'62 Ranchero - 250 - Aluminum Head update

@bubba,

There's enough spring pressure in the Clay Smith hydraulic lifters that it's difficult to measure the plunger travel with calipers - I pushed a plunger down with a pushrod and it looks like about 1/4".

Have the head installed:



You were asking about the rocker shaft assembly. They are adjustable stamped/cast steel rockers, 1.6:1, from Classic Inlines, photo below:



Thanks
Bob

Hi Bob good job and thanks for the rocker info it will make this a little easier. So the # 1 needs to set at TDC on the compression stroke (i.e. Both valve all the way up), rocker arms adjuster screws so that they have a little more adjustment towards the top i.e. more than the half way point at the top of rocker arm this is around 1 to 2 turns of the adjuster screws. Then to get the correct push Rod lenght you won't want to compress the lifters pistion any, it should be all the way up as with its internal spring pressure. You only want all the push Rod to rocker arm clearance taken up with just a very slight drag this is now the zero lash setting and should be the correct lenght when ordering the new push rods. Best of luck

@bubba,

I was finally able to measure for new ball and cup pushrods yesterday. Transitioning to working from home (due to COVID-19, everyone in my company has been told to work from home until further notice) has required quite a bit of my time in the last week. We've also had a complete management change on the project I'm assigned to, and the project has become much more beaurocratic (more meetings and issue tracking systems).

Wasn't able to use the adjustable pushrods, because the adjusting nuts fell on the upper edge of the pushrod hole in the head and interfered with pushrod placement, but fortunately already had a set of pushrods (custom from Smith Brothers) that fit closely enough to see how much longer they need to be.

With #1 at TDC on the compression stroke (both intake and exhaust valves closed) and the adjuster screws adjusted so that I could not spin the pushrods by hand, there is only about 3/4 enough thread to completely engage the locking nut. Therefore, I'm going to order the new pushrods about 3/16" longer (existing pushrods are 8 13/16" long, new pushrods should be 9" long).

Did turn the engine over (by hand) several times to find TDC on #1 compression stroke. Noticed that the observed lift at the valves was less than expected (with the 280H cam and 1.6:1 rocker arms, lift should be .512 at the valve). Expect that the lower lift is due to no oil pressure, so the hydraulic lifter plungers are being pushed all the way down by spring pressure, especially as the valve opens (125 lbs installed height, 260 lbs open).

I have already sent my pushrod order in to Smith Brothers, but they are in California (like most of the parts companies I deal with: Clay Smith Cams, for example), so it will be later this morning my time before they will answer the phone. I hope they are not completely shut down by the COVID situation in California, because I am not aware of an alternative source for custom pushrods.

Thanks
Bob

Manton is an alternative source for custom pushrods.
I prefer Manton over Smith Brothers.

Bob, you could also call Summit.
Comp Cams is on the East Coast & either one could supply them faster.

Last set of Comp pushrods that was ordered very recently had terrible quality with some being bent.
Go with Manton

You can make an adjustable pushrod from a stock pushrod by cutting it in half.
Then find a tight fitting bolt, cut off the head making it into a threaded rod and put two nuts in the middle to act as your adjusters.
Install the threaded rod with nuts in between the two pushrods halves and adjust to the right length.

HI Bob, from your description "you can't spin the push Rod" so you already have bottomed out the Hydrolic lifters piston. The valve spring pressure shouldn't even be a factor when you are determining the new push Rod lenght as you don't want the rocker arms adjusted down that tight just to zero lash. The Hydrolic lifters pistion should be all the way up at the top of its travel then adjusted so as to just barely feel it contacting the push Rod with the rocker arm adjuster screw and there isn't any clearance between them. That's going to be at zero lash and you don't tighten them down any further. With the extra milling you did to the head to get the CC's down I wouldn't be surprised if your current push rods are close enough to the right length to be able to use them. Best of luck

bubba22349":3vsr317h said:

HI Bob, from your description "you can't spin the push Rod" so you already have bottomed out the Hydrolic lifters piston. The valve spring pressure shouldn't even be a factor as you don't want the rocker arms adjusted down that tight. The Hydrolic lifters pistion should be all the way up at the top of its travel then adjusted so as to just barely feel it contacting the push Rod with the rocker arm adjuster screw and there no clearance between them. That's going to be at zero lash and you don't tighten them down any further. With the extra milling you did to the head to get the CC's down I wouldn't be surprised if your current push rods are close enough to the right length to be able to use them. Best of luck

Click to expand...

The lifter plunger springs are pretty stiff, they could definitely resist rotation well before bottoming out. Also, I think longer pushrods will improve geometry. Order placed, expect in ten days.

Thanks
Bob

That's excellent Bob, soon your Ranchero will be back running again!

Current rocker arm / pushrod geometry:



You can see that the pushrod is extremely close to the edge of the pushrod bore in the head. If I'm looking at it right, a shorter pushrod would move the pushrod even closer to the edge while a longer pushrod would move the pushrod farther from the edge.

Thank you,
Bob

Yes Bob you are correct those push rods are way too short and the rocker arm adjuster screws are at the bottom of their adjustment travel too. Getting the adjuster screws back towards the top, so they are at least in the middle 1/2 of adjustment plus a couple full turns will then center the push rods in the hole giving proper clearance and much better rocker arm geometry at the conection point of th rocker arm adjuster and push Rod.

Refresh my memory - just like measuring for pushrods, only an additional 1/4-1/2 turn after pushrod cannot move up and down?

No oil in lifters yet - only plunger spring pressure.

Thanks
Bob

Hi Bob, correct because people can have their faveriote rocker arm adjustments. Most people after getting to zero lash will use 1 full turn on their street cars this gives the quietest operation. Some use a 1/4 turn, half turn, or 3/4 turn too, I have tried them all in the past. For many decades now I have only used a full turn on customer cars that want it to be quiet. Some cars used to use a 3/4 turn spec in the 60's or early 70's after that most of the car manufacturers recommended 1 full turn so I only use 1 turn on any customer car because so many people get freaked out if they hear the rocker arms even a few seconds.

For my personal cars I like to use the 1/4 turn spec this extends a Hydrolic cams max RPM by another 200 to maybe 500 RPM because even when the lifters get to their limits and pump all the way up they are already near the top of their travel so the engine dosen't start miss fireing as soon. I started using this method on my race cars and street cars back in the 1960's after my uncle taught me. Be aware that with this 1/4 turn setting you might hear the rocker arms a few seconds at start up until there's oil pressure again most people just don't like hearing this rattle at start up. With 1/2 turn you may or may not hear it at start up Depends on the lifters rate of bleed down while sitting. Good luck

@bubba,

Thank you for the tips about the strategies between 1/4 turn and a full turn beyond zero lash - but my question was more about zero lash itself. Setting initial lash with new hydraulic lifters, no oil in lifters - zero lash is set at TDC on the compression stroke, tightening the adjuster until there is no vertical movement of the pushrod (but you can still spin it with your fingers), is that right?

On a side note, with no oil in the lifters you wouldn't get anywhere near full lift, because the valve spring pressure would overwhelm the lifter plunger spring pressure - is that right? Because currently, as I set the lash I'm seeing much less than the advertised .512" lift @ 1.6:1 = maybe .25". I also tried checking the cranking compression, which was higher than I expected - but if the valves are only opening about halfway, that makes sense, as the cam is effectively much less lift and duration with no oil in lifters, so the dynamic compression is much higher.

Some reassembly has been happening - got the radiator back in with hoses and coolant (Summit aluminum water pump inlet is at a different angle than the stock water pump ), the intake and carburetor, and the front bumper back on (the Ranchero blocks the attic door in the garage, wife needed access to the attic, so needed the front bumper on to be able to push the Ranchero back into the garage).

Biggest task now is to make up the new stainless braided fuel line, with which a friend will help me (haven't done that before).

Thanks
Bob

Hi Bob, glad to hear your making some progress on the reassembly. Yes thats correct when trying to set zero lash the engine needs to be on TDC on compression stroke. This hard for many people and is so easy to go past the zero lash point. It takes developing a real precise feel to notice as the push rods extra clearance between the rocker arm near the end its quickly being taken up during the adjustment. The hard part is to be able to recognize a very sleight drag starting as you are adjusting the screw while you are also turning (rolling / spinning it in your finger tips) each push Rod back and forth then stopping, with this slight drag you have reached the zero lash point, then do your 1/4 or 1 adistional turn more.

Yes you are right you can't get full cam lift when there's no oil in the lifters. This is were the Hydrolic lifters travel we talked about before comes in, so at zero lift your loosing from .150 to .180 of the cams lobe lift and a considerable amount of its deration also. As soon as the engine has had the rocker adjustments is filled with oil ready to crank or if you are going to pre oil it before starting this will all be were it should be. I used an aluminum GMB water pump on my 250 it matched up with the orginal I haven't seen the summit aluminum water pumps yet, who makes them for summit? Keep up the good work.

bubba22349":39rupgvz said:

I used an aluminum GMB water pump on my 250 it matched up with the orginal

Click to expand...

Summit #
GMB-125-1380
for the 250 (at least my iron head)
It may have more capacity (as described for vehicle w/AC) larger impeller.

Yesterday, spun the oil pump drive shaft with a drill and brought the oil pressure gauge to 40 psi (spilled some oil through the distributor hole in the process). Yesterday, my copilot was watching the oil pressure gauge.

After some initial difficulty, managed to stab the distributor at what I thought was TDC on #1, then turned ignition on and used remote starter switch to start the engine while using the timing light. My initial stab turned out to be a bit retarded (literally), but turning the distributor counterclockwise allowed it to start. Vacuum advance unit is now pointing directly towards the firewall. Checking the timing, it was about 20 degrees BTDC at a normal idle, the same as before the rebuild.

As soon as I locked down the distributor, I sat in the car and brought the engine up to a fast idle, which I held for 20 minutes. Oil pressure was initially around 65 psi and AFR was around 13.5-14.5. By the end of the 20 minutes, water temperature was up to about 185 (I haven't remounted the electric fan, so I put a large house fan in front of the radiator to keep the engine from getting hotter) and oil pressure was still at about 40 psi at a normal idle.

Finally, I adjusted the idle screws - the idle was a bit rich. Final AFR was 14 - 15 at about 900 RPM.

Issues:

There's some seepage around the oil pan gasket. I need to tighten up the oil pan nuts (I used studs).

There were a few drops of oil around the oil filter. When it cools down enough to touch, I'll tighten it as much as I can by hand. This oil may have been from when I spun the oil pump with the drill.

Most curiously, my vacuum gauge (permanently mounted) is showing only 5" of vacuum. That can't be right - I had 11" vacuum at idle with the 274/274/110 cam, and the 280/280/110 cam can't be that different. I suspect that I have a leak in the vacuum line to the gauge, or another vacuum leak somewhere else, that is skewing the reading.

Did not drive it - there's a cotter pin still needed on the castellated nut that holds the centerlink into the pitman arm, and I want to double-check the motor mount and under-engine brace fasters before I drive it. If no unexpected issues come up, I should be able to drive it tomorrow.

Thanks
Bob the Builder

P.S. With the help of a friend, I ran stainless braided fuel lines for the first time.

For anyone installing a distributor, put the TDC marker on what your initial should be. Then when you install the distributor & the reluctor is even with the pickup coil & the rotor is pointing toward #1 plug wire your setting should be very close to being close.
That saves a lot of time removing the distributor several times.

Hi Bill,

As far as the TDC marker, do you mean put a mark on the timing pointer at the position where you want your initial timing? Using that, you could be near TDC between the exhaust and intake strokes instead of near TDC between the compression and power strokes (where you want to be). Since I had removed and replaced the cam, I had to time the distributor to the rotating assembly.

For how many miles do you think I should drive the Ranchero before I change the break-in oil? For how many miles do you think I should "take it easy" before I open it up to evaluate the new cam and head work? For now, the previous Holley "500 CFM" carb has been reinstalled.

Thank you,
Bob

Yes, put a mark on the timing cover where your initial advance is set.
If you put some fast miles on the engine, i would change oil & filter after 100-200 miles.
Make sure you are using oil with high phosphorus & ZDDP or add an additive that contains both of these.
Is your 500 carb. like the one i have for sale??