exhaust manifold replacement

[graham lloyd]

Replacing the exhaust manifold on my 1920 Centredoor with a reproduction from Lang's. I have the insert rings and the gaskets are the copper clad gaskets, not the copper rings.

What torque should I use on the clamping bolts? Don't want to do too much and snap them, and of course, not tight enough brings its own set of problems.

Any tips or tricks?

I am having a lot of backfire under load and loss of power. I am told a warped exhaust head could be the problem. Hopefully this cures it.

Thanks for any help.

[Norman Kling]

I don't use a torque wrench on those nuts. I just use a wrench with about a 10" handle and tighten them starting toward the center and working out. That is the two closest to center and then the outer two. I turn them to where the nut won't turn with reasonable pressure. Then after I warm up the engine, I tighten them again the same amount. Seems to work for me. This might not fix the backfire problem. sounds more like either ignition or fuel problem, but this will at least quiet the noise.
Norm

[Susanne]

No torque!!! It is a slow an gradual tightening as you compress the gland rings... once they're compressed (mirrors and lights (not smoke) help) you snug them down, heat cycle it, and listen for leaks... Go from the center out as was said above.

[graham lloyd]

Thanks for the advice. I don't know why this would happen but local T guru looked at the car and deduced the issue. Starts and runs fine. Goes along fine until I hit a grade or want to accelerate from around 25 mph. Always fresh premium gas (no ethanol). We will see what happens.

If the problem persists, I will be looking for more help

[John Codman]

Not sure where you are, but premium gas for a T is overkill. There's nothing in a stock Model T fuel system that ethanol will hurt unless you don't drive it much (like me). I use ethanol-free 90 octane gas because it sits for weeks and even months. If I drove it weekly I wouldn't worry about ethanol in gas.

[2nighthawks]

John C. - Not to speak for Mr. Lloyd, but I also burn nothing but premium non-ethanol gasoline in my couple of Model T's and a Model A. This is because many of the few gas stations that sell non-ethanol gasoline only have "premium" grade. My cars love it and I don't see as it causes any problem,.....just a bit more expensive,.....FWIW,.....harold

[graham lloyd]

John, I am in Ontario. The only way to get gasoline without ethanol is to buy premium. And even then, some brands have ethanol in that.

Other than my daily driver, everything I own I use premium to eliminate the ethanol. I've seen the damage it does and not worth the risk.

[Stu Tomlinson]

No need to torque the exhaust nuts at all. Just run them down fairly tight to compress the gasket using your box end wrench. After you run it a while, do a re-tighten but not in sequence of the four nuts. There is no reason to over-tighten.
Regarding the fuel, T's in the day burned everything that had any calories in it. But to day, I do stay away from Ethanol unless you drive it frequently to where you are frequently refilling the tank. Back in the day they would burn junk so they would not spoil her. Today with their age --- I tend to spoil them a bit.

[Norman Kling]

Depending on how steep a grade you might not be able to go over 25 MPH, and some will require low gear or if you have an auxiliary transmission a shift to a lower range. If You notice that the car seems to feel like it is running out of gas and runs better when you back off the accelerator, you might have a fuel starvation issue. A center door has the gas tank in the rear, so you need to keep it nearly full for hill climbing because it runs by gravity to the carburetor. Some people add an electric fuel pump to help with this problem. If you do, you can add another fuel line to pump the gas back toward the tank so you won't cause the float valve to leak. All you need is to get the gas all the way to the carburetor with enough pressure to prevent starvation.
Norm

[graham lloyd]

Norm, just your run of the mill grades along the road. Nothing you could call a hill. Strangely enough, it pulls nice and hard in low gear all the way through the rev range. High gear from 20- 25 and accelerating is the problem times. I will try the full tank idea. Plus some Seafoam which can't hurt.

Doing a compression test as well. For the sake of eliminating possible head gasket contributions to the problem.

55 pounds about the right compression ?

[Steve Jelf]

55 pounds is to die for. Most don't get that high. If all are over 45 you're OK.

[John Codman]

I didn't mean to imply that premium gasoline with or without ethanol is bad for the T, just that the cheapest Panther pee that you can buy today is way better then anything the Model T ran on when new. The only downside to ethanol is that it will absorb water in our vented fuel systems, and due to the lower number of BTUs per gallon, ethanol-laced gasoline will deliver a very small decrease in miles per gallon.

[graham lloyd]

John, I appreciate you input. I know your intentions were to be helpful. Unlike many other forums, there is an atmosphere of trying to help. Unlike many which seem to thrive on the personal insults that today's society seems to think is a sign of strength or intelligence.

Thankfully, those here don't have that attitude.

As far as the ethanol, I have seen the damage it does to fuel systems and I won't take the chance in anything motorized. Premium fuel is the only way to get ethanol free gasoline in Ontario. At 50 cents or more a gallon more than regular, it is overkill. Possibly. But I have the peace of mind that I don't have government dictated contaminants in my fuel that will damage my other cars, and possibly my T.

Again John, I appreciate your input.

[Norman Kling]

I think it is in the fuel system. Some things to check for are: 1. Fuel filter. If you have an in line fuel filter other than the sediment bulb under the gas tank, those additional filters have been known to choke the fuel line. When you have a full open throttle, is when you need the most gas, and if the gas in the carburetor bowl drops because of constricted fuel line or filter, you will get a very lean mixture. With a good screen and clean fuel sediment bulb at the tank, you do not need any extra filter. 2. Vapor lock. This condition is caused by a bubble of air or vaporized fuel in the line between the tank and the carburetor. The vapor will compress and the fuel instead of flowing into the carburetor will just compress the vapor. The routing of the fuel line away from the exhaust system will help this condition. Also, the fuel line should have the lowest point between the tank and carburetor and go uphill at both ends with no high spot in the center. A high spot will cause a vapor bubble to rise and not flow out of the line. 3. Dirt somewhere in the line. most likely places are at the output of the tank where the fuel flows into the sediment bowl, float valve in the carburetor. Another problem is that some rebuilt carburetors have a non stock "gros jet" in place of the standard needle valve. This jet tends to cause the very problem you suggest. In fact I had one cause that problem in one of my cars until I installed a needle valve. 4. Incorrect intake manifold. I had a car with a stock engine and NH carburetor. I won as a door prize a "high volume intake manifold". That manifold would have probably given extra speed and power to a modified engine, but with a stock engine it is like the difference between whistling and blowing out with the lips open. The whistle would be the standard manifold. it would not take in as much air fuel mixture, but the fuel would be drawn in by the restriction in air flow. (think of the fuel as the air stream in your whistle) With the high volume manifold, and an open throttle, you would get a lot of air but not much fuel. I had the very symptoms you describe. It went along very nicely at high speeds such as reved up in low gear or level ground in high gear, but hard to accelerate or climb hills. 5. Fuel to air mixture controlled by the needle valve. You need to enrich the mixture for starting and cold engine. As soon as the engine warms up at a high idle, adljust the mixture needle to the point where the engine runs smoothest and leave it like that until the next cold start.

Other possible cause of the problem not fuel related would be the wrong spark setting. 1.Too far retarded will give you some noise in the exhaust system and possibly lead to a red hot exhaust manifold. As the manifold gets hot, some unburnt fuel will explode in the manifold and cause popping. This condition would cause a drag at all speeds especially as you increase speed. 2. Too advanced spark. In this case the car would run pretty well at high speeds expecially on level ground, however, it would tend to surge a bit as you accelerate or climb a hill. If the engine is hot and or you have very low grade fuel you might even get a "ping", rarely a ping on such a low compression engine, but possible if it is hot. In this case, retard the spark a few notches when you accelerate and see if it helps.

All these suggestions assume you have a good timer and coils and spark plugs. Other causes would be coil, or wiring problems with the ignition system.
Norm

[graham lloyd]

Norm: Thanks for the suggestions. I was thinking that I should take the sediment bowl below the tank apart and clean it. Blow the lines as well. One thing at a time. Hopefully I can get to the bottom of the problem. clean the carb with some carb cleaner.

Carb should be set around 1 1/2 turns from closed?

[halftracknut]

I agree with tightening above, as for gas I run aviation gas (100LL) ....worn out engine runs great...

[Norman Kling]

As to the proper adjustment of the fuel mixture adjustment, no one setting is the same for all carburetors. You can try the 1 1/2 turns and if you can get the engine started, adjust by turning leaner till it slows down and back the other way till it begins to surge. Then set at the point about half way between. It should run smoothest at that point. It will also change with temperature, so as the engine warms up try the same adjustment again. Once you find the point where it runs best when warmed up leave it alone. Next time you do a cold start, open about 1/4 turn to start and adjust to smoothest after it is running. This adjustment could also vary by altitude, so if you are driving up Pikes peak, you will need a different adjustment than at sea level. But the nice thing about it is that it will always have a "sweet spot" for your particular conditions. That spot might vary with weather or altitude.
Norm

[Bruce Compton]

Graham : A backfire is actually the explosion of accumulated unburned fuel anywhere from inside the cylinder itself, the exhaust manifold, or farther down the exhaust system. Unburned fuel happens when the fuel in the cylinder is not ignited and accumulates till a spark occurs or the heat of the exhaust ignites it. Check your plugs for carbon, clean them (no sandblasting) and set the gap at 0.025" and try your car again. Next thing to check would be the individual coils, their fit in the coil box, and finally the coil box itself for dirty/loose contacts and evidence of carbon tracking. Backfiring will surely cause a loss of power, but changing the exhaust manifold won't cure it. If you're still having issues, call Steve Stapley (Stapley Towing) in Cambleford

[graham lloyd]

Well, I got it back together and if anything, it is worse. Drained the tank and cleaned the sediment bowl. Same with the fuel lines. Fuel flows well to the carb. Took the carb (Holly) apart and it was clean. Needle looks good and float is not leaking. Overflow port is clean.

Changed the plugs. Gaps are around 30 to 35 thou. Compression test gives me just shy of 50 pounds consistent across all cylinders.

Thought I had found the problem. Exhaust manifold didn't have any of the inserts. Were some in the intake manifold. Exhaust manifold was leaking. Ever so slight gap along straight edge on the last exhaust port. Wanted to reuse my original "Made in Canada" exhaust manifold, but opted to go with the reproduction. Which is straight. I checked.

So. Starts and idles fine. No backfiring or smoke out the tailpipe. Pulls up to speed fine. No problems. Get up to speed, timing advanced and throttle 1/3 open. Then it begins to stutter and misfire. (feels and sounds like a misfire or backfire) Bring it down to idle, and slow speed. Same thing. Pulls hard (more or less) and then the stuttering starts. Loaded or no load, same result. quarter turn on the mixture, same thing. Retard the spark , same thing. Battery or magneto, same thing.

I'm baffled.

[Bruce Compton]

Change or re-gap your plugs to 0.025" and re-check your coil box for carbon tracking.

[graham lloyd]

Just to add, I did check the needle valve (looks like a thin rod with a point on the end, so I am assuming it is the original and not a grose jet design) .Ever so slight ridge about 1/8" from the tip of the needle. Just enough to feel with your finger nail. That something to be concerned about?

And, I cleaned out the timer and added fresh oil (30 weight engine oil). It is a Ford item, not aftermarket. Is there something else I should have attended to with the timer?

I haven't addressed the coils. They were tuned a while ago and the car hasn't been used hardly since. Should they be a tight fit in the coil box?

Sorry for all the questions. I am getting ready to push this car into the corner for another couple of years. Anybody around my area (Peterborough Ontario) I can seek for advice ? The Stapley family is grieving now, and Steve was my go to guy.

[graham lloyd]

25 thou? Didn't know that. They are Autolite plugs. I will give that a try. Thanks Bruce