1978 Lincoln Continental Coupe

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GMJohnny
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Re: 1978 Lincoln Continental Coupe

Post by GMJohnny »

If you guys work on cars like my buddy and I do, some spirits
always increase the quality of workmanship. We drink light beer,
but the more we have, the better we work and the more fun it
is! Bottoms up!


GM
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Basement Paul
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Re: 1978 Lincoln Continental Coupe

Post by Basement Paul »

I don't think with that monster motor, that you'll ever be able to bog it by opening the secondaries too early. I ran an 870 on my Caddy 500, and it wasn't near as hairy as your Ford motor. I hope all your hard work pays off.

-BP
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Maverick
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Re: 1978 Lincoln Continental Coupe

Post by Maverick »

GMJohnny wrote:If you guys work on cars like my buddy and I do, some spirits
always increase the quality of workmanship. We drink light beer,
but the more we have, the better we work and the more fun it
is! Bottoms up!


GM
We have to wait till road tests are done to imbibe. :(
Maverick
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Maverick
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Re: 1978 Lincoln Continental Coupe

Post by Maverick »

Basement Paul wrote:I don't think with that monster motor, that you'll ever be able to bog it by opening the secondaries too early. I ran an 870 on my Caddy 500, and it wasn't near as hairy as your Ford motor. I hope all your hard work pays off.

-BP
Interesting. When we get to secondaries, we'll open them as early as possible. If no bog, we'll leave it there.

A webcam w/LEDs ($8 shipped by Amazon) is supposed to arrive Tuesday. We'll install it to capture secondaries position. We'll then have RPM, A/F, fuel pressure, manifold vacuum, coolant temp, and secondaries position all in real time. We'll know what's going on and see the effects each change.
Maverick
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Maverick
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Re: 1978 Lincoln Continental Coupe

Post by Maverick »

Got the 10.5 High Flow power valve installed and replaced the #74 primary jets with #73s. Vacuum moved up a point to 18 in Hg.

Idling in the driveway, A/F was about 12.05 with air cleaner off; 12.50 with air cleaner on and drawing air from the cold air intakes. Something to think about when adjusting the idle mixture with the air cleaner off. The A/F will lean out when the air cleaner goes back on.

Carl suggested leaning out idle as a way to lean out cruise A/F. (Cruise uses both primary jets and idle circuit.) Haven't tried that yet. Need to try adjusting both timing and idle mixture for max vacuum.

USPS tracking reports the web cam was picked up yesterday in California and expects delivery tomorrow. We'll see.

WXO is busy. We'll get another T&T when he catches up.
Maverick
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Maverick
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Re: 1978 Lincoln Continental Coupe

Post by Maverick »

The USB web cam arrived from Amazon ($7.99 shipped!!) with built in, dimmable LEDs. Think it was cheap because it was USB 2 only -- didn't work in the USB 3 socket in my laptop. Fortunately, WXO brought his laptop with USB 2. We had both downloaded and installed Microsoft Movie Maker to record video of the secondaries opening/closing.

We got another run in yesterday. Video of secondaries works well. BIG DIFFERENCE with new power valve and smaller primary jets!! The engine felt smoother, quieter and stronger. A/F was good at idle (can't recall exact number) and in the 15s on cruise. Still leaning out on heavy load. So, back to the garage for some bigger secondary jets. Replaced 84s with 90s. Fuel pressure dropped from 10+ to 8" Hg, fuel level in the bowls down about 1/4", everything went lean. :?:

Maybe the alternator quit charging, dropping voltage and therefore fuel pressure, therefore lower fuel levels in the bowls, therefore lean conditions? Nope, 13.X volts at idle. Maybe a restriction in the fuel return line dislodged? Maybe something in the regulator forcing it more open? Fuel pump failing?? We quit with a big downer after some earlier euphoria.

After thinking about it overnight, we decided to adjust the floats to compensate for the reduced fuel pressure and see what happens. Recommended pressure for the QF carb is 6.5 PSI so 8 is better than 10.5 (the least the bypass regulator would do before). I'd welcome a permanent change to 8.

Started it up this AM and fuel pressure was back above 10+ PSI. :?: :?: :?: So, no changes this morning. We'll do another run this afternoon to see if fuel pressure stays up and what the #90 secondary jets do.
Maverick
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Fred32v
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Re: 1978 Lincoln Continental Coupe

Post by Fred32v »

When you hit that sweet spot with the tune on that 521 you'll know it.
You acceleration and gear changes will be a lot more violent.

It's a real "Hot Rod Lincoln"!
Fred32v
GMC Canyon Crew Cab Short Box 4x4 V6!
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wxo
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Re: 1978 Lincoln Continental Coupe

Post by wxo »

Fred32v wrote:When you hit that sweet spot with the tune on that 521 you'll know it.
You acceleration and gear changes will be a lot more violent.
We got our first taste of that the other day and we're not done yet. It's still going lean after going to the #90 jets on the secondaries. I think my TBSS is going to have some serious competition when we go to Rockingham the next time.
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Maverick
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Re: 1978 Lincoln Continental Coupe

Post by Maverick »

The #90 secondary jets helped but its still lean under heavy load. Need to go bigger.

The mysterious fuel pressure drop is still haunting us. Maybe its the season? Pressure stayed up at 10+ for today's run, except that it drops after shutting the engine off and restarting. We wanted to know if the decrease in fuel pressure was due to reduced voltage on the fuel pump. Two voltmeters were installed, one reading battery voltage and one reading voltage at the lead to the fuel pump. Voltage was solid on both, battery 14V and fuel pump lead 13V, while the fuel pressure varied. That eliminated voltage fluctuation at the cause for reduced fuel pressure.

Next theory to test: is the fuel pressure regulator delivering reduced pressure when hot? Heat sink after shut down no doubt raises the temp of the regulator. Idling in the driveway, the fuel pressure was down to 8 PSI, the fuel level in the bowls was near the bottom of the sight glasses (should be centered), and A/F was high 15s - 16. Temp of the regulator was in the low 120s. Running cold water from the garden hose on the regulator didn't affect fuel pressure. Looking for a new theory.

We're not going to get a stable tune with fuel levels in the bowls changing by 1/4". One thing I could try, although its a lot of work, is to get a 3/8" nipple on the tank for the return line. I suspect that the regulator can't get the fuel pressure down to the recommended 6.5 PSI because the 1/4" nipple on the return line is restricting return flow. Maybe if the carb was getting the recommended PSI, we wouldn't see this weird pressure variation. That's the only idea I have at this point but I'm not ready to take on the job of getting a 3/8" return nipple on the tank.
Maverick
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Maverick
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Re: 1978 Lincoln Continental Coupe

Post by Maverick »

Although it seems like the 8-10+ PSI fuel pressure can't cause the fluctuation in fuel pressure, it is well above the 6.5 recommended pressure. Think it would be a good idea to get the pressure in spec to take that anomaly out of the discussion.

The fuel pressure regulator is adjusted to provide the maximum reduction. There are two possible causes for the failure to reduce the pressure more: 1) the regulator isn't able to reduce it further or, 2) the 1/4" nipple for the return line at the tank is restricting the return flow and not allowing a lower pressure.

To determine which it is, the 3/8" return line was removed from the tank and a hose attached to run fuel into a bucket. The pump was run with the 1/4" nipple restriction removed. Pressure dropped to 7 PSI indicating that the 1/4" restriction is limiting pressure regulation and the pressure regulator is able to get the pressure down close enough to the 6.5 PSI recommendation. The return line should have a 3/8" nipple at the tank.

Don't expect that would cure the fluctuation; the pressure drop appears to be heat sink related since it occurs after the engine is shut off for a few minutes and then restarted. But it'd be good to have that issue out of the discussion.
Maverick
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Maverick
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Re: 1978 Lincoln Continental Coupe

Post by Maverick »

We're ready for another test run and plan on taking it out again tomorrow.

The secondary jets were changed from #90s to #96s. Hope to see richer A/F at WOT.

The restrictive 1/4" nipple on the tank for the return line has been capped and the return line moved to a 3/8" nipple brazed onto the filler tube. (Much easier to remove the filler tube than the tank for brazing.)

Image

Fuel pressure is now 7-7.5 PSI. That is, until the engine is warmed up and shut off for a few minutes. Then, when the engine is restarted, fuel pressure is down to about 5 PSI. :(

Adjusted the floats up for the lower 7-7.5 PSI. Idling A/F is in the mid-13s with no changes to mixture screws. Leans out to low to mid 14s when fuel pressure is 5 PSI.

Removed the tap into the fuel pump lead wire -- no variation in voltage to the pump was observed so we don't need to monitor that voltage anymore.

Put some header wrap and insulating tape around the fuel pressure regulator and placed a temp sender under the wrap. Swapped the lead from the coolant temp sender to the sender under the wrap so we can observe changes in the regulator temperature on the existing temp gauge. Don't expect, or need, the temp gauge to be accurate, just need to observe changes in regulator temp to see if it correlates with changes in fuel pressure. Temp gauge went to 200* after the hot engine was shut off. We'll be able to observe changes in the temperature of the regulator.
Maverick
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Maverick
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Re: 1978 Lincoln Continental Coupe

Post by Maverick »

Got a run this morning. Runs NICE under all conditions.

. After adding gas to the tank, no leaks apparent in the brazed on nipple on the filler tube.

. Still lean on WOT though less so. A/F doesn't stay at 16 now but bounces off it.

. Also lean when power valve is open and secondaries are still closed.

Bigger power valve restrictors are arriving by the big brown truck sometime today. The largest will replace the drilled out restrictors in there now. Since the larger restrictors will dump more fuel before and after the secondaries open, it makes sense to go bigger on the restrictors and see what effect that has when secondaries are open. If WOT is still lean on primaries plus the power valve, we'll go to bigger secondary jets. #96s in there now. #99s are the biggest I have.
Maverick
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Maverick
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Re: 1978 Lincoln Continental Coupe

Post by Maverick »

Got the .061 power valve restrictions (tiny jets w/6-32 threads) and installed them. Tied off the secondaries for the first part of the run so we could see what A/F the larger restrictions would provide. On the test run yesterday on just primaries, it was still lean under load, mostly in the 14s. Untied the secondaries and got about the same result. Need still bigger restrictions. WXO thinks maybe we should just leave the restrictions out and get some fuel to those cubes. :mrgreen:

An assortment of restrictions, ranging up to .071, should be delivered on Monday. When we get the primaries under load in the 12s, we'll find secondary jets that get us in the same area for WOT on all four barrels. THEN off to Rockingham for a 1/4 mile run.

The fuel pressure was ranging from 5-7 PSI depending on the temperature of the regulator. The regulator has to be relocated so a safe, cooler location to eliminate the varying fuel pressure. Maybe on the inside of the frame to get it off the block and out of the air from the radiator. Gotta work that out.

The transmission gave a shudder when pulling into Bo Jangles for a video viewing, coffee and cinnamon roll. Think we might have gotten it a little hot with our testing. :(
Maverick
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Basement Paul
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Re: 1978 Lincoln Continental Coupe

Post by Basement Paul »

My turbo400 used to shudder when it was warm all the time during part throttle operation. But never missed a beat when under power. I don't think there's too much to worry about there. It's been gone for at least a couple years, and the new owner hasn't had any issues with it either.

I hope all this work pays off!

-BP
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Maverick
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Re: 1978 Lincoln Continental Coupe

Post by Maverick »

It's like it couldn't make up its mind which gear it should be in when it was hot and under high vacuum. I could adjust the vacuum modulator for later (which would be good) and firmer shifts but the shifts are plenty firm under normal driving now. Shifts are great under heavy throttle. We can see the camera snap back a bit at the shifts. 8)

We're pretty confident now we can get the carb tuned right. Its fun to make a change, predict the effect, and see the theory confirmed on the gauges. Kinda like tuning on a mobile dyno in real world conditions. Success will be an 1/8th mile in less than 9 seconds.
Maverick
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