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48ply1stcar

ANSWERED Spring test drive - I want more top end

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7 hours ago, Sniper said:

I wonder if your choke is fully opening?  Might warm it up, wire the choke wide open and test.

Manual choke, so yes.

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Did you verify the choke is fully open when you think it is?  Not unknown for the adjustment to slip.

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On 3/11/2020 at 4:57 PM, 48ply1stcar said:

After two years of putzing with my rebuilt 230 (56 / 53) flathead, I feel like run out of engine before I should. . I get to about 60 . When I push on the accelerator the engine starts to bog down, not bad just doesn't accerate any more

 
 
 
 

 

Two years of putzing with your rebuilt 230. Are you able to provide a summary of some of the things you have done, and tried? I'm thinking about all the various things that could make your engine run out of oompph at higher rpm and load. The engine starts to bog down. 

 

Under those conditions you are running off the main jet fuel circuit. When you push on the gas pedal for more, the accelerator pump should provide a squirt of raw gas into the carb venturi. To provide the extra fuel needed. Is that happening? Instead of quickly pushing the gas pedal, if you slowly and gently depress it, does the engine slowly pick up RPM, or still bog down? 

 

What if the valve timing chain is out 1 tooth in either direction ? At higher RPM it sure might bog out. 

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Keithb7

The car seems to run well until 60 - 63 mph.  then no mater what I do the car does not increase and feels like it stalling out until I let off the gas.

Last year I disasembled the distribitor cleaned and lubed it and bought a new vacuum advance - no change. 

I also rebuilt the carb. I get a little smoke from the manifold at start-up then goes away in a minute or two.  Could the fuel level too high or too low in the bowl or maybe could a sticky step-up piston cause the issue I'm having.

This has no bearing but I just had a Cherokee rear installed, and next week I'm installing new disc brakes and master cylinder so I really want to enjoy the road.

 

Edited by 48ply1stcar
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1 hour ago, 48ply1stcar said:

 

The car seems to run well until 60 - 63 mph.  then no mater what I do the car does not increase and feels like it stalling out until I let off the gas.

 

 

Does the engine pull strongly in 2nd gear all the way to red-line?

 

If so.....too much final gear ratio?

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9 minutes ago, Sam Buchanan said:

 

Does the engine pull strongly in 2nd gear all the way to red-line?

 

If so.....too much final gear ratio?

Upgraded from a stock 3.90 to a Cherokee 3.55, Not much different than last year.  I can only think that it's still the carb or distributor.

To answer yes, the car does not seem to stall-out in second gear.

Edited by 48ply1stcar
added info

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If you can rev the engine up under load to high RPM in second gear and all is fine,  yet in the third gear, at same RPM the engine acts up sputtering....I'm stumped. What's so different in the engine when it revs to the same RPM? The engine does not care what gear the transmission is in.

 

I suppose air speed is greater to overcome in 3rd gear at 60-63 mph, compared to the same RPM in second gear. So there is a greater load for the engine to overcome. More torque is required I suppose to overcome this wind resistance, as well as the 3.55 diff gears while maintaining 60-63 mph. I assume you don't have a tachometer to tell us what RPM the engine is running at 60-63 mph in 3rd gear?

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1 hour ago, 48ply1stcar said:

Upgraded from a stock 3.90 to a Cherokee 3.55, Not much different than last year.  I can only think that it's still the carb or distributor.

To answer yes, the car does not seem to stall-out in second gear.

 

Just for comparison here are the numbers for my P15 with 3.91 final:

 

3.91, 28.36" tire diameter, 3000rpm = 64.76 mph

 

Change this to 3.55:

 

3.55, 28.36", 2700rpm = 64.20 mph

 

300 rpm drop from the 3.91 ratio. The little 218 may not be making enough power at 2700 rpm to push the brick into the wind any faster.......

 

It would be making even less power at 60 mph:

 

2550rpm = 60.63 mph

 

All 95 angry horses don't appear until 3600rpm.  :)

 

Transmission ratio calculator:

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

Edited by Sam Buchanan

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VW microbuses have less hp and even boxier shapes, last gens had a top speed of 75.  Pretty sure 97hp is sufficient for 65 or even 70 but I don't think he's making that hp with whatever his problem actually ends up being.

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1 hour ago, michaelmarks697@yahoo.com said:

god I thought the 3.55 would be the answer, (freeway speeds) dammit

now Im leaning towards a 3.27 swap out.

thanks for the invite to club meeting, 48 but cant make it tomorrow. Flatheads Forever

I think the point Sam's making is that I have less power / rpm with a 3.55 than with a 3.9.  My engine issuses are the same as before and I didn't expect the rear end to fix my engine.  I still must have a carburator or distributor issuse.  If I don't feel any better I might not go to the get together can't afford to get those old guys sick.

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My best thought?  🤪

Running short of fuel at higher demand in 3rd. gear and trying to accelerate.

Test? Only way I know of is to install a inline fitting in the fuel line to the carb and add a low pressure gauge that can be routed to a place where it can be see as you do your test drives and monitor the pressure, it should not drop at all if fuel system is operating to spec.

 

What fun-Not!

 

DJ

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2 hours ago, DJ194950 said:

My best thought?  🤪

Running short of fuel at higher demand in 3rd. gear and trying to accelerate.

Test? Only way I know of is to install a inline fitting in the fuel line to the carb and add a low pressure gauge that can be routed to a place where it can be see as you do your test drives and monitor the pressure, it should not drop at all if fuel system is operating to spec.

 

What fun-Not!

 

DJ

 

Yes, might be a bad fuel pump and/or a restriction in the tank pickup or lines. I would think a healthy flatty would pull the 3.55 final but I have no personal experience with that setup. I was just showing how rpm degrades pretty quickly with changes in the final ratio. Aerodynamic drag increases with the square of speed so drag increases rapidly.

Edited by Sam Buchanan

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If my math is right and it may not be, but the .70 ratio of the overdrive renders my 411 the equivalent of a 2.87 to one final drive. So quit a bit lower than your 355.  Still has plenty of grunt for most grades even with a full tank and a trunk of road trip stuff.  What size rear tires are you running?? 

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14 minutes ago, greg g said:

If my math is right and it may not be, but the .70 ratio of the overdrive renders my 411 the equivalent of a 2.87 to one final drive. So quit a bit lower than your 355.  Still has plenty of grunt for most grades even with a full tank and a trunk of road trip stuff.  What size rear tires are you running?? 

 

There may be some problems with the math. I ran those numbers with my 3.91 car and 3000rpm@65mph is reduced to 2100rpm @65mph by simply using a .70 correction. Does OD reduce rpm that much? That would result in 1800rpm@55mph.....

 

A 4.11 final drive goes from 3200rpm@65 to 2200rpm@65mph with the ".70 OD". A 1000rpm drop?

Edited by Sam Buchanan

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Just ran an on line calc.  With 28.5 diameter tires and 1 to 1 trans the 355 should be at 2510 at 60, mine with 28.75 and the .70 OD says 60 is 2280. So pretty close to the same place on the torque curve. Assuming good fuel flow, and good compression he should be able to do 60 and still have plenty of grunt.  If fuel is good I would be checking compression, timing advance and points bounce or misadjustment.  I'd throw the coil in also but he says second pulls good in second through the Rev range.

 

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   48ply1stcar,  Maybe you could adjust your throttle linkage, to get full throttle. Take the return spring off, put a brick on the pedal, disconnect linkage at the carburetor and see if you can get more movement. You might have to shorten the first linkage, so it doesn't hit the firewall. Don't forget to reconnect the throttle return spring. 

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Plymouth Owners Club facebook page is where I found a possible answer. MAIN METERING JET at the bottom of the bowl.  I went through a box of extra parts and found a larger larger jet.  I installed the larger jet and made a little adjjustment on the float (Higher).  Went for a a little test ride.  Eased the car up to 70, now on a nicer day I'll do a tune-up. Tomorow I get to share the news with the Plymouth Owner's Club, Tall Pines Region spring meeting. YAY ME!!!

Capture 2.JPG

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26 minutes ago, greg g said:

Thanks for posting your solution.  Now at 70 all you gotta worry is enough brake...

 

2000 Cherokee rear axle install two weeks ago.  Disc Conversion in the basement wating for a few nice days.

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Used to drive my OD 53 Savoy wagon 60-70 mph to Walla Walla Washington from Seattle  1984-86 with stock 10" brakes down the Cascade mountains...plenty of safe brakes.

 

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45 minutes ago, Dodgeb4ya said:

Used to drive my OD 53 Savoy wagon 60-70 mph to Walla Walla Washington from Seattle  1984-86 with stock 10" brakes down the Cascade mountains...plenty of safe brakes.

 

Yes and you were 35 years younger.image.jpeg.8e6b6d27c4366ee10fb2e77efa22e389.jpeg

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I still have the car too.

It's not in the shape I am though....

I out ran it😂

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