Thomas1971
Member
So a few years ago I was scrapping a 70’s Sears rototiller that had a good looking Briggs flathead 5hp on it so I kept the engine. I did some research on the engine and it turns out it’s from 1974. I also found that it is basically a Briggs Raptor II engine. But this specific model has a governor, a pull choke carb, a points style ignition system (being a 74) and a 3/4” by 1 1/8” keyed pto from the rototiller application. But last year I decided I was going to get it running but add a “few” performance parts...so here is what I did...
Performance block work;
I ported and polished the intake and exhaust alittle, not to crazy. I shaved the eye brows just alittle to give it better flow. I tapped and plugged the Governor hole.
Performance parts;
94ss camshaft
ARC billet 3.875 rod
ARC billet stock length lifters
20lbs valve springs
Heat treated lower spring retainers
ARC billet flywheel
22mm mikuni carb+custom intake manifold
Robertson torque tubes header
Non-performance block work;
I honed the cylinder for a fresh cross hatch, I installed a new exhaust valve guide, cut the valve seats, lapped in new valves, and plugged the points plunger hole with a press fit plug (Briggs part).
Non-performance parts;
New OEM crankshaft (correct pto)
New ring set
New valves
Upper spring retainers
New coil (non-points)
Burris Racing ball bearing side cover
PMI breather assembly
All new seals and gaskets
So that’s basically all I did to it. If any one that dyno’s engines can give me an estimate of how much horse power this engine makes (@6000-7000RPM on gas) i’d like to hear your guesses. I don’t have access to a small engine dyno so... yeah..
Performance block work;
I ported and polished the intake and exhaust alittle, not to crazy. I shaved the eye brows just alittle to give it better flow. I tapped and plugged the Governor hole.
Performance parts;
94ss camshaft
ARC billet 3.875 rod
ARC billet stock length lifters
20lbs valve springs
Heat treated lower spring retainers
ARC billet flywheel
22mm mikuni carb+custom intake manifold
Robertson torque tubes header
Non-performance block work;
I honed the cylinder for a fresh cross hatch, I installed a new exhaust valve guide, cut the valve seats, lapped in new valves, and plugged the points plunger hole with a press fit plug (Briggs part).
Non-performance parts;
New OEM crankshaft (correct pto)
New ring set
New valves
Upper spring retainers
New coil (non-points)
Burris Racing ball bearing side cover
PMI breather assembly
All new seals and gaskets
So that’s basically all I did to it. If any one that dyno’s engines can give me an estimate of how much horse power this engine makes (@6000-7000RPM on gas) i’d like to hear your guesses. I don’t have access to a small engine dyno so... yeah..