exhaust bolt patterns

[k&b guy]

need some help. are the exhaust bolt patterns the same on a mac21 p.h. & a cmb 21 p.h.? CARTER

 

[Mike Hughes]

There are no exhaust bolts on either (like OS, K&B, & others). They have exhaust stubs.

Mike

 

[k&b guy]

i`m learning!!!. let me rephrase that. are the stubs the same size? the reason i`m asking is i ordered the mac & a silver bullet pipe & header. they needed to make a adapter between eng. & header. they asked if the mac & cmb were the same. from what i`ve read i said yes. yes/no? CARTER

 

[Mike Hughes]

I seem to remember seeing somewhere that there is a slight difference but they are interchangeable. I am not positive. I have a MAC to measure. Its stub is .590". I don't have a CMB.

Mike

 

[k&b guy]

thanks for your input mike. i`m in new territory here!! CARTER

 

[Mike Hughes]

Maybe you should start a new thread with a question of the CMB stub size.

Mike

 

[k&b guy]

kinda looks that way. guess i`ll find out when everything arrives. CARTER

 

[Jerry Wyss]

kinda looks that way. guess i`ll find out when everything arrives. CARTER

Two headers that are made for 21 car & buggy engines work on most of these o/bs

we run, Ofna Part#31991 "Manifold,.21 W/Spring, Polished and the other is a Dynamite

product. I don't have the Part number in my immediate vision but they're all black

with a seperate ring that has two holes for the spring. I don't see the Dynamite header

in tower anymore and the hobby shops I have checked don't seem to have them ,

maybe they went outa buisness???

The CMB will probably fit even though I've never used one,,, if it don't there is a multitude

silicone gaskets in car hobby shops where ever you find them.

I'm in need of the Dynamite model myself for the VZ due to a Whacking at the last club race.

 

[Jerry Wyss]

I found the Dynamite header part number, "DYN6602" 21 Rear Exhaust Off-Road Manifold, Has Been Discontinued*

I located one in a Beaverton, OR hobby shop.

 

[k&b guy]

im getting the pipe & header from htb. he said he needs to make a adapter between eng. & header.he knew what adapter the cmb takes. his ? and mine is are the mac & cmb the same size? CARTER

 

[Boatshop]

Hi Carter,

I bought 2 Silver Bullit HP Pipes with headers, & adapters, for MAC-21 OB, From Mark at HTB last summer.

Very nice set-up, fit my MAC's exaust stub's very well. They clamp on tight, and best part, you don't need any

springs to hold the header on the motor.

Dave,

P.S. If I can I'll post a pic of one.

 

[Boatshop]

Hi Carter,

Just measured 1 of my MAC's @ 0.632

Dave

CMB Valvola Green Head Inboard stub is 0.592 With out the rubber header gasket.

 

[k&b guy]

thanks boatshop!!! that`s the answer i`ve been looking for. unfortunately i told mark i thought the stubs were the same size. i`ve never seen this type exhaust before. might have to do a little mach. when everything gets here & i get a look at it. thanks for the info. CARTER

 

[Jerry Wyss]

Tower Hobbies, $22.70, fits the Mac O/B perfect. Cheap enough to have two

 

[tnrcboatracer]

You can also check ebay. I got a complete header and pipe set for $5 + $4.50 shipping. I then resold the pipe for about $2.00