looking for dimensions on 21 dd turbo head

[Ron Zaker Jr]

I would like to double check a dimension. Looking for the "depth " from the sleeve landing to the bottom edge of the squish. I come up with .161. Can someone chime in here and tell me what they get? thanks.

 

[Ron Zaker Jr]

Question answered thanks GQ.

 

[dave roach]

Ron

Get in touch with Ron Shaw and he can tell you how to set the head clearance.

919-697-1129

Dave Roach

 

[steve wood]

Use blue plasti gauge to check clearance. Should be .007 +- 001. Blue can be hard to find(at least in the sticks where I live)

 

[Ron Zaker Jr]

Use blue plasti gauge to check clearance. Should be .007 +- 001. Blue can be hard to find(at least in the sticks where I live)

thanks and that "clamp" is working great so far. More to follow.

 

[RonShaw]

Use blue plasti gauge to check clearance. Should be .007 +- 001. Blue can be hard to find(at least in the sticks where I live)

Ron

Get in touch with Ron Shaw and he can tell you how to set the head clearance.

919-697-1129

Dave Roach

Thanks Steve and Dave. Yes, .007 is great for 60-65% nitro. For those using Plastigauge, be very cautious. The squish taper on these engines (some modify higher than stock), can make using Plastigauge very costly. With the steeper angle of the taper at the wall of the sleeve, it not only makes "squishing" the plastigauge harder but it may also try to squeeze the plastigaige inward making this clearance inaccurate. Engines with a flat squish may be more accurate but with a tapered squish, I would suggest using a depth gauge the old fashioned way, taking in consideration the depth of the dish on top of the piston. If anyone needs help with doing this properly, please PM me and let me know. Thanks.

 

[Ron Zaker Jr]

Use blue plasti gauge to check clearance. Should be .007 +- 001. Blue can be hard to find(at least in the sticks where I live)

Ron

Get in touch with Ron Shaw and he can tell you how to set the head clearance.

919-697-1129

Dave Roach

Thanks Steve and Dave. Yes, .007 is great for 60-65% nitro. For those using Plastigauge, be very cautious. The squish taper on these engines (some modify higher than stock), can make using Plastigauge very costly. With the steeper angle of the taper at the wall of the sleeve, it not only makes "squishing" the plastigauge harder but it may also try to squeeze the plastigaige inward making this clearance inaccurate. Engines with a flat squish may be more accurate but with a tapered squish, I would suggest using a depth gauge the old fashioned way, taking in consideration the depth of the dish on top of the piston. If anyone needs help with doing this properly, please PM me and let me know. Thanks.

thanks Ron.

 

[steve wood]

Calipers won't work. Depth mike only works if you mike to the flat on the piston,then add .007 to .008.,To that number to find the top of liner to top of piston at top dead center,daunting for a novice. That's why I use and recommend plastic gauge for tapered (dome head) Pistons. The dimension needs to be measured at the bore I.d., not up the angle to the center. Factory squish angle is the same on the piston and on the piston, one reason why we mod the button angle. If you can't do this at home have some one else do it

 

[RonShaw]

Depth gauge threaded into the plug mount, not calipers. Steve, yes, calipers are not accurate, good point. That's why I also never recommend using them.,

 

[David Murany]

Zero out a thread in gauge by putting the button against the piston. Then reassemble and check. Most accurate way to do it. It requires taking the motor apart but it is simple.

 

[Marty Slater]

Steve are you going to bring a toy boat up here an play

 

[RonShaw]

Zero out a thread in gauge by putting the button against the piston. Then reassemble and check. Most accurate way to do it. It requires taking the motor apart but it is simple.

Bingo David. That takes the dish on top of the piston out of the equation.

 

[dr gary turner]

Had problems with plasti gauge. No way to get an accurate measurement of a tapered squish. With plasti gauge one is trying to measure a "knife edge"

A taper to an edge is really a set of points creating a line that forms a circle when the taper is done on a cylindrical shape, i.e. The head button

The question can one get an accurate clearence squishing a malluable material between a line and a solid surface? Maybe but not accurately.

I could not get my Nova DD to run using plastic gauge.

Had a great discussion about this with MTJ

SOOO, My methodology is as follows. I took a turbo plug bored it out and tapped it to take my acucheck I got from Bill Mc Graw.

So screwed gauge into the bored and threaded plug that is screwed into the head button and put this combo on a flat surface and found"O".

Then placed the head button with dial indicator in the motor with no head shims and take a measurement when the piston hits the head

button thus you can set the deck clearence accurately with a dished piston.

My Nova DD now runs great with .006 deck clearence on 65% punch. Rarely burn a plug.

Just my way of doing it and works for me.

BTW, boring the plug took some time due to the ceramic material in the plug.

 

[mtruex]

The Only way to do it RIGHT and CONSISENTLY is a dial gauge, zeroed with the piston touching the head!!!!

A little trick, after you zero head on engine you can check the dial gauge number on a flat plate. Then you can record that number and zero a different head button by putting your dial gauge at the same number with the head on a flat plate.

 

[RonShaw]

Great additional tips Doc and Martin. The steps and tips described above will help our novice and veteran boaters accurately measure their Novarossi head clearances properly, especially when dished pistons and tapered squish head buttons are involved.

 

[steve wood]

The Only way to do it RIGHT and CONSISENTLY is a dial gauge, zeroed with the piston touching the head!!!!

A little trick, after you zero head on engine you can check the dial gauge number on a flat plate. Then you can record that number and zero a different head button by putting your dial gauge at the same number with the head on a flat plate.

exactly right, but most people don't have the indicator set up, especially for a turbo head

 

[RonShaw]

Daniel makes the adapters for standard and turbo heads and provides a complete setup with either a digital ($70) or analog gauge ($52) which is a great deal and insurance policy on making sure setting the head clearance is done correctly. Here is the link.

http://www.intlwaters.com/index.php?showtopic=45405