318 poly valve train

[Old Frat]

Hi Guys
Frank here.
I am a retired mechanic (60yrs in the field) my last 30 yrs has been in diesel and this is the first Poly engine I have seen, my exp. was with 360,383 and 440 in the late 60s and early 70s
I have inherited a night mare
I am working on a 1966 318 poly engine the was rebuilt and has had too may cooks involved.
My problem is this engine has had the cam replaced with a Hydraulic cam and lifters and retained the solid lifter rocker arms, first problem was the rocker adjusters were too loose and had no lock nuts, I am assuming the originals had friction locks. I replaced the adjusters with new ones and lock nuts, I adjusted so there was a little clearance between the pushrod and the rocker arm. I am having trouble getting the engine started,I'm beginning to think the pushrods are too long, I will be running a compression test later this morning,
If this turns out to be the case can I run the original solid lifters on the Hyd. cam?

 

[yella71]

no you can not run the OE lifters on the new hyd. cam. Hyd lifters need to be run at 0 lash. that requires them to be set up with preload on them. If you don't have enough push rod length to give them about an extra half turn once you get to 0 lash you will need longer push rods.

 

[Old Frat]

no you can not run the OE lifters on the new hyd. cam. Hyd lifters need to be run at 0 lash. that requires them to be set up with preload on them. If you don't have enough push rod length to give them about an extra half turn once you get to 0 lash you will need longer push rods.

Okay I will give them a little more preload, Thought maybe I had over done it, Thank you.

 

[yella71]

your welcome....good luck

 

[gkent]

Looks like Yella71 didn't read your post !!
The new cam came with hydraulic lifters so no problem there. But he is correct about the adjustment, unlike solids that require lash, hydraulics NEED a preload and generally a 1/4 or 1/2 turn does it.

 

[mopar 3 B]

Looks like Yella71 didn't read your post !!
The new cam came with hydraulic lifters so no problem there. But he is correct about the adjustment, unlike solids that require lash, hydraulics NEED a preload and generally a 1/4 or 1/2 turn does it.

Think some one need to go back and read #1

 

[wyrmrider]

hyd and solid lifters have different pushrod cup heights also if polys ever came with hyd lifters like the 273s did they would be a different lifter than thee amc/magnum 2011 lifter available today
there are some poly experts around and websites
if no one posts up the difference in cup heights you could get a solid and measure yourself then get pushrods that account for the difference

or get an adjustable pushrod and check with the adjuster screws with only a couple of threads shown + preload mesure and orde pushrods

 

[Demonic]

I adjusted so there was a little clearance between the pushrod and the rocker arm.

Not needed with a hydraulic cam and lifters.

 

[beanhead]

Before you make a decision or spend any more cash-

https://www.forbbodiesonly.com/mopa...put-solids-on-a-hyd-cam.58536/#post-909938968

https://www.forbbodiesonly.com/moparforum/threads/lifter-pre-load.122256/#post-910564404

There's more too, just open up the search tab at the top of the page.
Member 'IQ52' is an extremely accomplished and well-known engine builder, you might try sending him a Private Message as well...he may be tough to reach though. I would take his word over anyone else's on this subject..

 

[gkent]

Think some one need to go back and read #1

Oops !! I stand corrected !!

 

[mopar 3 B]

318 poly's came with both hydraulic and solid lifter cams. Either get the right rockers or longer push rods. I am not sure why the hydraulic and solid lifters would be a different length though.

 

[moose1]

Since I've been fortunate to never have taken the valve covers off my '66 Poly, I'll ask the question......would the '66 have solid or hydraulic lifters?

 

[mopar 3 B]

Since I've been fortunate to never have taken the valve covers off my '66 Poly, I'll ask the question......would the '66 have solid or hydraulic lifters?

All I can say is mine did. Does yours. Dont know.

 

[wyrmrider]

3 b
see ,my post 7
the distance from the face of the lifter to the bottom of the cups are different\
also early and late lifters and pushrods which must be used together as the cups and balls are different sizes and the changed in that 67 timeframe
if buying new get the late versions no matter what the parts book says by looking up by year and get both lifter and pushrod- no mix and match
what I'm afraid of is someone will want to shortcut and end up with early pushrods on late lifters which the cam and kit ones certainly are

 

[mopar 3 B]

3 b
see ,my post 7
the distance from the face of the lifter to the bottom of the cups are different\
also early and late lifters and pushrods which must be used together as the cups and balls are different sizes and the changed in that 67 timeframe
if buying new get the late versions no matter what the parts book says by looking up by year and get both lifter and pushrod- no mix and match
what I'm afraid of is someone will want to shortcut and end up with early pushrods on late lifters which the cam and kit ones certainly are

Got it. No difference in cup and ball on 66 lifters. Yes got to watch the years.

 

[wyrmrider]

a more direct link to the HRM article
https://www.hotrod.com/articles/solid-lifters-on-hydraulic-cam/

 

[PRHeads]

I’m not sure what the current flat tappet camshaft core situation is for the poly 318....... but there was a point in time where the “correct” core wasn’t available new.
Somewhere along the line someone looked at all the normal specs, which are the same as an LA cam, and decided they didn’t need the poly cam core anymore.
The problem with the LA core in the poly 318 is....... 1/2 the lobes are in the wrong place.
It’s the same situation as a hemi cam and a B/RB cam.
It fits....... but it doesn’t run.

I came across this situation when I got a new sealed-power replacement cam for a poly 318 one time, and could tell by looking at it that it was a LA core.
The LA core has the 14th and 15th lobes lined right up with each other, and the poly doesn’t.
The part number stamped onto the cam was correct, so it wasn’t boxed wrong.
A call to sealed-power had them check the others they had on the shelf(which was only 2 pcs)...... they were also done on the LA core.

I couldn’t find a new, correct poly 318 cam anywhere.
I ended up getting a reground piece out of a place in Washington...... I think the name was Delta Camshaft.

My point is....... you may have a poly 318 hyd cam........ or you may not.

LA cam lobes #14 & #15:



Visually watching each pair of rockers when turning the motor over would tell the tale.
When bumping the motor over with a starter, the sequence “appears” as though it starts with the exhaust valve opening first, then the intake starts to open before the exhaust is fully closed.

With an LA cam in a poly motor....... 1/2 the cylinders will be correct, the other 1/2...... not so much.

I’m def no Poly guru, but I don’t think the Poly 318 ever came from the factory with anything but solid lifters.
So, the factory pushrods would be the correct length for solid lifters.

Edit: after doing a little digging....... it appears new cores are currently available.

 

[Old Frat]

Okay after much T&E I have come to the conclusion that the Solid lifter push rods are too Long, they hit the bottom of the rocker even when the adjuster is backed all the way out and hold the valves slightly open. I find after extensive searching that push rods in the length I need are not available. So I have ordered a set of new cup ends and will shorten the stock push rods.
Like I said in my OP, there have been many cooks in the kitchen before I got roped into getting the car running, at this point I am trying to make Honey out of ****. I'M still not 100% sure the cam is in time, once I get this push rod problem solved I'll find out.

 

[PRHeads]

I highly suggest you check the valve opening/closing sequence for each pair.
To be sure the cam was ground using the correct core.

You’d only have to check 2 cylinders...... 1&3.
With a LA core...... 1 should be correct, 3 would have the intake opening first.

The pushrod seats in solid lifters are about .200” lower than in hyd lifters...... which is why the pushrods are too long.

Of course....... it might be a good idea to also do a leak down test.
If the pushrods are so long the valves are being held open all the time...... there could have been some valve to piston contact.

 

[Old Frat]

I’m not sure what the current flat tappet camshaft core situation is for the poly 318....... but there was a point in time where the “correct” core wasn’t available new.
Somewhere along the line someone looked at all the normal specs, which are the same as an LA cam, and decided they didn’t need the poly cam core anymore.
The problem with the LA core in the poly 318 is....... 1/2 the lobes are in the wrong place.
It’s the same situation as a hemi cam and a B/RB cam.
It fits....... but it doesn’t run.

I came across this situation when I got a new sealed-power replacement cam for a poly 318 one time, and could tell by looking at it that it was a LA core.
The LA core has the 14th and 15th lobes lined right up with each other, and the poly doesn’t.
The part number stamped onto the cam was correct, so it wasn’t boxed wrong.
A call to sealed-power had them check the others they had on the shelf(which was only 2 pcs)...... they were also done on the LA core.

I couldn’t find a new, correct poly 318 cam anywhere.
I ended up getting a reground piece out of a place in Washington...... I think the name was Delta Camshaft.

My point is....... you may have a poly 318 hyd cam........ or you may not.

LA cam lobes #14 & #15:

View attachment 922359

Visually watching each pair of rockers when turning the motor over would tell the tale.
When bumping the motor over with a starter, the sequence “appears” as though it starts with the exhaust valve opening first, then the intake starts to open before the exhaust is fully closed.

With an LA cam in a poly motor....... 1/2 the cylinders will be correct, the other 1/2...... not so much.

I’m def no Poly guru, but I don’t think the Poly 318 ever came from the factory with anything but solid lifters.
So, the factory pushrods would be the correct length for solid lifters.

Edit: after doing a little digging....... it appears new cores are currently available.

Well I finally got to investigate farther, I do have an LA cam in this engine.
Could you please send me the info as to where I can get a stock profile cam and lifters.