First assignment for Walkintall

C

Clayboy

New Member
I found a used engine a while back and want to put some big-time up-grades in it. I want this thing to be a power-house, but keep in mind it is just for fun. I would like to do a step by step progress report in this thread ,but please remeber this will take a while to complete so be patient.
I welcome anyone with any input to post what you think and later we will edit the thread to help it be more helpful and easy to read for the members.

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It is a Vanguard 20 HP 570cc
 
Ok, first things first. Let's put together a shopping list.
1) 265 lift cam
2) Extended rods
3) .040 main jets
4) tighter springs
5) Roller rockers
6) Billet flywheel (not sure if I want that ,cause you lose charging ability)
7) Machine .035 off the heads

This is just a list that I am looking at to get the most out of this engine. Not everything here will make the cut and some things will be changed. I want the max rpm to be around 7000 because with stock gears and current set-up that will be around 50 mph. I hope to get the power band to start around 3500 rpm.
 
If you want the power band to start at 3500, won't it flatn out too soon if your wanting 7000rpm out of it? I assume your putting billet connecting rods in it.
 
Frank, Yes on the billet rods. I was thinking the power band could really grab hold around 3500 and level off a little before 7000. Is this too wide of a curve? What do think would help keep the power more consistent.

Ace, I like having a stock drive system just for the fact that it will be easier to tune and the variable speed clutch system is very reliable. 90% of my driving is under 20 mph anyway so spending the money and figuring a gear set-up will just not be worth it to me. Belts are cheap! Don't take this the wrong way, but I really don't have much concern for the life of this engine as it is a toy for me to learn how to hot rod one.
 
With a lengthened rod you can shave the tops of your pistons,in order to get your rings closer to the head making a smaller chamber,which makes higher compression. You dont necessarily need them but billet rods are an good idea, longer or not. Was going to shave .070 off but found these rods and thought what the heck, lets see what can happen.
 
Oh ok, thats what I have in my black cart, but its store bought pistons...
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And shaving the heads. You can buy 110 octane near by right? That stuff is like $11-$15 a gallon...
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It should have plenty of power. These little EZGO motors I have with similiar mods are quite impressive.

Frank
 
There are a couple of stations around that are close to dirt tracks that sell race fuel. 110 is about $7.50 a gallon right now, so that ain't too bad. A good friend of mine that runs a mini tractor puller with a hot rod Kohler has recomended starting with a 50/50 mix of race fuel and pump gas and work my way up to find the happy spot that the engine likes. I just don't want to put too much heat on top of the piston right off the bat.
 
Thats a great price. I have to buy mine at a cycle shop,,, expensive. Not that it was necessary, but I used 100% 104 octane at the Bonanza.
 
It may be 106 octane, I'm not sure. I will have to check.
What do you think about removing the governor shaft completely. I know there are some oil slingers down there somewhere. I know they got to stay. And is removing the choke nessesary for going to a larger main jet? I have been told to do both of these items, but they were guys that do extream engines for racing. I still want this engine to hold up on a day of offroading, going 30 to 40 miles.
 
The motors I sell that have the higher horsepower, loose the choke, the antibackfire solenoid and the governor shaft. Like any hot rod, any restriction in air flow cost you power. They will be a little tuff to start during the winter if its been sitting a while. Thats about the only down side. Also on the carb jetting, these stock carbs can compensate quite a bit for the power increase without rejetting. The 60hp Briggs I sell uses the stock carb and jetting and the spark plugs burn a perfect brown with the dual pipes.

Frank
 
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