makesure you use the animal style spring(short style) springs you posted look to be long clone style springs.
good chance they might coil bind. also the animal retainer as a better off set for the short spring. look at my picture i posted and you can clearly see more of the end of the valve exposed.
good chance they might coil bind. also the animal retainer as a better off set for the short spring. look at my picture i posted and you can clearly see more of the end of the valve exposed.
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The last tec I did I was able to use tec motorsports aluminum split keeper retainers and 26 lb springs with the tec top steel thingy.
https://www.oldminibikes.com/forum/photopost/data/4221/2015-02-11_15_09_40.jpg
https://www.oldminibikes.com/forum/photopost/data/4221/2015-02-11_15_09_40.jpg
hey ole4, question for you on setting the valve clearance on a flathead. i see in the tecumseh hand book they want .004 on intake and .008 on the exhaust. now if you look at the aftermarket cams the setting can be from .003 to .004 on the intake and exhaust side.
i am assuming tecumseh wants more clearance because of valve expansion from the exhaust heat? just wondering want good results you have had on your flathead tecumseh's.
them aluminum retainers are nice ,heavy duty. ideal for 26 pound springs or stronger.:thumbsup:
i am assuming tecumseh wants more clearance because of valve expansion from the exhaust heat? just wondering want good results you have had on your flathead tecumseh's.
them aluminum retainers are nice ,heavy duty. ideal for 26 pound springs or stronger.:thumbsup:
Delray
Thanks for offering the spring retainers if I needed them I appreciate it. More questions: Is there any disadvantage running stock lower valve retainers, would it be easier to buy different valve springs to comp for the different valve retainer installed spring height/pressure, not having done the changes it would seem easier than machining the valve stems and retainers. What are you guys using for a valve spring compressor to install the split lock valve retainers.
Tony
Thanks for offering the spring retainers if I needed them I appreciate it. More questions: Is there any disadvantage running stock lower valve retainers, would it be easier to buy different valve springs to comp for the different valve retainer installed spring height/pressure, not having done the changes it would seem easier than machining the valve stems and retainers. What are you guys using for a valve spring compressor to install the split lock valve retainers.
Tony
my opinion tony i think the best way would be to purchase the briggs items that i mentioned earlier. both parts go together and give you the correct clearances you need and there is no machine work involved. unfortunately your not going to here any other opinions except for ole4 and markus. ole4 has played around with the flatheads when it comes to performance springs and retainers and markus knows is tecumseh numbers which sometimes can help alot when it comes to hot rodding a tecumseh flathead.
here is a mock up picture what i use to compress my springs. i originally purchase it for my ohv small block tecumseh's. it also works great on a flathead when installing automotive style retainers and keepers...:thumbsup: i believe got it for about $22 off of ebay.
Lisle 23300 Small Engine Valve Spring Compressor
here is a mock up picture what i use to compress my springs. i originally purchase it for my ohv small block tecumseh's. it also works great on a flathead when installing automotive style retainers and keepers...:thumbsup: i believe got it for about $22 off of ebay.
Lisle 23300 Small Engine Valve Spring Compressor
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The specifications listed are for both intake and exhaust and are the minimum and maximum clearance for both- at least according to the most knowledgeable Tecumseh builder to ever grace the pages of OldMiniBikes. This is further evidenced as you read down the specification pages where there are dual numbers used for single piece specifications.
Ole, are you referring to ATKRider? I recall him mentioning that the earlier model small frame valves were larger at .245 and the later were smaller at .243. I've found the same thing, which coupled with wear in the guide made me think about BS valves @.250 were as an option. You and I discussed this a couple of years ago. I never had any problem with oil. (Still haven't heard from him)
Are the original springs and keepers no longer working for 5 to 6K RPM Tecumsehs? :laugh: Who decided the springs needed to be 18 pounds, and doesn't Isky still provide slightly stiffer springs with his cams if requested? As I recall he sent you a set with the cam. I also recall reading that a few vendors offered heavier springs, and dual springs- but I no longer see them.
125ccCrazy, has used BS flattie five exhaust springs on the small frame Tecs. No idea of their tension. I think your method of using the shim is sound, if not at least a proven way of increasing spring tension without causing parasitic drag and wearing out components.
I'm sure many of us would like to see the spacer set up you came up with and hopefully an indication on how it worked. Also interested in seeing how your combustion chamber flow ideas work out. Ole4 has done quite a bit of flow testing on OHV stuff, but there's only so much you can get out of a FH.
By the way, the Raptor series of the BS 5HP flatheads had valves canted towards the piston. So at least Briggs and Stratton agreed with some of your ideas. :thumbsup:
Ole, are you referring to ATKRider? I recall him mentioning that the earlier model small frame valves were larger at .245 and the later were smaller at .243. I've found the same thing, which coupled with wear in the guide made me think about BS valves @.250 were as an option. You and I discussed this a couple of years ago. I never had any problem with oil. (Still haven't heard from him)
Are the original springs and keepers no longer working for 5 to 6K RPM Tecumsehs? :laugh: Who decided the springs needed to be 18 pounds, and doesn't Isky still provide slightly stiffer springs with his cams if requested? As I recall he sent you a set with the cam. I also recall reading that a few vendors offered heavier springs, and dual springs- but I no longer see them.
125ccCrazy, has used BS flattie five exhaust springs on the small frame Tecs. No idea of their tension. I think your method of using the shim is sound, if not at least a proven way of increasing spring tension without causing parasitic drag and wearing out components.
I'm sure many of us would like to see the spacer set up you came up with and hopefully an indication on how it worked. Also interested in seeing how your combustion chamber flow ideas work out. Ole4 has done quite a bit of flow testing on OHV stuff, but there's only so much you can get out of a FH.
By the way, the Raptor series of the BS 5HP flatheads had valves canted towards the piston. So at least Briggs and Stratton agreed with some of your ideas. :thumbsup:
dave
dave he is running a dynocam 245. dynocam recommends a 18 pound spring and for the guys that use a 255 cam it would be a 20 pound spring. isky black mamba cam would be a 26 pound spring and thats coming right from tim isky.
dave look at his picture he posted you can clearly see his springs are compress and they are not even open yet. i hate to see what they look like at 6000 rpm's and risk the stock retainers popping out. using the automotive style retainers/locks and correct treated springs all those problems are gone.
another trick you can do tony after riding the bike hard is to makesure you pull the motor over so it's not sitting with a valve open. the heat from the engine can be real hard on the springs.
dave look at his picture he posted you can clearly see his springs are compress and they are not even open yet. i hate to see what they look like at 6000 rpm's and risk the stock retainers popping out. using the automotive style retainers/locks and correct treated springs all those problems are gone.
another trick you can do tony after riding the bike hard is to makesure you pull the motor over so it's not sitting with a valve open. the heat from the engine can be real hard on the springs.
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For an OHV engine. Where has he recommended an 18 LB spring for the flat heads? At what RPM is a stock FH spring floating the valves? I'm just asking, because so far no one who has used the stock springs has complained of float.
Isn't a "Black Mamba" one of those bolt on parts for Predators?:laugh:
I can find no instance of anyone commenting on ignition timing with these hotter cams. The only cards I've seen for a flat head was the one Ole4 posted long ago, and there was nothing on it about ignition.
Granted, I have nothing to say here of any import, but the myriad posts on the subject seem to stop short of anything concrete regarding seat tension and ignition settings on FH's, and in every other four cycle application I've worked with, they're vital.
Great information on using the later springs and automotive keepers. I have found deformed keepers (top and bottom) on several HS and H engines upon disassembly, so I agree with you on their viability over sustained higher RPM. I use the same spring compressor you do. :laugh:
I recall this conversation, where you offered to let me use your seat tools! :thumbsup: I shied away from it, as I have no lathe. That engine still lives in it's original Cat Wildcat.
I am enjoying this thread, and the work you, Fast Tony, Delray, Rupp 72, Wulf and Markus do with these Tecumseh engines in not only modifying them, but in keeping them alive. (and there are others here whom I am aware of)
Isn't a "Black Mamba" one of those bolt on parts for Predators?:laugh:
I can find no instance of anyone commenting on ignition timing with these hotter cams. The only cards I've seen for a flat head was the one Ole4 posted long ago, and there was nothing on it about ignition.
Granted, I have nothing to say here of any import, but the myriad posts on the subject seem to stop short of anything concrete regarding seat tension and ignition settings on FH's, and in every other four cycle application I've worked with, they're vital.
Great information on using the later springs and automotive keepers. I have found deformed keepers (top and bottom) on several HS and H engines upon disassembly, so I agree with you on their viability over sustained higher RPM. I use the same spring compressor you do. :laugh:
I recall this conversation, where you offered to let me use your seat tools! :thumbsup: I shied away from it, as I have no lathe. That engine still lives in it's original Cat Wildcat.
I am enjoying this thread, and the work you, Fast Tony, Delray, Rupp 72, Wulf and Markus do with these Tecumseh engines in not only modifying them, but in keeping them alive. (and there are others here whom I am aware of)
dave
not sure where the differences would be from a ohv and a flathead when it comes to running a valve spring. both a 4 cycle engines and rev up the same way. a spring doesn't know the difference what it's in. for a factory spring floating it seems to be just below 5000 and that can vary from springs because of how much usage...etc.. and thats only base on the info i have read in the pass on poeple revving there engine higher then normal. for me i just think shimming the valve springs is a unsafe practice. when you can just purchase new correct parts for just little amount of money. also call that cheap insurance ...:thumbsup: i have notes too that most people that build a motor up don't regear there bikes so they can take advantage of the rpm's. so in a way it does make it hard to float the valves. unless they have a 1/4 mile or more area to open it up. but for most people the just have there back yard or trails where you can't really open it up.
dave yes dave there is some information out there on timing for hotter cams for flatheads and thats coming right from tecumseh.
nothing really written in any books unless there is a tecumseh motorsports book out there?
what i have found on there performance coil they sold for electronic ignition (part number 36605K) that it advances the coil from a stock 20+ degrees to 30 degrees.
this was the same coil they use in all there flathead motorsport engines.
dave yes dave there is some information out there on timing for hotter cams for flatheads and thats coming right from tecumseh.
nothing really written in any books unless there is a tecumseh motorsports book out there?
what i have found on there performance coil they sold for electronic ignition (part number 36605K) that it advances the coil from a stock 20+ degrees to 30 degrees.
this was the same coil they use in all there flathead motorsport engines.
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I purchased the springs, retainers, locks and Lisle spring compressor yesterday they should be in next week or the week after. I am changing the Rupp gearing lower so I can take advantage of the higher RPM's. I draw whatever I want for a sprocket and have it laser cut at work, look at the rear sprocket on my RR2 bike pictured below I reduced the number of teeth trying to get more speed with the HS50 awhile back, turns out a mostly stock HS50 doesn't seem to have anymore power than the HS40 so no real gain.
Thanks for the info
Tony
Tony
Thanks for the info
Tony
Tony
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nice you can make your own sprocket:thumbsup: have you decided how big to go?
you also might be able to go just little smaller on the jackshaft. that too will help wind up the motor quicker.
something else to look into is the front driver. i'm not a rupp guy so i never look into this. can you change the stall speed from the stock rpm's stall. assuming it is around 2200? to maybe around 2600-2800 . that too should help alot in making the bike pull better off the line or from a low speed take off......
you also might be able to go just little smaller on the jackshaft. that too will help wind up the motor quicker.
something else to look into is the front driver. i'm not a rupp guy so i never look into this. can you change the stall speed from the stock rpm's stall. assuming it is around 2200? to maybe around 2600-2800 . that too should help alot in making the bike pull better off the line or from a low speed take off......
I can put shims on the end of the crank setting the torque converter cover further out that prevents the drive belt from riding up high on the clutch and lowers the drive ratio, my first option before changing sprockets. If I have to increase the driven sprocket I can have a couple of different sizes cut and go by how the bike drives, with a mostly stock engine there was a narrow band where it performed best.
Tony
Tony
Tony
Tony
tony,early this summer i played around with some comet units (20&30) where i did the same thing by controlling how much travel in the driver and also the driven. for me it didn't workout so well because of multiple reasons. i was working with alot of power,fix locations where i could not move the motor or anything to adjust belt to help compensate for some of the problems and was running out of testing time for my drag bike. also i notes a unwanted balancing problem with comet driver when mounted to my race motor with a lite weight flywheel and also with my other race engine. that too had a billet flywheel. so off it went and on with a total different setup and a jackshaft in place to get my gearing right. maybe next summer i would like to still play around with my driver and driven.