Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

  • Announcements

    • Kent

      Sign In or Password Problems?   10/09/2016

      If you can't Sign In, you need to reset your password.  Use the Forgot Your Password link at the bottom of the Sign In screen, and the site will send you an email to reset it. If you have an AOL email account, use the Contact Us link at the bottom of the screen -- AOL is intermittently blocking email from the site.
    • Kent

      Feedback Please!   10/28/2017

      See News and Announcements forum.
Sign in to follow this  
rsnik

Briggs 717 carb

Recommended Posts

rsnik
OK I swapped out the new carb on the blown 728 for the wore out carb on the running 717. Huge difference IMO. Engine starts quicker and seems to run and accelerate more crisply. But the idle is high. My understanding of adjusting this carb is to run the engine wide open (amazing to me as on outboard engines you never run above 2000 RPM without a load on the engine) and twist the screw under the bowl in until the engine stumbles, out until it stumbles and find the sweet spot in between. Then you hold the throttle shaft shut and adjust the idle to your liking with the screw on the throttle shaft stop. What is the screw on top of the carb directly above the throttle shaft for, what does it adjust and what should you do with it regards correctly adjusting the carb? Best, rsnik

Share this post


Link to post
Share on other sites
mowerman1193
I am not sure what one you are talking about but I belive the set screw on the top is for your idle air/fuel mixture..You would need to adjust that just like you would the one under the float bowl only have it idling..Don't want to adjust that until you get it idled down though if its running to fast..

Share this post


Link to post
Share on other sites
Bunky
I think mowerman is also right on the screw being an idle mixture screw, and if you loosen the screw on the throttle shaft arm you should be able to idle it down til it dies Another thing you might want check is see if you have a vacuum leak??

Share this post


Link to post
Share on other sites
rsnik
OK, regards vacuum leaks I tightened the mounting bolts and used a cable tie to clamp the black hose at the carb that goes from the carb to the valve gallery. Any place else to look for vacuum leaks? The bushings on this carb all appear brand new. Other than high idle the 717 is a wild ride. With no deck or hood, just naked tractor with big nobby rear tires with chains it pulls a wheel stand real easy when you take off. I have 2 acres, very hilly with kind of a race track path that can take you through crazy stuff including almost straight up embankments and nothing slows this thing down in top gear. Keeping the front wheels on the ground is an issue. The rear swivels around to give you that traction but at WOT it pulls the front end right up in the air real easy on uphill off camber turns. Cresting an embankment you pull your weight way forward as the front end comes way off the ground. Not complaining. My neighbor has a Banshee and this is more fun. The throttle plate just won't stay shut to idle. This carb looks brand new or freshly, professionally rebuilt. I push the throttle to the stop with my finger and it idles fine. Take my finger off and after 10 seconds the throttle rod creeps open and continues to do so until the revs are at about 1/2 to 3/4 throttle. There is a vacuumb advance linkage and a tiny wire spring that runs along the linkage connected to the throttle rod. Obviously you can't have a spring to hold the throttle shut on the stop or it would defeat the throttle advance. What force is supposed to make the throttle shut and stay shut at idle? I am out of ideas and open to suggestions. Than, rsnik

Share this post


Link to post
Share on other sites
firefoxz1
Adjust the governer. The throttle rods may not have been the same length meaning you have to adjust the governer. With the engine off loosen the nut holding the governer arm to the lower clip, push both the arm and the lower piece toward full throttle as far as they go( not hard just till they stop moving), and retighten the nut/bolt.

Share this post


Link to post
Share on other sites
rsnik
Aye aye, cap'n, Will go give it a shot. Now, after a few spirited laps around the place it seems hard to start and backfires. I should give her a tune up from the git go. Is there a manual that covers sixties vintage 17 and 19 ci motors? Maybe articles in the archives? I can tell you on a 2 stroke outboard there are ignition trigger coils under the flywheel mounted on a ring attached to the throttle linkage. To adjust timing you loosen and rotate the ring. I imagine this 17 ci Briggs has points under the flywheel. No idea how timing is set or how the governor works, is it a vacuum advance? The throttle is not connected to the throttle rod but rather to the governor. The governor seems to provide timing advance while opening the throttle plate which lets in more air sucking in more gas by the old Bernoulli principle through the carb venturi. Best, rsnik

Share this post


Link to post
Share on other sites
rsnik
Aha! One thing I got figured out is, the spark has to fire on every revolution so the spark fires on the exhaust stroke too. If the Briggs gets flooded during a hot restart the spark is firing on the exhaust stroke with the exhaust valve open causing a big bang out the exhaust. The engine was actually not backfiring, it was probably flooded and firing out the exhaust on the exhaust stroke. The 717 has this oval hole on the side of the hood that I read somewhere is a points access hole? Obviously the points must not be under the flywheel in that case. rsnik

Share this post


Link to post
Share on other sites
mowerman1193
I am no mechanic on these little engines so I have a hard time to explain things..most of the time I figure things out just by messing with them.. I belive the timing is fixed timing with the flywheel lining up with the key on the shaft..And if someone has not updated the coil to a magnatron coil then the points are under the flywheel..I had a coil go bad one of my 717's and I put the electronic (magnatron coil on it..Best thing I ever did..faster smoother starting ect..The oval cut out in the hood is a standard hole in all the round hood style tractors for a rope start..

Share this post


Link to post
Share on other sites
rsnik
Thanks Mowerman, I just found the Briggs technical tips section so I will digest that. The first thing I found is about updating to a magnatron coil! I read much discussion about having to repolarize the flywheel and change beer brands. No consensus apparently. I may have a lead on another parts 728 and another running 728. If I put a 728 transmission in the 717 it would make sense to replace the 17 ci engine with a 19 ci, since you now have a rear PTO, right? Speaking of the transmission swap, I imagine you would recommend keeping the 717 rear fender setup? The 8rear fender is a clean design but I think it would leave a wide gap from the 717 console to the leading edge of the fender/seat pan. I have an outboard engine spark checker. You plug on as many as 6 spark plug wires and watch the spark in an enclosed chamber. The spark gap is adjustable to stress the coil as far as it can go and is a good quick ignition test. Think I'll do that and find and set the points. Got to get this engine running perfect before I tear it off and put an even bigger crappy running one on there! Best, rsnik

Share this post


Link to post
Share on other sites
mowerman1193
Well I probably would just leave the 7hp motor in it..as long as it runs good..The rear implements that hook to that don't take much power to run them..I fact I sometimes have it just off idle while tilling hard ground just so it won't bounce me off the tractor,LOL The shifter plate on the 717 would have to be cut out if you do a transmission swap..I think there is another part you have to swap from one transmission to the other too..I have never (YET) done the swap..but here are other members here that has done it..Might try a search to find the post to learn what they had to do..

Share this post


Link to post
Share on other sites
firefoxz1
I do not believe the vertical shaft engines need to be repolarized to switch to a magnatron coil, just the older points horizontals. Did adjusting the governor help? If not maybe I didn't explain it well enough.

Share this post


Link to post
Share on other sites
mowerman1193
quote:
Originally posted by firefoxz1
I do not believe the vertical shaft engines need to be repolarized to switch to a magnatron coil, just the older points horizontals. Did adjusting the governor help? If not maybe I didn't explain it well enough.
Your right..I didn't have to repolarize my flywheel when I did the coil swap..I ment to say that in my last post..When you type as slow as me you forget what you was going to say after you get the first work done..Whew, LOL

Share this post


Link to post
Share on other sites
rsnik
Hello Firefoxz1, Thank you for your interest. Ran out of tractor time for today. Took a break to see what info was available in the Tech Tips about tuning the 17 ci (is there some other designation for these engines, like is this a 17D maybe). I ran down and took a quick look but didn't see exactly how to do what you described. Best tractor time for me is in daylight when I can roll the 717 out on the driveway. No matter how much light you have in the garage you still can't see the way you can outdoors in daylight. I tried doing something like what you described by bending the end of the advance linkage so it aligned perfectly with the grommet it sticks through on the throttle rod. Still too short. Reminds me of woodworking (cut the board 3 times and it's still too short). Will have at it again tomorrow and keep you posted (any additional instructions welcome meanwhile). BTW I saw a picture of you, I believe, on maybe a 725 you bought up in Detroit? Best, rsnik

Share this post


Link to post
Share on other sites
rsnik
Hello Mowerman, Since the 717 and 728 swivel it's too bad the whole front and rear of each tractor won't separate at the swivel point and remount on the other. It also would make it really convenient buying parts tractors. You could just snap off the bad half and leave it in the seller's driveway and take the good half home. rsnik

Share this post


Link to post
Share on other sites
skot71
Well, they're supposed to disconnect after loosening a set collar, but I'm having a hard time disconnecting a rear of a B-207 (similar to a 728/717) to put it on another that's in better shape! Gotta do some more grinding/sanding on the end of the shaft to get it out of the sleeve. Look underneath one to see what I'm talking about.

Share this post


Link to post
Share on other sites
rsnik
I had a bad experience with the 717 when it had the worn out carb on it with vacuum leaks around the throttle rod bushings etc. I was off the tractor while it was running and the engine was shaking real bad and it shook the shifter into gear and the 717 took off at a pretty high rpm rate. I managed to catch it. I watched this WC Fields movie the other morning where they have these outrageous car chase scenes where vehicles repeated go off cliffs and drive down trenches with workmen working with picks and shovels etc; I have had tractors with trailers over the embankment twice and chased a runaway around the yard once in the last week. Seriously if I could get it all on video it would look like an episode of the Three Stooges. I suppose you should remove the drive belt every time before working on the 717. Looking at the manual I see parts in the brake linkage described as related to a parking brake. A device that keeps the clutch depressed and engages the brake would sure be a good thing. Actually maybe the tractor already has this feature and I don't know how to use it? Be nice, now, I don't want to hear no "Actually, rsnik, there seems to be quite a bit about driving tractors you don't know from." Best, rsnik

Share this post


Link to post
Share on other sites
gregc
quote:
Originally posted by rsnik
Is there a manual that covers sixties vintage 17 and 19 ci motors?
Here's an online manual: http://www.tpub.com/content/recoveryvehicles/TM-5-4240-501-14P/ Here's the Antique Briggs Bible: http://shop.briggsandstratton.com/BShopProductPage.asp?CatalogID=56B2B9AA-283C-11D4-8886-00B0D0203414&MECID=100&SessionID=9EBAD5AF-70D1-4DEA-88AC-66A3AB1EE63B&CategoryID=&lrid=&ProductID=56B2BB53-283C-11D4-8886-00B0D0203414

Share this post


Link to post
Share on other sites
mowerman1193
rsnik, Your story reminded me of when I changed the drive belt on my 717 for the first time..You see the belt goes from a vertical pulley to a horizontal pulley so it has to have a twist in it..I was in the garage with my son 4 years old and put the belt on and thought I was all ready to give it a try so I shoved my tools and trouble light behind the tractor and told my son to stand off to the side..I hopped on and fired it up..put it in high gear and let out the clutch..What a suprise when you think you are supposed to go forward and you end up going backwards..running over the tools and trouble light ect..Lucky my son was to the side of me..just laughing so hard he couldn't stand up..If you twist that belt th wrong way you will have only 1 forward gear but 2-3 reverse gears depending on the transmission you have..

Share this post


Link to post
Share on other sites
rsnik
Hello gregc, That is a nice gift. Thanks! I searched the web over and couldn't find one for love or money. BTW I think this is post #25, technically I should get promoted to Two Star Noob with this post. Best and thanks, rsnik

Share this post


Link to post
Share on other sites
rsnik
Hello Mowerman, Your 4 year old son already understands the fundamental concepts of the ancient Greek Classics. When I back over my multimeter and circuit tester that is the definition of tragedy. When I see you do the same thing that is the definition of comedy! Speaking of testers, I bought one of those Power Probe II circuit testers (think I gave about 70 bucks online). Hooks up to the battery with a 20 foot extension. The hand held unit supplies battery voltage and ground (can do both to power up components), identifies pos, neg and open circuits, continuity, finds and follows shorts without blowing fuses (has built in circuit breaker that trips instead). Made my big bag of jumper wires go from "ready alert" status to "present whereabouts unknown". They have the Power Probe III now with built in mutimeter for $170. Yeah. I guess I'll wait for the Probe IV with built in iPod, email and cell phone for $400. Best, rsnik

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  

×