E58 400 plus HP Dart sport build

They are true 1.6 ratio roller rockers red and blue in picture. Stock are actually below 1.5. checking cam spec valve lift I'm now 526 intake and 540 exhaust. This cam is @107 rather than 110 so has overlap. For sure need to go to 3.73 rear gear. I fixed the tachometer tonight pulled out of loom and wrapped in foil tape. Also put that inside a 1/4 vacuum hose ran through one of the plugs it used for firewall insulation. Then checked no RFI issues tach is steady at idle. Speedometer same issue fixed tomorrow. Ran it up first gear 4500 holy cow and into 2nd before I chickened out. She is ready to go for sure. Just needs miles like you said rumble fish. Temps still right at 190 or lower very pleased with AC I needed it down low Oklahoma is HOT.

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Here’s the thing, there are several companies that offer a 1.6 roller rocker but they do not all exact lift the valve a true 1.6 mathematically. Or in actuality. Is the differences in the contact point of the roller tip the push rod contact point and the frog buckram point and the differences between them, additionally, pushrod length also has a play in this. Double check to see what your actual lift is.