Failure on Initial Engine Start After Rebuild

[Brinkerhoff]

Correction , that looks like the intake valve is open and the exhaust is closed which would mean the cam timing were early or advanced. Either way check the point that both valves are open equally , then note the position of the crank pulley marks. I'm involved with a TR3 resurrection in the shop so not thinking clearly evidently!

 

[Gadwhite]

Correction , that looks like the intake valve is open and the exhaust is closed which would mean the cam timing were early or advanced. Either way check the point that both valves are open equally , then note the position of the crank pulley marks. I'm involved with a TR3 resurrection in the shop so not thinking clearly evidently!

Crank pulley marks are just before TDC with both valves closed on #1 Cyl., But I will play with it and see where they are with both valves open. I Have a new Compression gauge and leak down tester arriving today to just double check my compression, before I start pulling timing cover off. I will keep everyone updated. Car has not run since 1984 so I am on a mission

 

[Jim 58 BN6]

Without a degree wheel and a dial gauge it's tough to get exact numbers, but it sounds as if your cam timing may be close.

Look at the following page on this BB. About 8 posts down the page, Dave Russell does a good job explaining the camshaft numbers:

https://www.britishcarforum.com/bcf/showthread.php?41307-Healey-3000-Camshafts

 

[Jim 58 BN6]

Also, I would think that if the cam sprocket were off a tooth, the pulley marks would be farther away than "just before TDC".

 

[Dandare]

Has anyone a comment regarding post #105?

I don't have a factory manual to hand but BMC generally specified a clearance for the inlet valve rocker (on B and C series engines at least) for a valve timing check. If the pointer and notch is not trusted the piston at TDC could still be verified by other means.

Danny

Danny

 

[Brinkerhoff]

At TDC on the compression stroke both valves should be closed ( of course). At TDC on the intake stroke however , ( at the end of the exhaust stroke) both valves should be open , the intake having just opened and the exhaust almost closing. Just use std. valve lash to check . As long as your timing notch accurately indicates TDC you don't need a dial indicator for this test. A tooth off either way will be easy to determine.

 

[Gadwhite]

At TDC on the compression stroke both valves should be closed ( of course). At TDC on the intake stroke however , ( at the end of the exhaust stroke) both valves should be open , the intake having just opened and the exhaust almost closing. Just use std. valve lash to check . As long as your timing notch accurately indicates TDC you don't need a dial indicator for this test. A tooth off either way will be easy to determine.

Thanks. Leaving work early today , so I will go through this test, and put up some pictures. Also got my Leak down tester yesterday and will play with that to see whats up with compression.

 

[Brinkerhoff]

The factory manual specifies the valve lash to be set for .030" to check valve timing . On a Mk.III engine with the std. cam the intake valve would start to open at 16 degrees BTDC (at the end of the exhaust stroke / beginning of the intake stroke and the exhaust valve would finish closing at 21 degrees ATDC. Regardless of the valve lash ( as long as they were equal) you can see from the timing spec. that at TDC they are both open virtually the same ( within a few degrees of crank rotation). This is the valve "rocking" that is easy to see and careful examination and eyeballing with a straightedge on tops of the valve caps will give the point where the two are open the same. Since the cam lobes are fixed ,moving the chain a tooth on either sprocket therefore moves the point in relationship to TDC where both the valves are open the same amount. Find the point where both valves are open an equal amount and you've found the point where TDC is supposed to be without using a degree wheel or dial gauges ( which should have been done when the engine was assembled).

 

[red57]

Thank you Brinkerhoff - very good explanation. I've never heard of this method of checking valve timing and I really like learning new tricks (still gonna use the degree wheel though).
Dave

 

[Gadwhite]

The factory manual specifies the valve lash to be set for .030" to check valve timing . On a Mk.III engine with the std. cam the intake valve would start to open at 16 degrees BTDC (at the end of the exhaust stroke / beginning of the intake stroke and the exhaust valve would finish closing at 21 degrees ATDC. Regardless of the valve lash ( as long as they were equal) you can see from the timing spec. that at TDC they are both open virtually the same ( within a few degrees of crank rotation). This is the valve "rocking" that is easy to see and careful examination and eyeballing with a straightedge on tops of the valve caps will give the point where the two are open the same. Since the cam lobes are fixed ,moving the chain a tooth on either sprocket therefore moves the point in relationship to TDC where both the valves are open the same amount. Find the point where both valves are open an equal amount and you've found the point where TDC is supposed to be without using a degree wheel or dial gauges ( which should have been done when the engine was assembled).

I’ll gif this a try tonight if I have time. I did perform a leak down test on each cylinder and pleased with the result . I’m loosing 10% or less and that’s very good on the scale.

 

[Michael Oritt]

Gadwhite--

It's good to have an absolute number but the real advantage a leak down test offers is the ability to isolate each cylinder and test the sealing of both the valves and rings separately.

By rolling the engine over with the car in 4th and using a piece of tubing to your ear you should be able to determine whether compression is being lost out the valves or into the sump. If the valves you can determine whether intake or exhaust and which one(s).

If the valves are good and there is a leak into the sump you can remove the rocker arm and test the ring/bore seal of each cylinder through its stroke.

BTW with a newly rebuilt block and head I would be looking for 5% or less.

 

[red57]

BTW with a newly rebuilt block and head I would be looking for 5% or less.​

I agree with Michael, but don't be discouraged with your numbers.
I have never leaked a motor before running it so I can't be sure but

I bet as soon as it runs long enough to seat the rings leakage will go down a bunch.
In my experience, after running 20 minutes at ~2k to bed cam/lifters & seat rings I have normally had 2-4%.
So, leak-down says you have a good motor, it just doesn't say anything about cam timing.
Dave
​

 

[Michael Oritt]

Gadwhite--

Actually, assuming your gauge is accurate, the measured loss appears to be just under 15%. Ideally leak down tests are done on engines when they are at normal operating temps so you can probably reduce that number by a few points as the cylinder ring/bore seal will improve when things expand a bit.

Which brings us to the original question--why isn't this engine starting?

The only requirements for combustion in a gasoline engine are fuel, air and a spark--the latter timed to occur at a specified point prior to cylinder sealing (BTDC). According to earlier Q & A's you do have fuel getting into the cylinders and a spark, the advance of which is more or less properly timed.

It looks like we are back to valve timing.

 

[Deleted member 21878]

i think you have a lot better help here than me but reading one of the early posts you said:

I think I may have flooded engine ( strong smell of gas, but no gas on plugs) so disconnected fuel pump and will try again tonight.

if you are cranking the engine, have fuel to the carbs, then i would think the plugs should show some sign of fuel. is it possible someone placed a rag or something in the intake prior to installing the carbs and left it there? or left the back of the intake with tape on it?

 

[Gadwhite]

Re: trouble on 1st start

Gadwhite--

The fact that they are low and more or less consistent across the board makes me wonder. Perhaps your compression tester is not accurate. In any case I still think the car should start assuming good spark and proper cam timing. I hope you will keep us informed as to what the builder's response is to why the engine will not start.

Michael got another compression tester from Autozone (tool loan). Same results so my tester is good? Talked through everything with the engine builder. He admits it’s possible his guys messed up timing chain setup. I did verify pistons are correct for motor with .030 overbore. Decided to pul timing cover and it does not look correct from what I know. Here is a picture with #1 cyl at tdc h.

 

[Gadwhite]

Re: trouble on 1st start

Maybe there was some confusion about the bright links description in the manual, and the last new timing chain I installed wasn't so equipped. Now, I keep an old original one around for reference, though you could count the links from the picture (not the same as if you lined up the dots).

Unlike some engines, aligning dots on the cam & crank sprockets with a straight-edge isn't going to get the job done on a Healey.
EDIT: if you go to this hi-res version, and enlarge it (click on the opened pic) you can see the dots marked on the sprockets.
https://spcarsplus.com/gallery3/var/albums/LS_BN4_engine_build/IMG_1084.jpg?m=1304384677

Want to be sure? THEN CHECK IT!

Randy I pulled my timing cover off and this is what I have with#1 at TDC

 

[MarkP]

Wow, not even close.

Second post at the following link. Note position of dimples and 15 links from one dimple to the other dimple on right side.

https://www.ahexp.com/phorum/read.php?3,170715

You have found your issue.

 

[Randy Forbes]

Re: trouble on 1st start

Randy I pulled my timing cover off and this is what I have with#1 at TDC

View attachment 53138

Compare the dots in my picture (DOTS on sprockets, not the piston's location): crankshaft @ BDC and cam sprocket dot at TDC, identified by the red-inked links.

And now compare them with your picture.

Rough guess, but looks like the cam's retarded about 90*

I know exactly what happened; the builder lined up the dots with each other, never paying any attention to a Healey assembly manual, let alone checking his error. Gives me pause for concern about more of the assembly...

You'll note that I hadn't contributed any more suggestions for nearly a month while waiting until this was checked (and I was not the first nor last to suggest it).

Collective sigh of relief!

 

[Keith_M]

It's nice to finally see a resolution to this problem.

 

[RAC68]

Hi All,

I hate to disparage the reputation of an engine builder but if you're taking your engine to a rebuilder and not just having the block machined, isn't this something you would expect the builder to do correctly? I haven't rebuilt my engine yet and would be very concerned if I had to do it in the near future because we always seem to hear experience of unexpected issue. Before committing to a rebuild, is there a document that would present what should be requested of a rebuilder and what should be expected from rebuild services?

Randy and others with substantial experience in this space are a blessing to those of us with limited knowledge and have been very open toward contributing to problem diagnosis and solutions. However, how do we get to a point of not experiencing these after-rebuild issues? Is there a list of proven reputable rebuilders for the US and other areas of Healey activity?

Ray(64BJ8P1)