TR4/4A New valve gears/timing

I am at the place in my rebuild where it is time to set the valve timing. I had difficulty in determining the wear on my crankshaft gear and camshaft gear so I bought new. I also installed the BP270 Newman camshaft (from BPNW). The BP270 calls for a 12* rotation from the standard setting. So here is my question: If I follow the instructions in Haynes p50, sec 61or the shop manual 1-128 for new unmarked sprockets will that automatically set the new camshaft up properly or will I additionally have to afterwards rotate the 12* that the camshaft says? Bruce

I would suggest that you pose this question to BPNW. I have found them very helpful and knowledgeable about what they sell..

You could use the procedure on the Macy's Garage site to find true TDC. Then see what BPNW say about the timing.

David

https://macysgarage.com/cam degree.htm

I may not have made myself clear in my post so I will try again. I have new crankshaft and camshaft gear sprockets. New sprockets are UNMARKED without the lines that come on the the original sprockets that came on the car. So the manuals give a more involved procedure to set them up. This is a little above my head but I assume the lobes on the new BP270 cam are "profiled" different than the original cam so my question is: When I go thru this procedure to set up the new gears (with the head/rocker assembly on) as per the manual does that set the valve timing up to the new cam? Or once I have done this procedure would I have to go on and continue to set the 12 degree movement that the camshaft directions say? Bruce

Hello Bruce.

You should have got information on opening and closing degree times for your BP270 cam.

First you will need to have a degree wheel set to Zero at TDC so you can then set the cam shaft. The Macy's instructions work well.

David

The 12 degrees you speak of does not sound correct, is there a cam card that came with the cam? What information is on it, maybe snap a picture and post it.

Rod

David - Thanks I looked at the Macy's site and wish I could do it that way. Unfortunately I had looked ahead in the manual and it showed a procedure that requires the head and rockers to be on, so that is where I am. I have followed that procedure to the point that it is time to put the sprockets and chain on. My crankshaft sprocket does not slide over the key so I am trying to decide how to rectify this. I have used a light ball pein hammer to tap the key in but still not enough clearance to easily slide the sprocket on and I assume it should go on easy so as to aid putting the combination chain sprockets on. If I can get it back out I guess I could shave a little off of it - any suggestions welcome. Going back to the Macy's procedure I will study it to see if I can modify it to give results with the head on (I am not that good). Since Macy's says the factory procedure is not that accurate is there any instructions out there for doing the same procedure with the head on? I will wait for answers before proceeding. So as of yet I still do not have an answer to my original question - that if I follow the shop manual/Haynes procedure does that set my valve timing close to where it needs to be with the new cam or do I then have to go thru another procedure to do it?

Bruce David has you dialed in to set up gears. Your question is setting up lead and lag as to opening valves. Ideally would be same deg. before and after valve open and close. Gears do not let you do that so the question is longer valve opening for more fuel time or longer valve closing for EX. If the cam sheet says 12 deg at start to open what will be deg closing if it is also 12 deg that is what you got ( think split deg lead lag ) MG B is 12 to 14 deg. Also did the cam tell valve rocker setting that can also give you balance in valve timing. EX valves run hotter than intake valves so may also be different. And last as you set this up cold it may not be the same at temp so check twice you need not burn new valves. ( NOTE you may need a offset woodruff key and the TR6 offered an adjustable gear for just that reason ) If your not there yet keep the question coming. Madflyer

If this went thru here is a picture of the instructions. I have a degree wheel and a dial indicator with a magnetic base. Is this all I need to do and forget the manual procedure? Bruce

Yes, you are all set with the correct tools.

1) First, you are going to have to get the crank sprocket in place. Whatever it takes to get it down over the key.

2) Next, find a properly sized bolt and/or washers to be able to bolt your degree wheel to the nose of the crank. You will have to be able to tighten the bolt to lock the wheel in place, but for now, just leave the bolt loose to barely snug.

3) Find top dead center for your #1 piston from the front of the engine. There are many ways to do this. If you need a suggestion, just let us know and we'll give you some ways to do it easily.

4) With the crank at TDC for #1, take some piano wire or an old hanger wire, and find a way to bolt it to the front of the engine, then bend it and/or turn your degree wheel until the makeshift pointer lines up with the degree wheel for TDC, which should be 0 deg on the wheel. Tighten both the pointer bolt and degree wheel bolts so they will not slip.

5) Now, we are referring to your instructions above. The #1 intake is the second lifter from the front of the block. Find a way to set up your dial indicator so it reads the lift of that second (#1 intake) lifter. Let us know if you have any trouble finding a way to do that and we can help with ways that will work.

6) Loosely install the cam sprocket with no chain, just to give you a handle to work with. Turn the cam clockwise from the front of the engine until you reach the absolute maximum lift point as read on the dial indicator. The amount of the reading is unimportant, just so it is the maximum without bottoming out the indicator.

7) Gently remove the cam sprocket without changing the cam position.

8) Now, turn your crank clockwise from the front of the engine until the degree wheel goes from 0 deg TDC to 112 degrees past TDC in the clockwise direction.

9) Your timing is now set! But, we still have to install the chain. Run the chain around the cam sprocket, then, with the loose end dangling, install the chain over the degree wheel onto the crankshaft. You will have to remove either the pointer or the degree wheel for a minute to accomplish this.

10) Finally...the cam sprocket is manufactured in a way that the bolt holes can be aligned to give right on timing, or, jump the teeth in one direction and you get 1/2 tooth behind timing...jump the teeth in the other direction so the next bolt holes line up again, and it is 1/2 tooth advanced. This may seem complicated, but here is the easy explanation:

a) Hold the sprocket up to the cam and see if the bolts holes align. If so, you are golden. Install the bolts and you are done.
b) In all likelihood, the holes will be off a hair. Note the amount they are off, then jump the chain on the sprocket one at a time until the holes almost line up again. Continue to do this until you find the best alignment. Turn the crank as needed and install the bolts.

Here is the extra credit:

If the cam is installed slightly advanced to the crankshaft, then you move the torque band to a lower RPM, which is normally desirable for a street engine. Likewise, if you retard the cam in relation to the crankshaft, then torque is moved to a higher RPM, which is normally better for a car that is tracked. So...since we know the holes in the installation procedure above are never perfectly aligned, you can choose that to customize where your torque comes in. If you pick the sprocket teeth so that you have to turn the crank CCW to align them, then you advance the cam up to 1/2 tooth for better street torque...with the added advantage of allowing for chain stretch and sprocket wear. Use the holes so the crank has to be turned further clockwise to align the holes and you get your track torque band.

Of course, once you have installed your cam bolts, and before fully torquing them with the tab lock (if you are using tab locks), it is a great idea to put your degree wheel and pointer back in place and locate TDC again. Then slowly rotate your crank (and cam since they are now bolted together) clockwise until the dial indicator on your #1 intake lifter again shows the maximum lift. Now read your crankshaft degrees. 112 degrees is the recommended perfect setting. Less than 112 degrees is the amount of advance the cam has in relation to 112 degrees. For example:

Actual reading comes out at 105 degrees. Recommended is 112 deg. So 112 - 105 = 7 deg of advance. Up to 10 is fine. Torque band will be a bit lower RPM.

If your reading is more than 112 deg at the max lift, then you have a retarded cam by the difference from 112 deg, once again. Your Torque band will be at a slightly higher RPM.

That's all I can think of. If you compare my expanded instructions to Macy's sheet, you will see we are just doing what they recommend. Let us know if you run into any problems or have questions...Motors are my favorite part of a restoration!

John - As usual you answered my question exactly and in detail. I will not be able to get back to this until tomorrow afternoon but I was able to get the crank sprocket on over a very reluctant key, made a crappy wire pointer (I may try to do better but I believe this will work) and modify my degree wheel to fit over the crankbolt and a PVC pipe extension to use a spacer. I do have a question - During this process will the zero on the degree wheel always be straight up and down or will I find that it moves sideways? Is there a good way to verify that it is straight up when you have found TDC. Also - My flywheel is still exposed and it has marks on it for TDC - can I use this to give me a accurate TDC or will that have changed due to the new cam? Thanks Bruce

The pointer doesn’t have to be vertical. Install the pointer to a convenient location where it’s easily mounted. Then turn your degree wheel until the TDC, 0 deg mark aligns with the pointer. Then tighten the wheel...it could end up at any position where it’s convenient to have the pointer.

I was going to ask if your flywheel was still on...but figured it likely was not. You’re on top of it if you noticed it has a timing mark! This flywheel mark is likely very close to perfect. Since you have a degree wheel, it is worth the time it takes to verify it, though. Once verified, you can then use that as a quick reference to realign your degree wheel while you’re working.

Also the degree wheel will allow you to turn the crank the required number of degrees.
It may have been mentioned before but if it has not just to let you know the bolt holes in the cam sprocket are not symmetrical so if you are 1/2 a tooth off you can move the sprocket to a different set of holes and turning the sprocket over will give you a 1/4 tooth movement. Check the alignment of the sprockets if you turn it over.

David

I remember reading somewhere that you can replace the tip of a spark plug to make a piston stop if the head is on the motor. Should work the same as the bolt in the Macy's instructions.

David

John did a great service to us all. It is one thing to know what to do but much better to know why it is done that way. I used lead and lag but John said what the differents would make. Madflyer

Ok guys - I think following John"s above instructions I have accomplished this job almost. There is an important item to add to the above instructions IF you are using the mark on the flywheel as I did to find TDC. There are TWO marks on the flywheel, one is a straight line and the other is a ARROW. Use the arrow. I tried did not remember the arrow and set up using the straight line and fortunately followed John's double check at the end and could not figure out why it was way out of whack. I was so happy the cam sprocket holes lined up perfect first time that I was wondering it I needed to double check. What a mistake that would have been. After this miscue I started over and ended up with what I believe is 111* with the cam instructions calling for 112*. According to the instructions above this should be great - Right? (This is for a street machine that will be living in hilly/mountain SE Tennessee.) I was wondering what would be a good way to permanently mark the sprockets with lines as they came from the factory. I thought of a spring loaded center punch but I don't have one (Lowe's did not have one) and don't know if paint would last. Thanks for everybodies answers all were helpful. Bruce

Do you have a regular center punch?
Straight edge across the cam sprocket and the crank sprocket a couple of small dots to indicate the line.

David

This is for a stock cam but the set up and tools and method may help.
https://youtu.be/W0zvpImhvHc
Might help might not...worth a look...
Jim

Jim - I have set the timing up already using John's instructions above which I recommend for it's simplicity. But it never hurts to learn from the way others do it does it? David I appreciate your input on this thread. I do have some good center punches I was just reluctant to hit on the sprockets (in particular the larger cam sprocket) since they are now mounted. I think I will try it without hitting on them very hard and see it I can get enough mark to show. If not I will order a automatic center punch and wait to put the cover one. Bruce

I would suggest drive it, and the next time if there is one, take a felt pin and mark it in place then after the gears are off punch them.