RE: How much priming question?
I would agree with DaveG55 about pulling the starter just enough to get fuel to the carb. At that point the engine should fire within 2 pulls. If it does not and you need to prime more you are most certainly running lsn too lean! If the engine get fluid locked then you are too rich! It should never be difficult to start your engine if it is properly tuned![:D]
Posted on: 10/19/2007 9:30 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6510937

RE: Proper use of RTV
Personally, it depends on the application as to whether I allow a cure. On the race engines I generally apply a thin film on both sides of intake manifold gaskets and allow a forced full cure under heat lamps(takes less time). Once cured I apply another thin film for final assembly but do not allow a full cure this time. When sealing the intake manifold valley I do not allow a cure! I set the manifold on and hand snug the bolts, allow a full cure over night, and 3 step torque......DONE! On fuel pumps, water pumps, and most everything else I generally try to allow a thin film to fully cure then apply another layer, set part, and torque. Many will disagree but once you witness an intake manifold gasket peel off so you can reuse it you'll be convinced otherwise. My engines NEVER leak oil,,,, first time,,,,,, every time!!!!!!!!!
Posted on: 10/9/2007 2:44 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6465529

RE: Proper use of RTV
Your supposed to be an engineer so go plot the curve for cure time as a function of temperature and prove me wrong. Applying heat does indeed facilitate shorter cure time! Mating surface has nothing to do with my method at all. If you ever took Material Science in Engineering school you would understand non-linear displacement(warping) as a function of temperature. Your really proving how little you know!
Posted on: 10/9/2007 1:27 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6469131

RE: Proper use of RTV
It is ALL TOO COMMON for people to apply a bead, torque, and forget about it. This is what increases the risk of leakage. It presses the sealant out and allows tiny amounts of metal to metal contact, which through expansion/contraction could cause leakage. A gasket of any kind reacts to pressure by compressing! This is what creates the seal! If you can understand this simple principal you may also understand why I pretreat mating surfaces with a thin layer and allow a full cure followed by another thin layer(un-cured) for final assembly. Most engine builders do not use this method because of wait time. They need to make money and therefore take short-cuts to speed production. I suggest you go back to school for some basic Material Science before you go shooting off about things you don't know!
Posted on: 10/9/2007 9:22 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6468360

RE: Proper use of RTV
You really should be quiet now!
Posted on: 10/9/2007 12:40 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6467534

RE: Proper use of RTV
This is my world Anthop! Where are yours?
Posted on: 10/9/2007 12:39 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6467524

RE: Proper use of RTV
Sorry, should have clarified! Specifically, I apply a thin film allowing a full cure. I then follow up with a thin film, assemble, allow full cure, and final torque sequence. Final torque sequence is progressively increased in steps. Three to be exact! I seal all but the manifold valley using this method with 100% oil free,,,, air-leak free race engines time after time! You seem to be quit @retentive there Anthrop! Perhaps some anger management would help you!
Posted on: 10/9/2007 12:22 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6467477

RE: AWW shoot i messed up big time Help???
Find a hex wrench that just barely won't fit, heat the screw directly with a torch, tap the hex wrench into the socket, then remove quickly before it cools down! A trick is to always apply heat with a torch before removing loctited metal to metal screws!
Posted on: 10/8/2007 9:33 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6463808

RE: Doubled my fuel economy!
I have more need for fuel economy than for power! I have other mods for power that almost throw the tires off the rims....!!!!! This mod has proven mileage benefits but a few timing issues which I will have worked out by late next week. I have one good engine for which I have posted complete timing profile on preceeding pages. This engine has performed very well with minimal power hits, excellent mileage, and extremely good thermal stability(no lean-out stalling under severely sustained high speed runs).
Posted on: 10/5/2007 11:07 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6455209

RE: STS 30 ?'S
O-ring is really not needed if you know what ur doing with RTV!
Posted on: 10/5/2007 4:50 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6453788

RE: Doubled my fuel economy!
Here is a degree wheel from another thread! I don't like it because I prefer measuring everything from TDC=0,360 but this will work fine. It just takes patients and being very careful. It is common to see measurements like ATDC, BTDC, BBDC, ABDC where A=after and B=before. I don't like this method because it cannot be used in a database to perform calculations without interpretation of the numbers. Another solution would be to get a school protractor and drill the hole to fit the output shaft.
Posted on: 10/5/2007 10:03 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6452494

RE: Doubled my fuel economy!
Get yourself a degree wheel, fix it to the flywheel, make a pen mark on flywheel at TDC=0, then turn crank till crank induction port just starts to open. Record your results and repeat for crank induction close point. Do the same for the SPI timing. You don't really have to worry about the exhaust or intake port timings.
Posted on: 10/5/2007 9:17 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6452459

RE: Easiest 1/8th to wrench?
They're all easy to work on! A can of WD-40 and a pressure washer is all you need! LOL!
Posted on: 10/4/2007 4:24 PM by Author "lsurber" in the forum "RC 1/8th Scale Buggies"
http://www.rcuniverse.com/forum/fb.asp?m=6449713

RE: Doubled my fuel economy!
The headbutton mod probably has more to do with reducing compression than it does directing burn. I am almost there Blaze! I believe by next week I will have a fix for the erratic idle. It will probably involve using a degree wheel and modifying crank induction timing! Do you feel up to it? It would be a good idea if you were to degree your engine and post results here. The most important measurements are crank induction and SPI timing marks.
Posted on: 10/3/2007 11:55 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6447421

RE: Doubled my fuel economy!
I personally feel that most engines offer more than enough power to win races! This thread was started to learn about economy mods. There have been numerous threads on RCUniverse with questions on how to increase runtime! This mod has proven to me that it is indeed possible to get more runtime, sacrifice little overall power, and susbtantially improve the thermal stability of a modern engine. Maybe you shouldn't post in this thread anymore if you are so negative and do not want to contribute anything worthy![:'(]
Posted on: 10/3/2007 4:09 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6445223

RE: More Nitro Content?
I did say compensate not regain! Once it's gone, it's gone! Best to replace! We can agree on that![;)]
Posted on: 10/3/2007 1:17 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6444617

RE: More Nitro Content?
Wow! This thread just went crazy!!!![:D] One thing I notice is that everyone has valid points but very few can agree! Example: Does more nitro make the engine run hotter? Well, if you don't change mixture settings,,,,,,, yes! If you do change mixture, no! Also, when piston/cylinder clearance exceeds spec you lose compressive abilities. This means less pressure! It can be compensated for by removing shims OR going hotter with the plug! The plug method is GOOD, shimming is BETTER, and replacement of the worn parts is BEST! When it comes to stress in the engine, more energy= more stress! STRESS/TIME=STRAIN If you believe this statement then it is fare to say that parts designed for X amount of stress over time will indeed fail sooner if 2X stress is applied to them. That is why they make performance parts! With all that said, can't we all just get along![;)]
Posted on: 10/3/2007 12:06 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6444399

RE: Doubled my fuel economy!
Once the timing issues are ironed out I would do this mod more because it REFUSES to stall even after extended high speed runs! Every other engine I have seen without this mod would stall when throttle is lifted after such abusive lean-out pulls!!!!![:D] The fuel economy is just a bonus!
Posted on: 10/3/2007 10:51 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6444186

RE: Doubled my fuel economy!
Ok, degree'd the SH engine with erratic idle! Here it is! Crank induction: open=210, close=40, Duration=190 Intake: open=100, close=260, Duration=160 Boost: open=100, close=260, Duration=160 Exhaust: open=90, close=270, Duration=180 SPI: open=328, close=32, Duration=64 Case Pos. Pressurization: Start=32, End=180, Duration=148 Case Neg. Pressurization: Start=180, End=328, Duration=148 Combustion Pressurization: Start=270, End=360, Duration=90 Notice: Look at the induction close point vs. SPI close and you will notice 8 degrees compared to 14 for the good engine! I will first increase Crank Induction close point to match that of the good engine then test. After that the only other change would be to extend the SPI duration. I will make these changes over the next week so stay tuned! We are almost ready to silence the critics![:D] I had to edit this post because I found an error, sorry![:)]
Posted on: 10/3/2007 10:41 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6442970

RE: Doubled my fuel economy!
Ok, degree'd the good engine! Here it is! Crank induction: open=210, close=54, Duration=204 Intake: open=100, close=260, Duration=160 Boost: open=110, close=250, Duration=140 Exhaust: open=90, close=270, Duration=180 SPI: open=320, close=40, Duration=80 Case Pos. Pressurization: Start=40, End=180, Duration=140 Case Neg. Pressurization: Start=180, End=320, Duration=140 Combustion Pressurization: Start=270, End=360, Duration=90 Now, I have not degree'd the SH28 yet but I did check the SPI timing on it and.....!!!!! SPI: open=328, close=32, Duration=64 It is looking pretty much as if the Crank induction close point OR SPI duration is causing this! I will let you know after I fully degree the SH28 engine tomorrow night. I will be mostly concerned with crank induction vs. SPI timing.
Posted on: 10/3/2007 10:39 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6438880

RE: clutch engagement question............
Leave the screws out! Less weight means later engagement!
Posted on: 10/2/2007 3:31 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6440721

RE: Doubled my fuel economy!
I would still use the radius cut because of strength and the fact that it is the only type of SPI port that is working properly on the above engine. This engine has been running great and refuses to stall with no high/low idle problems at all!
Posted on: 10/2/2007 9:19 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6439479

RE: Doubled my fuel economy!
JB, Here is the photo you requested. I am going to degree the engines tonight to see what is different between the two. Lee
Posted on: 10/1/2007 5:08 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6436667

RE: Doubled my fuel economy!
I PM'd Blaze about this very same problem of high/low idle fluctuation. I did experience this with another engine but thought I probably had an air leak and until I get a starter backplate for the engine it's just been sitting in the box. Now that multiple people have the same problem I believe that I may have just gotten lucky with the original SPI mod because it does not exhibit these symptoms. I will degree the original engine and compare to my engine which idles erratic! I am betting there is a critical timing between crank pressurization and the crank induction that I just missed before. I will find it though! Very interesting stuff now! Don't be discouraged! It may be that a simple induction timing mod or a longer SPI port duration is all that's needed! In the beginning of this thread I mentioned not making the port too big or idle will drop too low........... Well my SH 28 engines port was cut flat with a short duration and exhibits the problems mentioned! Furthermore, it has quite a low idle! So, we may need to disregard that recommendation now! Get UR degree wheels ready! Lee
Posted on: 10/1/2007 10:19 AM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6435230

RE: Induction Timing
No, I don't do all that stuff, just eyeball it and work slowly!!!! LOL!!!![;)]
Posted on: 9/27/2007 6:05 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6421762

RE: Induction Timing
If you measure the incidence angle of the port and sleeve wall thickness then use the law of sines you can determine where to transcribe the line! SinA/a = SinB/b =SinC/c Note: A and B will complement each other so you only need to find one and you know the other! C=90 degrees Sorry, sometimes I assume too much![8|] It's also easier for me to cut referencing the outside rather than the inside of the sleeve![8D] Personally, I just make a good guess!!!!!!! LOL!!!![:D] Tape inside is also an excellent idea to avoid flaking the plate! If you do make timing changes to ports you may end up with a paperweight if the plating comes off!!!!!![:o] Lee
Posted on: 9/27/2007 6:03 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6421617

RE: Induction Timing
Once you have crank position locked for your new timing marks measure depth from top of sleeve to top of piston. Next, transfer the inside measurement to the outside of the sleeve, mark with scribe, and start cutting! For crank induction, remove the carb, turn crank to new open/close timing and scribe a line on the crank. Remove crank, cut, polish edges, reassemble, and go run! Works for me![:D]
Posted on: 9/27/2007 2:30 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6420920

RE: Doubled my fuel economy!
That's very consistant with an air leak! I had the same thing happen to me before! Is this engine pretty worn?
Posted on: 9/26/2007 10:48 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6418734

RE: Doubled my fuel economy!
That is normal for SPI! You will need to increase throttle opening using the idle set screw. Screw it all the way in till the slider is bound then back it out just enough to free the slider. When you get the engine running burp the throttle for a minute or so to get some heat in the engine. Once you have heat built up it should idle very low rpm but shouldn't stall! Mine simply refuses to stall, even after super long high speed passes! Also be aware that the engine will produce more smoke than normal,,,,,, that's the oil re-combining! I like to use my finger to check for oil spatter in the exhaust stream. You should have a fair amount of oil spattering on your finger at idle and burping the throttle should produce a quick shot of smoke. Good Luck, Lee
Posted on: 9/26/2007 6:02 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6417601

RE: Engine dies at full throttle???
When you let it idle the engine cools down which richens the mixture. Rich mixture causes load up, which, causes the engine to stall almost immediately when you go full throttle. You can eliminate the condition by leaning the lsn a little or blipping the throttle repeatedly to get temps back up. If you still experience stalling on full throttle after lsn adjustment then you may have to lean the hsn as well! I usually try to set my lsn so the engine starts right up cold after priming with very little effort at normal idle position. If it takes too long on the starter or too many pulls(more than one) then it is too lean! If it fluid locks quickly then it's too rich! You need to be right on the edge of too rich on a cold start! Your engine should never be hard to start! If it is then something is not right, whether it's the lsn, hsn, idle set, plug, air leak, etc.
Posted on: 9/26/2007 4:45 PM by Author "lsurber" in the forum "Car Nitro & Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6417222