13 replies to this topic

[Tony.p2]

Hey Engine Gurus.

 

Its been a while since I've worked one of these so correct me if I'm wrong. If I set #1 piston at TDC and then install the cam and line up the timing marks dot to dot, shouldn't the motor be on the power stroke as in both intake and exhaust closed and dizzy firing on #1 piston. As you can see in the photo it shows #1 intake valve about to open. What am I doing wrong?

 

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[S pack]

Been a long time for me too. At the end of the day just chuck it all in and sort it out later. Install the cam and line up the appropriate timing marks. Looks like you are going with the 4 deg advance so line up the dot on the cam gear with the +4.

 

Install your lifters, push rods & rockers and turn the engine over until the valves on cyl 6 are on the rock and mark on the balancer lines up with the 0 mark on the timing cover then install your dissy to fire on cyl 1.

[rodomo]

If no.1 inlet is opening, no.1 exhaust should be closing? If that is the case, no.6 is firing and as Dave says, all should be ok.

Something I've never noticed though but I have a cam and crank in the shed and if I remember, will look tomorrow.

Edited by rodomo, 14 August 2018 - 11:37 PM.

[Dr Terry]

Yeah, many engines do that, even SBC V8.

 

Dot to dot is TDC of the exhaust stroke on No 1, but TDC of the power stroke of its opposite cylinder, no. 6.

 

Dr Terry

[Tony.p2]

Thanks for the feedback guys. Dr Terry so in this case you would set the dizzy to be firing on #6. Here is some more info on the issues I have had trying to get this motor to run correctly.

The motor is in a car I recently bought. The engine would start first go and pretty much idle straight away but just didn't sound right , like it was muffled if that makes any sense. I could rev the engine to about quarter throttle but anything over that and it would blow atomised fuel out the top of the carby, instead of sucking it in, and it would loose revs rapidly until you backed off on the throttle. I checked the carby, put a kit through it and jetted it down thinking the engine was getting to much fuel. Fired it back up and it still had the same problem. I then connected a timing light only to find that the timing at idle was somewhere around +40 to +50 deg advanced at a guess. Setting it back to +6 deg, it barley started and coughed and spluttered .I also tried it turning the dizzy 180 deg which made it back fire through the carby. I then tried another dizzy, and checked TDC, still no change. I then decided to dig deeper and remove the timing case for further investigation. At TDC #1 piston the cam timing mark was 180 deg out,so I decided to remove the cam and reinstall the Cam by lining up the timing marks which is where I'm at the picture above.

 

Tony

[Dr Terry]

Have you checked to see if the balancer outer ring has slipped ?

 

In other words is TDC really TDC ?

 

Dr Terry

[Tony.p2]

Yes Dr Terry, I have checked the balancer against a spare new one that I have.

[S pack]

I then decided to dig deeper and remove the timing case for further investigation. At TDC #1 piston the cam timing mark was 180 deg out

Turn the crank another full revolution and the timing marks will align. Remember the crankshaft makes two full revolutions to every one revolution of the camshaft.

[Tony.p2]

Hi Dave, yes the crank does make 2 full revolutions to one of the cam. My issue is that when the CAM timing mark is positioned towards the crank, the inlet and out let valves should be closed in order to set timing at # 1 piston TDC. I'm have never seen this on a cam where you cant set your timing on number 1 piston TDC and timing marks dot to dot. When you aligned the timing marks on this cam, its actually TDC on number 6 and inlet about to open on number 1, if that makes any sense .To set the timing on #1 piston TDC, you have to rotate the cam 180 deg. Again I have never seen this before. 

[I'm a Red Motor fiend]

Dave pointed out above it has been set up 4 deg advanced, but you didnt acknowledge this? If your crank gear was at zero on the keyway instead of being 4 deg advance you would have to turn the crank in order to line up the marks therefore your pistons will be positioned differently to where they are now? Not sure if this is the issue though?

[S pack]

Hi Dave, yes the crank does make 2 full revolutions to one of the cam. My issue is that when the CAM timing mark is positioned towards the crank, the inlet and out let valves should be closed in order to set timing at # 1 piston TDC. I'm have never seen this on a cam where you cant set your timing on number 1 piston TDC and timing marks dot to dot. When you aligned the timing marks on this cam, its actually TDC on number 6 and inlet about to open on number 1, if that makes any sense .To set the timing on #1 piston TDC, you have to rotate the cam 180 deg. Again I have never seen this before. 

Hi Tony, I get exactly where you are coming from.

As Dr Terry has informed us, many engines are like this, incl the small block chevy.

Probably explains why many home mechanics, including myself, have swapped over the cam in a Holden red 6, installed the distributor to fire cyl #1, put the rest of the engine back together and then found the engine was backfiring out the carby.

Edited by S pack, 16 August 2018 - 11:24 AM.

[Tony.p2]

Hi Adam. I agree with every comment that has been offered, and I'll be going with Dave's first suggestion on how to set it up. I didn't acknowledge the 4 degree advance as I was trying to understand why the cam is the way it is. As for the 4 degrees advance, I think that is part of the problem as to why I cant rev the engine. The spec sheet for the cam mentioned only 2 degrees advance but I'm actually going to remove the crank gear and set it all back to zero to see if that eliminates the problem, as I'm not chasing performance. I just want to get the old girl on the road. Thanks to all of you who have offered your thoughts and suggestions.

[I'm a Red Motor fiend]

Yep, I think that's a good idea mate.

[I'm a Red Motor fiend]

Or better yet if you have the cam card and the know how, dial it in.