My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Hi guys, some of you may be aware that I acquired a ‘69 c10 last year (250 i6, 3OTT). The truck sat for years with the previous owner before he decided to list it for sale. It was shipped from Washington to California and was able to get onto the trailer and off the trailer under its own power, but barely.

Since then, life happened and believe it or not I actually haven’t started it since it was driven into the garage last year.

Today I finally managed to remove the Rochester MonoJet carb for rebuild. It looks pretty rough as you can see from the pics.

Being new to carbs, I’m hoping you may be able to help me identify several parts of this carb. I’ve numbered the pictures for reference:

#1: what is this screw? It can’t be the idle screw as that’s on the back of the carb. Anyone know what it does?

#2: what is this capped vacuum line? Am I correct to assume that when I do power brake conversion, this is the vacuum port I will utilize for that upgrade?

#3: this port was connected to the vacuum advance. By the way, should I replace the vacuum advance? Do these have a wear out and go bad?

#4: what in the world is this? It looks to be a plate with 3 holes and it swivels. However, it wasn’t attached to anything. I wonder if that’s right or if I’m missing some connection?

By the way, one of the two nuts that holds the carb to the manifold was finger tight. That can’t be good :-)


Beyond the carb, I have a set of new plugs, wires, coil, cap, rotor, condenser, points, and fuel filter. I am about to order a new gas tank and replacement lines. I’ll get those items replaced, crank it, and see where we are.

I hope to utilize this as a progress thread to get this engine running again (I hope).

At some point I’ll ask for help with verifying timing, checking vacuum, and setting points.

Big thank you guys for the help!

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Not all parts in pic are on your carb.
https://www.carburetor-parts.com/mon...g1ElE4Y6XI5Her

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

#1 Idle Mixture screw. Not idle speed screw.

#2 Could have been available for some option such as auto trans. power brakes generally use a much bigger hose. Square head, tapered thread plug in manifold at very bottom, center of first image would be good for P. brake.

#3 Vacuum advance diaphragms do go bad and leak. Apply vacuum to test.

#4 High speed idle cam. Part of your manual choke. It may be missing a choke rod.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Here's a link to Mike's carburetor parts. It has good photos and descriptions of the choke system. Shows the missing linkage from your #4.

https://www.carburetor-parts.com/Mon...Tsm2VC1pqOgehf

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Great information, thank you all. Mike’s carbs looks to be a great resource, wow.

This total carb newbie now knows where his idle mixture screw is and that his carb apparently is missing a choke rod (fast idle). I’ll be sure to get that during the carb rebuild.

Question: what’s the procedure for setting the idle speed and the mixture? My understanding is that you warm up the engine with the choke engaged, then set idle speed, then tune the mixture to the sweet spot. Any tips on that?

Thank you

Luke

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

I welcome better explanations, but here's mine for a start!

• Start with idle mixture screw 1.5 turns out from fully CW
• Warm up engine to normal operating temperature with choke fully open and fast idle speed cam disengaged
• Set idle speed screw to desired idle speed
• Turn mixture screw CW until engine speed slows, and then turn
  it CCW until it picks up again. Shoot for max RPM, but don't go CCW past where you get the max RPM.

Reset idle speed screw as many times as you need to. It's kind of a dance between the two.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Very good summary.

I assume this procedure only applies once timing has been set and confirmed stable vacuum?

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Correct. If you have a vacuum tuning gauge, you turn the mixture screw out
(CCW) until the vacuum reaches it's highest point. You will have to reset the idle speed screw after this is done. Don't forget, disconnect the vacuum advance and plug the port on the carb while setting the initial timing.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Nice! I am in to follow this thread since I too have an old i6 that I will attempt to revive. Good luck!

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

I debated rebuilding the carb myself but given that I’ve never done that before and I’m trying to get this old engine running, I decided to send the carb out to CarburatorUSA in New Jersey. Should have it back in a couple weeks.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Do you do any kind of model building, such as scale plastic or some such? You'd be able to rebuild that carb, if so. That monojet is dead simple, as is a Quadrajet, believe it or not. I'm really a 2-pound hammer kind of guy, but even I can rebuild a Q-Jet carb and make it work properly.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Gotta pick your battles if you want to stay on schedule

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Thank you for the encouragement.

Given that this engine is tired and needs no shortage of help, I want to take the carb out of the equation and leave it to a pro this time.

Next time, I will rebuild it!

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

I understand completely!

Be sure to send us pictures and tell us how well it works.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Carb shop called and said that the carb was in really bad shape but looking new and back in transit to me.

When I replace the spark plugs, should I give the spark plug holes a spray of any oil since the car been sitting for so long? If so, what oil and amount is advisable?

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Definitely share pics of the rebuilt carb when it gets back to you.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

I'd just make sure the oil looks good on the dipstick. I guess spraying some kind of lubricant into each cylinder would help, but I don't know what to suggest.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

>>carb was in really bad shape but looking new<<
Not sure what that is supposed to mean.

Be conscious, that rebuilt carbs ARE NOT PLUG-N-PLAY . You still have to adjust the mixture screw. You still have to adjust the idle speed. You still have to adjust the choke cable so that you have full choke on-off and check that high speed idle works properly.
Bench adjustments on a carb only go so far. It then has to be adjusted for your engine, running and warmed up.

>>give the spark plug holes a spray of any oil<<

If the plugs are already out, what is that supposed to do. If the plugs were really carboned up or hard to get out you probably should run a plug thread chaser.
Aluminum heads call for Anti-Seize compound, but that is controversial.
Be sure you have the correct plug type. Some heads use tapered plugs and earlier have gasketed plugs. Various reasons why you could have the wrong ones, so it doesn't hurt to check.

For reference - https://67-72chevytrucks.com/vboard/...t=tapered+plug

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Are you asking if you should lube the spark plug threads or cylinders?

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Cylinders

Sorry for not being clear.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Here are some pics of the rebuilt Monojet.

Thing looks new, will install it soon.

After that replacing the tank, sending unit, and lines…

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Nice plating job! May it extend to the operation, thereof.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Thank you sir, let’s hope :)

Still have the plugs, wires, coil, cap, rotor, and points to replace.

Just not sure what the health is of the engine itself yet. The truck did get off the trailer and into the garage on its own power, but barely… I guess that’s promising right?

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

What was it, 3 weeks turn time on the carb? Seems pretty good

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Just over 2wks

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Haven’t yet bolted on the carb but managed to get to the plugs.

Looks to have been running rich but no oil on the plugs thankfully.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

I use this for long storage.
It would be good for what your wanting as well.

Link: https://www.amazon.com/STA-BIL-Rust-...000H7CKAY?th=1

Most parts stores carry this also.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Yes, that’s exactly the fogging oil I gave each cylinder a squirt of before I reinstalled the new spark plugs.

Also, how do the points/condenser look to you guys? I found some weird white material inside the rotor, what can this be?

Strangely, the Blue Streak replacement rotor feels totally loose when I set the rotor onto the distributor. I’m gonna head to the parts store and pick up another rotor as there is no way this one should be wiggling around this much. The old one I pulled off was nice and snug.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Fresh Points, Rotor and Condenser are always good insurance at this juncture. New points
take an .035 gap. [.045 for HEI]. Dwell meter and Vacuum Gauge are best tune up tools.

As my L6 blocks aged [gained miles, that is] I gradually increased the oil viscosity. I went from Valvoline 30 weight Racing [VR1 -- formerly P/N 223] -- Thru 40 weight to 50 weight when mileage got around 250.000. That was a 25 year process.
Back to VR1 SAE 30 on rebuild.
I took off my Monojet in 1978, so I'm no help there.
Good luck.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Rotor is beyond terrible. I would also replace the condenser, because they can go bad just sitting on a shelf. What do the points contact surfaces look like?

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Blue streak was and still may be Standard Ignition's budget brand. What you put in back in the 70's when you didn't have the money for the good stuff or were working somewhere that did cheap tuneups.

I'd at least run a point file or emery board though the points if I didn't change them.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Thanks guys

Im still puzzled at why a brand new Blue Streak DR314 would be so wobbly. The new Blue Streak cap looks good and fit just fine.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

I’ve read new points should be 0.019” gap? Can anyone confirm?

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Blue streak was the premium part. The points, for instance, have an extra conducting strap that ran with the spring. It is made out of copper for better conduction of electricity, to keep the points spring from getting too hot. Not that that was really needed, IME.

Looking at that "new" rotor, that thing's beat, and I'm not sure if it is even the right one. I've never seen a "new" rotor that was all chipped up like that. Maybe it was sent by USPS in a previous life?

Point gap of .019 is good.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Apologies if I wasn’t clear, the new rotor is the blue one… that’s the one that doesn’t fit snug and wobbles.

The black one is the one that I removed from the truck today. That white thing, is waddled up paper, or tissue rather. Scratching my head on why in the world that would have been there…

Did you mean that the blue one looks beat? Sort of does from the picture now that you mention it lol.

And to check the gap, feeler gauge after rotating the engine and finding the high spot (max gap) ? Is that right?

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

By the way, wonder if anyone can guess how old the coil is that I pulled off today :)

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Bolding mine. Yes. No idea on the paper. If that rotor doesn't fit tight, it is junk. Period.

As for the coil, I can't tell. Have you downloaded the service and overhaul manuals for your year truck? All the specs for ignition parts are in them.
https://67-72chevytrucks.com/vboard/...ghlight=hatzie

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

I agree with steeve, Blue Streak was their flagship. Standard Plus was OK, and their "T series" was their budget brand.

Maybe this sounds insane but I wonder if it was a poor mans antitheft, they stuck that paper in there so it wouldn't start and would be very cumbersome to diagnose in a quick way--if the person letting the truck sit for a long time didn't want their truck messed with or stolen.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

Yes, I’ve always understood Blue Streak to be their top of the line.

And regarding the paper/tissue, interesting theory. However, the truck did start and run in this condition last year when it was driven off the transport company’s trailer and into my garage.

So that paper didn’t prevent the engine from firing and running. I’m not sure what it impacts but you can see burn marks on that paper if you zoom in.

Re: My Own Vice Grip Garage - Getting the 250 i6 Running Again
 

.019 New