O-ringed heads

[TB21]

Someone that runs O-ringed heads on a 260 merc give me the scoop on em good and bad....what to use for o-rings? where to get it? how to seal the water jackets up? who cuts em? will they hold up for lengthy lake use? I'd like to be able to swap from loose to tight heads without buying gaskets everytime. Thanks for any info. TB

[Rusrog]

o-ringed heads built for several reasons....

First of all...
No more paying out the nose for head gaskets from Mercury.
O-rings are much cheaper and can be had at most local supply houses. Found several places here in Ft Worth to get them from at GREATLY reduced cost.
Easier on the block...since you are not relying on pressure to seal the cylinder you can use less head bolt torque. I torque mine to only 30#'s since installing o-ringed heads.
I use Super Blue Permatex to seal up my water jackets...just a very thin coat does the trick...

Hope this info helps you out....


Russ Rogers
Ft Worth TX

[Russ]

Nothing but good in using these. All that the other Russ is saying too. The Mercury o-rings are pretty good, they're thick and stout and can be reused a number of times if they don't get frayed up too much. Don't have the part number for these handy, but can get easy enough. Also, if not using Merc's another one can be used as well. It a viton o-ring, stands up to high temps. Have to look that one up as well for the p/n.

[TB21]

Thanks Guys , Russ a part # for the merc 0-rings would be a help if you can locate it , and how pricey are they? Thanks TB

[stvhelm]

how often can you reuse the o-rings? arent the outer water jacket o-rings like $50 each?
what cc 0-ring head would produce about 165-170lbs compression?
im considering switching after what happened to my motor cause of bad head gaskets

[steve]

Were they Merc or aftermarket? Please reply to me by email if aftermarket. Thanks

[stvhelm]

I emailed you through the forum

[Russ]

TB, haven't forgot ya. Was real busy getting ready for the Westlake race. Man it was brutal down there! I've got the P/N at home, just put a new set on my heads. There not expensive either...

[TB21]

no problem.....how'd the races go? TB

[Techno]

I don't think merc is making their own O-rings. They don't even cast the clamps since they have ALCOA cast into them. At least thats what I surmise.
O-rings follow an industry standard of numbers. Once you find the diamater, inner or outer and the thickness you only need to choose material. The number and material are all you need.

If you want you can look up one at http://www.mcmaster.com/ for a price comparision.
A 5" ID 1/8" thick $7 for a pack of10 -Buna N
$8 each for Teflon-Encapsulated Silicone
$13 for 5 Viton

[Russ]

Personally I enjoyed myself, in my class. Lake Racer for the most part are a well behaved group of racers. Only 1 issue that put a sour face on a few in there. Overall, they're were issues with some racers in Pro Gas/Pro Fuel and Starting Barge starting sequence conduct and Start Barge performance. I'll leave it as being classified as "Human Factors/Sportsmanship/Start sequence conduct were not working well together in that race in those classes. Something needs to be done to take Human Factors out of the loop and something to control the racers to sequence them in line up all the way to release of the green fairly/equally. Anyways, here's your P/N: 859772 1 (Seal). Takecare, keep in touch...

[Casey]

thanks for putting me on the trailer so early, i got to see some good racing.:cool: that was a hell of a race between us, i just need a few more mph. later casey

[Russ]

LOL, I went out quick myself on Sunday. Robbie's STV is too well setup to beat out of the hole, same goes for Coonie, Shane as well. Yes, understood the pass we made looked real good and the pass Robbie and I made (2 STV's) on Sunday looked good as far as 2 STV's going at it. Prop work may be all you need Casey to pick up some of what your looking for. I've got more serious changes to make to get out of the "middle of the pack" Takecare...

[Casey]

i have done all the prop testing i can stand for this year. my problem is not in the prop, it's in the my lower unit. early this year i swapped my 1.87's for 2 to 1's. they work real good 1/8 mile, but it falls off fast after that. i pulled my lower unit off last night to have my 1.87's put back in. with the 2 to 1's and my 22 i was at 10K at half track. with the 1.87's i should have my rpm's back where they need to be for a full 1/4 mile.

[Russ]

that may help for sure. What do you have to weigh? Make sure you trim thyat thing good too. You were running abit low at Mt. Pleasant. Looking from the shoreline that is.

[Sashsqash]

I think you guys have it all wrong.

The two of you being good friends of mine and all. I dont want you guys running around like "Chickens with your heads cut off"
SO

I want to give ya'll the best advice I can come up with.

[Casey]

i'm running at 1800 (Modified Production rules). i'm running a stock drag block w/ 21cc heads and very light pistons and pins. your not the 1st to tell me to trim it. the list goes on and wally's at the top! i did trim it alot higher at west lake.

[Casey]

you bringing that thing out this year or are you scared? btw let me know when i can come over and have you weld that plate up for me!!!

[Sashsqash]

How did Wally get higher on the list than me. I have been telling you to trip up for a long time. Welding some tonight, Give me a call.

[Casey]

here's a picture i bought of us racing. i wish it would of looked like this at the end of the track instead of the middle.:D :D :D

[Russ]

Would be nice if I could have fit into the 1800 category. Think Im the only one running 1900+ lbs. 21cc heads is allot of compression. Im sure she's pretty snappy off the git go. 21cc was looked at on mine awhile ago on the dyno and after seeing the results elected to drop back to what essentially yielded 190 psi. Wanted something that would support both ends of the powerband and not favor one more than the other. Thats a nice pic...hate seeing myself behind though, although most passes I make, this is the position I see for the 1st half of the track! Who's this "Bigfoot" fella that butted in on us? Also, what does "2Time" stand for? Quit racing for 2 years in a row? Wooohooo...hehehe....la la la....

[Casey]

yep that's what it means! he quit racing 2 years ago when he got married. his wife said either no more racing or no more p&%%$.:p

[Russ]

the smart one's can get both! You going to Demopolis next month?

[Sashsqash]

HELL NO he aint going. Talk about P^@sy WHIPPED. :D

[stvhelm]

back on the o-ring subject. I know the o-rings are cheap, but the water jacket preformed o-rings are like $50each. someone mentioned using blue RTV sealer for the water jackets. would you use the silicone instead of the water jacket o-ring or with the o-ring? how often do they need to be replaced?
2nd question, what cc o-ring head would produce about 170-175lbs of compression on a 260? right now 28cc gasket heads give me that.

[Casey]

stvhelm i'm not real sure about the cc's because i run head gaskets, but i do remember seeing that it takes like a 27.2cc o-ring head to equel a 21cc head gasket head, but i could be wrong.

Russ i am not going to make Demopolis next month becasue the weekend after is the 1st DSRA race and i really wan't to make it becasue it's so close (3 hrs). i have my motor and lower unit apart right know trying to get it ready for the next race. i sure hope that chucky (2-time) shows up for it, because it's been a long time since he got his ass kicked my a little ol 2.5! you should really look into the DSRA. next year thay plan on having a lot more races.

http://www.byuboyz.com/forums/showthread.php?s=&threadid=3781

http://www.byuboyz.com/modules.php?s=&name=Content&pa=showpage&pid=21

[stvhelm]

in the mercury accessory guide it shows mercury 27.9cc , 43.9cc , and 52.9cc o-ring heads. it does say that the 27.9 o-ring heads are equivelent to 21cc gasket heads. now thats only about a 6cc difference to get the same compression. now I would think the next one up being 43.9cc's would be equivelent to the 26cc gasket head, but there is about a 17cc difference there. I must be missing something here. Im also assuming that the 52.9cc o-ring heads are to be equivelnt to 37cc gasket heads. thats only about a 15cc difference. I think i should stop assuming someone please explain:(

[Jay Smith]

O ringed heads have a machined squish band as the gasketed heads use the depth of the fire ring to create the squish. Hopefully you are running a blend of race gas to be succesfull running that compression ( 175 psi ) At that compression on pump gas in my opinion you are doomed to failure due to detionation and inconsisity of gas at the pump! I am a gasoline blender at the largest oil refienery in the world and believe me the acceptable tolerance of octain targets vary a great deal from region to region and state to state due to enviromental critireia. A cushion should be used for this reason. A person can run his hand in a bag with a rattlesnake in it and not get bit 9 out of 10 times but the 10th time BINGO your nailed. ( Piston and sleeve repair)

Just my experiences,

[stvhelm]

I doubt that will happen. At the rondak romp I had no choice but to fuel up with 89 octane on the trip back from the dam or run out of gas. Still the egt stayed under 1200 the whole way back. I also kept it around 95mph so mike could keep up.;)
Now, I wish someone could tell me what cc o-ring head will make about 175lbs or is equal to 28cc gasket heads.

[Jay Smith]

YOU know more about what compression numbers that will live and what won't in a 2.5 being in the head cutting and motor building business like you are than I do so go for it and send Jim Ruck's kids to Harvard ( your business and your money ! )

end of the subject for me !

[Techno]

I'm not sure that EGT readings are going to go higher on low octane gas. It's faster burning -maybe not hotter burning.
High Octanes sole advantage is it is a slower burning fuel to allow time for the flame front to progress. The lower octane on high compression allows this flame front to explode rather than progress. Or develop at the right area rather than the back or whatever. This may not be a temperture thing especialy way down in the exhaust. Your concerned with combustion temps not exhaust. Also it's a pressure rise which feeds itself and produces even more auto- ignition and more pressure rise.
I think eventually this higher pressure does produce more heat but may dissipate once expanded in the exhaust. Expansion= temp reduction.
If your going to run Hicomp heads you should be carrying octane booster as a safety filler.

On the O-ring/CCing deal I think they're comparing the heads. 27 and 21 are almost the same volume. 47 and 59 are not quite as close together but are closer than 26 and 49.
Equivalant to heads not gaskets on those particular heads?

[Pale Rider]

the pale rider wonders why someone would retard timing and have a motor run super fat to run high compression. I think i'll just listen to jay smith on this one and spare my wallet from silly experiments. just like on the frontier, a man has got to know his limitations.
pale rider is with jay smith on this one, all the way.

[Earl Moorman]

Stvhelm, I must not measure the cc's of o-ring heads the way everyone else does. I measure the cc's of the chamber its self not including the relief or squish machined in the head, with that in mind the o-ringed heads should be the same as the head gasket heads 28cc's.

[steve]

Ok this is like the 50th time someone has posted this.
Do some actual research guys----Octane is ONLY a measure of a fuels resistance to detonate. ( I believe Diesels use Cetane numbers). These are NOT a measurement of how fast the fuel burns. In fact the aromatics that vaporize first in many race fuel burn FASTER not slower then lower octane gasolines.
You need to tune the motor to the specific fuel for max performance as well.
Exploding fuel is called detonating. Preignition is when the fuel lights before a spark plug lights it. Fuel needs to burn to make heat not explode to make small useless pcs of aluminum .
Do your own test if you are a pyro. :eek:
Or ask some of the race fuel manufacturers--Trick, VP, Sunoco, Powermist, and see what you find.
Also Helmut and Novalves and a couple other guys are running some very high compression on low octane fuel. Can you guys share a little info on how that you are doing it? Most everyone agrees with around 145psi max on pump gas and stock heads and pistons. 30 more psi is 20% higher then the accepted norm. Sounds like another head design post is in order. ;) :p
Please share. :cool:

[stvhelm]

well I guess i shouldve detonated one by now since Ive been doing it for 5yrs now. Ive been doing 100hrs a season running like this. It runs even better when I take the front cover off the cowling to ram the air right down the bored horn:p. Here this was taken 4 yrs ago with the same heads and compression and the same 93 amoco gas. 2 people in my 1800lb full interior hydrostream virage turbo. the max speed was with me alone. my passenger took the shot. I did it then and I'll keep doing it now.

[steve]

Did you get your new head gaskets installed yet? Sooooooo are they factory style pockets? You gotta share man. I'm not denying you have been running them like that. I'd just like to know the how part. Email me if you want. Didn't you have a Virage a while back that Ron Pratt was telling me about?

[stvhelm]

yes, were all back together and running now. Lawrenceburg marine was a big help. they had my parts in stock and shipped to me overnight. I have the factory gaskets now. all better:D although breakin for the second time is a real bummer:( I'm making the best of it though. Ive been tubing and skiing with my son and his friends. I think a few reasons added up allow me to run the compression and octane that i run. first thing I know is that 2 degrees down on the timing will add about 200 rpm on the big end. second thing is more fuel and more air. I have a bored plentum which keeps vacuum at a minimun at wot. we all know the ecu reads off vacuum pressure. the less vacuum the more fuel and air delivered. I set the a63 box at 105 to be safe. she runs at 103 with no problem but for breakin and regular use I leave it at 105. third, I also swing a tall prop (28-32p). i do notice that small props like say a 24 will generate higher egt's while cruising. the motor is not working and is almost freewheeling using almost no gas which can cause a problem. a motor that is loaded is using fuel which ofcourse will burn cooler. a motor which is running alot of rpm with almost no throttle and little fuel is gonna run hot. combine these few things and it'll build power on the big end. thats my secret ssshh:cool:
now just for comparisons sake. i found a gas dock in town that sells 100octane on the water. Im gonna put my timing up and ecu down to 101-102 and see what difference on the big end is. I'll bet its nothing but better accelleration.

[steve]

Depending on the brand of race gas, try leaving the ECU at 105 or even add a little fuel and see what you get first. ;)
I understand your thinking, but even though the motor is running cooler and richer, I would assume the fuel will still detonate at nearly its same point. The rich / lean condition does effect the motors octane requirements but its not a huge amount. I hope it keeps working for you! Sounds like it is. The retarded timing does help the big end a bit, I definitely agree with that. Have you ever met Novalves out your way? He's north of the city I think. I was just out there in earlier this month, never met up with him but I wanted to. Just kicking some tires on the heads he builds. Take care!

[Russ]

I use just plain clear silicone for sealing up the outside perimeter of the head and Mercury o-rings around each jug. The 260 exhaust port timing is similar to what I ran at one point and with the heads I ran, 25cc was yielding 170-175 psi. Im recalling this quickly from memory, that water went under the bridge awhile ago and I've slept acouple times since then. But anyways...
Jeeze Jay, was that earlier response really needed!?