Some light reading with questions about rough running issues

[BNC04]

I’m back with more questions and observations 

Got the timing light yesterday and was able to clean the balancer to be able to read the marks and rubbed some chalk in them for added visibility for my old eyes.
It shows IΓÇÖm running 38-40 BTC. Is this even possible? I canΓÇÖt get anywhere before 25 without it stalling.

I have not been able to verify 0 = TDC yet but will hopefully when the wife gets back to bump it for me.

I used the vac gauge hooked to the back of the carb where the PCV valve is attached normally. Dist vacuum disconnected and other small port on carb is blocked off. The timing is set now at max vacuum. IΓÇÖm at 15 on the vac gauge at 900 RPMΓÇÖs idle

The truck is running rough still especially at low speed, like idling through the neighborhood it feels like itΓÇÖs missing. Once I get on it, It seems to do ok and the throttle is responsive.

The RPMΓÇÖs fluctuate 20-25 up and down at least when idling and regardless of which wire I have the tester on.

Question- with the PCV hose unhooked from the back of the carb, The Idle goes way up is this normal?

Question- Does this seem like it could be dizzy or points related?

Plug wires look ok, the strobe looks pretty even in intensity on each wire
Dist cap looks ok.
The dizzy where the points and condenser sit is a bit dirty but it seems to be functioning ok- I might get new points and condenser or a pertronix igniter to see if that makes any difference.
Rotor looks ok, I cleaned the contact a bit
Pulled #2 and #6 plugs, they donΓÇÖt look bad, not black and oily and not white.
Verified firing order is right for the HO 1,3,7,2,6,5,4,8 and plugs are on the cap counter clockwise.
Plug wires are 7mm. New plugs gapped at .035

The motor is a 5.0 HO Roller from a mustang GT. Not rebuilt.
The PO put a comp cam in it part number 35-420-8 grind 270hr
Exhaust closes at 21ATDC and opens 69 BBDC
Intake opens at 29 BTDC and closes 61 ABDC
Hmmmmm.. 40-29=11 could it be he installed the cam wrong and TDC would actually be at the 29 mark…. I really grasping and have no idea if that’s even a realistic possibility

Edelbrock 1405 carb with offroad needles and seats, .095 primary and secondary jets and .065X47 rods. Fuel pressure at 5.5 psi

ItΓÇÖs running better, but not where it should be, It just feels rough running, IΓÇÖve never had a vehicle that had a cam upgrade so maybe some of what I am feeling is a lope.

Thanks for listening, if you have any idea on things to try, verify and what I might need to recheck IΓÇÖm all ears.

Brett

[BFD305]

You need to check TDC, you could be a tooth off and need to set the timing that far off because of it. Does not sound like a points issue.

Is it possible that the outside of the balancer slipped on the hub of the balancer?

[Shawns Fords]

I would definitely verify TDC is correct. A trick to do that on your own is to put the Crank pully right before and with #1 plug removed use a small pocket screwdriver to slide into the plug hole and as you hold the driver turn the crank with a ratchet with socket. you can feel the piston push the driver to the top. you wont drop it in there if it is long enough and thin enough.

I would also make sure the idle mixture screws are not in too far. Maybe back them out a turn or two and see if it smooths out.

you cant go wrong with a pertronix points replacement.

I have also seen the balancer/damper slip on the insulator.

you may also have a worn timing set as well.

A loose distributor drive gear.

Cant think of anything else right now.

[Viperwolf1]

I bet your Bronco timing pointer is on the wrong side with the 50 oz mustang balancer. It's about a 40 degree difference. Verify with a piston stop then get some Mr Gasket timing tape to remark the balancer.

[BNC04]

I bet your Bronco timing pointer is on the wrong side with the 50 oz mustang balancer. It's about a 40 degree difference. Verify with a piston stop then get some Mr Gasket timing tape to remark the balancer.

You know, I wondered about that also. If I'm in front and facing the engine, It is on the drivers side at about 2 O clock.

But as you all have said, I need to find TDC and figure out where to go from there to set it up to read correctly.

I think it is actually timed pretty close to correct via vacuum though.

It's the rough idle/low speed roughness that I'm more worried about fixing. I'll get time tomorrow afternoon to play with it some more.. Off to the rockies game here in a few



Brett

[Viperwolf1]

Yep. Mustang pointer was on pass side. If you subtract 40 from your reading you should be real close. You would want it to read somewhere around 50 BTDC with that pointer.

[Shawns Fords]

That new timing light should be able to do that too.

[BNC04]

Quick Update.

TDC has the pointer on 24BTDC on the balancer. I'll get a tape and install it so it will read correctly. Going to be a few days before I can get back at this section. Might be tackling the rear quarter panel next:) or the doors.. or putting different seats in..

Lol.
Brett

[Viperwolf1]

Quick Update.

TDC has the pointer on 24BTDC on the balancer. I'll get a tape and install it so it will read correctly. Going to be a few days before I can get back at this section. Might be tackling the rear quarter panel next:) or the doors.. or putting different seats in..

Lol.
Brett

24???

That's odd sounding. I don't know of any balancers/pointers that were offset 24 degrees. Did you use a piston stop and rotate the engine both directions to get the TDC in the middle? If so it might be a slipped balancer.

[BNC04]

I checked it by placing a wooden dowel in the #1 cyl and cranked it until the it stopped coming out. The wife was holding it to make sure it had stopped completely.
I'm using the pointer that's in place on the drivers side of the engine if I am facing the engine. I could be off by a degree perhaps depending on when she told me to stop but it should be pretty close. The rotor is pointing to plug 1 on the dist cap at this position as well.

I can do it again if this does not sound like the correct method to get TDC.
Brett

[Viperwolf1]

I would do it again with a piston stop. There's probably 10 degrees of crank movement at the top where the piston doesn't move.

[crawlercreations]

Please correct me if I am wrong but I believe I remember seeing somewhere that all of these issues arose after you changed a bunch of stuff on your carb? Offroad needle and seat and such? If it was running fine before the change then it is all in the carb as long as that is all you changed?

[BNC04]

I would do it again with a piston stop. There's probably 10 degrees of crank movement at the top where the piston doesn't move.

ordered one, I was just messing with it again to see if I could gain a better comfort level that my number was right and, well, Lets just say it's best I stop before I have to another piece out of the cylinder.

Brett

[BNC04]

Please correct me if I am wrong but I believe I remember seeing somewhere that all of these issues arose after you changed a bunch of stuff on your carb? Offroad needle and seat and such? If it was running fine before the change then it is all in the carb as long as that is all you changed?

Basically changed parts in the carb and timed using vaccum gauge.

The flow went something like this.

Replaced rods, jets and seats in the carb. Ran like hell. Suggested I check timing, No timing lite so I timed to max vacuum using the gauge I did have. Runs MUCH better but still some idling roughness. Got timing light, and see that according to the balancer, my timing is 38-40 BDTC so it was clear something was not right. (Pointer in wrong spot or balancer slipped or PO did something goofy." To find out for sure what the something was, I needed to find TDC which, everybody in the world can do,, except me.
The timing marks and referencing TDC etc, is really just for future Diags and to make it accurate and correct. I have it timed via Max Vacuum now and am just piddling with getting it to "look" correct while I wait on some other parts to take the old parts and PO's work out of the picture.

I'm going to replace wires, coil, cap, rotor and ignition to give me a known baseline because there are many items on this truck that were just cobbled together.

Thanks
Brett