Boss 351 Valve Train

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kcmash

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My Car
1971 Mach 1, Grabber Blue w/Argent stripes. Original 2V 351C Auto, Tilt, rear defog, Black Comfortweave Interior. Under restoration. Original colors, 4V 351C, 4-Speed, Spoilers, Magnums, Ram Air. All Ford parts.
I really need some expertise on this. Ford Boss 351 heads on a the 351C block. Ford studs and C9ZZ guide plates. Rockers have roller fulcrums on stamped rockers with poly-locks.

How do I figure out the right pushrod length?

At this point I don't know how long I should go with a 5/16 pushrod and the factory guide plates. Should I sell the vintage Ford stuff to a Boss 351 owner and go with a full forged, roller system from Crane or Ford to go with the Motorsport cam in the engine.

1) How far down the stud should the rocker arm sit? Right now I have the polyloc running all the way down to the end of the stud threads so there is no adjust ability at 8.5 inch pushrod length.

2) What length pushrods are used with an adjustable rocker system and a .5 lift on the cam?

3) Do I maybe have incorrect polylocks?

This area is NOT my expertise! This is my first try at the adjustable rocker system, I thought it would be easy!

View attachment 31166

View attachment 31167

 
Last edited by a moderator:
I really need some expertise on this. Ford Boss 351 heads on a the 351C block. Ford studs and C9ZZ guide plates. Rockers have roller fulcrums on stamped rockers with poly-locks.

How do I figure out the right pushrod length?

At this point I don't know how long I should go with a 5/16 pushrod and the factory guide plates. Should I sell the vintage Ford stuff to a Boss 351 owner and go with a full forged, roller system from Crane or Ford to go with the Motorsport cam in the engine.

1) How far down the stud should the rocker arm sit? Right now I have the polyloc running all the way down to the end of the stud threads so there is no adjust ability at 8.5 inch pushrod length.

2) What length pushrods are used with an adjustable rocker system and a .5 lift on the cam?

3) Do I maybe have incorrect polylocks?

This area is NOT my expertise! This is my first try at the adjustable rocker system, I thought it would be easy!
Click to expand...
Here is the Cam I have:

M-6250-A341

Motorsports SVO

Hydraulic

.510"/.536"

292/302 {214/224 @ .050" lift}

Good all around Performance Cam

4 Speed or high stall converter and Low Rear end gears Recommended

 
Last edited by a moderator:
You do not want to tighten down the nuts all the way, if you do and still have play then you will need to determine the correct pushrod length that you'll need. After reading this article let us know if you have further questions.

http://diyford.com/ford-351-cleveland-performance-guide-valvetrain/
Click to expand...
Thank you for the reply. I had read that article and many others earlier today before posting here. I see what they are saying and understand the adjustment process, but have a concern over the length of Pushrod I will need to be able get the correct rocker travel. Looking at it right now I think I will need an 8.90 long pushrod in 5/16 dia. Some of the press I have read say the cleveland vlave pressure will bend your pushrods if you go too long. So my questions after reading the article are.

1) Does 8.90 long sound unreasonable for a pushrod length in this engine setup?

2) Should I be going with full roller fulcrum/ roller tip rockers instead of the factory HD stamped units with roller fulcrum and factory guide plates that I have now,

 
Stock length is 8.40 so yeah I'd say 8.90 are too long not knowing what was done to your motor. Watch this video.



If you can't get the play out of the pushrod before you bottom out the nut then you will need a longer rod. There is an adjustable pushrod that you can get that will tell you how much longer or shorter the rod needs to be. You just keep adjusting the rod until you get the desired results. Try doing what the video says and see if your current parts work. If you go with roller tip then the adjustment becomes even more critical as you need to ensure the roller tip rides equally on each side from the valve tip centerline.

I went with the roller tip and had to get shorter pushrods because my heads were milled and I have .550 lift and to get the correct wear pattern on the valve stem tip the were like 8.25 (don't remember the exact lengths) but they were shorter.

 
Your cam specs say hydraulic

Do you have solid lifters ?

Don

 
I recommend Jim Miller's approach using his "Mid Lift" principle. His approach results in the most efficient valvetrain geometry possible and valves moving by the intended amount and timing as specified on the cam card.

Here's a link to an article on the subject: http://www.aera.org/technical-articles/rocker-geometry

At the end of the article is a link where you can view a pdf of the article with all illustrations/diagrams.

Post #32 on this thread discusses how to take measurements on an OEM style rocker. http://www.hotrodders.com/forum/mid-lift-rockers-206836-3.html

 
Your cam specs say hydraulic

Do you have solid lifters ?

Don
Click to expand...
No, I have the recommended Ford Hydraulic units.

Not sure if I have the wrong Polylocks, or what. Looks like from the posts here I probably out to take 3 steps back and recalcualte the valve train geometry. Considering how long a pushrod I am calculating I feel pretty lost right now! Summit racing will sell me long pushrods, but i don't think they will last based on what everyone is saying.

I need to read the articles that were posted here today before spending money.

 
I thought you only need adjustable rockers for solid lifters.

 
I thought you only need adjustable rockers for solid lifters.
Click to expand...
That's correct because there isn't any preload that you can do with solid lifters so you need to use a feeler gauge to set the clearance between the rocker arm and valve tip. For hydraulic lifters and the stud mounted rockers you normally turn the nut from 1/4 to 3/4 additional turns after the play is removed from the pushrod. This compresses the hydraulic lifter slightly and uses the oil pressure to take up any clearances so that you don't get the chatter.



Your cam specs say hydraulic

Do you have solid lifters ?

Don
Click to expand...
No, I have the recommended Ford Hydraulic units.

Not sure if I have the wrong Polylocks, or what. Looks like from the posts here I probably out to take 3 steps back and recalcualte the valve train geometry. Considering how long a pushrod I am calculating I feel pretty lost right now! Summit racing will sell me long pushrods, but i don't think they will last based on what everyone is saying.

I need to read the articles that were posted here today before spending money.
Click to expand...
This is what I would do:

**Back off all the nuts and allow the lifters to pump back up.

**Rotate the motor to TDC for CYL 1 on compression stroke.

**Remove the rocker arms and clean any oil from them and the valve stem tip for cyl #1.

**Get a black sharpie and blacken the whole tip of the valve stems. This is normally done for roller tip rockers but I believe the same principle should apply here.

**Use the 8.40 pushrods (stock) and put the two rocker arms back on and tighten the nut until all play both up and down and twisting is just removed from the pushrod. Don't over tighten, you just want the play out.

**Then turn each nut an additional 5/8 of a turn. This preloads the lifter.

**Rotate the motor for 2 compression cycles for #1 cyl, 4 complete turns of the damper.

**Remove the rocker arms

**Look at the rub pattern of the valve stem tip, it should be centered on the stem. The black sharpie mark will be worn off where the rocker arm contacts the valve stem. You want to see equal wear on both sides of the centerline.

Take pics of the wear pattern and post. If the wear is off center it will indicate that a longer or shorter length is required depending on whether the wear is more towards the exhaust or intake manifold.

 
Last edited by a moderator:
I thought you only need adjustable rockers for solid lifters.
Click to expand...
That's correct because there isn't any preload that you can do with solid lifters so you need to use a feeler gauge to set the clearance between the rocker arm and valve tip. For hydraulic lifters and the stud mounted rockers you normally turn the nut from 1/4 to 3/4 additional turns after the play is removed from the pushrod. This compresses the hydraulic lifter slightly and uses the oil pressure to take up any clearances so that you don't get the chatter.



Your cam specs say hydraulic

Do you have solid lifters ?

Don
Click to expand...
No, I have the recommended Ford Hydraulic units.

Not sure if I have the wrong Polylocks, or what. Looks like from the posts here I probably out to take 3 steps back and recalcualte the valve train geometry. Considering how long a pushrod I am calculating I feel pretty lost right now! Summit racing will sell me long pushrods, but i don't think they will last based on what everyone is saying.

I need to read the articles that were posted here today before spending money.
Click to expand...
This is what I would do:

**Back off all the nuts and allow the lifters to pump back up.

**Rotate the motor to TDC for CYL 1 on compression stroke.

**Remove the rocker arms and clean any oil from them and the valve stem tip for cyl #1.

**Get a black sharpie and blacken the whole tip of the valve stems. This is normally done for roller tip rockers but I believe the same principle should apply here.

**Use the 8.40 pushrods (stock) and put the two rocker arms back on and tighten the nut until all play both up and down and twisting is just removed from the pushrod. Don't over tighten, you just want the play out.

**Then turn each nut an additional 5/8 of a turn. This preloads the lifter.

**Rotate the motor for 2 compression cycles for #1 cyl, 4 complete turns of the damper.

**Remove the rocker arms

**Look at the rub pattern of the valve stem tip, it should be centered on the stem. The black sharpie mark will be worn off where the rocker arm contacts the valve stem. You want to see equal wear on both sides of the centerline.

Take pics of the wear pattern and post. If the wear is off center it will indicate that a longer or shorter length is required depending on whether the wear is more towards the exhaust or intake manifold.
Click to expand...
Well, I may have found the solution. I had 2 sets of Polylocks around for some reason. One set has a "skirt" to them that pushed the roller fulcrum down farther on the stud without bottoming out on threads.

I set the pushrod length checker to approximately 8.40 inches and tightened the lash out of the rocker. The picture of the assembly shows the rocker position for a closed valve and the 8.4 pushrod length. I have not turned to engine over to check the wear pattern on the valve head, but it looks like these Polylocks will allow me to properly adjust lash with an 8.4 or 8.5 pushrod length.

Let me know if you see any areas of concerns in the pictures. I think I am good with a 8.4 length on this setup. My only fear now is if the Boss Valve covers will clear those polylocks.

Don, good question above. Am I the only one trying to use adjustable rockers with hydraulic lifters?

Per the post from John, this is a fresh engine that has not been fired, so nothing has been run and nothing is pumped with oil. I actually bought the setup from another owner locally with all the stuff except for the pushrods, I assembled the engine several years ago, and worked to get the rest of the car together.

View attachment 31171

View attachment 31172

View attachment 31173

View attachment 31174

View attachment 31175

 
Last edited by a moderator:
Yeah I think that you might have valve cover clearance issues, just test fit to be sure. With the higher lift cam I was figuring that you would need a 8.35" long rod, just a guess though. I was looking at the stock lift and the new lift and looking at what the length should be. Since you have the adjustable rod you can dial in the exact length you need to get the proper wear pattern. You only need to do this on a couple of cylinders on each side and you should then be good.

 
I thought you only need adjustable rockers for solid lifters.
Click to expand...
That's correct because there isn't any preload that you can do with solid lifters so you need to use a feeler gauge to set the clearance between the rocker arm and valve tip. For hydraulic lifters and the stud mounted rockers you normally turn the nut from 1/4 to 3/4 additional turns after the play is removed from the pushrod. This compresses the hydraulic lifter slightly and uses the oil pressure to take up any clearances so that you don't get the chatter.



No, I have the recommended Ford Hydraulic units.

Not sure if I have the wrong Polylocks, or what. Looks like from the posts here I probably out to take 3 steps back and recalcualte the valve train geometry. Considering how long a pushrod I am calculating I feel pretty lost right now! Summit racing will sell me long pushrods, but i don't think they will last based on what everyone is saying.

I need to read the articles that were posted here today before spending money.
Click to expand...
This is what I would do:

**Back off all the nuts and allow the lifters to pump back up.

**Rotate the motor to TDC for CYL 1 on compression stroke.

**Remove the rocker arms and clean any oil from them and the valve stem tip for cyl #1.

**Get a black sharpie and blacken the whole tip of the valve stems. This is normally done for roller tip rockers but I believe the same principle should apply here.

**Use the 8.40 pushrods (stock) and put the two rocker arms back on and tighten the nut until all play both up and down and twisting is just removed from the pushrod. Don't over tighten, you just want the play out.

**Then turn each nut an additional 5/8 of a turn. This preloads the lifter.

**Rotate the motor for 2 compression cycles for #1 cyl, 4 complete turns of the damper.

**Remove the rocker arms

**Look at the rub pattern of the valve stem tip, it should be centered on the stem. The black sharpie mark will be worn off where the rocker arm contacts the valve stem. You want to see equal wear on both sides of the centerline.

Take pics of the wear pattern and post. If the wear is off center it will indicate that a longer or shorter length is required depending on whether the wear is more towards the exhaust or intake manifold.
Click to expand...
Well, I may have found the solution. I had 2 sets of Polylocks around for some reason. One set has a "skirt" to them that pushed the roller fulcrum down farther on the stud without bottoming out on threads.

I set the pushrod length checker to approximately 8.40 inches and tightened the lash out of the rocker. The picture of the assembly shows the rocker position for a closed valve and the 8.4 pushrod length. I have not turned to engine over to check the wear pattern on the valve head, but it looks like these Polylocks will allow me to properly adjust lash with an 8.4 or 8.5 pushrod length.

Let me know if you see any areas of concerns in the pictures. I think I am good with a 8.4 length on this setup. My only fear now is if the Boss Valve covers will clear those polylocks.

Don, good question above. Am I the only one trying to use adjustable rockers with hydraulic lifters?

Per the post from John, this is a fresh engine that has not been fired, so nothing has been run and nothing is pumped with oil. I actually bought the setup from another owner locally with all the stuff except for the pushrods, I assembled the engine several years ago, and worked to get the rest of the car together.
Click to expand...
Would really want to know who makes those funky rockers and rollers.

do you know the manufacturer and part numbers ?

Boilermaster

 
That's correct because there isn't any preload that you can do with solid lifters so you need to use a feeler gauge to set the clearance between the rocker arm and valve tip. For hydraulic lifters and the stud mounted rockers you normally turn the nut from 1/4 to 3/4 additional turns after the play is removed from the pushrod. This compresses the hydraulic lifter slightly and uses the oil pressure to take up any clearances so that you don't get the chatter.



This is what I would do:

**Back off all the nuts and allow the lifters to pump back up.

**Rotate the motor to TDC for CYL 1 on compression stroke.

**Remove the rocker arms and clean any oil from them and the valve stem tip for cyl #1.

**Get a black sharpie and blacken the whole tip of the valve stems. This is normally done for roller tip rockers but I believe the same principle should apply here.

**Use the 8.40 pushrods (stock) and put the two rocker arms back on and tighten the nut until all play both up and down and twisting is just removed from the pushrod. Don't over tighten, you just want the play out.

**Then turn each nut an additional 5/8 of a turn. This preloads the lifter.

**Rotate the motor for 2 compression cycles for #1 cyl, 4 complete turns of the damper.

**Remove the rocker arms

**Look at the rub pattern of the valve stem tip, it should be centered on the stem. The black sharpie mark will be worn off where the rocker arm contacts the valve stem. You want to see equal wear on both sides of the centerline.

Take pics of the wear pattern and post. If the wear is off center it will indicate that a longer or shorter length is required depending on whether the wear is more towards the exhaust or intake manifold.
Click to expand...
Well, I may have found the solution. I had 2 sets of Polylocks around for some reason. One set has a "skirt" to them that pushed the roller fulcrum down farther on the stud without bottoming out on threads.

I set the pushrod length checker to approximately 8.40 inches and tightened the lash out of the rocker. The picture of the assembly shows the rocker position for a closed valve and the 8.4 pushrod length. I have not turned to engine over to check the wear pattern on the valve head, but it looks like these Polylocks will allow me to properly adjust lash with an 8.4 or 8.5 pushrod length.

Let me know if you see any areas of concerns in the pictures. I think I am good with a 8.4 length on this setup. My only fear now is if the Boss Valve covers will clear those polylocks.

Don, good question above. Am I the only one trying to use adjustable rockers with hydraulic lifters?

Per the post from John, this is a fresh engine that has not been fired, so nothing has been run and nothing is pumped with oil. I actually bought the setup from another owner locally with all the stuff except for the pushrods, I assembled the engine several years ago, and worked to get the rest of the car together.
Click to expand...
Would really want to know who makes those funky rockers and rollers.

do you know the manufacturer and part numbers ?

Boilermaster
Click to expand...
Let's see.

Stamped Rockers - Ford Motor Company(PN unknown right now)

Roller Fulcrums - Ford D0ZX-6A585-A(Boss 302 Race Rollers)

Locknuts - Who knows? I had them turned down to slip inside the rollers.

Tell me if I am stupid to not go with a more modern rocker assy.

 
With a fulcrum setup like that, it's easy to apply the mid-lift principle to the best of the rocker arm design's ability. The pushrod length is determined by adjusting the pushrod length until the center of the fulcrum is 1/2 the total valve lift below the tip of the valve and measured perpendicular to the valve stem with valve closed.

 
Well, it looks like the 8.5 length is the correct one for this. All I need is for Summit Racing to have an open line so I can get my exchange processed.

Question of the day: What do you guys use to turn the engine over when the balancer is on or off, so you can go through the valve setting process? Mine is on an engine dolly, no starter on it.

 
When I tried the crank bolt it kept tightening and the engine did not turn. I guess I need to check the torque on the crank bolt to make sure it is in all the way. I would HATE to snap that bolt off in the crank at this point!!!

 

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