Yamablue
Member
I want to switch heads on my viper, but the heads I want to go to have o-rings cut in the deck to eliminate the head gasket. Sounds great right? Well my problem is I already have grooves cut in the cylinder to accomidate rings. Is there an epoxy I can use to fill the grooves of either the head or cylinder? Any help is greatly appreciated.
so either mill off the tops of cylinders and reset up head squish clearance or mill the heads underneath and do the same.
Yamablue
Member
Removal of material does not seem to be an option. I do not want to use the head gasket for the clearance.
what head gasket? I thought this was a o-ringed cylinder viper or whatever?
if you either mill the heads or the tops of the cylinders you would cut the squishband in the head to get the proper clearance. you wouldnt use a head gasket, just the o-rings like a srx.
you need to be more clear as to what you have and what your trying to do to solve your problem.
if you either mill the heads or the tops of the cylinders you would cut the squishband in the head to get the proper clearance. you wouldnt use a head gasket, just the o-rings like a srx.
you need to be more clear as to what you have and what your trying to do to solve your problem.
Yamablue
Member
I have a Peak head (for the viepr) with removable inserts. The head is setup for a head gasket. THe cylinders I have are cut for O-rings. I had just been leaving the o-rings out and running head gasket since the chambers don't have the clearance in them. Last year I finally picked up some rings and am running both. The speedwerks head has orings cut in the head and has the recess to makupe for no head gasket. I need to find out if I can fill one or the other with epoxy. Maybe I can find some quad rings to fill both.
Yamablue
Member
I'm thinking JB weld will fit the bill. 0% expansion, good up to 500 F. If an o-ring can survive, JB weld should.
Running 4 0-rings if all were the same diameter o-rings would work if they didnt overlap on spacing in head/cylinder.
Be alot simpler to just use the head set up for your cylinder(peak), whats the benefit of going to the speedwerx?? more compression? better cooling? What are you looking to gain?
or lastly using 1 layer of headgasket allows you to run either head on your grooved cylinders, 1 layer is .010", that isnt enough to make 1 bit of differance that you could tell the differance riding the sled either way, your simply going to add .010" squish to the motor, what is your squish as of right now?
The epoxy fix would not be very good, your just creating a problem to go wrong down the road, the head sees alot of rapid heat/cooling cycles(expansion/contraction), I would not trust jb weld in a groove, if it cracks, the oring would move to the crack and thus create a problem spot, maybe not right away, but rest assured it will be when you dont want it to happen, like when your a hundred miles from camp. You do as you like, its your sled/time, just giving you some ideas to think about.
Be alot simpler to just use the head set up for your cylinder(peak), whats the benefit of going to the speedwerx?? more compression? better cooling? What are you looking to gain?
or lastly using 1 layer of headgasket allows you to run either head on your grooved cylinders, 1 layer is .010", that isnt enough to make 1 bit of differance that you could tell the differance riding the sled either way, your simply going to add .010" squish to the motor, what is your squish as of right now?
The epoxy fix would not be very good, your just creating a problem to go wrong down the road, the head sees alot of rapid heat/cooling cycles(expansion/contraction), I would not trust jb weld in a groove, if it cracks, the oring would move to the crack and thus create a problem spot, maybe not right away, but rest assured it will be when you dont want it to happen, like when your a hundred miles from camp. You do as you like, its your sled/time, just giving you some ideas to think about.
Yamablue
Member
The Peak head in its original configuration was piece of crap. It had a squish band angle of 8 degrees and I believe contributed to multiple burn downs of my motor. I had a friend machine some new chambers to the size I wanted and a revised angle of 14 degrees. Chambers worked great, but compression was too low (21.5cc), squish at adjusted between 0.040 and 0.055" with gasket layers. I had him to machine some 19.5 to 20 cc chambers with an angle starting at 17 degrees then changing to 19. We ended up making the band too wide and although the pressures were good I still got some detonation.
It was a pain in the butt to make the new chambers since it required both lathe and milling operations. The peak head has the head bolts and coolant passages in the chamber insert, the Speedwerx head does not. It would be much easier to do a run of the speedwerx inserts. I can get a pretty good deal on the new head, and hopefully I can recoup some expense selling the Peak head with the good 21cc chambers. If I can run 2 orings on top of each other I won’t worry about it. I have just had problem sealing with the oring and head gasket combo.
It was a pain in the butt to make the new chambers since it required both lathe and milling operations. The peak head has the head bolts and coolant passages in the chamber insert, the Speedwerx head does not. It would be much easier to do a run of the speedwerx inserts. I can get a pretty good deal on the new head, and hopefully I can recoup some expense selling the Peak head with the good 21cc chambers. If I can run 2 orings on top of each other I won’t worry about it. I have just had problem sealing with the oring and head gasket combo.
simplest way to correct your problem would then be to deck the bottom of the cylinders slightly, about .010-.012", youd then raise your compression because youd be reducing your deck clearance, and reducing your squish clearance by same amount, but thats a 5 min job to open up(squish band)(if needed for application) on lathe.
How much compression are you trying to run and with what fuel (octane)more importantly? pipes-rpm range?
How much compression are you trying to run and with what fuel (octane)more importantly? pipes-rpm range?
Yamablue
Member
92 octane, 9300-9400 rpm, 135 psi. CPR pipes. Ported cylinders and raised exhaust port. Don't want to change squish height, Don't want to run the gasket anymore, just the o-rings. I mainly like the werx head because it has the squish clearence in the head and not in a gasket.
I dont think your following what I am saying, if you deck the bottom of the cylinders this raises the compression and reduces the squish, you posted that you want from .040"-.055" squish, thats .015" differance!!, cut the bottom of the cylinders and not only did you raise the compression from reducing the deck clearance, you made the squish clearance reduced the same amount. The compression gain is big because your reducing the entire bore area by that much, effectively making the head volume/deck clearance area smaller. This is running the head with o-rings, no head gasket involved.
So the easiest way to get where you want to be, is simply bolt on the head with o-rings like you had it set up before, and check the squish, set it up
(by decking bottom of cylinders) to be at the minimum squish you want, deck the differance from the before squish to the desired squish, like say its at .055" squish before, you want to be at .045" squish, well deck the bottoms of cylinders .010". It will increase compression alot at the same time. The stock motors have between .010-.012" deck clearance from the factory, so theres your limit without getting into cutting the heads to clear the piston and having positive deck clearance, this is for strictly race engines, no advantage for trails.
Why did you raise the exh port to run only 93-9400rpm in a viper? what did you raise it too?, this is why you show low compression with your squish clearances you have posted with 21.5cc domes. What else did you do to the cylinders when you ported them? I am just trying to help you sort this engine out, sounds like you have a couple things maybe out of whack.
So the easiest way to get where you want to be, is simply bolt on the head with o-rings like you had it set up before, and check the squish, set it up
(by decking bottom of cylinders) to be at the minimum squish you want, deck the differance from the before squish to the desired squish, like say its at .055" squish before, you want to be at .045" squish, well deck the bottoms of cylinders .010". It will increase compression alot at the same time. The stock motors have between .010-.012" deck clearance from the factory, so theres your limit without getting into cutting the heads to clear the piston and having positive deck clearance, this is for strictly race engines, no advantage for trails.
Why did you raise the exh port to run only 93-9400rpm in a viper? what did you raise it too?, this is why you show low compression with your squish clearances you have posted with 21.5cc domes. What else did you do to the cylinders when you ported them? I am just trying to help you sort this engine out, sounds like you have a couple things maybe out of whack.
Yamablue
Member
OK, I think you are missing something here. I will give you everything. 2002 motor, Porting by Bo Whiteman, (practically lake race, raised exhaust 28.5mm I believe). Cylinders have O-ring grooves cut in them. CPR Pipes. Peak head with 20 and 21cc chambers originally w/8* squish angle, running with head gasket. 38mm carb rack off of 2001 XCR800 w/tps. Phazer manifolds. V-force2 reeds. Uni-filter pods. Jetting is 420 mains and 50 pilots. Yami SRX Hi RPM box. Deck clearance is 0.025 with no head gasket. Stock viper base gasket.
I had a friend make some 21.5 cc chamber heads with 14 degree squish band. With all three layer of gasket I was around 115 to 120 psi cranking compression. Motor ran real reliable with big chambers, but was missing something. Made smaller 20 cc chambers with a 17 and 19* squish angle. With that steep of an angle the dome was pretty small. Didn’t know if there was a limit how shallow I can go with the dome, so we made the squish band a little wider. Ended up having 0.052” at the wall and 0.102 at the ID of the squish band. I think this was causing it to ping a little. I was going to have him make me a set of heads that had the squish clearance cut into the chamber instead of the gasket so I could just run the O-rings. Turned out to be a pain in the butt to machine the chambers and he has since let the company he was doing them at. I like the speedwerx chambers due to the squish cut into the chamber, but the head and chamber also have the o-ring cut in them. If I can run O-rings in both top and bottom grooves, I will just do that. I do not need to modify the cylinders anymore as far as cutting the bottoms. I would just pull the base gasket and use silicone (hmm, maybe that wouldn’t be the best with it possibly squeezing into the airstream). Anyway, I was told to run the motor between 9300-9500 per the porting. I know this is post is more or less a rant, but hopefully you can piece something together.
I had a friend make some 21.5 cc chamber heads with 14 degree squish band. With all three layer of gasket I was around 115 to 120 psi cranking compression. Motor ran real reliable with big chambers, but was missing something. Made smaller 20 cc chambers with a 17 and 19* squish angle. With that steep of an angle the dome was pretty small. Didn’t know if there was a limit how shallow I can go with the dome, so we made the squish band a little wider. Ended up having 0.052” at the wall and 0.102 at the ID of the squish band. I think this was causing it to ping a little. I was going to have him make me a set of heads that had the squish clearance cut into the chamber instead of the gasket so I could just run the O-rings. Turned out to be a pain in the butt to machine the chambers and he has since let the company he was doing them at. I like the speedwerx chambers due to the squish cut into the chamber, but the head and chamber also have the o-ring cut in them. If I can run O-rings in both top and bottom grooves, I will just do that. I do not need to modify the cylinders anymore as far as cutting the bottoms. I would just pull the base gasket and use silicone (hmm, maybe that wouldn’t be the best with it possibly squeezing into the airstream). Anyway, I was told to run the motor between 9300-9500 per the porting. I know this is post is more or less a rant, but hopefully you can piece something together.
.025" deck clearance ?? why is the piston sitting so far down in the cylinder when at TDC? with only 1 base gasket should be .010-.012", only way it could be that much is if you ran 2 base gaskets. The deck clearance is the distance from the top edge of the piston (not the center dome)to the top of the cylinder edge when the piston is at top dead center, no head installed to check this. Squish is the clearance between the piston edge and the head when at TDC, they are not the same thing.
Anyways, first thing I would go back to is the stock viper cdi box, thats most likely where your detonation problems have come from, on the race box it holds full advance out alot longer in the curve, if your running 9400 rpm, you will be on the down side of the timing curve in a stock viper box and yield better topend anyways, timing hurts topend.
Your squish clearance should always be cut into the dome on a o-ring engine, sometimes when you have positive deck clearance, meaning the edge of piston sticks up beyond the edge of the cylinder edge, you cut out the dome and allow the piston to go up into the head. So if you didnt cut any clearance into the dome, I could see where youd have problems, and had to use a gasket. To fix those domes is a 5 minute operation in a lathe, very simple to do.
you can run o-rings in the head and cylinder as long as they do not overlap each other, you cant seal 2 o-rings on top of each other, wont work.
Anyways, first thing I would go back to is the stock viper cdi box, thats most likely where your detonation problems have come from, on the race box it holds full advance out alot longer in the curve, if your running 9400 rpm, you will be on the down side of the timing curve in a stock viper box and yield better topend anyways, timing hurts topend.
Your squish clearance should always be cut into the dome on a o-ring engine, sometimes when you have positive deck clearance, meaning the edge of piston sticks up beyond the edge of the cylinder edge, you cut out the dome and allow the piston to go up into the head. So if you didnt cut any clearance into the dome, I could see where youd have problems, and had to use a gasket. To fix those domes is a 5 minute operation in a lathe, very simple to do.
you can run o-rings in the head and cylinder as long as they do not overlap each other, you cant seal 2 o-rings on top of each other, wont work.
Yamablue
Member
OK, now we are getting somewhere. Yeah my bad, I meant my piston to cyl head clearance is 0.025 with no head gasket and I am using my 14* chambers. As far as my the CDI, the sled runs much better with it. When I was burning the motor down, it was never at WOT, always around ¾. No burn down since SRX CDI. When I put the motor on the dyno, I’ll try both boxes just to see which one makes more power.
As far as an easy 5 minute lathe job, you are going to have to explain a little more. What tooling are you using to cut the chambers cleanly and consistently? The whole reason I was asking about epoxying the grooves was due to the grooves bein in the same spot.
As far as an easy 5 minute lathe job, you are going to have to explain a little more. What tooling are you using to cut the chambers cleanly and consistently? The whole reason I was asking about epoxying the grooves was due to the grooves bein in the same spot.
The timing helps accelarate the motor faster but it slows it down on topend with the higher rpm's, retarded timing would yield better topend results. The reason the motor seems to run better in the field is because the timing is making up for either higher then needed port timing and or low compression/wide squish clearance, these all affect the response of the engine from a rev standpoint.
The detonation coming in at 3/4 throttle would be the overlap of the needle/main jet period and the timing together. More times then I can count the number of burn downs are always on the needle of the carb, guys just dont take the time to set this up correctly and this is where you will burn them down even on a long pass, the very second you let off the gas, it goes directly to the needle from wide open, if there isnt enough margin in there, mr. squeeky will visit you. just because you have a big main jse will not solve the problem of burn downs when you let off, the needle will take out a engine if incorrectly set up every time, no matter how rich the main, if the needle and nozzle are too small, or way to lean of a set up. High timing advance in the mid range only multiplys this problem.
To machine those domes you simply need a arbor to attach the domes to via the spark plug hole, I just turned down a peice of steel and it has the sparkplug threads(male) on the end of it, you chuck it up and check with dial indicator for run out, then spin on the dome and check the runout, usually very close. If needed adjust to 0.
Once thats done you just use the cross slide on the lathe, set it to 0 or 90 degrees cut, when you just touch the dome surface, then you cut straight in how ever much you need to increase your squish clearance to, once this is done you adjust the cross slide to the angle of the squish, if you want 10,12,14 degrees whatever you want, tighten it up and then slowly turn in from outside where you first cut straight, till you come to dome opening. Its that simple. So in your case youd simply cut into the dome edge where the edge of the bore is on dome .025" to have .050" total squish clearance in the engine with head bolted on with o-rings. After the straight in cut, set up cross slide to what ever squish angle you want and cut em, your done.
The detonation coming in at 3/4 throttle would be the overlap of the needle/main jet period and the timing together. More times then I can count the number of burn downs are always on the needle of the carb, guys just dont take the time to set this up correctly and this is where you will burn them down even on a long pass, the very second you let off the gas, it goes directly to the needle from wide open, if there isnt enough margin in there, mr. squeeky will visit you. just because you have a big main jse will not solve the problem of burn downs when you let off, the needle will take out a engine if incorrectly set up every time, no matter how rich the main, if the needle and nozzle are too small, or way to lean of a set up. High timing advance in the mid range only multiplys this problem.
To machine those domes you simply need a arbor to attach the domes to via the spark plug hole, I just turned down a peice of steel and it has the sparkplug threads(male) on the end of it, you chuck it up and check with dial indicator for run out, then spin on the dome and check the runout, usually very close. If needed adjust to 0.
Once thats done you just use the cross slide on the lathe, set it to 0 or 90 degrees cut, when you just touch the dome surface, then you cut straight in how ever much you need to increase your squish clearance to, once this is done you adjust the cross slide to the angle of the squish, if you want 10,12,14 degrees whatever you want, tighten it up and then slowly turn in from outside where you first cut straight, till you come to dome opening. Its that simple. So in your case youd simply cut into the dome edge where the edge of the bore is on dome .025" to have .050" total squish clearance in the engine with head bolted on with o-rings. After the straight in cut, set up cross slide to what ever squish angle you want and cut em, your done.
Yamablue
Member
Thanks for the explaination. It was pretty much all greek to me, but I talked to a machinist down in the shop and he knows what's going on and showed me on the lathe. I'm just going to take the original peak chambers that have aluminium melted on them and work on those. Man it sure is different talking to a manual machinist vs. a CNC machinist. The guy that made my new chambers is a hell of a programmer and machinist, but he just though it would have been too difficult to recut the old chamber.
ok, hope everything works out for ya . 