# Toro 421, Predator engine swap?



## frankjc

I am considering a Harbor freight Predator engine for my Toro 421, which threw a rod through the block last winter.
With a coupon that can be had pretty cheap. I have seen a few Tecumsehs on CL, but the price of a new Harbor Freight engine is pretty tempting.
Anything I should know before I do this? 
Thanks.


----------



## 43128

not really, its pretty much a direct swap at least on a toro 521. the only thing you will have to change is is the bolt for the belt guide and the engine crankshaft bolt


----------



## Shryp

You will also need to change the arrangement for the chute crank. The new engine will be a bit wider.


----------



## 43128

whoops left that out


----------



## warreng24

Watch the linkage carefully when you use it. It tends to get gummed up with the snow you're blowing and it can freeze up on you.

A few members have made a shroud/cover to keep crap out of the throttle and governor linkages.


----------



## 43128

this is how i extended my crank arm, i used one long bolt, one nut and two locknuts. very simple and it allows you to reuse the existing holes and bracket


----------



## frankjc

Looks good. What size is the crank bolt for the predator?


----------



## 43128

crank bolt is a 5/16-24(aka 5/16 fine thread) and the bolts surrounding the crankshaft are the same


----------



## 43128

i was also able to reuse the existing kill switch, simply cut off the existing plug where they connected to the old engine, extend the wires, and follow the pics for the rest. both switches will function normally


----------



## frankjc

Looks good! I'll be doing mine some time soon. Hope I won't need it as much this year as last.


----------



## GtWtNorth

Farmers almanac seems to think you will.

Cheers


----------



## frankjc

Do you guys run them with or without the air filter?


----------



## YSHSfan

Some with, some without it. I chose to take it out.


----------



## Shryp

I leave mine in. I figure if there is a problem it won't take long to remove and if there isn't a problem it will add a little extra protection.


----------



## 43128

i leave mine it, hasnt iced up yet


----------



## frankjc

I'll try with the filter and see how it works out.
Thanks again.


----------



## chet0729

I just did this swap on a 3521 with the HF engine.
3 of the 4 are very easy to get a ratchet on from underneath. One I had to use an open end wrench on.
I used some spacers I bought at Home Depot to move the auger control mount out so the rod would clear the engine


----------



## Bdpittt

Doing the operation NOW on a Toro Power Throw 622. Engine output pulley, and rework of chute crank are the only things I've run into. Otherwise going smooth as can be. I'm using a $99 predator 6hp I think, can't remember for sure as I had put this motor on a different blower 2 years ago that now has a transmission problem and its from the 1960's so parts are a joke. At least this Toro is fairly newer model. Less than 30 years old is newer to me. Anyway, the swap should be nearly painless. If I run into any other issues or problems, I'll get back on the thread and let you know.


----------



## frankjc

Where is the best place to get the sleeve to fit the 1" pulley onto the 3/4" output shaft on the predator engine?


----------



## YSHSfan

frankjc said:


> Where is the best place to get the sleeve to fit the 1" pulley onto the 3/4" output shaft on the predator engine?


Ebay

Make sure that you get the proper lenght.

3 4" to 1" inch w Step Key Gas Engine Pulley Crank Shaft Sleeve Adapter Predator | eBay


----------



## frankjc

Finally got it done. The only problem I ran into was getting the pulley off of the old engine, some PB Blaster and a hammer (carefully) fixed that. I am not 100% happy with the spacer I made for the chute crank, I will probably replace that. Next I will wire the key switch.


----------

