- Thread starter
- #41
Oh yea. Compression stroke for #1 --> rotate flywheel to the bead --set distributor in, rotor pointing to #4 spark plug/#1 on cap.
Desmogged 74 struggles on cold starts (1 Viewer)
- Thread starter Matt1260
- Start date
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Mark A introduced me to Pertronix ignition on my desmogged 74 F.5>>>>
Valves adjusted, one pump on accelerator= fired up and idled no matter the weather, & get outta da way!
Initially, your low compression numbers seemed to me that your head bolts need to be torqued.....recently went thru a mild rebuild on my 2F, and the vac gauge is a big help fo sho
Valves adjusted, one pump on accelerator= fired up and idled no matter the weather, & get outta da way!
Initially, your low compression numbers seemed to me that your head bolts need to be torqued.....recently went thru a mild rebuild on my 2F, and the vac gauge is a big help fo sho
- Thread starter
- #43
I'm using a mityvac gauge. The reading is very stable when I connect it to the vacuum advance port on the carb. But the brake booster port gives me a shaky reading. Cranking vacuum doesn't show up either--i thought there should be at least some. SOR rebuilt this engine so it has to be sound...
hopefully you got a rebuild from a Tuesday, Wednesday, or Thursday.....
@Matt1260, I know I'm a bit late to the party here and maybe it's already been discussed.... It seems like you've taken the time to really go over things very thoroughly at this point. Have you tried taking the distributor out and moving it a tooth back (to retard it) and then recheck the total timing? Over 30 degrees of timing just seems egregious for a motor originally designed for 7 and one that is normally run in the 10-12 degree range.
I only mention this because on a prior 5.7 Vortec swap, I was off by one tooth on the distributor gear and the timing was advanced 20+ degrees. It ran, but the OBDII had a trouble code. I'm guessing that you've already tried this but I just wanted to make sure. I'm going to be in the exact same boat as you as hopefully I'll be starting the rebuilt 66' motor next week and breaking it in.
I only mention this because on a prior 5.7 Vortec swap, I was off by one tooth on the distributor gear and the timing was advanced 20+ degrees. It ran, but the OBDII had a trouble code. I'm guessing that you've already tried this but I just wanted to make sure. I'm going to be in the exact same boat as you as hopefully I'll be starting the rebuilt 66' motor next week and breaking it in.
- Thread starter
- #46
I'm looking at the valve seals as the potential culprit. If something happened and they didn't have sufficient oil during the first startups/breaking in and thus developed leaks... I did find a slight oiliness on the spark plugs a couple of times.
That's the vacuum taken from the booster side right? Directly off the manifold is steady? The FSM mentions tuning based on the manifold port only. I could see how a valve seal issue/leak could cause plug fouling but it doesn't explain why the timing is so far advanced.
- Thread starter
- #48
yea that's the reading straight from the manifold port. I've read in other forums about high timing advancement being a mystery--some figured it could be the timing light itself. But I doubt that is the case.
- Thread starter
- #49
At TDC the rotor is point halfway between #1 and #5. If I had a spare dizzy I'd try another one. Where Can I find this pertronix electronic part?
It's gotta be something with the valves...... is it advisable to not drive it like this?
It's gotta be something with the valves...... is it advisable to not drive it like this?
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@Matt1260, from what I understand, too much timing is likely not going to damage the engine assuming it's not pinging under accelerations. They much timing is just not correct for the Toyota 6 however and the odd part is it's not even close. I'd be concerned about overall drivability given the fact that the spark advance curve is going to get worse (even more advanced timing spark) as you accelerate.
Have you re-torqued the head bolts to 95 ft/lbs after the initial 30 or so minutes of running?
And I don't think the valves are going to contribute much to your timing issue assuming that they are even "close" to adjustment which your's seem to be.
Again, have you tried moving the distributor to a different tooth?
Have you re-torqued the head bolts to 95 ft/lbs after the initial 30 or so minutes of running?
And I don't think the valves are going to contribute much to your timing issue assuming that they are even "close" to adjustment which your's seem to be.
Again, have you tried moving the distributor to a different tooth?
initially you might like the highway power, however.........i went to Mark A to get my rebuilt carb, and upon install, he found I had 21 degrees advance and roasting valves. Well, that noise got corrected before my drive home!
too much advance & you could expect to go thru repeated exhaust gaskets, basically torching the side of the cylinder over time. Also the rod bearing took a beating...ya 15 degrees opposite TDC
I believe @Rock40 has the tooth answer
too much advance & you could expect to go thru repeated exhaust gaskets, basically torching the side of the cylinder over time. Also the rod bearing took a beating...ya 15 degrees opposite TDC
I believe @Rock40 has the tooth answer
thebigredrocker
SILVER Star
I got my Pertronix from 65swb45. F engine ran much better after the conversion to electrinic ignition. My dissy is the Nippondenso extra small cap vac advance w/octane adjuster.
- Thread starter
- #53
So I re-did timing yet again and I think @Rock40 was on to something this time around because it was possible to set the rotor in pointing either directly at #4 plug or just in between #4 and #3. I remember a diagram somewhere that showed the rotor position just in front of #4. I also re-adjusted the points again. The gap was really close and this time I set it to .016 exactly. Turning the housing by hand I could see the spark in the points was bigger at .016 than before. That was more appealing. It fired up smooth and maybe ran more consistent. Sparks and plugs seemed to fire a lot better. THIS time the optimal timing landed at 15° btdc. 
This is definitely an improvement and I had no issues driving it around save for trying to floor it at 55 mph on the freeway at which point it choked.
I'm going to test vacuum again tomorrow, don't know if that's solved.
This is definitely an improvement and I had no issues driving it around save for trying to floor it at 55 mph on the freeway at which point it choked.
I'm going to test vacuum again tomorrow, don't know if that's solved.
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Damn, good deal. 15 degrees is a whole hell of a lot closer 
- Thread starter
- #55
Still got the same vacuum problem, and same cold start problem. At least I know its not ignition/timing/compression/valve adjustment...back to the valve seals...
- Thread starter
- #56
How does it go from firing perfectly one day to totally misfiring all over the place the next day? Crappy points? Coil? I moved nothing! This almost hilarious.
Could be possible that the distributor is worn or sticking and giving you odd/uneven/unreliable timing also
- Thread starter
- #58
I had a friend over today who is an aircraft mechanic.. we messed with the timing more. Concerns were raised about the rotor being movable by a few degrees while attached to the shaft. Seems like it shouldn't really move at all.
The timing light showed misfire on all the plugs so we attached it to the coil's wire and found that it was inconsistent there too.
We think maybe the coil went bad.
To be continued...
The timing light showed misfire on all the plugs so we attached it to the coil's wire and found that it was inconsistent there too.
We think maybe the coil went bad.
To be continued...
- Thread starter
- #59
coil tests ok. 1.6ohms on primary
11.5 on secondary
11.5 on secondary
JohnnyC
Long ago TLCA# 2231
I didn’t see a pic or hear it stated...
Are you using a factory advance or retard dizzy?
Are you using a factory advance or retard dizzy?
