul 14, 2015 6:42 pm
Location: Northern Virginia

Re: Carb return spring question ??

Postby RBP » Mon Feb 19, 2018 6:06 am

The carbs come in one configuration only, when installed you will have one with the return spring on the connecting linkage crank side and the other with the spring on the opposite side. There is a product made to remedy this, web link I believe. Look close at the picture and you will note that there are springs on both sides of the throttle plate linkage, the web link is visible on the right. Its been argued that its best to have springs on the connecting linkage crank sides on both carbs.

I also have an additional spring at the pedal location inside the car.
Attachments
PA290243.JPG
Vintage, 2316 Type IV
User avatar
RBP
$$Donating Member$$
$$Donating Member$$
 
Posts: 1063
Joined: Sat Apr 08, 2006 6:45 am
Location: Ottawa, Canada

Re: Carb return spring question ??

Postby RS-60 mark » Mon Feb 19, 2018 10:09 am

Dang RBP, do you hire-out for engine detailing?! ;)

Here is a link to the "link": http://vwparts.aircooled.net/WebLink-We ... eblink.htm
User avatar
RS-60 mark
$$Donating Member$$
$$Donating Member$$
 
Posts: 2920
Joined: Wed Jan 23, 2002 12:00 am
Location: Windsor, California

Re: Carb return spring question ??

Postby RBP » Mon Feb 19, 2018 1:42 pm

No detail service for me. I only drive once in a while on nice days and never in rain. I have maybe 5,000 miles so thats why it looks so clean. I also try and keep it clean and give the engine bay a good wipe down after an outing. I find if I keep on top of it its easy to keep it looking like that.

Thats the device, I got mine from CB Perf but for some reason I can't find it on their site, odd since they actually manufacture it.

What are you running in that 718 for power?
Vintage, 2316 Type IV
User avatar
RBP
$$Donating Member$$
$$Donating Member$$
 
Posts: 1063
Joined: Sat Apr 08, 2006 6:45 am
Location: Ottawa, Canada

Re: Carb return spring question ??

Postby RS-60 mark » Mon Feb 19, 2018 4:19 pm

RBP -- 2332 T-1. Details @ second post in line: viewtopic.php?f=24&t=11433

Every spring I do a hood-off engine bay cleaning. It never looks like yours, not even when new. Nice job!
User avatar
RS-60 mark
$$Donating Member$$
$$Donating Member$$
 
Posts: 2920
Joined: Wed Jan 23, 2002 12:00 am
Location: Windsor, California

Re: Carb return spring question ??

Postby RBP » Mon Feb 19, 2018 5:04 pm

Very nice, I like your gearing, same as mine except for 4th, I'm running a .89 so I have a bit more top end. My 2316 is rated at about 180 HP and 180 ftlbs of torque, and moves very fast even with the 3/44. I like the gearing, I had the 3/88 initially and had it changed out. That sounds like a high output engine, what does that run for HP and torque and what does that weigh in at? I suspect its somewhat similar to mine, maybe a bit more power so I have a pretty good idea of what that would perform like!
Vintage, 2316 Type IV
User avatar
RBP
$$Donating Member$$
$$Donating Member$$
 
Posts: 1063
Joined: Sat Apr 08, 2006 6:45 am
Location: Ottawa, Canada

Re: Carb return spring question ??

Postby RandyM » Mon Feb 19, 2018 5:30 pm

Guys thanks so much for the feedback and the link. I appreciate the help.

Dang, now I gotta detail my engine bay!
Randy
RandyM
$$Donating Member$$
$$Donating Member$$
 
Posts: 40
Joined: Tue Oct 23, 2012 4:23 am

Re: Carb return spring question ??

Postby RS-60 mark » Tue Feb 20, 2018 11:13 am

RBP: 1456.5 Lb with approx. 5 gal gas and full oil. Front / Rear weight ratio is the same with or without me aboard: 43% F / 57% R. HP, Torque?: Don't know -- I built the engine myself, a story beginning 15 years ago that I don't think anyone wants to read through again now. Suffice to say spyderclub rescued me from one disaster after another! :nana: The big mistakes still buried on the engine are the over-sized carbs and the undersized cam. The carbs I have tamed down, the cam needs a case split to fix. But after 25,000 miles, obviously I've decided to live with it. The car is very quick and I don't spend a lot of time at 6K rpm anyway. Besides, I will be as old as Larry Jowdy this year and should start thinking of backing-off a little. :D

Speaking of Larry, you know we are about to get hammered for thread drift . . . . ;)
User avatar
RS-60 mark
$$Donating Member$$
$$Donating Member$$
 
Posts: 2920
Joined: Wed Jan 23, 2002 12:00 am
Location: Windsor, California

Re: Carb return spring question ??

Postby RBP » Tue Feb 20, 2018 11:39 am

Larry hasn't beat me up for thread drift, yet! Thanks for the info, I agree having to pull the engine and split the case, painful. As bad as my situation, I can only crawl in reverse! I had a guy change my 4th and R/P a few years ago, got the trans axle back and the builder must have moved the internal slider or whatever its called so now if I try and reverse too fast it pops out of gear with a horrible grinding sound. The fix, pull the trans again and resend it out to the builder! Likely not quite as bad as pulling the engine and splitting the case but right up there!

I can say that if I hit the throttle hard in 1st gear at about 3500 RPM the front wheels are almost coming off the ground. Fast enough for me thats for sure. I don't need it to be the fastest car around, just fast and fun for me.
Vintage, 2316 Type IV
User avatar
RBP
$$Donating Member$$
$$Donating Member$$
 
Posts: 1063
Joined: Sat Apr 08, 2006 6:45 am
Location: Ottawa, Canada

Re: Carb return spring question ??

Postby Mtflyr » Tue Feb 20, 2018 3:41 pm

Man I'm embarrassed about the mill scale rust I just noticed on mine when I sent the pic's compared to RBP's great looking engine bay. I just came back from a drive temps here in Northern Virginia were in the 70's. I take mine out to Katie's C&C most Saturdays unless it's wet even in 20 degrees just gotta dress warm.

RBP I like your Jet doc's, I installed them on my car last summer and knock on wood have not had any carb issues lately. I plan on removing the rust this week. :D

I met Randy a few months ago and saw his Vintage 550 and I can tell you his 912 in the picture is a super cool looking ride, you can get a glimpse of it in his picture above.
I love that color blue on the 912.

Pete
User avatar
Mtflyr
$$Donating Member$$
$$Donating Member$$
 
Posts: 153
Joined: Tue Jul 14, 2015 6:42 pm
Location: Northern Virginia

Re: Carb return spring question ??

Postby RBP » Thu Feb 22, 2018 5:07 am

Well Pete, on the bright side you don't have to worry about high head or oil temps at 20 deg.! I thought I was tough and been out in low to high 30's, you da man. It was mid 50's and rain last few days so looks like winter is slowly exiting. One can only hope, right. Usually mid April to early May before I'm out in a permanent way, but it is colder here so takes a bit longer for things to warm up. I didn't think it got down that cold there, I have friends in NY and Chicago and their weather is very much like here, January being the worst of it.
Vintage, 2316 Type IV
User avatar
RBP
$$Donating Member$$
$$Donating Member$$
 
Posts: 1063
Joined: Sat Apr 08, 2006 6:45 am
Location: Ottawa, Canada

Next

Return to Tech General

Who is online

Users browsing this forum: No registered users and 11 guests