Top Speed 48 mph

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can2
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Top Speed 48 mph

Post by can2 » Wed Aug 10, 2016 7:43 pm

Howdee,

Nice place. Though I'd visit for a spell.

And maybe pick some random topic to discuss - such as what in the world is wrong with my daily driver?

I am hoping one of you well seasoned airheads out there can show me the way back to happy trails.

My car a 1971 Riviera stock with a SVDA and pertronix has taken a turn from the pleasant and peaceful state we once shared so well.

A couple weeks ago I notice hard starting and weak power around town and on the short highway run I made then.

I kitted the carb a 34 PICT 3 and suddenly the car starts much nicer and a little more power - still not where it should be though.

After a short in town test drive, the next morning I hit the highway early just to find out I have a top speed of 48 mph and a top rpm of 32K.

All my gears rap-out early and the car does not like being pushed AT ALL. It starts missing and backfiring if I try to get up to any real speed. The car used to go 75 but I kept my speed at 60 to 65 depending on traffic.

I have replaced the fuel pump and the in-line fuel filter and the fuel tank was off and cleaned about 2 years ago so the in-tank screen should not be the problem.

Also I do not know if a vacuum canister failure would cause me to lose top-end and acceleration - I did get the rpms up to 2K and pulled the vacuum off and the rpms dropped by 150. Does that sound right?

Last thing, when I timed the ignition at 3K rpm to 28 degrees BTDC I lost my 850 rpm idle, it dropped significantly (don't remember exactly). So, I adjusted the timing back to 8 degrees BTDC at the 850 rpm idle.

OK I'm done. Anyone familiar with such a problem? I could sure use the help.

Thanks.

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Piledriver
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Re: Top Speed 48 mph

Post by Piledriver » Thu Aug 11, 2016 2:00 am

Welcome to the STF!

Ignoring basic tune up items like new plugs/rotor/cap/wires etc as all done...
Most likely:
Pertronix can provide a worthless and weak spark when they are dying.

Best second guess:
the mechanical advance is frozen up. Happens, almost no one remembers to oil that felt wick under the rotor every oil change.

Second second guess:
The + and - wires to the coil are swapped.
This will make for a very weak spark that will blow out under any real load, but will idle great.
Would make for an excellent valet mode.

One more time:
Huge vacuum leak?

And last but not least likely:
Muffler collapsed internally/plugged up.

Final shot:
A mix of any of the above.

Set the timing to 30-32 at 3K (no vac connected) and see what it is at idle. That's probably good.
Disconnect the vacuum retard, cap the fitting on the carb and leave the back fitting on the vac can open.
(assuming dual vac can, and assuming the connections on the carb are hooked up right)
Leave the retard disconnected, your heads will run much cooler.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

can2
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Joined: Mon Aug 08, 2016 4:59 pm

Re: Top Speed 48 mph

Post by can2 » Thu Aug 11, 2016 5:54 am

Thanks Piledriver
Sounds good advice, all except for "A mix of any of the above." which sounds kinda scary.

can2
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Re: Top Speed 48 mph

Post by can2 » Thu Aug 11, 2016 10:24 am

I removed the SVDA to put in an 009 with points. This would eliminate my problem down to either the vacuum canister, vacuum advance linkage sticking or the Pertronix.

I put the pulley at TDC and the rotor was pointing at #1 spark-plug.
I pulled the distributor and saw that the distributor drive-shaft slot is not at a right angle to the crankcase seam as my repair book says it should be. It is very nearly parallel with the off-set (thick side) toward the case seam.

How can I remove the distributor drive-shaft while the engine is still together?

I tried prying on the slot with a large screwdriver while pulling upward but no good. I tried using a super magnet, no good. The drive-shaft has just enough free-play to tell me it is not "stuck". I am thinking I should be able to lift it out - but how? Any ideas?

Perhaps I should back up - is there a reason why the distributor drive-shaft slot would not line-up at a "right angle to the crankcase seam"?

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Piledriver
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Re: Top Speed 48 mph

Post by Piledriver » Thu Aug 11, 2016 1:02 pm

Don't sweat the distributor drive shaft, it's orientation is not your immediate issue, and isn't likely to cause any long term issues.

The only time it really matters is if you have a T3 or T4 in order to clock the distributor can properly for range of adjustment,

Put the SVDA back in if points didn't work, a 009 will cost you fuel economy, driveability and jack your EGT at cruise due to lack of vacuum advance at light loads.

There is a special ID puller for that job, but in a pinch I have used a bit of tomato stake (bamboo) in the hole for the spring.
There is a risk of dropping the thrust washers under the drive into the case, so its usually not worth messing with.
Don't forget to put the thrust spring back in.

Some common input shaft bearing pullers might work.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

can2
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Re: Top Speed 48 mph

Post by can2 » Thu Aug 11, 2016 6:42 pm

0-0-9 ohoh WOW

Haven't had this much power since I went from tricycle with a flat to go-cart with a McCullough Mini-Mac10.

So, my problem must be in the SVDA mechanical sticking, the SVDA vacuum canister or the Pertronix. Now, I will still have a car to get around in while I sort that out.

I did wonder how my car was supposed to run with the distributor drive-shaft out of sync - but I was not asking questions, I was going full steam ahead by the book. Now that you pointed it out to me I can see clearly where it should not make a difference - if the piston is at TDC and the flywheel pulley is at TDC and the rotor is at #1, it is a go. So, why do the manuals say to put the distributor drive-shaft in with the slot at a right angle to case seam? And, why was this one not put in that way? hmmmm?

I do have another hmmmm. Minor issue that has surfaced with the car back to peaches and cream - for some odd reason the tachometer went berserk. Where I once had 850 rpm at idle it now shows 2200. Where I once rapped out the gears at about 3.3K it now shows them at 6K. I could hear my idle did move up after the 009 and engined warmed-up, but not much maybe a 50 rpm. I know I am still in the same and normal rpm range as before while going down the road but, seeing the tach go up to 6K between shifts with the windows down and wind keeping me from actually hearing the engine is going to take some getting used to.

OK Piledriver, thanks for seeing me through this mind expanding episode of another day in the life with the VW Bus.

Oh yeah, I did time the 009 to 30BTDC at 3k rpm.

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Piledriver
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Re: Top Speed 48 mph

Post by Piledriver » Thu Aug 11, 2016 6:51 pm

Your tach doesn't like points.

The various manuals show two orientations depending on model, the t3 and t1/2 differ and its just due to clearance issues for the vac can. The case, drive and distributor are for all intents and purposes identical.

There is a little oil splash/drain port on the distributor body that from time to time folks say has to be "aimed" a certain way, but to be honest I have never seen any value in either "legal" clocking other than simple standardization.
Worry about it when you rebuild it next, or do a clutch job, the dist drive should come out BEFORE the flywheel comes off, and after it goes back on. (out first, in last)
...Prevents dorking the brass drive gear, which requires a ~full tear down to replace.

In your case, its not causing your performance issue, it only gains perhaps warm fuzzies, messing with it can cause problems, so its simply a matter of Do Not Poke the Bear.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

can2
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Joined: Mon Aug 08, 2016 4:59 pm

Re: Top Speed 48 mph

Post by can2 » Fri Aug 12, 2016 8:02 am

yeah that helps.

The tach and points versus pertronix - did not see that.

And the distributor - thanks for clearing up these details.

I still got warm fuzzies from yesterdays test run - guess I'm just easy that way.

later -

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Piledriver
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Re: Top Speed 48 mph

Post by Piledriver » Fri Aug 12, 2016 5:41 pm

Pick up a set of points and condenser for the SVDA, and check the mech and vacuum advance works, it could be simply the Pertronixs dying somewhat gracefully.
Carry a spare points/condenser or simply the 009 as a ready-to-go spare,
Distributors are not complex beasts, all they usually need is a drop of oil and checking/replacing the points per the manual.
I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

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