Either way you’re running it will get the job done. I’m referencing my 496 with the cool fuel 3 module, no return fuel rail, and has the test port on the rail. When I built my lsa swap Silverado I had my fuel system regulator setup very similar to yours. Set my pressure and used the port for boost as the aeromotive regulator has instructions on how to do it, I don’t remember off the top of my head as it’s been a few years. I had my pressure gauge same as yours, only mechanical gauge tho as I always had afr to read in the vehicle. Enjoy the build they never seem to end

Guys,

So the decision to convert to roller rockers hasn’t come without its complications. The roller tip is too far out over the valve tip and the ARP studs are considerably shorter than we’d like to see, significantly reducing thread engagement of the polylock nut. Initially, the builder decided to shorten the pushrods, tilting the rockers away from the valves and increasing thread engagement, but i was worried about the potential for side load on the stud. After some considerable back and forth (in a good way) I’ve decided to pull the heads and drill and tap the stud holes for 7/16-14, and use a different, taller rocker stud. This will also present us with an opportunity to move the stud hole a bit. How much depends on…. Factors.

https://cimg0.ibsrv.net/gimg/www.off...52aa5d138.jpeg

Above are three sketches that show my options. The white lines represent the machining that will be done. The magenta represents the original M10X1.5 tapped hole and the green dashed line represents the theoretical outside diameter of the stud bosses in the head, assuming they are all currently centered. The red is the dimensions, indicating both the shift from original M10 to the new 7/16 tapped holes and the material left in the boss on top and bottom after the respective shifts. Trust me when I say i CAN move a hole when making it bigger. I am showing both the major and minor diameters, which is why the double circles for each. The sketch on the right shows just a simple drill and tap, which will leave some vestigial threads on the lower side that is tangent to the new threads. The center and left sketches show what i can do if I plan for Heli-Coil thread inserts. The center sketch shows the maximum shift in hole location that will eliminate all threads from the M10 holes, and the left sketch shows the maximum shift I can make happen without stepping beyond tangency of the original M10 and the new 7/16 threads, which would, again, leave vestigial threads at the lower sector.

I have no idea how far we actually need to shift the holes at the moment, but I hope to by the end of the evening. Given the difference between the 1.7 and 1.8 rockers is in the geometry between the pivot and the pushrod seat, this shift will only serve to correct any shift in pushrod seat resulting from the change from 1.7 to 1.8 rockers, so we are no worried about pushrod clearance in the guide holes between the rocker and the lifter.

Thoughts?

Thanks. Brad.

You are way overthinking it.
I wouldnt shift the holes. I would buy the correct length pushrods. Dont forget you will need taller valve covers or spacers too in order to clear the taller valvetrain.
I just went thru this a few months ago. OEM pushrods too long, not enough thread engagement.
I used the ARP metric conversion studs and measured for correct (shorter) pushrods to go with the stainless roller rockers.
Pushrod lengths I needed were 7.900" and 8.800".
I also plugged and redrilled one bolt hole in each cylinder head to allow me to use conventional valve covers... so no need for spacers.



https://cimg3.ibsrv.net/gimg/www.off...2844cc8462.jpg
https://cimg2.ibsrv.net/gimg/www.off...11497423ab.jpg
https://cimg8.ibsrv.net/gimg/www.off...6b5c25a6c0.jpg

DragRacer,

I tend to do that....

Just so I understand correctly.... Are you suggesting that shorter pushrods are just part of the conversion to roller rockers? That the shorter pushrods will achieve proper rocker geometry? As I thought I understood it from the builder was that the rockers were in correct geometry with the OEM pushrods, just too tall, and the shorter pushrods were a compromise to correct for a culmination of geometries between valve angle and stud angle coming together, forcing the roller tip beyond center of the valve tips. No?

I still have the utmost of faith with the builder. I just think this is probably the first time he's done a roller rocker conversion on stock 496 heads. Probably not a lot of them out there that go to that effort without first upgrading heads. He initially intended to go the shorter pushrod length and explained it to me. I probably just misunderstood the process. My skill set and an incessant need to find a problem to fix, at it again. :picard1:

FYI, I've already got the valve cover spacers.

Thanks. Brad.

:picard1:

I think a call to Raylar with your credit card would be so much easier.

UnderPSI,

As I stated, I've spoken with Larry. I don't fault him for it, but all he wants to do is sell me parts I can't afford. He's obviously the GOAT on the 496 (and likely just about anything else internal combusion), but I'm on a path that I'm happy with, even if I keep stumbling over rocks and roots along the way, and he's not interested in helping me along that path. Plus.... We already have all the parts (shorter pushrods aside ATM), and Larry ain't gonna fly to Dayton to help me put them all together.

They guy I have building this engine is a really good builder. I'll post pics once we get the rockers installed with the proper pushrods and rocker geometry. This is literally the last hurdle before we start hanging all the peripherals. From there, it's jut a matter of getting the boat back up to him to drop it in. Then I'll have to sort out the exhaust modifications, mostly made necessary by the elimination of the SilentChoice diverters.

Thanks. Brad.

New cam or different rockers generally warrant new pushrods.

Rookie,

I’m gathering that. I guess I assumed the rockers would be designed to be drop-in replacements. When the builder first informed me that we needed shorter pushrods, he also mentioned that the roller tip was out to far on the valve tip. My mind went right to the 1.8 ratio rockers, I equated the problem with that and thought the builder was using the shorter rods to make them work. Now that I understand the difference in ratio is determined by the “rear” dimension of the rocker instead of the “front”, along with a better explanation from the builder and the guys here on OSO, the rest of the puzzle makes a lot more sense. I’m getting there. Ever…. So…. Slowly.

The builder has an adjustable pushrod and has worked out the pushrod length. He is sifting through his pile of parts to see if he’s got a set that will work. If that doesn’t work out, pushrods will be on order.

Thanks. Brad.

definatly too much thinking for me, since it sounds like chinese to me ! LOL !
But glad some ofyou know better than I do !

Jeff,

There's definitely a LOT more that goes into building an engine than buying the parts and assembling them. Not that I ever thought that was the case, but the extent to which that’s not the case is what has surprised me. I’m having a ball with the process, and the builder is having a ball watching the gears grind in my head, solving problems that aren’t really problems.

Thanks. Brad.