All Small Six 170 issues

[Rodders]

Have been having ongoing issues that I just can't seem to resolve.
I rebuilt my 170, first time ever done an engine. Replaced pistons, rings all the gaskets and bearings etc. I got it running finally after a lot of tinkering. It has compression readings of 100psi on each cylinder. I have put some oil in each cylinder and the checked and stays about the same, so pretty sure rings are sealing ok.
Is the head leaking? Somewhere?
I have checked and re checked the rocker spacing, timed the engine, checked points, replaced the advance valve thing on the distributor.

When try to drive it, it has no power and will stall under virtually any load.

I am really struggling to work out what's going on and honestly at point of giving up.... Not one to be beat but it's been 6 months of trying and trying again. Appreciate any help!!!!

 

[rickwrench]

That seems on the very low side for compression psi. Did you check it with all plugs out, carb wide open? Fresh/fully charged battery, good starter, etc. How did you break in the engine?
Also, was the block at least honed?
Check/set initial timing with the vacuum dashpot disconnected and hose plugged.
Accelerator pump working?

Run through each possibility, completely, before moving on to the next. Very hard to solve anything shotgunning every problem at once.

 

[Frank]

Have been having ongoing issues that I just can't seem to resolve.
I rebuilt my 170, first time ever done an engine. Replaced pistons, rings all the gaskets and bearings etc. I got it running finally after a lot of tinkering. It has compression readings of 100psi on each cylinder. I have put some oil in each cylinder and the checked and stays about the same, so pretty sure rings are sealing ok.
Is the head leaking? Somewhere?
I have checked and re checked the rocker spacing, timed the engine, checked points, replaced the advance valve thing on the distributor.

When try to drive it, it has no power and will stall under virtually any load.

I am really struggling to work out what's going on and honestly at point of giving up.... Not one to be beat but it's been 6 months of trying and trying again. Appreciate any help!!!!

All symptoms point toward late camshaft timing. Did you degree the camshaft when installing it?

 

[Rodders]

That seems on the very low side for compression psi. Did you check it with all plugs out, carb wide open? Fresh/fully charged battery, good starter, etc. How did you break in the engine?
Also, was the block at least honed?
Check/set initial timing with the vacuum dashpot disconnected and hose plugged.
Accelerator pump working?

Run through each possibility, completely, before moving on to the next. Very hard to solve anything shotgunning every problem at once.

Yeah carb fully open. Plugs out. Engine hasn't been broken in other than just sat idling. When try to drive it it just wants to die under any load, will run back and forward on very level ground that's about it

 

[Rodders]

All symptoms point toward late camshaft timing. Did you degree the camshaft when installing it?

No didn't degree as it's original cam shaft with all lobes so couldn't do that from what I understood. Anything I can do now to rectify that?

 

[B RON CO]

Hi, as mentioned, any new cam needs to be degreed. Vintage Inlines has the adjustable timing chain set. Besides that, if you are using the adjustable rocker arms, they could be set too tight. A vacuum gauge showing low vacuum indicates improper cam timing. Good luck

 

[frozenrabbit]

100 psi even with oil in cylinders seems like cam degree, or if you have adjustable rockers, they are over lashed.

There is a different way to set lash with adjustable rockers over hydraulic lifters, as opposed to solid lifters.

 

[ActionYobbo]

I had this problem with an engine from a reputable builder. The joins on the rings were lined up. Had to pull the pistons and 60 the rings.

 

[B RON CO]

Hi, if you changed the timing chain and sprockets, the is a chance that the new timing set threw the cam timing out of specs. Good luck

 

[frozenrabbit]

I had this problem with an engine from a reputable builder. The joins on the rings were lined up. Had to pull the pistons and 60 the rings.

I think that's a myth. Rings should actually rotate in the grooves when running. Adding oil to the cylinders should have upped the compression numbers if it's a piston/ring issue.

I'd back off the rocker adjustment 1 full turn on all cylinders, and compression check again.

 

[drag-200stang]

How much oil pressure does it have?

 

[ActionYobbo]

I think that's a myth. Rings should actually rotate in the grooves when running. Adding oil to the cylinders should have upped the compression numbers if it's a piston/ring issue.

I'd back off the rocker adjustment 1 full turn on all cylinders, and compression check again.

I have the myth in my yard ready to pull the motor. This time is a 289 thats a fresh build. Been to several mechanics and it still won’t run. Will idle and rev in park but dies as soon as is given gas under load. Vacuum test shows bad rings. Come on over and watch me pull it down and see the myth live with your own eyes.
Now the reality is if you set the rings at 60 on a build then the chances of all cylinders lining up the ring gap at the same time while running is impossible to calculate but it would be in the trillions to one. But if you line them up while building it’s 100% and that’s why I pointed it out with this being a fresh build and I have seen it before.
So the question for Rodders is did you 60 degree the rings or did you line them up?

 

[frozenrabbit]

Even with aligned gaps, oil would have brought up the compression numbers.

 

[aussie7mains]

Do you really think the factory sets the ring gap positions during assembly?
Ive seem video of sectioned engines being motored, everything spins quite quickly. And even if they did line up momentarily, the gap is tiny.

 

[Rodders]

I have the myth in my yard ready to pull the motor. This time is a 289 thats a fresh build. Been to several mechanics and it still won’t run. Will idle and rev in park but dies as soon as is given gas under load. Vacuum test shows bad rings. Come on over and watch me pull it down and see the myth live with your own eyes.
Now the reality is if you set the rings at 60 on a build then the chances of all cylinders lining up the ring gap at the same time while running is impossible to calculate but it would be in the trillions to one. But if you line them up while building it’s 100% and that’s why I pointed it out with this being a fresh build and I have seen it before.
So the question for Rodders is did you 60 degree the rings or did you line them up?

I off set the rings. Didn't line them up.

 

[Rodders]

How much oil pressure does it have?

Had good oil pressure I want to say was 50-60. Can't properly remember off the top of my head

 

[frozenrabbit]

What sequence/method did you follow to adjust the rockers?

 

[Rodders]

So with the new timing chain set as per photo. The cog on the cam has the groove so is set position and the the cog on the crank has the groove that line up with groove on cam. I did that as per instructions. (I didn't degree it, as thought with these markers it was a set position) The cam is the original.

Is the lack of degreeing the cam causing the issue? Can I do anything with timing etc to get around this problem? Or do I have to strip down to degree the cam??

 

[aussie7mains]

So with the new timing chain set as per photo. The cog on the cam has the groove so is set position and the the cog on the crank has the groove that line up with groove on cam. I did that as per instructions. (I didn't degree it, as thought with these markers it was a set position) The cam is the original.

Is the lack of degreeing the cam causing the issue? Can I do anything with timing etc to get around this problem? Or do I have to strip down to degree the cam??

Looks correct to me, the fact that it runs, and has some compression would indicate is right, even a tooth out would make it run really bad or not at all. What head have you got on this engine?

 

[DON]

I would like to see another photo of the sprocket dots and how they line up. I see the dot on the cam sprocket, but not clearly on the crank. I would have thought it could have been seen but the angle of perspective is not square