The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by dapirate, Dec 7, 2013.
bent push rod/timing/carb,ex
ok my buddy told me drop some water on the headers while running.
The good cylinders water drops immeadiately sizzle and evaporate
Cylinder 1 water runs off
Cylinder 4,6 some sizzling some water run off
Cylinder 7 sizzle more than 4,6 but not like the good ones.
Not sure if this helps
I think I will get a infrared thermo gun from the store.
That's an indication of not not converting fuel to the same heat energy as the others or those cylinders aren't working as well.
Are the those plugs sooty, wet or fouled (not firing the available fuel) or ashy white ( not much fuel to fire)
You could try screwing with the idle adjustment screw on the side that feeds 1467. Note the results. If there's no change that's a problem related to the carb.
Watched the video. How does it behave when you snap the throttle to WOT?
To me, it seems like the timing is a little behind (retarded)
I'd say the plugs all look normal except for #1 which was wet and black, not sure if it was oil or fuel, but if I had to guess I would say oil.
I actually replaced 1 and it looks good so far, but of course I haven't driven it.
I played with the left air adjustment on the carb and it does change the engine so I guess its ok?
when you snap to WOT it Revs up with no issues. I only get the backfire on Deceleration.
checked the temps with a heat gun after about 2 min on idle
1 - 98
3 - 224
5 - 201
7 - 170
4 - 203
6 - 225
8 - 185
As you can see, 1 is your odd ball and 4 6 & 7 are right even with 2358.
So they must be doing close to equal work. Still puzzled as to why there's no change when they 467 are canceled, I can see #1 having little to no effect.
I don't think this is going to help anything other than confirm #1 isn't as hot or having some troubles.
#1 isn't firing--rest of readings look ball park--ck the valve adjustment on #1 amd ck for fire at end of #1 plug wire.
Rocker arm studs on #1 ??????????
My guess would be a vacuum leak on the intake close to the number one cylinder that is screwing up the mixture. If you set the idle up to 2,000, does the temperature on 1 match the other temperatures?
As for the backfire, are the header gaskets sealing well? Back in the 60s it was hard to get them sealed and almost anything with headers backfired. It was why Joe started Mr Gasket.
When I get home from work, I'll check the valve adjustment on #1 and inspect the headers.
Is that #1 wire resting against the headers?
no, these are the MSD multi-angle wires you can actually bend to fit and its bent away from the header, and the rest of the wire is clear as well.
Is the intake used?
I had a similar problem a while back and ended up having a cracked intake manifold. Took forever to find the problem in that thing.
Also, did you ever change the cap and rotor? Bad cap or rotor would probably be my first stop with this type of issue.
Did you put new plugs in and have number one foul out immediately?
Did it hit on number one with a new plug?
You can check for a intake leak in the lifter valley by removing the PCV start the engine and plug all the holes in the valve covers but one and hold your hand on the one open hole and see if the crankcase is building pressure or drawing vaccum if its drawing vaccum it has a leak in the lower intake gaskets if not than its ok.
The intake is new, and the cap and rotor have been changed.
New plug in cyl 1 is slightly fouled.
I did what Saltflats suggested and with my thumb over the hole in the valve cover its drawing vacuum.
So I guess I need to remove the intake and re-install?
No, before I'd remove the intake, I'd double check the valve lash adjustments. It's always best to try the easy stuff first. Sounds like #1 might be a bit tight and not closing completely.
Might also consider grabbing a cheap used stock points distributor off craigslist and drop it in to confirm the Pertronix is good or bad? I keep one around I bought for $10, just in case I need to test on a SBC or BBC V8. Had an MSD box fail me and a quick swap of the distributor helped me find the problem. Left it in while I had the MSD box rebuilt.
Does the needle bounce on the vacuum gauge ?
What's the reading ?
Your points need to be reset. Sounds like they are to close. That the first thing I would check.
Where's the points in a pertronix ?
I'll double check the valves on Cyl 1.
I had the backfire before the pertronix ever went in.
I removed the #1 plug, plugged the hole with another spark plug and saw spark so that would confirm the plug and wire are good.
I also swapped the wire and plug with cylinder 3 and there was no change in symptoms
I hooked up the vacuum gauge and it bounces between 15"-18"
I thought with a leak it would be lower???
A rhythmic bouncing is an indication of a problem.
Dropping manifold vacuum isn't normal.
There's another diagnostic link some place, it has gif files to show the gauge and what it means.
It's quite possible you have a manifold leak under the manifold.
I don't know which new manifold you have but the cheapY ones are know to have problems.
Forget the name but summit sells them in the 100 range.
I have the Edelbrock Air Gap.
Ok, then the cheapy manifold problem probably doesn't apply
Check for broken valve spring at location of bent pushrod.
ok I found the link if anyone else needs it
I'd say the vacuum looks more like a sticking valve, but wouldnt I have low compression with a stuck/sticking valve?
That's where the broken spring suggestion make sense. Sometimes an engine problem will be visible at different times.
Here's what I would do: Pull the motor & pull the intake & heads. You can make a decision on how deep you want to get into it, but at least with the heads off, you can get a real good look at what's going on. Once your heads are off, a machine shop can check them for you and give you an estimate if they see any issues. I've done many top-end rebuilds. It's a real easy way to bring back performance to a motor & fix any problems. You can also pull a rod & main cap to inspect the bearings. If the bearings look good, & the cyls look good (no ridge), you will be good to go.
On a positive note, it's a good time install thinner head gaskets to bump up the compression & maybe a new (better) cam
Maybe this engine had this problem before & it was the reason it was sold to you.
Yes if it were a stick valve, it would show up low on the compression gauge.
But think about what the vacuum gauge is seeing and what it shows.
Ponder this : I'm just thinking out loud.
If you had intake gasket leak at #1 runner,
The gauge would be show lower vacuum than normal
every time # 1 was on its intake stroke the manifold vacuum would drop
#1 would be sucking oil.
Your vacuum signal to the carb would be low causing lean condition.
Un accounted for air entering the system would cause a lean condition.
In general, backfire on deceleration is caused by a lean condition.
Exhaust leaks can cause a lean condition too because it effects scavenge and scavenge is directly related to cylinder filling efficiency.
I'm just thinking out loud here for you.
Before I changed the #1 cylinder plug it was fouled black, not sure if it was oil or what. So does that point more to the intake?
If I have to pull the engine, I'd most likely go back with a 350 or a vortec 350.
Well if a compression test for # 1 shows good,
That eliminates a bunch of causes for oil getting in.
What's your plugs gapped at ?
Separate names with a comma.