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General Category => General Discussion => Topic started by: neetones on May 25, 2026, 04:12:33 PM
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Hi everyone.
I've pieced together my frame-up mechanical restoration of my '69 Ambassador. New bearings, seals, reground cam, new valve guides, new exhaust valves, wiring, frame paint, etc.
Everything seems to be fine and came together well. Fuel, spark, valve lash, ignition timing. It simply will not start. Cranks happily but won't start. Here's where I'm stuck:
On left cylinder, as it comes up to TDC on compression, I'm getting leaking and it's blowing fuel/air out of the intake valve and spurting out of the carb vent. So I cracked the timing chest open again and confirmed that the paint marks line up as they did when I tore it down.
1. Is it possible that the gears are not timed correctly still? How can I confirm?
2. What do I check next? Is it just that the intake valve isn't seating well?
Thank you!
(https://i.ibb.co/LdRvW40q/PXL-20260516-040403543-PORTRAIT.jpg) (https://ibb.co/LdRvW40q)
(https://i.ibb.co/67r8vz6J/PXL-20260525-190536089-PORTRAIT.jpg) (https://ibb.co/67r8vz6J)
(https://i.ibb.co/VY5rx2qN/PXL-20260525-205221710.jpg) (https://ibb.co/VY5rx2qN)
(https://i.ibb.co/7Jbg5BX3/PXL-20260525-205230750.jpg) (https://ibb.co/7Jbg5BX3)
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I would put a degree wheel on the crank & check cam timing, make sure it matches the book. Make sure distributor is timed also with a timing light.
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The important relationship is the cam to the crankshaft. Those two marks are the cam to the idler gear. I have no experience with the loop frames, though I suspect they're very similar to the tontis, but more importantly, I have no experience with gears rather than sprockets. Usually, on other machines I've worked on, there's a dot (punch mark) on the teeth that need to align. I'll look in a manual and see what I can find, but I'll bet someone more knowledgeable will be along shortly. As for the distributor, it would be difficult timing the distributor with a timing light when I won't even run. Have to set it initially using the flywheel timing marks.
This is what I found doing a little search:
The mark on the cam gear will be at 6 o'clock and the mark on the crank gear at 12 o'clock. The oil pump gear has no marks so don't worry about that one
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The important relationship is the cam to the crankshaft. Those two marks are the cam to the idler gear. I have no experience with the loop frames, though I suspect they're very similar to the tontis, but more importantly, I have no experience with gears rather than sprockets. Usually, on other machines I've worked on, there's a dot (punch mark) on the teeth that need to align. I'll look in a manual and see what I can find, but I'll bet someone more knowledgeable will be along shortly. As for the distributor, it would be difficult timing the distributor with a timing light when I won't even run. Have to set it initially using the flywheel timing marks.
This is what I found doing a little search:
The mark on the cam gear will be at 6 o'clock and the mark on the crank gear at 12 o'clock. The oil pump gear has no marks so don't worry about that one
On Loops with gears, there are paint marks only. There is no "idler gear" - his marks are on the cam gear and crank gear.
Loops also have no flywheel marks, other than an arrow (unless the flywheel has been replaced with a Tonti one). Timing is set with marks on the crankshaft belt pulley and an arrow cast into the timing cover. You can check timing with a strobe even if the engine isn't running - plugs out so it spins fastest, crank it with the starter, shoot the marks.
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Your gears look to me like they are lined up correctly. IIRR even the cam pin is in the correct position, as in upper left. So I think I would rule out a valve timing issue, unless.....
They ground the cam way off. Highly unlikely.
You may have a valve issue due to the re-builder. Might want to consider renting a leak down tester and see if you have an intake valve stuck open. For that matter if you TDC the cylinder on compression, and blow air into the spark plug hole, there should be no air coming out of the intake or exhaust ports.
Hope this helps a bit,
Tom
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On Loops with gears, there are paint marks only. There is no "idler gear" - his marks are on the cam gear and crank gear.
Loops also have no flywheel marks, other than an arrow (unless the flywheel has been replaced with a Tonti one). Timing is set with marks on the crankshaft belt pulley and an arrow cast into the timing cover. You can check timing with a strobe even if the engine isn't running - plugs out so it spins fastest, crank it with the starter, shoot the marks.
I'm glad you were there to correct my misinformation. These loops are more different than I thought!
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A little more detail:
I pulled the head and the valves seat just fine. No leaks, springs appear to be okay.
Compression on the L cylinder is weak and leaky - sounds like air is hissing into the crankcase. Maybe the rings moved around a bit and gaps aligned?
I still can't make sense of why I get NO ignition on either cylinder. I've checked ignition timing many many times.
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UPDATE! The issue was just weak spark!
Points cleaned and she started right up! Now to get the carbs synced and get her not to want to die on idle.