Starting to understand why building engines may be best left to the professional

[Yellow Truck]

I'll fiddle with the carb a little more to reduce the idle. I will also look for leaks.

The drift on timing was happening before we added the MSD box, and I think it is binding in the vacuum pot/connection to the base plate in the distributor. We noticed last year that tapping on it made the timing move as much as 5 degrees. I think it may have been some advance trapped in the vacuum pot when I removed the vacuum hose. I don't expect it to come back when I start it again since the vacuum advance is not in the equation at the moment. This is why I decided to go MSD (sigh).

Steel pushrods vs aluminum - interesting question. Two side by side rods of equal length, clearly aluminum will expand more (coefficient is almost twice that of steel). But we have on solid rod about 8 inches long compared to an iron block and a couple of inches of aluminum head and rocker, and gaps that allow expansion in two directions. Not really able to do that kind of modelling in my head. Or on a computer. I think that is why Ford had so many engineers. I'll listen to my betters on this and just be a tad more aggressive setting the pre-load.

[Tobbemek]

There is another way around the "dieseling" problem on hot soaked shut down. If you are happy with curent idle speed and throttle position
get your self a AC idle solenoid find a good used one and fabricate a bracket to fit your carb,int,gas linkeach.or bay a new for ca 100$ with bracket
and then close down your pri throttle blades and" whalla" dieselproblem gon now you can have yuor idle to what ever suits your combo.

[Drew Pojedinec]

I'll listen to my betters on this and just be a tad more aggressive setting the pre-load.

With a SFT cam, iron block, aluminum heads it's customary to decrease lash .006 to allow for the extra cylinder head growth.  (head grows, which puts rockers further from the pushrod, so you set it up tighter)

If you think the distributor itself is moving and that is the loss of set timing, try clamping the distributor better (I use a stud instead of a bolt) or take a punch and make some small light marks where the clamp goes to help grip it.

[Yellow Truck]

Drew,

I don't think it is the distributor moving, I think it was in the vacuum pot or its connection to the base plate. I will watch it and see. If it moves again I'll suspect that it is the whole distributor. A stud and nut is a good option.

[chris401]

Drew,

I don't think it is the distributor moving, I think it was in the vacuum pot or its connection to the base plate. I will watch it and see. If it moves again I'll suspect that it is the whole distributor. A stud and nut is a good option.

At times old ignition will run points fine but can't handle the load of a Duraspark box. I have had timing moving around at idle and very little timing gain with some rpms. Your MSD box could have the same problem. See if it stabilizes when wired directly to the battery.

[Yellow Truck]

I took it out for a dive today, about 40 minutes total. A few open throttle shots but mostly moving along in light traffic.

It is civilized to drive, but two things continue to annoy (aside from the fact that it is ticking like a cheap sewing machine) - the timing was back around 16 when I started it and let it run long enough to settle down and hold an idle. I'm not running any choke so I have to stay on the throttle to keep it up around 1,000. With it lumping along at 500 rpm I went and got the light. Back down to around 16 degrees. Released the clamp, turned it back so I could just see the "2" under the mark, and idle came up to around 800. It was fairly quiet, so drove it over to my brother's and back. I needed someone on the throttle who could watch the tach - and it never went over 35 degrees, so I think I'm fine to leave that alone.

By the time I got to his house the idle had crept back up to 1,000. This is annoying, so I'm going to go and buy a nice large baking tin so I can lift the carb off without getting gas all over, and see what the plates look like.

[gdaddy01]

check your carb gasket , had similar problem , idled well until engine warmed up good and then the idle would go up ,after a lot of grief , changed the gasket , solved the problem . just a thought .   

[Yellow Truck]

I did get the carb off yesterday - I haven't figured out how to adjust the rear plates without taking it off. Reduced both plates to just a tiny bit of exposed transfer slot.

Then I pulled the plugs in preparation for adjusting the preload and took this picture of the plugs:


Some of them seem a little sooty. More variation than I expected but I'm really new to this.

On the preload I was surprised that I could rotate all the pushrods with my fingers, a few of them very easily. I backed off each screw, then turned them down until the pushrod would not rotate between my fingers (and could feel the screw engage the pushrod) then turned down one full turn and torqued the lock nut.

Haven't started it yet - ran out of time. I find it a real pain to keep a 15/16ths socket on the crank bolt to turn the engine - I put some duct tape on the bolt to hold the socket a little better but it is still a chore, makes it much slower going.

[jayb]

Based on what you wrote, you may have adjusted the rockers incorrectly.  Don't start it yet, you may damage parts!  The pushrods may rotate in your fingers when properly adjusted on a hydraulic lifter engine.  Rather than rotating the pushrods with your fingers, move them up and down as you tighten the adjustment, until the clearance is gone and they won't move up and down anymore, then go another 1/2 to 1 turn.  If you adjust them as you described, you may have pushed the plunger seat in the hydraulic lifters all the way down, and possibly even left the valves hanging open. 

As it is, if you did go far enough to bottom out the plunger in the lifters, you have forced all the oil out of the lifters, and they may clatter on startup until they fill up with oil again.  If you can, pre-oil the engine before starting to eliminate this concern.

[Yellow Truck]

Well, I haven't started it.

On each rocker I rotated until I saw the associated intake or exhaust drop. I then backed off the lock nut and threaded the adjustment screw out.

None of the pushrods showed up and down movement with the screw backed out. This seemed a little odd to me, in fact most of the pushrods were as loose before I backed off the screw as the were after. I recall that the last time I had some up and down movement.

In any case I turned the adjustment screw down just enough to feel the screw engage (beginning to feel resistance from the screw turning on the pushrod) and the pushrod began to resist rotating. In most cases this was 1/4 turn, then 1 full turn.

I could see all the rockers beginning to push down on the valve at 1 turn, but that is what I saw the last time.

Being a Canadian, took me a few minutes this morning to realize it is Memorial Day. We are the last country to celebrate Queen Victoria's birthday, and did so last Monday. Will have to wait till tomorrow to call T&D and get their instructions. What I've been fighting is alternating too tight (hanging valves) and too loose (ticking). Only ticks when fully warm/hot.

[Yellow Truck]

Went back and looked at the instructions from Barry (on a previous thread about the hanging valve problem) and I think I followed them accurately, HOWEVER when Jay Brown warns me not to start my engine, I have to say I'm not starting that engine!

In the mean time, is there a better way to rotate the engine? I don't have an "under the hood" starter switch, but it might be worth getting one if you can use the starter.

[My427stang]

Maybe we can keep this more simple, because this is NOT a critical adjustment, but if way too tight, you can bent valves, pushrods, etc

1 - You need to be comfortable identifying the point where there is zero slop in the pushrod, lifter rocker path,
2 - After you get there, you compress the plunger .045-.060 more, by turning the adjustment farther in a fixed amount based on thread pitch.

It really isn't a critical measurement unlike a valve lash, you just need to not have slop and not go too deep.

I am not saying to do this, but think of how you adjust a Chevy.  You let it idle, back one off until it clacks, slowly tighten until it JUST stops clacking, then go 1 turn more.

You are trying to do the same thing without it running, back off until slop, tighten until no slop, then 1 turn more or so.

The reason your procedure was confusing is because of you tightening it down until the valve opened, I "THINK" you just seated everything then backed off, but if you are too tight, things can hit

[jayb]

None of the pushrods showed up and down movement with the screw backed out. This seemed a little odd to me, in fact most of the pushrods were as loose before I backed off the screw as the were after. I recall that the last time I had some up and down movement.

You should have up and down movement of the pushrods, essentially clearance, with the rocker adjusters backed all the way out.  If you don't have that, there is some issue.  I'd check that again.  Especially if you had that clearance before.

Use a flashlight and try to see down below the intake, and look at the tops of the lifters.  There are small clips that hold the lifter plunger in place, so that the plunger can only come up so far.  I have seen cases where those clips have come out; then there is nothing stopping the lifter plunger from moving up farther than normal.  If this happens to be the case with your engine, that would explain why you felt up and down movement previously, but you don't have that anymore; the lifter plunger just keeps coming up as the rocker adjustment gets looser.  This is probably not the case with your engine but its worth looking at.

The reason for my caution is that I've seen on numerous occasions that spinning the pushrods between your thumb and forefinger while you tighten the rocker adjuster will give a false reading.  If the lifter doesn't have oil in it for some reason, all you are doing is compressing the spring in the lifter body, and sometimes this does not impart enough force on the pushrod to make it feel any different as you are spinning it.  So, pulling the pushrod up and down while you tighten the adjuster is the best way to do it, because then you have a positive indication that the clearance has gone away, when you can't feel that clearance anymore.

Hope that helps - Jay

[cjshaker]

The reason for my caution is that I've seen on numerous occasions that spinning the pushrods between your thumb and forefinger while you tighten the rocker adjuster will give a false reading. 

Ditto this. Even with a little pressure, a smooth mating surface between the pushrod and rockers/lifters can allow them to spin like there is clearance. Been fooled on that before.

[Yellow Truck]

You should have up and down movement of the pushrods, essentially clearance, with the rocker adjusters backed all the way out.  If you don't have that, there is some issue.  I'd check that again.  Especially if you had that clearance before.

Use a flashlight and try to see down below the intake, and look at the tops of the lifters.  There are small clips that hold the lifter plunger in place, so that the plunger can only come up so far.  I have seen cases where those clips have come out; then there is nothing stopping the lifter plunger from moving up farther than normal.  If this happens to be the case with your engine, that would explain why you felt up and down movement previously, but you don't have that anymore; the lifter plunger just keeps coming up as the rocker adjustment gets looser.  This is probably not the case with your engine but its worth looking at.

The reason for my caution is that I've seen on numerous occasions that spinning the pushrods between your thumb and forefinger while you tighten the rocker adjuster will give a false reading.  If the lifter doesn't have oil in it for some reason, all you are doing is compressing the spring in the lifter body, and sometimes this does not impart enough force on the pushrod to make it feel any different as you are spinning it.  So, pulling the pushrod up and down while you tighten the adjuster is the best way to do it, because then you have a positive indication that the clearance has gone away, when you can't feel that clearance anymore.

Hope that helps - Jay

Boy, you are full of good news!

On the happy side, I decided to do this to learn some new stuff, so I'm getting the opportunity. I'll go and start taking it apart again. Couple of questions, it takes me a huge amount of time to advance the motor and not that much time to do the adjustment. Can it be done by flicking the starter? If so I'll get an under the hood starter rigged up.

I may as well yank the rockers off to block the oil passages - I can get a better look down the pushrod holes if I can pull them. I'll check to make sure they are all straight while I'm at it.