The Official John Lee Jr Thread

[Sharps40]

So, New engine, would not run well below 18 degrees BTDC and I did not know my mechanical curve in the dizzy nor the vacuum advance rating. Fortunatly, I got some good advice here and figgured those out....18 mechanical + 10 on vacuum advance. That particular thread didn't go well, was particularly frustrating for lack of documented/actionable data points for a stock motor with minnor reliability upgrades and I deleted the info and will attempt to clarify how I located what I believe to be a safe and adaquate engine tune here.

I started over several weeks by driving on hi test only and examining all functions in the engine as time and work allowed. Its a daily driver and as such a tune what ya got proposition.

The first fix implemented was to return to stock jetting on the Weber....The first engine ran well there with both points and electronic dizzys and I knew it was adaquatly rich to keep me out of trouble.

I then corrected the pcv system with a new valve installed with the arrow pointing to the source...no more uncontrolled vacuum hole there....still wouldn't run well below 18 BTDC initial.

I corrected smaller leaks at the 3, 4 runner and at the adapter to manifold junction. Now it would run well at 16 BTDC...tweaked the jetting IAW Mr. Langdons recommendations. (Factory idle circuit jet, slightly leaner on the main, much richer on the secondary)...engine ran great, thought I was done.

But, I was at 16 BTDC and "knew" the factory inital was 4 BTDC. I never considered that 4 was for points.......still didn't know if an HEI was different and didn't know the mechanical or vacuum advance.

Followed some advice, between the frustrating moments and mapped out my Dizzy, finding it brings 18 degrees mechanical to the table and the vacuum can brings another 10 degrees.

Considering how well it was running as newly rejetted (18 + mpg smooth and powerful) I was still concerned about being at 16 to 18 BTDC.

So, I lowered the initial advance in increments. First 14 BTDC, ran better and it stopped kicking back against the starter as it would occasionally do on hot restarts at 18 BTDC.

Then tried 9 BTDC (Still didn't know there was a difference in factory inital timing between points in the 60s and electronic in the late 70s) and it ran great but was weaker at low speeds, especially cold.

Then went to 4 BTDC, the factory points initial advance recommendaton for many 250s thru the early 70s. Ran okay but was weak across the entire rpm range and sucked fuel like a BarPig on cheep wine every Payday Saturday Night.

So....now suspecting a range of 9 to 14 was more correct for the engine as currently outfitted I reset to 10 BTDC. (10 initial + 18 mechanical + 10 vacuum brought 38 degrees total to the table and it was comeing all in by 3000 rpm as indicated by movement of the marks on the balancer under the timing light....figgured this out with a bit more advice after weeding back thru a rather frustrating thread on engine tuning.) The truck ran great here.

How wonderful it was to finally receive confirmation from a member in the form of a photo (from a haynes manual) of the timing specifications for a Chevy truck 250 with a stock GM HEI.....factory recommendaton for my late 70s engine and similar era HEI was in fact 10 degrees BTDC! Now we're getting somewhere, actionable and documented information for a daily driver stocker with HEI, confirmation, not frustration, not remachine to race engine set up, not timing is easy so close the hood and enjoy the ride....

Comfortable now, I increased the timing a small step.....9 to 14 seemed about right from driving and performance, 10 was factory and drove/felt well, so I selected 12 degrees BTDC. Went out for a drive. Made it to 80+ mph before I backed off. Couldn't get it to ping. The engine seemed alive...pulling hard on the main and harder on the secondary in all gears and without rattle, clatter or any hesitation. Plugs, though hard to read, showed some indications of tanning up and none of the black or silver flecks that I am told are a sign of detonation.

So I have set my engine 12 initial + 18 mechanical + 10 vacuum advance for a total timing of 40 by 3000 rpm. With the T5 transmission, I tach 2800 rpm at 75 mph. Its unlikely I'll ever break 3000 rpm. It appears we are going to remain in the 18 mpg range for this set up.

I'm about 200 miles down the road now on this setting...plugs still look fine and I am pleased with the performance and fuel mileage.

[Sharps40]

With luck, I can get my fuel lines replaced this weekend and insulated and an oil change. Hopefully then I can close the hood for a few weeks and focus on finishing up the rebuild of the rear suspension.

[TJ's Chevy]

I run 92 octane in my truck. Mainly because of the large carb and really hot spark, 65000 volts needs lots of octane to burn. Lol.

[Sharps40]

Dropped in a 19 tooth driven gear today and road with Missy Garman. With the ratio adapter looks like the ol speedo is close enough to dead on that I finally will be readin accurate speed and miles. Math works even though the spedo shop said it couldnt be done by checkin gear counts an usin a ratio calculator. Ha!

[TJ's Chevy]

Well at least yer truck ain't sheriff bait any more.

[Sharps40]

What is sheriff bait?

[TJ's Chevy]

Yeah, the speedo. lol. My truck is Sheriff bait..only when I sneak down our road; cause it ain't registered or insured and all that crud. lol. But won't be fer long...later this year or early next year I'm a thinkin of getting her legal.

[Sharps40]

Dude, ya got all that engine and it ain't registered? Hell, I'll drive it for ya!

[TJ's Chevy]

Originally Posted by Sharps40

Dude, ya got all that engine and it ain't registered? Hell, I'll drive it for ya!

LOL!! Yeah....it ain't yet. I take it for drives though. In my parts the law hardly even checks us anymore cause we are 36 miles from the city. So...a little cruise is okey once in awhile. lol. But, we'll be fully legal here soon. And having all the extra engine just helps it blow dust better! LOL!

[Sharps40]

I'm lovin drivin on the more correct tune now. John Lee is performin lika Hooker at Homecoming - with Gusto!!

[Sharps40]

Started out this morning tryin to finish up eliminating all the potential sources of post shut down carb percolation.

So far I'd tried insulating the manifold and carb lines to no avail. All that did was slow it from 15 minutes to perk out to 25 minutes till it perked. Perking occurs after shutting down from a drive on any day over 60 degrees.....doesn't matter whether its E10 or straight gasoline.

So....the other day, pulled the hose hot and watched it perk and perk and perk out the hose. Hmmmmmmm.....insulated the full length of the fuel line as shown below (factory routing for the fuel line, next to the radiator hose, head and waterneck and out over the exhaust manifold....)

Full length insulation had no positive impact....neither did adding a 1/4" thick fiber carb gasket and two 1/4" thick phenolic insulators. Runs like a scalded raped dogape but perks fuel into the intake after shut down on warm days.....making it just a tad harder to start.



So, off with the factory hard line that runs around all the hot points in the engine and a new 5/16" hard line is bent up to run out a bit and to the rear coming up between cylinders 2 and 3....much further away from the block than before and out in the wind.



Connect up the fuel filter, up and over with new rubber line and 3/4" fuel line insulation sleeve from the nut on the fuel pump to the clamp on the carb. Aimed to keep the line at least 2" from the motor at all times and was successful....



Using a convenient tapped hole in the block (the old coil mount) I bent up a nice aluminum strap and mounted it to the block. The other end captures the new metal line to prevent it from shakin loose.



Plenty of room to work and no leaks after a test drive....



Crap, its still perkin. So....breaked out the spanky new combo vacuum and fuel pressure gage after it cooled completely off.

First pulled the lid....I'd already installed spanky new needle and seat and checked float level was 39mm, factory setting.... but maybe with the hose perkin it was overcoming the ball check valve.

So, ignorin the float setting I adjusted the float to be parallel with the lid, ball check valve fully closed......the float setting was now at 43mm, a bit lower than before.

Webers, per the manual, need low pressure, higher volume. Mr. Langdon indicates running the stock mechanical fuel pump, no regulator.

Checked it out, cold start, 3.5 psi on the fuel....hot running, 3.5 psi on the fuel, rev it up, 3.5 psi rock steady on the fuel. Ran it till it was hot and shut it down....over 30 minutes the pressure in the line climbed up to 5.25 lbs and no perkin.

Oh my....hope I got this fingered out!

[TJ's Chevy]

I was starting to think of fuel pressure as being an issue...Its funny..my fuel line is straight rubber from the frame to carb(metal from the frame back to electric pump) and I have never had fuel perking out of the lines..or carb. And my fuel lins runs between the valve cover and thermo housing and and over the intake an headers to the carb. I was running the truck yesterday and it was a round 65+ out and no fuel issues. But..I am running a large carb that takes up to 5 pounds pressure..so that helps. I do know that one time I believe I could feel the fuel boiling in the metal filter. But I'll have to check 25 min after shutdown next time an see what happens. lol. I've never seen smoke comin out from the hood so me thinks were ok.

[Sharps40]

I found three sets of float level adjustment specifications for the Weber with plastic floats....Haynes, Weber America and Redline. Basically ignored em all and set the float top parallel with the lid, check ball slightly compressed. This lowered my float from 39mm to 43mm check ball uncompressed. Slightly tweaked the stroke to 49mm. The initial hot check indicated no perking. And subsequently found that setting close to the Redline recommendation for current installations (lower than haynes and Weber America). Its been cooler last couple of days but so far no perking...and no change in the feel/performance out on the road...we'll see how it goes.....lookin like the back sliding glass and rear suspension projects are moving up the punch list...I hope.

[1963c-10]

Nice job Rich, glad your able to work out the small issues so you can get on to more projects!!!

[TJ's Chevy]

X2! Glad its starting to fix! Hopefully now you can get to other projects!

[Sharps40]

I hope its worked out. If not, I should know thursday when the temps go back into the 60s and 70s. I suppose the last ditch is a cooling fan on an adjustable thermostat to circulate air under hood till things cool off.

[shok]

A seperate fan just for that or an electric rad fan that besides cooling the rad will stay on a minute or so after shutdown?

[Sharps40]

Yep. Wire it hot (not ignition switched) and a rad fan or cooling fan will cycle on and off after engine shutdown till the set temp is reached....just like modern cars. If ya use an external probe type you can put the sensor in the fins, on the head, the block, near the manifold, on the fuel line, in the air, whereever ya want.

[Sharps40]

Bit o the Scaries this morning. Hopped into John Lee and kicked the ignition and nothing. Not even a touch of clatter....neglected to check the lights for function/drain from being left on or for function/dimming to see if it was a starter issue and went straight to the 6 amp chager.....in the red.

Gave the ol boy 10 minutes at 6 amps and kicked the switch and clatter at the starter........10 more minutes and VROOOOOM! Off and runnin.

Got to work....36 miles at highway speed, it should be fairly well charged. But I guess I need to check idle voltage tonight and start lookin at switches for leaks to ground. Its possible I left somethin on in the rain last night....but in my confusion, neglected to check this AM. Fortunatly I got jumpers in the truck and selected a parking spot thats jump start accessable for this afternoon.

The headlight switch is good/new. I note my wipers don't park unless I cycle the switch once or twice....could be that original switch or the 1964 wiper motor leakin. Or could be the ignition switch. Hope its not the 12SI....its just out of warrenty!

[TJ's Chevy]

Stop scarin me!!!! My electrical is 48 years old an working fine so far!!! SHHH!!!!

[Sharps40]

Well, it started and ran fine at lunch, twice....so I'm hopeful it was just me leavin the park lights on last evening. But, I'll at least check the charging voltage tonight at home.

[Sharps40]

A beautiful day with John Lee. 5 qts of 10w40 Accel oil with the ZDDP already in it and a new large size Fram from Lowes (1.75 ea clearance so I got 2).

Topped off the water. First I added any in 14k miles since puttin on a cheep overflow tank.

Topped off the T5 with 1 pint of DexMerc.

Gave the ol boy a bath and vacuumed out the cab....even pulled the rags outta the vents on accounta its finally warm.

Rotated the tires.

Pulled up the brake shoes.

Gave the new suspension its every second oil change shot o greese.

Dayum. I'm tuckered out. Goodwife is takin me out fer a burger anna R-o-C Co-Cola!

Spring is here an now we're ready ta head out fer trout an turkeys.

[TJ's Chevy]

Nice work Rich...glad the truck is going good!

[Sharps40]

Its good to go. I gotta get some long bolts so I can slide back the trans and get at the release bearing. Its in three pieces, we used the inexpensive masterpro bearing and it ain't up to the job. I gotta go look at the national bearing....I believe its one piece machined collar and if so, that'll be the service replacement. For now, a bit noisy and crunchy!

[TJ's Chevy]

Well..ol trucks are supposed to be a bit noisy an crunchy! LOL!