Timing with mismatched parts

JEFFREYAB1968

MEMBER
CHEVROLET NOVA

I have replaced the original inline 230 in a 1966 Chevy II Nova with a 250. I used the timing gear cover from the 230 and I am having a hard time getting the timing set (please don't giggle I am not a mechanic, this was a project for me and my ten year old son to try). Is there any way to use the timing marks on the 250 harmonic balancer with the cover plate of the 230 to find top dead center? Or can anyone give me an estimate of where the balancers mark should be? Once I get it to TDC I think the rest of it should fall into place with getting the distibutor set the right way.

3 Replies

MIKE H R

MECHANIC
3,094 POSTS

230 and 250 engines are just about identical. The timeing I believe is 4 degrees before tdc. If unsure about getting it to tdc, do what my father taught me years ago. Take out the plugs. Make sure you mark each wire to corresponding order. Turn over the engine by hand. Look in number 1 cylinder. You should have enough room to see inside. Do you have the valve cover off? If not its all right. It would just make it easier. Put your thumb over the number one hole and turn the engine you will feel when it is on the compression stroke the pressure will push on your thumb. Once you feel that stop turning the engine. Look at the piston then turn the engine over by hand again. The next time it comes the piston comes up it will be the exaust stroke. Turn the engine over slowely until the piston goes down and comes back up. When you see it up you will be close to tdc.

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Sunday, August 19th, 2007 AT 11:21 AM

JEFFREYAB1968

MEMBER
2 POSTS

OK, just this week I had found some information about getting a straight six chevy to TDC. After reading this it was kind of a duh moment. With the valve cover off turn the engine until both valves on #1 are closed, that puts it TDC. I did this trying to completely reset the timing on the chevy 250. After turning it to this point I found out, amazingly enough, that the timing marks from the cover and the balancer were exact. So any one woundering about this, to my experience, the timing marks for a 1966 230 and a 1972 250 are identical. If it's not perfect I got it pretty close, she fired right up! Thanks for the post M J, that's about the only info I could get on the net. I believe with the valve method I used there is a chance to get the timing 180 degrees off.

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Sunday, August 19th, 2007 AT 12:45 PM

MIKE H R