Cam timing Question? #6 or #1

[clm15]

I bought this engine,I have ran it for 5 nights.Runs like a champ. It has about 600 laps on it so this week I took it apart rebuilt it.
I checked the cam timing before I took it apart.The timing marks on the timing chain didn't line up? After a long nite of trying to figure out what im doing wrong,I figuerd it out.The timing lined up with #6 not #1. I have talked to a few engine guys and one told me it don't madder,The other said it shouldn't run.
Its a 388 chevy,and I put the cam back on #1 at centerline on the cam,I have not taken it to the track yet,But it sounds like a new engine. We won with it before, I changed the cam!
Anyone out there have any idea why they would time the cam on#6?

[Chaps46]

The 1 and 6 will always be at TDC at the same time. One on the compression stroke one the exhaust stroke. I think when you took it apart you had 1 at TDC but just on the exhaust stroke. So the cam gears was probably off 180..........

[clm15]

I went over this about 20 times. The Intake valve opened then closed,on number 1. This set number 1 ready to fire.The timing gears dots were both pointed up. Another revolution and #6 intake opened and closed,#6 ready to fire,Timing marks close but cam was behind the crank. This engine came from a well known builder,Not saying names but I don't think anyone else got to it since he built it.
I was told he experiments with things from time to time. My plan is to call him,but wanted to know if I could find out what everyone thinks he was trying to do. Thanks

[usafracer]

There is your problem you cant have both dots pointed up. One needs to be up and the other needs to be down so they are almost touching. If you had them both up then you are 180* out.

If that is the case then the builder migh have done the same thing.

[SLM98]

When the dot on the crank gear is at 12 oclock and the cam gear dot is at 6 oclock you are on #1 overlap.When the dot on the crank gear and the cam gear are both at 12 oclock you are on #1 compression,doesn't make any difference the cam is in time according to the dots.Remember the cam turns at half speed of the crank.

[dirty white boy]

I went over this about 20 times. The Intake valve opened then closed,on number 1. This set number 1 ready to fire.The timing gears dots were both pointed up. Another revolution and #6 intake opened and closed,#6 ready to fire,Timing marks close but cam was behind the crank. This engine came from a well known builder,Not saying names but I don't think anyone else got to it since he built it.
I was told he experiments with things from time to time. My plan is to call him,but wanted to know if I could find out what everyone thinks he was trying to do. Thanks

if timing marks line up,..then you spin motor 1 complete revolution an timing marks not lining up something is not right!!!

[fast_crew]

As mentioned, when the gears are dot to dot, the distributor would need to be set to #6 cylinder, because it is on the compression stroke.

[let-r-eat]

I'd just let a proven builder come and look at it. Show him how it was ect. If it was running on all eight chances are it was close. Not gonna run with cam and crank out too much......bad things would have happened.....

[mbaker76]

I think somebody already mentioned this but when the dots are lined up 12 oclock on the crank and 6 oclock on the cam thats actually #6 TDC firing position, turn the crank 1 time and it puts the crank gear back at 12 and cam gear at 12 oclock, which is #1 TDC firing position. It can be confusing because you hear TDC and think firing position but in reality both positions are TDC #1 cylinder, just different phases of the combustion cycle, one is firing and one is overlap. It wouldnt matter if the cam was ground 180 off because the firign order doesnt change and u still put the distributor in during the TDC of #1 firing position.

[clm15]

Cam was 180 out. I found out this is common practice for this engine builder. Both timing marks up.
I put the motor back together with new rings and bearings,It runs better then it did. I set the cam at 106 un like it was 103. It had the crank gear on retard so that was why the marks were off.Plus dial a cam sprocket from cloye. The cam button and the cam adj was broke,glade I pulled it when I did. Its a running fool now!
I think the builder was thinking it would help it in the slick. And it wasn't bad at all,just alittle lazy on the restarts. After running at speed it wasn't bad.
Like to thank all of you for the remarks. Thank you.

[mbaker76]

I still dont understand what you think was wrong with it?

When the dots are lined up that is TDC of both #1 and #6 pistons in the block, but only one is in firing position, and is actually #6. Turn the crank 1 time both pistons are back to TDC. It puts both dots up at 12 oclock and this is #1 firing. If you have the crank gear at 12 oclock it doesnt matter whether you put the cam gear dot at 6 or 12.

[fast_crew]

Agreed and to add to that, the distributor is the only thing that can be 180 out, and the engine won't run AT ALL like this.

103* compared to 106* would be advanced not retarded. Did you actually degree it (with a wheel, and positive stop), or just go by the marks?

[clm15]

Yes I put a wheel on it. I thought 103 was retarted from center line. I will tell you this thing is stonger then it was. The cam was dowlpin at 9 oclock and now 3 oclock. don't that make the cam 180 out?
Im a Bodyman by trade not an engine builder. But I guess I know enough to get me in trouble.Lol I just keep things simple stupid. Its been working for 20 + years.....

[Dirtrunner35]

Go find a old timer with some old engine books and the book will show you to line the marks up different than a newer book. And it also says to time in on Number 6. The marks together or both straight up is OK. You just need to put the dist in on number 6 firing order. So a dist CAN'T be 180* out and run.

[rubbinsracin]

now im no motor builder but i agree with Dirtrunner35. there has been a couple times at the track where i have had to pull the dizzy. i just note where it was when i pull it out to put it back in the exact same way. as long as you put the dizzy in where it is pointed to the correct piston that is firing, you should be able to fire it. you could have it set for any one of the pistons at TDC as long as you put the dizzy into the correct location it should fire and run fine. obviously when you are putting a motor together for the first time, it is best/easiest to set it at #1 TDC and go from there

[mbaker76]

There are 2 different timing events, you have valve timing, and you have ignition timing.

The cam position relative to the crank sets valve timing, which determines when the valves open based on crank position. With the timing dots lined up #6 is at TDC compression and the dowel pin will be to the right. The cam gear turns 1/2 speed of the crank so 1 revolution at the crank moves the cam dot from 6 to 12oclock which is #1 compression, and the dowel pin will be on the left. Thats why it doesnt matter whether the cam gear dot is at the top or bottom, because either way the vavles are tied to the crank rotation the same way.

Ignition timing sets the distributor relative to the cam position as well as the crank since they are tied together and determines when the spark occurs based ultimately on crank position. Like the previous poster mentioned, you can do this on any cylinder but #1 has in effect become the default. But if you had a marked balancer and bring #3, (or #2 or whatever) to TDC on the compression stroke, you can stick your distributor in pointing to that cylinders terminal in the cap and get the same end result. You can also set timing with a light off of any cylinder if you have a degreed balance at 90* intervals, just follow the firign order through 90* steps to know whether you should be reading at the 0 90 180 or 270 degree marks.