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TR2/3/3A engine assembly cam timing issue

Kolecki

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I would say I have been pulling my hair out over a simple (?) TR 3-4 engine issue, but since I haven't had a full head of hair since 1975, I won't go there.

I have rebuilt perhaps 15 TR 3,4 and 4As over the past 30 years but only recently got back into body off frame full restorations in my retirement. It's a time consuming but worthwhile challenge made easier with access to the British Motorheads out there. Most often I had taken running cars and rebuilt everything but in the past 2 years I acquired a 1964 TR4 which sat in the CA desert for 35 years- no rusty body or frame issues but also no interior and everything was sandblasted and baked due to the lack of a good storage choice. Then I purchased a 1961 TR 3A that was a spare parts car from a collector here in Florida- It needed everything and was very rusty.

All that being said when it comes to replacing flood pand, fender sections etc, I am fine. And having been a mechanic since the 1960's (not todays' replacement technicians) usually the engines are so basic that I can work miracles.

Except for the initial set up of the timing marks and position of the Cam and crank gears/chain.

I have the original Triumph Spare Parts Catalogue and Workshop manuals by The Standard Triumph Motor Company ( even a TR 2 Service Instruction Manual for supplement for the TR3, Tuning Your British Sports Car by Charles Williams and after an exhaustive on line search I have Tony Drews website

Is there a timing set up for Dummies for these simplistic engines with pix or videos? I have a total of 5 TR 3-4 engines all basically rebuilt from the ground up waiting for this final critical set up.. I have become frustrated that after I thought I had it correct on 2 different engines, when I tried starting them backfires thru carbs.. So I tried to read the information more carefully and what should be simple is not. You don't line up the teeth/marks on the cam with the teeth/marks on the crank to come up with a perfect match or close enough that you can get the engine running.

These engines all have new liners, pistons, wrist pins, rings Fresh machined Crank and new bearings, oil pump cam bearings, re machined heads with all new valves, springs guides and hardened seats where needed.

At a total loss. Thanx for any leads or help from someone knowledgeable.

Ron Kolecki
Merritt Island, FL 32953
cell 321-408-1462
 
If you are working with marked gears from another running engine, there is no reason that CAM timing is not just drawing a line from crank center to crank sprocket mark to cam sprocket mark to cam center. If you have done this, your backfire is in ignition timing.
Bob
 
Try this...
On the distributor, remove the spark plug wire for # 4 cylinder and replace it with the spark plug wire for #1
Then complete the reorientation for the firing order from there.
 
I had the same problem, no marks and a non-production cam. Even good YouTube videos were confusing and contradicted each other. The clearest instructions I have found come with the BP270 cam I bought from British Parts Northwest. They will email the instruction sheet that comes with the cam if you ask. They take calls and are extremely helpful. To paraphrase the instructions:

1. With a dial indicator find top dead center of number one cylinder.
2. Attach a protractor to the crank and set it at zero against a pointer.
3. Again with a dial indicator find the maximum lift of the cam lobe for the number one cylinder intake valve. (I will probably do this step using the top of the push rod when the head is back on.)
4. Turn crankshaft to whatever value the cam calls for (112 degrees ATDC for mine)
5. Without turning either the crankshaft or camshaft, attach the cam sprocket and chain.

I trust that members will correct me if I’m wrong.

Even YouTubes with confusing mathematics and theory will show different ways to find TDC.

Steve
 
The first question is if your sprockets are marked with either lines and/or dots just inside the teeth? We can go from there...
 
Macy's Garage has a good description for finding TDC. Using the TDI you can be off several degrees because the piston does not move up or down in the last few degrees BTDC and ATDC. The Macy method uses a bolt or other stop to prevent the piston getting to TDC. Mount a protractor on the crank shaft. You turn the motor till #1 cylinder touches the stop then note the degree reading. Turn the motor back in the other direction to touch the stop. Note the degree reading. TDC is halfway between the readings. Set the protractor to read Zero at the pointer.

David
 
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