Failure on Initial Engine Start After Rebuild

[Jim 58 BN6]

Wow 90degrees. Randy is, as usual, correct, and I apologize if I contributed to the confusion. When you said that both valves were closed at TDC, and the crank and pointer basically lined up, I figured there wasn't a cam timing problem - I mean, the valves were closed, right? Then I looked at a valve timing diagram, and lo and behold, with the cam 90degrees advanced*, both valves look to be "closed", and 180 cam degrees later, the intake is opening (or open), and exhaust is closed. Just like your pictures. The timing diagram is attached (generic, not Healey specific).

Anyway, I'm glad you found the problem. It might be worthwhile to have a friendly discussion with the engine builder. Good Luck, Jim

*Edit: I guess I meant retarded...

 

[Gadwhite]

Re: trouble on 1st start

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!

Randy (et al) thanks for your patience, you are right I was hesitant to pull the timing cover because of all the stuff I had to disassemble, but I am glad I did. I did it in the car so had to pull carbs, exhaust linkage, etc. to get the motor up enough to get at things. Now I learn how to pull off the chain, etc. I’ll keep you guys posted with the reassembly.

 

[MarkP]

Installing sprockets and timing chain is Tech101, basic engine rebuilding.

It's good that these are non-interfering designs. I do wonder about the builder. New employee? Lack of quality control process?

 

[roscoe]

It looks like the lock tabs on the chain tensioner are not bent to lock the nut. Is that what it looked like when you opened it up? If so mention that to your rebuilder.

 

[Gadwhite]

It looks like the lock tabs on the chain tensioner are not bent to lock the nut. Is that what it looked like when you opened it up? If so mention that to your rebuilder.

yep I’m going to fix that.
One more question guys. The camshaft nut, is it a weird whitworth size? It looked like 1 1/4 when I went to take it off but it’s not. It seems to fall between 1 1/4 and 1 1/2 and on my metric set I have 32mm and 36mm which it also falls between.

 

[Randy Forbes]

Shouldn't be any Metric sizes on that lump__a couple of Whitworth, maybe, but not enough to justify the purchase of a set of tools.

From memory, I'm thinking the cam nut is 1-5/16" (same size as MGB crank nut) and is a regular RH thread.

 

[Gadwhite]

Thanks I actually used a 34 mm and it worked fine. Pulled and refitted gears and chain. Before I button every thing up here is the picture.

 

[Bob_Spidell]

Side note: I'm hearing through the grapevine that the aftermarket tensioners are prone to failure. Next time I have my timing cover off I'm springing for one of these:



https://www.bighealey.co.uk/engines/3000-top-end?page=4

NFI, but I've found that DWR stuff generally lives up to advertising.

 

[Randy Forbes]

Thanks I actually used a 34 mm and it worked fine. Pulled and refitted gears and chain. Before I button every thing up here is the picture.View attachment 53153

Picture angle is throwing me off, but compare the number of links in the picture where I show them painted red (copied from an original chain with "T" stamped into the links) to how yours is set up.

One other thing while you're right there, and I wouldn't have thought of it had Bob not raised the point; there is only a pinhole through the block and the front plate that feeds oil through the tensioner to lubricate the chain and slipper__MAKE CERTAIN THAT IT IS NOT BLOCKED by gasket sealant! Pass a paperclip (if it fits, or other small wire) through the hole into the oil galley. Perhaps such an oversight is why there are reported failures of that tensioner...?

 

[Gadwhite]

Picture angle is throwing me off, but compare the number of links in the picture where I show them painted red (copied from an original chain with "T" stamped into the links) to how yours is set up.

One other thing while you're right there, and I wouldn't have thought of it had Bob not raised the point; there is only a pinhole through the block and the front plate that feeds oil through the tensioner to lubricate the chain and slipper__MAKE CERTAIN THAT IT IS NOT BLOCKED by gasket sealant! Pass a paperclip (if it fits, or other small wire) through the hole into the oil galley. Perhaps such an oversight is why there are reported failures of that tensioner...?

Yes saw that and it’s clear, too small for a paper clip though. My engine is still clean. 15 links including ones over the dots, so matched

 

[dcarlg]

Please let us know when you fire it up.

 

[Brinkerhoff]

Well I think you're in the right direction !

 

[Michael Oritt]

A review of the many posts reveals that several of us had pretty much concluded about a month ago that valve timing was the issue.

 

[Gadwhite]

Got the timing cover back on today proceeding to re mount the engine and then i’ll Redo the distributor drive to get it back in synch. Will keep everyone posted on when I try to fire her up.

 

[Gadwhite]

Today got the motor mounts back on, distributor,alternator back in. Compression is now up at 120 to 150 across the board. Installing carbs but have to go out of town this week. Will keep you all updated. Thanks again to everyone I am learning a lot!

 

[MarkP]

Good to see the compression numbers come up but somewhat concerned that the difference between highest and lowest on a rebuilt engine is greater than 10%. You're at 20%. We may still have some investigation to be completed. What are the numbers in cylinder number order?

 

[steveg]

I would guess the compression or leakdown tests wouldn't be valid until you'd run the engine long enough for the rings to seat.

 

[Randy Forbes]

Good to see the compression numbers come up but somewhat concerned that the difference between highest and lowest on a rebuilt engine is greater than 10%. You're at 20%. We may still have some investigation to be completed. What are the numbers in cylinder number order?

COLD compression test readings on an engine that has only been run on the starter motor aren't at all representative of the engine's health, in my opinion.

Once he's got 400-500 miles under it and can test it when it's stinking hot, there'll be some numbers worth paying attention to

 

[pdplot]

In retrospect, the answer was obvious. He had gas at the carbs and spark at the plugs - but - they were not arriving at the proper time, so in effect, the engine was fighting itself. As someone pointed out, he was lucky this was not an interference engine. As some of you wisely and correctly pointed out early on, it had to be the timing. Internal combustion engines may be complicated and technical - especially today's computerized cars - but our cars are not rocket science. How many times does it turn out that our MG, A-H or TR3 won't start because we assembled a new set of points incorrectly and shorted them out? Or even stupider, left the rotor laying on the valve cover? I know I have at least twice. Gadwhite's rebuilder should correct the problem withut charge. He could have ruined the engine.

 

[Brinkerhoff]

Great point sir! The factory service manual by no means contains all the tips and common knowledge needed to successfully rebuild the engine. Since evidently it was assembled without a factory manual its easy to wonder what other knowledge was missing. Like I said earlier , I think he's in the right direction now that he's got his hands and head involved. Hopefully it works out for the best !