valve events queston

[minimember]

I recently rebuilt my engine and now fear that the cam and crank may have rotated while putting the case halves together.

To verify this without taking apart the engine I assume that I need to know where each of the valve events should be when the #1 cylinder is at TDC.

Right now when I have the #1 cylinder @ TDC my current valve events are as follows:

#1 intake closed - Exhaust closed
#2 intake open - Exhaust starting to close
#3 intake starting to close - Exhaust closed
#4 intake closed -exhaust closed

Is it safe to assume that #3 should have an open exhaust and intake at TDC for #1?

[telford dorr]

As the firing order is: 1,4,3,2

#1 is at TDC on the compression stroke; intake closed, exhaust closed
#2 is at BDC on the power stroke; intake closed, exhaust opening
#3 is at TDC on the exhaust stroke; intake opening, exhaust closing
#4 is at BDC in the intake stroke; intake closing, exhaust closed
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[busdaddy]

[Wildthings]

I don't remember what engine you have, but if a type 4 remember that the timing mark doesn't line up with the split in the case. Most cams are going to have noticeable overlap at the top of the exhaust stroke.

[minimember]

Thinking about it, it does seem rather unlikely that the teeth rotated while putting the cases together but I would love to be able to check if not just for piece of mind.
If I were to get a snake camera, what what would be my point of entry to confirm that the 3 dots are in alignment? Doesn't seem like there would be much space to much of anything at the point the dots intersect.
I have a 70 type 2 engine, with a stock 69mm cam. The book I used to rebuild it mentioned that when I'm at TDC for #1, that #3 should be at overlap. which I am definitely not at.

So confused, have done plenty of valve adjustments in the past, but something about this has my brain in knots.

[busdaddy]

I'll have to look at one that's apart but I'll bet you could go in through the fuel pump hole, my scope has a 90 degree mirror on the end that does close up stuff like that well, I don't know if those "look inside the wall" cameras that you can rent from Home depot can get up that close.
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[vincev]

Cranks and cams are intended to rotate so no problem there. If you think they are out of time with each other then you will have to split the case to know for sure or just run it.

[williamM]

Simple test is put fingers on #3 valves and rock the motor thru #1 tdc. Its called the rock point. and those valves must move as #1 TDC comes across- Otherwise split the case.

Does your engine have stock rivited cam or some after market, "adjust -a - cam" front gear?

As they say "Well- that thars your problem - right thar "
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[minimember]

I thought for sure the dots were aligned and didn't shift when put the halves together, but the valves just seem funky. The events don't seem to make sense. Perhaps I set them in reverse, but I tried rotating the plugs 180 and still no luck. All that I get when I try to start the car is an occasional backfire. Obviously pulling it back apart would tell me for sure but can't I check to see if the cam and crank our out of sync by using the specs of the cam lobes (inlet opens 7.5 deg BTCD, closes 37 deg ABDC, exh opens 44.5 deg BBDC, closes 4 deg ATDC) and the degrees on my pulley to verify?

[/quote]

[Wildthings]

Looks like you only have about 11* of overlap at TDC exhaust, but it is overlap. You should be able to find the point this overlap is occurring. If anywhere besides TDC exhaust you know you have a cam timing problem.

[williamM]

Did you static time the engine to 7.5 degrees? with a trouble light? and found TDC with finger over #1 SP hole and did rock point show up on #3 rockers and your ig rotor points at #1 and ig wires go 1432- or as I do it backwards to 1234?

Did you leave the pistons out?

coil wired up correctly?

battery hooked up correctly?

Should be able to solve this in an hour.- so go take a nap and try again.
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some days I get up and just sit and think. Some days I just sit.

opinion untempered by fact is ignorance.

Don't step in any!

[williamM]