Longer pushrod Question

[bax]

I have installed a new H Roller cam into a 1986 302 truck motor. It has the stock pedestal rockers. I knew I was going to need longer pushrods due to the smaller base Dia. of the new cam. So I got my pushrod checking tool and figured out I needed 32 thousandths longer pushrod to get to zero lash. My Question is : How much longer do I need to add to the length to get the proper pre load on the lifter??? Remember, pedestal rockers. No adjustment. It is all in the pushrod length. Any Help here? I want to order pushrods.
Thanks

 

[ntsqd]

Adjustable Push-rods? Or is that contrary to the goal?

Got a set of those stock parts that you can lay-up?

 

[bax]

The adjustable pushrod is the tool used to measure what pushrod length you need to get to zero lash. I just dont know how much to add to the zero lash length.

 

[ntsqd]

What I meant was to use adjustable push-rods like some engines do.

However, it occurs to me that the answer is somewhat simple to find. How many turns/partial turns is the spec for once contact is made with something like a rail rocker? Assuming a 3/8"-24 UNF stud thread the nut moves .042" for every full turn. If the spec is 1.5 turns (a guess, no idea if real) after contact then .0625" longer than what you've measured. If it's 3 turns then .125" longer than measured.

 

[Grey owl]

1/2 - 1 turn of preload is probably just fine

 

[ntsqd]

So .021" to .042" longer.

 

[jamesroney]

So .021" to .042" longer.

I like your first answer better.

Ford says nominal travel is .140”
Half of that is a good place to be when cold. But you have to pick your poison, and choose whether you want lifter noise, or hung valves when everything gets hot and wears out.

I’ve always opted for right at .060 at the plunger.

 

[jamesroney]

What I meant was to use adjustable push-rods like some engines do.

However, it occurs to me that the answer is somewhat simple to find. How many turns/partial turns is the spec for once contact is made with something like a rail rocker? Assuming a 3/8"-24 UNF stud thread the nut moves .042" for every full turn. If the spec is 1.5 turns (a guess, no idea if real) after contact then .0625" longer than what you've measured. If it's 3 turns then .125" longer than measured.

Did you divide by the rocker ratio to get this number? Or is this at the fulcrum?

 

[ntsqd]

I blatantly assumed a 1:1 MR figuring that the difference was noise. But also because I hadn't thought it completely through.

 

[Bruners4]

You also have to take into consideration the off the shelf lengths that are available currently. I've been using 0.030" lifter plunger travel down from the top as my spot. Then check how close that is to the available pushrods.

 

[Grey owl]

I like your first answer better.

Ford says nominal travel is .140”
Half of that is a good place to be when cold. But you have to pick your poison, and choose whether you want lifter noise, or hung valves when everything gets hot and wears out.

I’ve always opted for right at .060 at the plunger.

I am using the comp cams hydraulic flat tappet lifter that uses virtually no pre load. You go to Zero lash and add maybe a 1/16 th of a turn. I am not sure why my parts guy sold me these or if its part of the cam kit. I also bought Comp roller rockers so setting the lifters fine tolerance was a little easier. They also included new pushrods

 

[bax]

This is a pedestal rocker mount. There is no adjustment after they are torqued down. But I like the preload answers. .060 seems to make the most sense to me. So adjustable pushrod tool set to zero lash and then add .060. Now to find a pushrod that is close. Thank you all.

 

[jamesroney]

This is a pedestal rocker mount. There is no adjustment after they are torqued down. But I like the preload answers. .060 seems to make the most sense to me. So adjustable pushrod tool set to zero lash and then add .060. Now to find a pushrod that is close. Thank you all.

Pedestal shims too.

 

[ntsqd]

Smith Bros will make push-rods by .05" length increments. Seems easier than trying to find a OEM application that is the correct length.
https://www.pushrods.net/

 

[jamesroney]

I have installed a new H Roller cam into a 1986 302 truck motor. It has the stock pedestal rockers. I knew I was going to need longer pushrods due to the smaller base Dia. of the new cam. So I got my pushrod checking tool and figured out I needed 32 thousandths longer pushrod to get to zero lash. My Question is : How much longer do I need to add to the length to get the proper pre load on the lifter??? Remember, pedestal rockers. No adjustment. It is all in the pushrod length. Any Help here? I want to order pushrods.
Thanks

Wait. What? Huh?

The entire point of a reduced base circle on a retrofit roller camshaft is to put the lifter plunger in the EXACT same place as the factory unit.

So if you have a 1986 Ford 302 truck motor, it would have had a factory flat tappet cam, and use 6.905" pushrods.

Who's cam are you running, and how big is it? (lift and duration?) Is it a retrofit roller, with a reduced base circle?

Where are you ending up if you use your stock pushrod and bottom the pedestal? Are you saying that you are .032 short with factory (6.905) pushrods?

OR are you running an E5TE block and YOU retrofit a factory hydraulic roller cam with a spider plate, and h-bars? So you need the nominal 6.25 pushrods?

When you put your checking tool in at +.032, what does the tip to rocker location look like?

I'm not saying that you don't need custom pushrods...but as soon as you say pedestal heads, I KNOW you do not intend to go fast. Ford 302's have been built in every configuration known to man. VERY few end up with oddball length pushrods.

Something is goofy here.

 

[bax]

The stock motor had pedestal heads on it. it also had the stock 6.25 pushrods. yes I used a retrofit cam with a smaller base circle. I have no history on the engine, but when I took it apart it looked great on the inside. The rocker arm issue caught me off guard. When I was measuring for pushrods I did note the contact patch on top of the valve. It is pretty much in the center perhaps just a little off center to the downward side. It still has the stock rockers on it. I ordered a set of 1.6 scorpion roller rockers last night. I am going to install two rockers and measure out what I need for pushrods. I am interested in what length they will be. I will also compare block and head casting numbers to confirm what I really have.

I started the motor with the stock 6.25 pushrods in it. Lots of rocker arm noise so I shut it down. stock 6.25 pushrod. Pushrod tool at zero lash measured 6.274. My original question was how much do I add to the 6.274 number to get the proper pre load on the lifter. Lots of different answers from .030 to .120. But .060 seems to be a more common answer. So 6.274 + .060 = 6.334 I did find a pushrod that is 6.350. Since it seems I can go as much as .120 I dont have a problem adding .016 to the 6.334 making the pushrod 6.350

Clear as mud?

 

[jamesroney]

The stock motor had pedestal heads on it. it also had the stock 6.25 pushrods. yes I used a retrofit cam with a smaller base circle. I have no history on the engine, but when I took it apart it looked great on the inside. The rocker arm issue caught me off guard. When I was measuring for pushrods I did note the contact patch on top of the valve. It is pretty much in the center perhaps just a little off center to the downward side. It still has the stock rockers on it. I ordered a set of 1.6 scorpion roller rockers last night. I am going to install two rockers and measure out what I need for pushrods. I am interested in what length they will be. I will also compare block and head casting numbers to confirm what I really have.

I started the motor with the stock 6.25 pushrods in it. Lots of rocker arm noise so I shut it down. stock 6.25 pushrod. Pushrod tool at zero lash measured 6.274. My original question was how much do I add to the 6.274 number to get the proper pre load on the lifter. Lots of different answers from .030 to .120. But .060 seems to be a more common answer. So 6.274 + .060 = 6.334 I did find a pushrod that is 6.350. Since it seems I can go as much as .120 I dont have a problem adding .016 to the 6.334 making the pushrod 6.350

Clear as mud?

Better, thanks. But still confused.

You said "1986 302 truck motor" There are exactly zero 1986 Ford trucks with a roller camshaft. So why are we saying "truck motor"

There's no reason to run a reduced base circle cam in an HO block. (E7TE, E6SE, E6AE) Since we are only out .030. Are you running link-bar lifters, or the spider plate? I've never seen an aftermarket cam that was out .030.

 

[bax]

I was told it came out of a truck. We dont have to call it a truck motor. Going to re check casting numbers
Cam card.

 

[jamesroney]

I was told it came out of a truck. We dont have to call it a truck motor. Going to re check casting numbers
Cam card.

35-349-8 That's a very popular cam. You will like it. 114LSA will keep your computer happy. It runs more lift than I like on stock heads, so your Scorpion 1.6 rockers will be perfect. Some are tempted to run 1.7 rockers, but Comp put the lift into the cam for you already.

I think that @Timmy390 or @Viperwolf1 run it.

It is not a reduced base circle cam, and is not a "retrofit" cam.

It is a mild performance camshaft upgrade for an 86-95 Mustang 5.0 HO, or 96-00 Explorer 5.0 HO.

It should be a bolt in. Kinda surprised that your pushrods ended up short. Curious now if you rebuilt the heads, and if you used factory head gaskets. But your measurements don't lie. If the rockers are centered, I'd cut .020 off the pedestals, re-measure and send it. But I'm cheap.

 

[Timmy390]

Yup, I run that cam in my SN95 EFI 351W. The only issue I had was the SN95 EMC (per the mustang guys) can't handle changes very well. I had idle issue till I added a 1986-1993 Mustang 5.0 Idle Air Control Adjuster. Ford service used them on about anything that had an IAC and had idle issues back in the day and now they're considered a "mustang" part....

Once I got it dialed in she idles GREAT. Just needed more air....

I run GT40P heads and the stock pushrods from the 351W (came from a 96 E350 van), E7 heads and explorer cam (the EFI 351w have the same cam stock F4TE-6250-BA) with stock 351w lifters worked perfectly. I did upgrade springs on the GT40P's as the stock springs cant handle the lift of the Comp 35-349-8

Tim