Reply With QuoteThe cam would have to be ground in the reverse direction in a four stroke. A two stroke will run backward.
But, uh, why on earth would you want to do this?
How do you make a engin rotate in the revers direction, what parts are needed
The cam would have to be ground in the reverse direction in a four stroke. A two stroke will run backward.
But, uh, why on earth would you want to do this?
I have a right hand trany and got the parts from a doner engine. I know it can be don it lets me run props off our 5 litre hydro.I have been building a glen L rampage and built a fixed surface drive .
The camshaft doesn't turn backwards on a reverse rotation engine. Instead of being driven by a timing chain it is driven by a two gear set. This turns the camshaft in the opposite direction of the crank. The distributor and oil pump would turn the wrong way if the camshaft ran counter clockwise! The camshaft also needs a special cam retainer between the timing gear and the block. The camshaft is still different because of the different firing order. Make sure that the rear main seal is for a CCW rotating crank or you will leak oil.
Sincerely
Dennis Moore
MERC MASTER TECH
Dennis Moore:
The camshaft doesn't turn backwards on a reverse rotation engine. Instead of being driven by a timing chain it is driven by a two gear set. This turns the camshaft in the opposite direction of the crank. The distributor and oil pump would turn the wrong way if the camshaft ran counter clockwise! The camshaft also needs a special cam retainer between the timing gear and the block. The camshaft is still different because of the different firing order. Make sure that the rear main seal is for a CCW rotating crank or you will leak oil.
Sincerely
Dennis Moore
MERC MASTER TECHAre you sure about this? A gear drive without an idler third gear rotates in the opposite direction and requires a different dist gear and starter rotation. Hense the crank rotates counter clockwise. I didnt know about the cam thrust plate but that would make sense, I think. The oil pump runs the correct way since the dist gear rotates the dist the same. You have me confused. I am trying to reverse rotate to run a R.H. prop for racing in circles. I also hear the harmonic balancer is different and the cam profile is unique. We used to run the old Isky 505 reverse grind cam with a two gear timing set and we had to use the reverse distributor gear to make it run. And it did at 8.58, 158mph in the quarter with a small block. Help me out please before I make an expensive mistake. The Jerk....I'm headed for the engine stand right now!!
There were several different ways of "reverse rotating" and engine.
One described here already was a 2 gear set for the timing gear. This allows stock distributer and oil pump. It is a custom cam, and needs a different starter. The harmonic balancer was the same on most engines. This is what is on my 1964 SBC engine from Chris Craft.
There was also a version that had a reverse rotating cam. This ment a custom distributer (for reverse points) and a custom oil pump added to the cam and starter. This was mostly done in the less common engines to "reverse" or with older technology. The big Inline 6 Hercs, for example.
The most common way today is to run standard rotation, and flip it in the transmission. Depending on your drive type, it may be a cheaper route to convert a drive, rather than convert an engine.
Yes the doner motor was a chis craft and yes it is a 2 gear drive .The trany that i am useing is a Paragon P- 31-R .I have a starter and would like to know where to get the cam that i need.
Most rebuilders can get it, as it is a basic engine. You just need to narrow it down. Do you know the year? (Only important for a rebuild. Small or large journal crank.) Is it a driect drive, or V drive? The term Chris used is "flywheel Forward" for the V drives. Assumming it is a straight out the back SBC from the 60s, you would have a 283F or a 327F. 8.0 to 1 compression with small valve truck heads that have an additional casting flange for mounting the raw water pump. These engines will readline about 4300, but the manual advises against operation "above 4100 rpm for any length of time" and it would void the warrantee to do so.
If you will be doing a lot to this, I have some good parts sources, and a lot of info on these engines. Feel free to e-mail me...
So far here I have not seen any mention of the pistons, they have to be reversed so that the wristpin offset is toward the other side. If your pistons have double eyebrows you can just put them in backwards. If not, you are hurting, custom pistons will be needed. Unless you plan on using the pistons from your donor engine?
DJ
ok this is what i think we used to run k boats old howards if your driving off the crank turn the motor around and drive it off the balancer this will reverse the rotation we ran them this way for years also the torque is right for left hand turns just a thought
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