Time for an overhaul...

[Dodgeb4ya]

I have balanced a nickel on edge on my 48 Chrysler straight eight engine before.

 Your Plymouth sounds like you can do the same.

[Don Coatney]

Spinning the engine that long with the starter motor is a sure way to melt the starter motor. Short 10-15 second bursts with at least that much cool down time in between starting attempts will insure much longer starter motor life 

[thebeebe5]

6 hours ago, Don Coatney said:

Spinning the engine that long with the starter motor is a sure way to melt the starter motor. Short 10-15 second bursts with at least that much cool down time in between starting attempts will insure much longer starter motor life 

 

??????

[Cpt.Fred]

Jim,

 

good job as always, i really love your car!

 

speaking of jets, where do you get yours, and do you have a list that indicates which number jet is leaner or richer?

i haven't found anything like that yet, and i would really like to see one. i always find it confusing to sort through the different

mains and step ups and test drive them with the afr sensor, only to be confused again by their behaviour in the carb

 

thanks,

 

Fred

[David Mac]

What a great read. I really enjoyed following your build and the attention to detail. I only wish I had a shop, like yours, near me. Great job and thanks for sharing.

David M

[thebeebe5]

On 8/17/2018 at 1:52 AM, Cpt.Fred said:

Jim,

 

good job as always, i really love your car!

 

speaking of jets, where do you get yours, and do you have a list that indicates which number jet is leaner or richer?

i haven't found anything like that yet, and i would really like to see one. i always find it confusing to sort through the different

mains and step ups and test drive them with the afr sensor, only to be confused again by their behaviour in the carb

 

thanks,

 

Fred

 

Fred, 

jets were obtained buying cheap “basket case” carbs off ebay and hoping the jets were still in place.  

 

Here’s what I did today.  This carb is really basic.  The power circuit (I believe they call it a “step up jet” in the manual) is controlled by this trident of brass gadgets seen here. A vacuum plunger, a “step up jet” plug and an idle circuit emulsion tube.   Unscrew the idle circuit emulsion tube and lift the trio out.  

 

 

 

Under vacuum the plug in the middle of the group is held down tight into the step up jet keeping it closed to fuel flow.   When the gas pedal is pushed down and vacuum drops the engine will want more fuel for a WOT run up to speed.  The spring expands in the absence of vacuum (as during WOT) to allow fuel to flow through the step up jet thus providing the required fuel for rapid accelleration. That jet is being removed here.   The main jet is screwed down in the bottom of the bowl just to the right of the step up jet.

 

 

This is what it looks like.  I had two different jets among the three carburetors I had available.  

 

 

In the carb the car came with was a 149-43S step up jet and an unmarked main jet.  The step up jet had an orifice that measured 0.037”.   I had a duplicate of this same jet and another marked 149-63S which measured 0.039”.  The main jet was somewhere between 0.050 and 0.054” (all three I had were).   A 0.050 drill bit dropped through it, but a 0.055” bit would not.  It was close though, so I drilled it out easily by hand with the 0.055” bit.   Figured I could go up a little at a time.  Now the cruise AFR should be a little fatter, and my target was about 14.5:1 (down from around 15.2:1).   BUT opening that jet would only add to the already too rich WOT AFR of 12.8:1.   Remember, the main jet is still dumping fuel into the circuit when the step up jet opens in the absence of vacuum.    So, I need a smaller step up jet....   But, I don’t have one.  So I modified one of my extras.   Got some 60/40 general purpose solder, some flux and a torch. The orifice of the step up jet is up where the plug makes contact.   Below that the jet is wide open.  I think I measured them all around 0.067”.  I didn’t want to permanently modify the jet if I could help it, so I flowed some solder into the bottom of the jet only and kept it well away from the jet/plug interface.  

 

 

Then I made a mistake....  ?

I make them often.  With luck I learn from them....   I drilled down through the jet into the solder with a 0.029” drill bit chucked up in a tiny hand held chuck, but halfway through I realized the shavings were going to end up between the solder plug and the original orifice and clog it up. 

 

 

Easy fix, really....  just reflowed the solder and melted the shavings back into the solder plug, then redrilled.  

 

 

As far as leaner or richer jets, obviously larger holes in jets let more fuel pass through.  What the wide band told us last week was that the WOT AFR was a bit rich and the cruise AFR was lean.  The main jet is responsible for the cruise AFR and the two combined are responsible for WOT AFR.   A smaller step up and a bigger main jet on the wide band gave these results:

 

Cruise of 14.5:1 (perfect!) and WOT of 14.9:1.   Remember I decreased the step up jet orifice by about 25%.   Brian wanted to see WOT richer, so I pulled the plug, drilled it out to 0.033” and went for another spin.   WOT was now 14.2:1 AFR.  Still a tiny bit leaner than he wanted to see, so I went up to 0.034”.  That should get it down in the high 13s.

Tiny changes yielded significant results  in this carb.  Will run it tomorrow and check.

 

I also tried to lean out the idle, but kept ending up with a lean misfire with AFRs above 12.1:1.  So it will stay in the high 11s.

Edited December 24, 2021 by thebeebe5
Grammar

[sser2]

Fascinating read.

 

Old carbs were jetted for straight gasoline. It is not surprising they run lean with 10% ethanol.

 

You might consider transistor ignition, which allows for stronger spark - wider plug gap and longer spark duration. Burning leaner mixture in modern engines critically depends on it. Original distributor can be used, with points triggering an electronic switch (a Darlington transistor) connected to coil's primary. A 6V coil designed for electronic ignition will be needed. A very simple setup. An additional advantage is complete elimination of points' erosion.

 

Are you planning on using the original oil bath filter? These filters don't clean air as efficiently as modern paper filters, and are #1 cause of rapid wear of old time engines. There are paper filters that will dimensionally fit inside oil bath filter case, if original look is to be preserved.

[Cpt.Fred]

thank you Jim, great info once again.

 

i really had hoped for a place to buy these parts new and in logical order from lean to rich,

but i guess that would be too easy...?

 

i was running 159-59S mains in my triple carb setup on the 265. these were too lean at cruise. 159-61S were better, 14-14.5 AFR.

the engine was drowning in fuel above 3000rpm and under heavy load in overdrive, i experienced 10,5-11 AFR, intolerable.

i tried two sorts of step up jets, 149-113S (leaned out the cruise too much and still flooded under load) and 149- 43S (too much in general)...

i can see the logic behind the numbers on the main jets, but the ones on the step ups don't quite add up for me.

funny thing was that somehow the test results were not exactly what i had expected, especially changing the step ups had far bigger effects

over the whole rpm range than i had thought before.

 

good to know your measurements now, i will check the orifice diameters and then try soldering and drilling as well.

another thing i did on my first triple setup on the old 201 was putting weaker springs into the step up jet assembly, allowing it to stay shut just a little longer.

on the smaller engine that gave me pretty good results and the AFR was in an acceptable range.

 

thanks for taking the time and sharing all your measurements!

 

Fred

Edited August 20, 2018 by Cpt.Fred

[thebeebe5]

7 hours ago, Cpt.Fred said:

thank you Jim, great info once again.

 

i really had hoped for a place to buy these parts new and in logical order from lean to rich,

but i guess that would be too easy...?

 

i was running 159-59S mains in my triple carb setup on the 265. these were too lean at cruise. 159-61S were better, 14-14.5 AFR.

the engine was drowning in fuel above 3000rpm and under heavy load in overdrive, i experienced 10,5-11 AFR, intolerable.

i tried two sorts of step up jets, 149-113S (leaned out the cruise too much and still flooded under load) and 149- 43S (too much in general)...

i can see the logic behind the numbers on the main jets, but the ones on the step ups don't quite add up for me.

funny thing was that somehow the test results were not exactly what i had expected, especially changing the step ups had far bigger effects

over the whole rpm range than i had thought before.

 

good to know your measurements now, i will check the orifice diameters and then try soldering and drilling as well.

another thing i did on my first triple setup on the old 201 was putting weaker springs into the step up jet assembly, allowing it to stay shut just a little longer.

on the smaller engine that gave me pretty good results and the AFR was in an acceptable range.

 

thanks for taking the time and sharing all your measurements!

 

Fred

I’m not sure why the step up jets would influence cruise AFR.  If you’re running three carbs maybe there’s different spring rates for the springs between carbs?  Just a guess...

That jet should be closed while cruising.   Vacuum should hold the plug down in that jet and block it off. 

[thebeebe5]

On 8/18/2018 at 10:03 PM, sser2 said:

Fascinating read.

 

Old carbs were jetted for straight gasoline. It is not surprising they run lean with 10% ethanol.

 

You might consider transistor ignition, which allows for stronger spark - wider plug gap and longer spark duration. Burning leaner mixture in modern engines critically depends on it. Original distributor can be used, with points triggering an electronic switch (a Darlington transistor) connected to coil's primary. A 6V coil designed for electronic ignition will be needed. A very simple setup. An additional advantage is complete elimination of points' erosion.

 

Are you planning on using the original oil bath filter? These filters don't clean air as efficiently as modern paper filters, and are #1 cause of rapid wear of old time engines. There are paper filters that will dimensionally fit inside oil bath filter case, if original look is to be preserved.

 

I’m just keeping it stock.  The original ignition is lighting the fire, and the oil bath air cleaner suits me fine.  Been running that filter on my old cars for years.   They really don’t get lots of miles on them, and i avoid driving in dust storms around here. ??

[Cpt.Fred]

14 hours ago, thebeebe5 said:

I’m not sure why the step up jets would influence cruise AFR.  If you’re running three carbs maybe there’s different spring rates for the springs between carbs?  Just a guess...

That jet should be closed while cruising.   Vacuum should hold the plug down in that jet and block it off. 

i will look into that. my experience is they move upwards pretty quickly once the butterflies open.

 

by the way, you have to post a video of the car driving by and some more outside views of it

[Pete]

Good post guys. I'm curious, what are using using to measure AFR?

[thebeebe5]

6 hours ago, Pete said:

Good post guys. I'm curious, what are using using to measure AFR?

 

 

[Cpt.Fred]

nice piece.

 

i'm using the AFR gauge from Innovate Motorsports

 

Edited August 22, 2018 by Cpt.Fred

[Matt Wilson]

On 8/14/2018 at 12:39 AM, Don Coatney said:

Spinning the engine that long with the starter motor is a sure way to melt the starter motor. Short 10-15 second bursts with at least that much cool down time in between starting attempts will insure much longer starter motor life 

I think the slow-turning fan was just an illusion caused by the camera recording speed. I believe the engine was idling the whole time it appeared to be cranking slowly.  You can see the fan appear to speed up, slow down, even go backward throughout the video.  Maybe you knew that and were just joking, but I thought I'd mention it, in case you weren't joking.

[DonaldSmith]

Stroboscopic effect.  Stagecoach wheels going backwards.   

I had heared that fluorescent lighting is bad at operating machinery, because it can make moving parts appear to be standing still. 

[kencombs]

On 12/3/2017 at 11:44 AM, thebeebe5 said:

Got the crankshaft back from the grinder.   They hit the specs on all journals within 0.0003", so pretty happy there. Will have oil clearance of 0.0018"-0.0021". Need to have the main machinist look at the crank though.  Journal 6 didn't completely clean up.  There's a slight blemish mid journal.   I'll trust his opinion on weather to run it or get a 20 under bearing for that rod and have it re-turned.  

Also, got the oiling mod complete for full flow filter.  Will be installing 3/8" AN fittings and probably mounting the adapter right to the oil pan rail behind the oil pump boss keeping things nice and compact.  

I'm considering this mod for my 230.  Do you have more pics or info on the placement and/or details of the drilling and tapping??

[thebeebe5]

9 hours ago, kencombs said:

I'm considering this mod for my 230.  Do you have more pics or info on the placement and/or details of the drilling and tapping??

There should be several images in the thread scattered throughout. Make sure you aim carefully so you don’t hit the center hole or the righthand bolt hole.   1/2” drill is essential and go slow!    If that bit bites it’ll wrench that drill out of your hands and take fingernails or anything else with it.  At worst you’ll end up with a pinched finger or two.  Know what size fittings you’re using and keep them separate enough.  Mine were too close and I’d do it a bit different next time. It’s fine as is, but i would have saved myself some time machining fittings.  

[kencombs]

Thanks for the info and advice.  The pic I quoted was the only one I could find in the thread specifically about the oil mod.

Are the threads in the block pipe thread or just straight?  i think you stated that you using 3/8 AN lines and I think 3/8 uses 1/2x20  , on the hose/tubing side.  Does that sound correct?

Most of the add on full flow systems I've seen seem to be 1/2 hydraulic hoses.  Any info on the actual size comparison from that to the AN you're using? 

 

thanks

[thebeebe5]

23 hours ago, kencombs said:

Thanks for the info and advice.  The pic I quoted was the only one I could find in the thread specifically about the oil mod.

Are the threads in the block pipe thread or just straight?  i think you stated that you using 3/8 AN lines and I think 3/8 uses 1/2x20  , on the hose/tubing side.  Does that sound correct?

Most of the add on full flow systems I've seen seem to be 1/2 hydraulic hoses.  Any info on the actual size comparison from that to the AN you're using? 

 

thanks

 

The threads for the fittings are pipe thread.  The thread into the oil passage are standard.   The ID of the fitting was very similar to the oil passage, but I don’t remember if I measured them.   I’ll have a look back though my photo documents and see.  

[BobT-47P15]

1. Placement of air filter decal...….
2. 

[kencombs]

deleted

Edited November 11, 2019 by kencombs

[greg g]

Just read this thread. The step up valves are entering  he equation of afr at cruise because the total vacuum signal that held one valve closed is now being shared by each carb.  So each carb is getting half or 1/3 of the single carb signal meaning that the spring tension will not be completely overcome leaving valves partially opened when they would normally be closed at steady level road cruise.

[Stewart Woollard]

As I am planning on rebuilding my engine soon, I just took the time to read this in one sitting. The high level of machining is fabulous. The attention to detail is incredible. Thank you so much for taking the time to document your build, I realise how time consuming that is. Being new to these flathead 6s, I don't even know what I don't know! This thread has helped enormously. Thank you again.

Cheers,

Stewart.

[Andydodge]

Beebe......I too have just reread the entire thread and still get info and enjoyment out of it............its 12 months since your last post, how have things panned out re the engine rebuild and the possible turbo install?...........I trust you are going o/k and again thanks for all the effort in posting this thread......regards from Oz.........andyd