Vacuum advance..? (1 Viewer)

[euclid537]

Howdy! I'm pretty new to the forums here, done quite a bit of lurking - this place is a gold mine! Thanks for all of your amazing contributions/input.

Quick question for you guys around the distributor vacuum advance.. I recently picked up IrishCRZR's '85, and before I drive it 1200 miles across the country I am planning to give it a once over to make sure everything is kosher (and tuned for the best gas mileage, if possible!)

I haven't even seen it in person yet, but upon closer inspection of the pictures, I noticed that the vacuum advance on the distributor is wide open. I know that the truck is desmogged, but still, I was surprised to see these disconnected.

My question: Do I need to pick up some vacuum line and re-connect this? Where to? Fat one to the glove box, skinnies to the air box, right? I'm told that it runs fine. Thoughts?

 

[Output Shaft]

Leave it as is and test drive it. Feel if the engine has at least some power and doesn't ping. The distributor hasn't been recurved for non EGR use and will likely ping if the vacuum advance is connected. The owner may have tweaked (advanced) the mechanical advance to try to offset the disconnected vacuum advance.

On your test drive, before your big return trip, get the engine up to 23-2500 rpm or so with med throttle and listen for pinging or lack of (some) power when you stomp on it.

These trucks are pretty pokey slow, so don't expect to be jerked back into your seat when you floor it. You're doing pretty good if you can pass a car. Any car.

 

[euclid537]

Thanks for the quick reply. I guess there's a certain "if it ain't broke don't fix it" aspect here, but assuming it's not pinging all over the place would you still recommend a replacement/upgraded disty that's been recurved to match? Worth it?

 

[euclid537]

 

[SteveH]

I would find a ported vacuum port on that carb, and connect a line to the vacuum advance port on the distributor (one or the other), and adjust the timing until it barely stops pinging on uphill climbs. You can wait until after your trip home - but you need all the power you can get from a 2F!

 

[LAMBCRUSHER]

forget about it. I have no vac advance on my built 2F and it does fine. granted, it has a hopped up head and is relatively fresh, but it was daily drove 5 times a week, 100 honest miles with a total of 9000+' in decent/ascent a day, for well over 18 months, and a good 60+ daily mountain driving for the year prior. I have never thought, "self, you should hook up the vacuum advance..." in case that helps you any...

 

[LAMBCRUSHER]

your EGR is not and the thingy looks to have been purposely blocked off at the port where it should inject its nothingness into the combustion stream. HTH.

 

[LAMBCRUSHER]

oh, and weber. GRILL ON!!!

 

[euclid537]

1200+ miles - she made it!

There does appear to be a bit of an RPM-dependent "tick", but only under load. If it's not in gear, it sounds like a normal 2F sewing machine. Under load, and even at speed, I get a pretty loud noise. That being said, it doesn't SEEM to me to have any loss of power - which should help to rule out timing/lash, right? Gets 12mpg cruising 70mph at 2900rpm.

My first thought was exhaust manifold leak... I'll crawl under it this morning to look for any apparent suit.

 

[euclid537]

...maybe I should start another thread. What do you guys think of this?

The sound doesn't present itself at idle, or even revving it up sitting still. Only under load. It seems more prevalent when I apply throttle quickly versus slowly. Any initial thoughts?

 

[Output Shaft]

Sounds like a common and infamous FJ60 exhaust leak to me.

Often the source of that racket is a leaky gasket seal at the bottom back of the manifold where the EGR tube connects.

If not there, it could be the main manifold gasket. Not a big deal.

 

[euclid537]

Thanks, those are great pointers that I'll check tomorrow.

I actually developed a pretty gnarly oil leak during the cross-country trek, which I feared was RMS. My tailgate even had oil on it . Worry got the best of me, so that's what I paid most attention to this morning. Pulled the flywheel cover and was so so relieved to find all of the spinny parts dry. The cover itself was soaked, but it looks like that was just MPH working its magic.

Turns out ALL of the oil pan bolts took at least 1/4 turn.. just to get to hand-tight! I think I still have a slight leak - although it may just be residual drippage from everything under there being bathed in 10w30. The original culprit was definitely on the passenger side. I'll go through and double check the oil filter/fuel pump/oil pan after I tackle the exhaust tomorrow.

Oh, and back to the original point of this thread - I discovered the vacuum advance port on the carb to be wide open... Capped it, and what do you know, she runs much better! I tried to eyeball the disty vacuum port sizes and got it wrong, so I need to pick up a smaller adapter. I'll hit the auto parts store mañana during my test drive.

 

[LAMBCRUSHER]

mcmaster carr has silicone vacuum hose for a good price. even pick you favorite color. test that pot before hooking it up, it may be bad and have a leak. good catch on the open vacuum port on the carb...check for the infamous oil galley plug to see if that's been delt with or put it high on your list of things to do.

 

[euclid537]

So I started to poke around today to see if I could find anything around the exhaust manifold needing tightening. As I put my hand on the carb to lean in, it shifted about 1/4"! You could literally grab the carb and jiggle it around - front, back, side to side.

So I pulled it. Looks like someone installed some sort of 3-piece aftermarket carb spacer with mis-matched hex screws, half of which are missing. Also, one of the bolts that go straight down from the intake manifold (into the exhaust mf?) was missing, the other two had rusty threads and were loose as a goose.

I was planning on replacing the de-smog gaskets/nuts as part of this exhaust leak troubleshoot anyway. Now I'll pick up a few carb gaskets and some replacement screws/bolts as well!

 

[micruz60]

Get an Aisin stock carb, with the insulator / spacer with gaskets prebonded to it.

 

[klinetime574]

If you're going to stick with the Weber I would consider one of these from Man-A-Fre.

I ran that type of adapter you have now and had no issues, but I was the original installer.

Really wanted the one piece for looks alone, but I'm back with the Aisin now.

 

[Michael Hanson]

Hi, I'd get rid of the Webber and go stock . My 2 cents. Biggest thing I've found to make a difference on the 2F and 3F is to adjust the valves. Check for exhaust and intake leaks. Mike

 

[euclid537]

Well, that was interesting.

Looks like whoever originally installed this carb had a couple screws loose. The small piece that the accelerator linkage connects to, in stock form, would hit the head of a bolt (90101-10486, the aft one)... so what did they do? They just removed the bolt.

So I slightly modified the throttle linkage and replaced both of those bolts. Refreshed the carb gaskets, and reinstalled everything the way it is supposed to go. Also threw a new gasket on the J tube, hoping that was the culprit for my exhaust leak/tick.

No such luck. She seems to run quite a bit better now, and no more vacuum hiss, but my exhaust tick is still there. I put a wrench on each of the manifold bolts and they were all tight as a teenager.

Do you think the exhaust gasket has just slipped/expanded? Or maybe the manifold has warped a bit? Call me crazy, but due to the frequency of the tick I would think I'm chasing down a single cylinder's port, not something downstream - right? Thoughts?

 

[Output Shaft]

If you can smell any hint of exhaust in the engine compartment when the hood is up and your head is poking in there... there's an exhaust leak.
Manifolds warp all the time. Not uncommon at all.
The manifold gasket can leak but the offending location may not be visible while installed.

 

[gregnash]

Yeah, my manifold gasket leaks. Only way that I can tell is by spraying carb cleaner around the gasket/manifold interface while running and listening to the idle up. I had my manifold surfaced when I redid the top-end however it seems like the shop really didn't know what they were doing and thus did not truly machine it flat. Mine does not smell of exhaust in the engine bay nor does it tick excessively so I am good with it.