OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Victa , briggs quantam

Hi all, i have a victa corvette series 500 with a quantam engine. there no transfers left on the engine, only on the mower base.the engine has 35 quantam. could someone please tell me what HP these mowers are, i dont if the 35 is the model or the HP,but its bigger than my other 35 quantams, thanks micka

There are a couple of different styles of the 3.5hp quantum both being 3.5hp, one is the vertical pull type with the big plastic shroud and the bit that spins in the middle not covered by the starter. The Bigger type in my collection is one with the starter on top like most of the newer motors.

i have the one with the vertical pull start.the reason i asked was i had a few sets of rings given to me with just 4 to 5 HP written on them, but ended up not being right, i'll get the serial numbers together and order from the online store, it looked all good for a while but ah well not to worry. thanks joe

intereesting, one of my 3.5hp quantums is the same cubic capacity than one of the 4hp ones, i will check the older style one later on...

and the older style with the vertical pull is 10ci not eleven like the newer one

I think also i remember something about the quantum going to an over square design. 3.5 rings fitting a 5Hp or something.

Not sure why you would want to take torque away from an engine/

It would add torque being a long stroke and a small bore,

I had a 202 in my commdoroe a fairly square 3.3l rev happy six, and in my XF ute I had a 250 crossflow six, it had a very long stroke, did not rev very well but would pull harder at very low engine speeds.

On the other hand in one of my corollas had a 1.2l motor that was a big bore very short stroke, it revved happily to 8k while paddock bashing but severly lacked pulling power.

Joe is correct - all other things being equal, a longer stroke gives improved low speed scavenging and better low speed torque, but has weaker high speed performance due to higher frictional losses and limitations on maximum valve size caused by the small bore. However large bores cause combustion chambers to have large surface areas, increasing noxious exhaust emissions - and this means additional control measures have to be taken, which may reduce power and fuel economy. The outcome of all this is that modern engines broadly aim for a stroke of 1.1 times the bore, as the best overall compromise.

Some of the small Briggs engines have bores bigger than the stroke ("oversquare") which was an idea that seemed good at the time (mainly in the 1960s and early 1970s) but turned out not to be good in practice. However remember that what Briggs did was to make a range of engine sizes in quite small increments just by mixing and matching cylinders and crankshafts of different dimensions, without worrying much about bore to stroke ratios.

And some car engines are still oversquare, because it turns out to be the only way to get a large capacity into a small overall package size.

Nah, i was saying 5hp rings that fit a quantum 3.5Hp.

over square, bore bigger than stroke.



Bob.