“…What gears you planning on running out back?…”
Currently 3.55
With the steeper 1st gear of the 4R, it makes the rear end effectively a 4.10 (2.84 / 2.46 = 1.154 * 3.55 =4.10). With the modest boost in power, some healthy torque multiplication going on, this thing should rocket off the line. And with OD, the rear would be more like a 0.70 * 3.55 = 2.49 and spinning around 2100rpm vs the 3000 of the C4.
Quicker, faster and I might actually hear the music rather than the whine of the motor 🤣 Can’t wait to try it out!
Once I get the results I’ll be sure to post them!
The you should have different intake and exhaust pushrods...
technically true, but I don’t think the juice is worth the squeeze.
Most of the off-the-shelf pushrods come in 0.050” increments, and buying spec pushrods becomes very expensive for little gained.
The best blend of cost and a performance pushrod I could source was trickflow, and with my discount from summit it was $116 for the set. Custom ones from trend are some $13 each plus shipping making them almost double the cost.
Just look at the difference in each 0.050” increments, not sure sourcing a pushrod with just a 0.020” change from the intake side would be a concerning difference.
All I really wanted was least sweep near the center and less than 0.050” wide. The 6.550” & 6.500” were the only ones that fit the bill.
When you created these patterns did you notice if the rocker arm was sweeping outward and then back inward to its starting point as the valve goes from zero lift to full lift? This creates the narrowest pattern. 6.550 looks to be doing this or close to this as it is the narrowest pattern. As you use progressively shorter pushrod lengths, the pattern is getting wider and wider and moving closer to center. I like the narrow 6.550 patterns the best, but they are not quite centered. Pushrods deflect so the pattern will be closer to centered in a running engine, but not enough to center them in this case. You can achieve the narrowest possible pattern, but that does not mean the pattern will be centered because the rocker arm length from the fulcrum to the tip may be a bit short or long or the stud is not quite in it's correct location. Rocker arms and heads don't always have perfect dimensions. In a perfect world, you'd get the narrowest pattern that is centered. I tend to go for a centered pattern or slightly outboard pattern (because deflecting pushrods will drive the contact patch back to center a bit) that is still relatively narrow. I'll accept a bit wider pattern from optimum if that's what it takes to center it.
Agree with everything you said, except I favored the smallest sweep pattern which was found by using a light weight checking spring and adjustable pushrod.
I did look for any lateral movement when in operation and observed none.
interesting enough, when I doctored up a solid lifter from the guts of an old 5.0 OE unit and threw in the actual 6.550” pushrods and head springs, the loads and forces acting on the rocker essentially better centered the sweep pattern, which was one of your points. See post #7.
I may order the 6.500” and throw those in and see how they compare as a last check. In the end, I’m giving this more thought than it probably needs.
