53 flathead. Trying to figure out a timing issue. When purchased the engine was partially tore down (heads removed, carb off, and generator removed). Everything is reassembled and now we are troubleshooting what appears to be a timing issue. Setting the timing by the book leaves the car backfiring through the exhaust and sometimes the carb. Reset the pulley at TDC, pulled the distributor up, turned the rotor 180 degrees, and dropped it back in the hole. No more backfiring but no signs of wanting to start. Which why is closer to the truth? Any tips on finding actual TDC with the head still on the engine?
If you are using the stock 8BA distributor do this: Turn engine over by hand by putting socket on crank pulley bolt. Engine turns clockwise when viewed from front of car. Rotor also rotates CW. Turn the engine CW with socket until the timing mark on the timing cover lines up with timing mark on crank pulley AND the distributor rotor points to the number one cylinder on the distributor cap. That is usually near 6 o'clock or a little past. Your number 1 piston is now at TDC on the compression (power) stroke. Engine should now start. If it doesn't. rotate the distributor a little CW or CCW.
Your theory could still land you 180 off. Should TDC indicator be lined up right after number 1 exhaust closes or right before it opens? Remember, cranks spins around twice for every one camshaft rotation.....
I see you usually work with General Motors engines . Don’t forget,,,the Ford cylinders are numbered. 1 -4 down the right bank,,,,5 - 8 down the left bank . If the wires were crossed before,,,it would backfire like you were describing,,,maybe it wasn’t 180 out ? Tommy
I've always had success with my method because when the timing cover mark and the crank pulley marks are aligned at the same time the rotor is pointng to #1 plug wire terminal on the cap, the engine is on the compression stroke, not the exhaust. It's not 180 degrees off. Guess , I was just lucky all these years.
When its time to fire up a fresh Flathead or one thats been apart like yours I just take the time to get cylinder number one on compression ready to fire. Once I have that blast of air from the cylinder I then set the dist so the rotor is lined up with cylinder number one plug wire. Im sure you have already done all of this. Now at least the engine will fire up once its running I continue to advance the dist until the engine is running smoothly. Note I never use any books to get timing information. I find its best to set the initial timing as I wrote. Then I drive the vehicle and see how it feels. What I have determined after doing this for many years and on hundreds of Flathead's is that the initial timing will be from 8 to 12 degrees to get the Flathead running extremely well. Also in the past using Champion H-10 spark plugs I have experienced issues with skipping I now only use NGK plugs B-4L or B-6L Ronnieroadster
Zip tie method works well for getting in the ball park. Stick the fat end of a plastic zip tie down the plug hole of #1 and spin engine over slowly by hand. You'll feel the piston bump the zip tie and you should be very close to tdc and check the valves to make sure you're on compression stroke. From there you should be able to set your rotor pointing at #1. If it's anywhere remotely in the ball park it should try to start. Mixed up plug wires and distributor/rotor rotation are common errors.
Hi Nick I decided to take afternoon off from working on the next Flathead for Speedweek to post some info. Thought I might be able to help
It also takes compression for it to fire. Old engine.... check your compression. I just ran into a dyslexic problem with my new flathead.. Wouldn’t start. Here I hooked up the plugs to the distributor in the correct order but totally opposite pattern. See link. https://www.jalopyjournal.com/forum/attachments/1941815d-0233-44a9-9760-82601d9e9712-jpeg.4627556/
We are just trying to make sure the dist isnt 180 off. When it was first installed it popped back through the carb and exhaust. We pulled the dizzy, spun it 180, and dropped it back in. No we get no backfire and no signs of it wanted to start. Most people arnt understanding that the number one piston comes up twice during one cam revolution. Therefore the number one piston can be up with the rotor pointed at the number 1 cylinder AND the dizzy can still be off by 180 (because it will line up on the next crank rotation. I figured will all of these people that are "pros" with flatheads (including the idiots that say to look down the spark plug hole at the top of the piston) would realize this.
Take the #1 spark plug out, put your thumb over the hole, and have someone else "bump" the engine with the starter. When it's on the compression stroke, it will blow your thumb off the hole if it's got any compression at all. Watch the "timing bump" as it may go past the pointer. Bring it back or forward so the pointer is pointing at the bump.
you probably had the distributor right the first time, the popping and backfiring may just be valves hanging open....
USMC4LIFE: Are you sure the timing gear and crank gear timing "dots" are lined up? Are you sure 8BA the timing gear on the end of the cam shaft has not rotated off its "assembly mark" with the cam? It's only pressed on. Not a very good design. I had that happen once.
i think you can see the edge of the valves in the plug hole with a flashlight. when both #1 valves are closed and piston is up you are close enough to TDC. rotor points to #1 plug tower on the cap, fire it up
Since you did all of that, did you watch the valves to see of they are opening and closing properly? Could be that they aren't closing properly. Only use a book for reference. Don't rely on them 100% of the time. Use your ears. You'll find a big difference. We used to use match book covers to set the points where the book will be too specific. Are your points set properly?
Where are these idiots you mention? I've done this a number of times lately. Do the thumb deal, like we said. While looking at the bump on the pulley, (hopefully you got one). Now, this has happened to me 3 times in a row: I had my timing mark lined up, #1 cylinder on compression stroke, rotor pointed right at the wire for #1 plug. But...........I was still one tooth off on the distributor gear. When I've done that, sometimes she'll start and run real rough, sometimes won't quite start. Move it one tooth and everybody happy.