engine running funny

[firebane]

So I found tdc and it appears that my tdc is about 3* btdc but wouldnt that make my true degree reading 25*?

TDC will never be perfect 0. It may be off a degree or two which is normal.

 

[Mmoore031908]

So there is nothing wrong with it being off 3 degrees or so?
I will tear it apart this weekend and let you guys know what I find. How many degrees does a double roller timing chain stretch after break-in?

 

[firebane]

So there is nothing wrong with it being off 3 degrees or so?
I will tear it apart this weekend and let you guys know what I find. How many degrees does a double roller timing chain stretch after break-in?

Double roller shouldn't stretch much at all. My original chain was sooooooooooooooooo bad I could almost squeeze it completely together in the middle.

When finding TDC remember to never roll it backwards. Always go clockwise and if you pass by TDC go around again and again until you get it perfect.

 

[rich weyand]

So I found tdc and it appears that my tdc is about 3* btdc but wouldnt that make my true degree reading 25*?

I assume you mean that when the #1 piston is at true TDC, the timing tab shows 3* BTDC on the wheel. In that case, the three degrees SUBTRACTS from your reading (that is take 3 degrees off the wheel reading, so the wheel reading 3* BTDC means the crank is at true TDC), so your timing showing on the wheel at 22* BTDC is actually 19* before true TDC. Which is a good spot if it's not knocking.

Why it's running so stinky is still a mystery. That is a lot of cam for a small motor, but it shouldn't flatline in the mid-range, if anything it should wake up there.

Something else is going on....

 

[Mmoore031908]

Like I said I'm going to start from scratch and see what's going on. To make sure everything is correct just in case I missed something.

 

[rich weyand]

Another stupid question, but this did happen to me. At one point, when I was messing around getting the throttle linkage sorted, a wobbly cam on the throttle pivot interfered with the mech, and I couldn't get full throttle. I had to shim that little cam plate, and then all was good.

So, are you sure your throttle pedal/cable setup is getting the carb fully open? If someone pushes the pedal all the way down, can you see that the throttle plate on the primaries in the carb is getting fully opened?

 

[Mmoore031908]

So I hadn't put it back together yet but I took it down and somehow my cam was retarded. At TDC instead of the cam gear being in the 6 o'clock position the dot on the gear was at about 5 or 5:30. And the crank gear was pointed about 11 or 11:30. Not sure how that happened since I degreed it and knew where tdc was. But that would explain why it was retarded. My cam timing was in fact retarded.

 

[79K10]

so can you just advance it now or do you have to pull the timing chain off and turn it?

 

[firebane]

So I hadn't put it back together yet but I took it down and somehow my cam was retarded. At TDC instead of the cam gear being in the 6 o'clock position the dot on the gear was at about 5 or 5:30. And the crank gear was pointed about 11 or 11:30. Not sure how that happened since I degreed it and knew where tdc was. But that would explain why it was retarded. My cam timing was in fact retarded.

No degreeing should be done. The cam gears should be install with the upper dot at 6 and the lower dot at 12 and this indicates TDC @ #6 not #1.

TDC #1 would mean the gears are are 12 on the top and 6 on the bottom.

 

[Mmoore031908]

Yes tdc on #6 is what I meant sorry. But either way it was retarded. I have not had a
chance to start it up and drive it yet. When I drive it I will let you guys know how it goes.

 

[Mmoore031908]

79k10 yes I pulled the timing chain so that I could make sure it was all line up once again and correctly.

 

[Mmoore031908]

Ok so I got it running and it runs much better. It still seems a little sluggish below about 2000 rpm but once its over it runs like great. It spun to about 4000 rpm before I let off the gas. Also my throttle cable doesn't open the blades all the way. It is about 80% open when the pedal is on the floor. Will it not opening that much will that make that much of a difference and how can I adjust the throttle cable?

 

[firebane]

Ok so I got it running and it runs much better. It still seems a little sluggish below about 2000 rpm but once its over it runs like great. It spun to about 4000 rpm before I let off the gas. Also my throttle cable doesn't open the blades all the way. It is about 80% open when the pedal is on the floor. Will it not opening that much will that make that much of a difference and how can I adjust the throttle cable?

Yes not opening all the way can make a difference. But I would be also looking at your distributor weights and springs as well now and ensure they are all properly functioning.

 

[Mmoore031908]

I have another quick question. From what I have found it with cfm formulas my carb even though a 600 cfm is way to big for my application. If the carb is too big how will that affect my a/f ratio if at all. The reason I ask is at idle it is very sluggish like its either lean or rich and seems to clear up above about 1800-2000 rpms.

 

[firebane]

I have another quick question. From what I have found it with cfm formulas my carb even though a 600 cfm is way to big for my application. If the carb is too big how will that affect my a/f ratio if at all. The reason I ask is at idle it is very sluggish like its either lean or rich and seems to clear up above about 1800-2000 rpms.

Depends on the carb. For example I have a 800cfm carb on my truck but it won't use all 800cfm and will only use what it needs.

If you think it maybe lean or rich then you need to look at things like idle speed, idle speed mixture, float levels etc. There are a lot of working components to a carb that may need tweaking or adjusting to get things right.