So I have a plan but now im Second guessing myself.

[THE FRENCHTOWN FLYER]

I have a current build going on that I am going to use stamped stock rocker arms. The reason for that is I am running a back-to-back experiment on replacing a 240 with a 300 in the same vehicle and I want to keep the engines similar in build-up. I plan to contour dress the valve tip ends with a fine emery wheel since they show some wear witness marks. We'll see.

 

[pmuller9]

The reason for a little concern using the stamped rockers over .500" lift has to do with the extra pressure on the pivot ball causing squeaking.
Also need to check the pattern on the valve stem tip.
Otherwise there is some performance to be gained with the extra lift and duration from the increased ratio.
There is no harm starting with stamped rockers and if they give a problem they can be switched to a roller rocker.

There is not a problem with piston to valve clearance on a 300 six unless a domed piston is being used.

 

[pmuller9]

It would be interesting at this point to see a video of yours running. I'm excited to get mine together.

Here is a video of the Erson cam equivalent E270321 (Hi-Flow AH) .504"/.504" 220/220 284/284 110deg.
https://youtu.be/Ah7alvyiYT0

This is also one of the engines that had squeaky stamped rockers and finally switch to rollers to solve the problem.

 

[1986F150six]

AbandonedBronco's ride!

 

[BigBlue94]

AbandonedBronco's ride!

Yep, I got to ride in it when we were both in Moab for the Bronco Safari a few weeks ago. It's got great power and smooth performance. Definitely a good build.

 

[48kenworth]

Okay I must be calculating something wrong here.

Trying to decide about milling the head and using a dcr calculator my dynamic compression is to high.
So here are the figures I'm using
Bore 4.03
Stroke 3.98
Combustion chamber volume 68cc
Gasket thickness 0.048
Gasket bore 4.17
Deck clearance .025
Ivc @ .050 41 degrees for the Schneider 140h this is all numbers I sourced trying to do this myself.
I'm coming up with 7.56 for
8.85 static.
I came up with ivc @ .050 by the following 222÷2= 111+110= 221- 180= 41.

 

[Max_Effort]

Okay I must be calculating something wrong here.

Trying to decide about milling the head and using a dcr calculator my dynamic compression is to high.
So here are the figures I'm using
Bore 4.03
Stroke 3.98
Combustion chamber volume 68cc
Gasket thickness 0.048
Gasket bore 4.17
Deck clearance .025
Vic @ .050 41 degrees for the Schneider 140h this is all numbers I sourced trying to do this myself.

If you are going by .050” for IVC, use this calculator https://uempistons.com/p-27-compression ... lator.html

Is the gasket actually .048”? Typical is .038”

What is the piston top? Flat top, no valve relief, no dish?

 

[48kenworth]

Okay I must be calculating something wrong here.

Trying to decide about milling the head and using a dcr calculator my dynamic compression is to high.
So here are the figures I'm using
Bore 4.03
Stroke 3.98
Combustion chamber volume 68cc
Gasket thickness 0.048
Gasket bore 4.17
Deck clearance .025
Vic @ .050 41 degrees for the Schneider 140h this is all numbers I sourced trying to do this myself.

If you are going by .050” for IVC, use this calculator https://uempistons.com/p-27-compression ... lator.html

Is the gasket actually .048”? Typical is .038”

What is the piston top? Flat top, no valve relief, no dish?

I tried a few calculators. I don't really like the .050 part but it seems all the calculators that ask all the questions use it. Pistons are just stock rebuilder pistons, The .048 was taken from some fine internet forum research. If 0.038 is correct for our gaskets and the math I'm doing is right i won't be able to run 87 octane. Y'all bear with me. I'm a class 8 truck mechanic and not accustomed to doing custom builds on a gassers. My math has to be wrong.

 

[CNC-Dude]

Another issue with using stock style stamped steel rockers for valve lifts over .500" is that the slots can't allow the rockers to pivot that much without binding against the rocker studs. Even in high performance versions of Big Block Chevy's, GM had to make special long slot stamped steel rockers for use with cams that had more than .500" lift. So if using higher ratio steel aftermarket rockers, don't assume they can accommodate lifts beyond a certain lift unless they clearly specify they can.

 

[48kenworth]

Another issue with using stock style stamped steel rockers for valve lifts over .500" is that the slots can't allow the rockers to pivot that much without binding against the rocker studs. Even in high performance versions of Big Block Chevy's, GM had to make special long slot stamped steel rockers for use with cams that had more than .500" lift. So if using higher ratio steel aftermarket rockers, don't assume they can accommodate lifts beyond a certain lift unless they clearly specify they can.

Yea I've been looking into that and I'm take going to take a wait and see approach to that deal. But I've already been on summit scoping out roller rockers and deciding on how I'm going to graft two valve covers together if I have to. Or buying your spacer.

 

[48kenworth]

Right now I really need somebody to help me learn how to grasp the math and do it right without having my hand held.

 

[Mdixon300f100]

The felpro 1024 is .038 torqued. Bore is 4.18. What’s the dish in the piston? Common rebuild piston is 20cc dish.

 

[48kenworth]

The felpro 1024 is .038 torqued. Bore is 4.18. What’s the dish in the piston? Common rebuild piston is 20cc dish.

The engine is currently a runner and I can't afford for the pickup it's in to be eating up a bay in my shop for weeks with the head off so
I'm having to assume the dish in the pistons. I didn't check them when I lapped the valves on the stock head. I assumed 25cc.

 

[Max_Effort]

 

[48kenworth]

Yea I used that calculator. I may have to rethink things here. I need to run 87 octane and I am under the impression to do so requires dynamic compression to be in the low 7's?

 

[pmuller9]

That is the calculator I use also but I use the intake valve closing point based on the .006" lobe lift point (advertised duration) not the .050" plus 15 degrees.
There are too many variations between the advertised and .050 durations on camshafts.

For the purposes of detonation, DCR is simply a reference number that is specific to an engine in our case being the 300 six.
It is observed using many different 300 engine builds that at sea level the DCR range for pump gas is between 7.0 to 7.5 allowing margin for other variations.

This reference number is calculated by using the actual intake valve closing point approximately .010" off the seat.
The SAE standard for the advertised duration is calculated on the .006" lobe lift.
Some will argue that some cam companies will use a lesser lobe lift to increase the advertised duration but all you can do is use what is given
Using the .006" lobe lift number gives that value using the many different DCR calculators available online.

If you install the 140H cam straight up 280÷2 = 140 + 110 -180 = 70 degrees ABDC

 

[Max_Effort]

This is with the IVC at .006” timing (adding 29 to the 41 at .050”) if Schneider uses gross duration at .006” . Some cam companies use different lift points...

 

[48kenworth]

It's amazing how much the numbers change when not following the calculators instructions. I was following the instructions on different calculators and coming up with Dcr's closer to 8.

It's hard to play the game when you don't know the rules were changed.

But at least the question is answered, No I cannot mill the head any further than necessary to flatten it.

 

[Max_Effort]

The SAE standard for the advertised duration is calculated on the .006" lobe lift.
Some will argue that some cam companies will use a lesser lobe lift to increase the advertised duration but all you can do is use what is given
Using the .006" lobe lift number gives that value using the many different DCR calculators available online.

This is or was done quite a bit, listing advertised anywhere from 004", .006", .012", .020"

The company makes the cam seem larger, smaller, more or less aggressive. Very common with marketers of the generic "white box" cams that are made by CMC and sold under many different brand names. It was a big reason Harvey Crane pushed the .050" duration numbers. Of course there is a lot more than advertised or .050" to a lift curve and how the cam performs.

Then there is Harley with .053" lift numbers....

 

[48kenworth]

It's not enough for somebody to tell me what I need to do. I want to understand the reasoning and gain the wisdom to make determinations without help. I am truly grateful for the people here who do not know me but take the time to share knowledge and wisdom. To be honest knowing this stuff will likely make me better at my job! At least indirectly.

So as I have been figuring this, i cannot safely mill the head to reduce combustion chamber size considering my goals. If I were working over the short block I may would have been able to get my pistons to zero deck and polish the combustion chambers to improve the Quincy area and be able to squeeze a little more. But that part is only a hypothetical idea I came to in my figuring.