Novarossi DD owners

[Tommy Levescy]

what pipe are yall getting the best results out of. Ive tried the zippkits pipe, a bouche copy, and a cmb .21 pipe(the newer one everyone likes) and can't get this dam thing to pull any decent prop. spins ungodly rpms but no grunt at all. this is in a sgx .21. Motor has lots of compression and ive got a .350 orlic carb on it.

 

[aaron alberico]

What head volume, clearance and pipe length you running on 21DD?

 

[ScottHowe]

I run the novarossi carbon fiber pipe from SPP

 

[P THOMAS]

The novi non muffled pipe worked better for me on my novi 21 dd motor, 7.5-8 inches long to weld.
I have a used one if you like to try it

 

[ALLAN YUEN]

Tommy which one did you use glow plug turbo or std? And tell shim measure?

 

[Greg Bonahoom]

What size props are you trying? I remember cmdi racing had a recommended props chart for 21’s and they liked smaller diameters like in the 45-47 mm range.

 

[Tommy Levescy]

Tommy which one did you use glow plug turbo or std? And tell shim measure?

standard, head volume and height set for 60%.

 

[Tommy Levescy]

What size props are you trying? I remember cmdi racing had a recommended props chart for 21’s and they liked smaller diameters like in the 45-47 mm range.

1817, 645,445,1445,cut down m447. honestly i threw the whole prop box at it and the only thing that ran but was obviously too small was a modified 645 that was detounged and had the tips rounded and it spun it like no tomorrow making all kinds of rpm and no speed.

 

[Marty Davis]

What head volume, clearance and pipe length you running on 21DD?

Aaron:

I turn off the top of the piston flat and run the stock head button at .008"

I have had BAD detonation with close squish and the domed piston. It is good this way.

I also run the SPP Rpm Pipe. Length depends on prop.

 

[Danny King]

standard, head volume and height set for 60%.

What is height set for 60%?

 

[Tommy Levescy]

Aaron:

I turn off the top of the piston flat and run the stock head button at .008"

I have had BAD detonation with close squish and the domed piston. It is good this way.

I also run the SPP Rpm Pipe. Length depends on prop.

it's set at .008. Stock button. orlic .350 carb. domed piston??? do you mean the pistion isn't flat and it had the "dimple" in the center or the piston is actually domed or rounded on top?

 

[AzMandella]

The piston has a dished top to it .

 

[Tommy Levescy]

The piston has a dished top to it .

exactly. when he said domed i didn't understand it being called that lol.

 

[aaron alberico]

it's set at .008. Stock button. orlic .350 carb. domed piston??? do you mean the pistion isn't flat and it had the "dimple" in the center or the piston is actually domed or rounded on top?

Reduce your bowl size, .16-.17cc

 

[John Beardslee]

it's set at .008. Stock button. orlic .350 carb. domed piston??? do you mean the pistion isn't flat and it had the "dimple" in the center or the piston is actually domed or rounded on top?

Tommy, I can’t speak for Marty but I’ve heard some were turning the piston in a lathe and making them into flat tops.

 

[Marty Davis]

it's set at .008. Stock button. orlic .350 carb. domed piston??? do you mean the pistion isn't flat and it had the "dimple" in the center or the piston is actually domed or rounded on top?

After the piston and head button get detonated, I turn off the top of the piston and buy a new button and set it at .008". There is still a slight dimple in the top of the piston. The stock head button has a 5.5 degree squish which I leave on the button. So the squish becomes 5.5 degrees rather than 3 degrees with the domed piston. John is correct....

 

[Brian Sorgente]

exactly. when he said domed i didn't understand it being called that lol.

It's not a standard dished piston with a flat top. It's actually tapered up (or domed). As you know, it also has a dish (or dimple) in the middle. If you remove it from the engine and put a straight edge across the top you'll see what he's talking about. If you didn't realize this when you measured the head clearance, depending on how you measured, it could be set to a different clearance than what you think.

Hope this helps,
Brian

 

[Charles Perdue]

IF you use plastigage (this was invented and developed for engine assemblers to be able to measure the internal clearances accurately) to check the piston to head clearance then you can see exactly the clearances, what is going on, whether it is flat top, tapered, domed, checking head squish angle, squish matched to the piston angle, ect.......you do not have to guess.

It is cheap, simple to use, dummy proof, accurate to tenths of a thousand of and inch in standard and metric measurements and sold at most good auto parts stores.

Charles

 

[Marty Davis]

IF you use plastigage (this was invented and developed for engine assemblers to be able to measure the internal clearances accurately) to check the piston to head clearance then you can see exactly the clearances, what is going on, whether it is flat top, tapered, domed, checking head squish angle, squish matched to the piston angle, ect.......you do not have to guess.

It is cheap, simple to use, dummy proof, accurate to tenths of a thousand of and inch in standard and metric measurements and sold at most good auto parts stores.

Charles

Exactly what I use Charles

 

[Charles Perdue]

It is what I use also....that is why I described it as "Dummy Proof"