Heads up on Tool Tuff 420 engines...


New member
Hi, I'm not sure if this should go here, clones or elsewhere, but I wanted to share what I found. I bought this engine because it was $300, shipped. A Chinese 420 is a Chinese 420, right?


I'm not sure how the header I have coming from NR is going to fit, but I may have to swap heads. I was planning on a Stage 4 from NR at some point anyway, so I'm not too worried, but I wanted to save you guys from this, should a head swap not be in the cards. I suppose too, if you had an end mill, you could just machine the exhaust flange down to where it is on the Predators.

Additionally, it seems to be a bit of an oddball... It has a hex valve cover and is not a hemi, but it has the same airbox and filter as the hemi, and I believe the same carb and\or main jet as well (#98).


Last edited:


Dawg 89
Not having any idea whats differnt on the exhaust , I assume its flat coming out of the head vs that angled nub the muffler is attached too .
Good heads up .


New member
Yep, sorry... I guess I assumed the difference would be obvious. The Predator flange is machined vertically, while this is on an angle. The port is still round, though. It'll make port matching a header impossible because the header will be round. I'm also unsure if the stud spacing is different between the Predator and this thing. We will see later this week.


An exhaust port does not need to be matched to the header as long as it steps down into the pipe that is the correct method.


New member
Yep, but when a round port ends at an angle, you have an oval. And when you bolt a round header to it, you get a bunch of mismatch. Half the port has the step on the right side of the flow, the other half has it on the wrong side. Depending on my motivation, I may cut the flange off the header then grind it out to match the oval, then cut the header at the same angle of the head and reweld it together. Or I might just bolt it together and say screw it until I build the engine this winter.

Anyway, I just wanted to share this discovery so nobody else is surprised by it.