cmb 67 gold head break-in

[m brater]

Got 4 tanks of fuel thruogh it on rich needle leaning out 3 clicks each tank with no more than half throttle on new engine until 4th tank gave full throtle and went lean,it quit. Took out plugs and elements were twisted and won't light on both plugs. I'm using 20% redmax w/2%castor oil added,just runnin for sport.I'm die'in to run again but waters scared stiff. Do you fella's think I blew her up? thanks, Mike :unsure:

 

[Dan_Cousin]

Sounds like you went too lean. When it died, did it sound like it locked up / popped or did is just spin down to a stop. The EVO gold heads had a problem with the piston sticking when you got into it. If you ran it slow it would run all day long. When you leaned it out, it will make about a lap to a lap an a half and it'll pop then stops on a dime. Sounds exactly like a rod breaking.

The only cure is to run it rich and keep barely push the limits until it finally lets you play. Should take about a gallon or so.

If thats not the case. You probably just went too lean. Going lean is the main reason that plugs blow. Normally this doesn't hurt the engine.

The dual plug head on that engine is something most folks get rid of. Just doesn't work for some reason. Might be OK with low nitro though. Tidewater sells a single plug that is better.

What plugs are you using? We typically run Mccoy MC#9 or MC59, K&B HP or 1L.

The #9 and HP plugs are tougher than the other two but the 1L and MC59 offer better throttling and make the motor easier to start and keep running.

Tell us more about you're setup and I can help more if you wish.

 

[Lar'Dog]

Sounds like you went too lean. When it died, did it sound like it locked up / popped or did is just spin down to a stop. The EVO gold heads had a problem with the piston sticking when you got into it. If you ran it slow it would run all day long. When you leaned it out, it will make about a lap to a lap an a half and it'll pop then stops on a dime. Sounds exactly like a rod breaking.

The only cure is to run it rich and keep barely push the limits until it finally lets you play. Should take about a gallon or so.

If thats not the case. You probably just went too lean. Going lean is the main reason that plugs blow. Normally this doesn't hurt the engine.

The dual plug head on that engine is something most folks get rid of. Just doesn't work for some reason. Might be OK with low nitro though. Tidewater sells a single plug that is better.

What plugs are you using? We typically run Mccoy MC#9 or MC59, K&B HP or 1L.

The #9 and HP plugs are tougher than the other two but the 1L and MC59 offer better throttling and make the motor easier to start and keep running.

Tell us more about you're setup and I can help more if you wish.

Dan, I have a gold head.90 w/2 plug head,is there a single replacement for it? If so do You have a web address! Thanks much!!

 

[Chris Wood]

Sounds like you went too lean. When it died, did it sound like it locked up / popped or did is just spin down to a stop. The EVO gold heads had a problem with the piston sticking when you got into it. If you ran it slow it would run all day long. When you leaned it out, it will make about a lap to a lap an a half and it'll pop then stops on a dime. Sounds exactly like a rod breaking.

The only cure is to run it rich and keep barely push the limits until it finally lets you play. Should take about a gallon or so.

If thats not the case. You probably just went too lean. Going lean is the main reason that plugs blow. Normally this doesn't hurt the engine.

The dual plug head on that engine is something most folks get rid of. Just doesn't work for some reason. Might be OK with low nitro though. Tidewater sells a single plug that is better.

What plugs are you using? We typically run Mccoy MC#9 or MC59, K&B HP or 1L.

The #9 and HP plugs are tougher than the other two but the 1L and MC59 offer better throttling and make the motor easier to start and keep running.

Tell us more about you're setup and I can help more if you wish.

Dan, I have a gold head.90 w/2 plug head,is there a single replacement for it? If so do You have a web address! Thanks much!!

I used to run the 67 gold evo motors.. had one running 91 mph before i give it up...

You WILL POSITIVELY NOT BLOW THAT THING UP.. impossible.. i have tried.. started the motor went full lean on the bench full throttle just to see lol.. won't happen..

The wrist pin is a big issued with these motors( there is a fix )

Take the wrist pin out.. clean the rod. take some w-d40 and chuck the pin in a cordless drill. go back and fourth in and out with the pin in the rod. till the pin FALLS in the rod with no drag..

It will take a while..

also. on the zimmerman disc.. if you want the motor to run right it HAS to have NO MORE than .0003 clearance..

hope i helped out.

chris

 

[Dan_Cousin]

Chris, I think you have too many zeros in that clearence. 0.003" is the clearence I've been setting mine.

Tidewater Engineering in Bastrop LA has single plug heads for the 67 and 90. (318) 281-2460

 

[Chris Wood]

Chris, I think you have too many zeros in that clearence. 0.003" is the clearence I've been setting mine.

Tidewater Engineering in Bastrop LA has single plug heads for the 67 and 90. (318) 281-2460

lol yep to many numbers...

chris

 

[m brater]

Dan and Chris, thanks for the help and info. I forgot to mention its a cam(has drum rotor) not an evo. I'm running mc59's, was told this was a hotter plug to run better w/ lower % nitro. Was wondering if I should take out the head shim maybe it would run better on the 20% or wait after break-in? thanks, Mike

 

[Dan_Cousin]

I'm pretty sure the can had the same piston and sleeve problem as the EVO. Just keep running it rich gradually lean it out and you'll have a good motor.

Don't take a shim out unless you can measure the head clearence. If you can, set it to between 0.010" and 0.014" and you should be good for general purpose running.

 

[Don Ferrette]

Dan and Chris, thanks for the help and info. I forgot to mention its a cam(has drum rotor) not an evo. I'm running mc59's, was told this was a hotter plug to run better w/ lower % nitro. Was wondering if I should take out the head shim maybe it would run better on the 20% or wait after break-in? thanks, Mike

Try it richened up & with an MC-9. Even with 20% I feel the MC-59 is too hot a plug. BTW- those CMB cam motors run real well on 50%.

 

[[email protected]]

Chris was absolutely right when he said The wrist pin is a big issued with these motors( there is a fix )

 

Take the wrist pin out.. clean the rod. take some w-d40 and chuck the pin in a cordless drill. go back and fourth in and out with the pin in the rod. till the pin FALLS in the rod with no drag..

Tidewater used to sell the gold heads on clearance for $150 and they'd give you a bag of new wrist clips and tell you to replace the old one before you ran the motor or you risked blowing it up.

Also, the needle knob is the kiss of death if you don't give it a squeeze w/the old channel locks. The vibration would actually vibrate them so much they'd actually turn in or out. You need a 3rd channel for sure w/a CMB or you'll have real problems.

I wish Tidewater still had them for $150 because I loved the gold heads, never bothered to go to a single plug as I never had a problem w/the dual plugs. I always ran McCoy 9's, another thing you'll need to do to the plug is take a dental pick and pull the first coil of the element out a little so it protrudes. It'll allow the motor to run much hotter. And Don was right, 50% is the way to go (I always used 50% RedMax)

 

[Scott Norris]

Chris was absolutely right when he said The wrist pin is a big issued with these motors( there is a fix )

 

Take the wrist pin out.. clean the rod. take some w-d40 and chuck the pin in a cordless drill. go back and fourth in and out with the pin in the rod. till the pin FALLS in the rod with no drag..

Tidewater used to sell the gold heads on clearance for $150 and they'd give you a bag of new wrist clips and tell you to replace the old one before you ran the motor or you risked blowing it up.

Also, the needle knob is the kiss of death if you don't give it a squeeze w/the old channel locks. The vibration would actually vibrate them so much they'd actually turn in or out. You need a 3rd channel for sure w/a CMB or you'll have real problems.

I wish Tidewater still had them for $150 because I loved the gold heads, never bothered to go to a single plug as I never had a problem w/the dual plugs. I always ran McCoy 9's, another thing you'll need to do to the plug is take a dental pick and pull the first coil of the element out a little so it protrudes. It'll allow the motor to run much hotter. And Don was right, 50% is the way to go (I always used 50% RedMax)

What pipe worked best with the Evo 67 in your opinion?

 

[[email protected]]

I had the best luck w/the slim CMB .67 black pipe. I tried every pipe and that one was money.

 

[Chris Wood]

I had the best luck w/the slim CMB .67 black pipe. I tried every pipe and that one was money.

totally agree.. the only pipe to run on that motor 11 1/8 - 11 1/4 long on a hydro..

chris

 

[Scott Norris]

I had the best luck w/the slim CMB .67 black pipe. I tried every pipe and that one was money.

totally agree.. the only pipe to run on that motor 11 1/8 - 11 1/4 long on a hydro..

chris

How are you measuring that Chris? The Fat pipe has a band at the fat part and then a big seam, or weld. And are you measuring from the plug or from the case center? Also I take it that a Mono setup would be a little longer, or should those numbers work OK.

Oops, I see you are discussing the CMB Slim Pipe. Seems you and your Dad disagree on which is the best pipe to use. Might just have to try both huh.

 

[Chris Wood]

sorry scott.

i thought he was talking about the FAT PIPE.. that is the ONLY pipe to run on these motors.... i measured from the center of the case to the WELD JOINT on the pipe.. give it a wirl. let me know how it works out.

chris

 

[Scott Norris]

sorry scott.

i thought he was talking about the FAT PIPE.. that is the ONLY pipe to run on these motors.... i measured from the center of the case to the WELD JOINT on the pipe.. give it a wirl. let me know how it works out.

chris

Great! The Fat Pipe is what I have!! I'll let you know how it works after Atlanta.

Thanks to you Chris and your Dad, Steve!

 

[Chris Wood]

no problem scott. that is what we are hear for....

let me know how things works

chris

 

[mark voorhies]

I had the best luck w/the slim CMB .67 black pipe. I tried every pipe and that one was money.

totally agree.. the only pipe to run on that motor 11 1/8 - 11 1/4 long on a hydro..

chris

How are you measuring that Chris? The Fat pipe has a band at the fat part and then a big seam, or weld. And are you measuring from the plug or from the case center? Also I take it that a Mono setup would be a little longer, or should those numbers work OK.

Oops, I see you are discussing the CMB Slim Pipe. Seems you and your Dad disagree on which is the best pipe to use. Might just have to try both huh.

Scott,

Lots of good info.here, mono pipe on big belly CMB about 3/8th longer than hydro.

 

[Scott Norris]

I had the best luck w/the slim CMB .67 black pipe. I tried every pipe and that one was money.

totally agree.. the only pipe to run on that motor 11 1/8 - 11 1/4 long on a hydro..

chris

How are you measuring that Chris? The Fat pipe has a band at the fat part and then a big seam, or weld. And are you measuring from the plug or from the case center? Also I take it that a Mono setup would be a little longer, or should those numbers work OK.

Oops, I see you are discussing the CMB Slim Pipe. Seems you and your Dad disagree on which is the best pipe to use. Might just have to try both huh.

Scott,

Lots of good info.here, mono pipe on big belly CMB about 3/8th longer than hydro.

Gotcha, This Forum is worth it's weight in Gold!!!!

 

[[email protected]]

Man,

you guys got me scratching my head?? I went down to my scale to prove you guys wrong that the skinny pipe was better then the fat pipe. I popped the cowl off and ****, I have the fat pipe. :lol: :lol:

I rememer why I liked the skinny pipe now. It was the one I used well on my CMB .45. My fault for screwing that up!... :lol:

Gotta love this board!