Setting up my 416" small block and I am now checking pushrod length. Factory 340 block, Hughes 1.6 rocker arms and Comp #8043 lifters. Cam is a Bullet solid roller with .665" gross lift on the intake lobe, lash is .016". Cam is degreed (108 installed at 104 or thereabouts). Springs are PAC 1238 which are 220# on the seat but I'm not sure what the open is. I am using a light checking spring for this procedure though. I have not checked piston to valve clearance yet but I will before I order the pushrods. I think it's fine anyway.

Sort of pulling my hair out with the length and I am looking for confirmation that I am seeing things right. Working on the intake only right now. When checking max valve lift, I included the lash so the net lift would be .649" which I hope is the correct way to do that part.

The thing that has me questioning what I am seeing is that the best results seem come from an existing Smith Bros. pushrod I used with a completely different set of heads (RHS/Indy) and a solid flat tappet cam. (same block though) Everything I have read leads me to think this would not work at all - the lifters are different, the cam is totally different, everything but that's neither her nor there. I've had these pushrods for several years and don't recall the exact length but I'm pretty certain they are shorter than the nominal 7.5". These existing pushrods are also 5/16" and with the current springs I'm going to order a set of 11/32" which is the largest diameter that will fit my heads. Most likely going to order from Manton.

Please note the yellow tape in the pics is to prevent the indicator plunger from marring the Ti retainer and help keep it from slipping as there is no real flat surface. In any event, here's what I have observed so far;
[img]https://photos.app.goo.gl/qYYgTbB6cP1HVX7o6[/img]

#1 - the valve tip sweep pattern seems good to me. I am basing this on the idea that it should be as narrow as possible and shaded toward the intake side which it is. I've tried a longer length with an adjustable length checker but it makes the pattern much wider and more centered on the valve tip which means the roller is sweeping out farther as it goes down. The pattern in the pic is about. 085" wide. The longer length creates a swipe of about .120" give or take.
[img]https://photos.app.goo.gl/m3MgmHqEVUf8rqa96[/img]

#2 - at "half lift", (approx. .3245" or .649"/2) the pushrod is pretty much in line with the adjuster screw which I believe is what you want. It's hard to tell if it's at a 90º angle to the roller but it looks pretty close. Is that what I am looking for?
[img]https://photos.app.goo.gl/qzKtDGskTM2osSMGA[/img]

#3 - per what the dial indicator reads, the max valve lift I seem to be getting with this particular length pushrod is .641-.642" so if the lash is correct I'm losing around .007" lift. I presume this is probably fine and when running it wouldn't make much if any difference. I've read on here and elsewhere I should expect to be losing at least .020" lift due deflection and to the 59º lifter bore angle.
[img]https://photos.app.goo.gl/umPSEb8rYmhZDAob6[/img]

#4 - when I try to use a longer pushrod length, the rocker shaft won't physically seat in the pedestals nor can I get lash without turning the adjuster almost all the way up and the pushrod cup is almost touching the rocker. This to me indicates I'm in the ballpark with the shorter one in terms of obvious physical limitations - I don't believe the cup should be that far up and the adjuster should have some amount protruding down to be able to adjust it either way. I tried shimming the shaft to a couple different heights ( Hughes .020" and .040" shims) but again, the valve tip sweep pattern with the longer length was much wider and pretty much centered in the valve tip.
With the shorter length rod, there are about 1-2 threads showing.
[img]https://photos.app.goo.gl/zKZQB8hUy3YphyE56[/img]

#5 - I have another 340 that also had a solid roller with Morel lifters. I didn't compare the heights of the two lifters but that pushrod is even shorter than what I am measuring here and by a lot. This sort of confirms that pushrods in a 59º block with a solid roller might very well require a shorter pushrod but I'm not sure if that holds water or not.

Here's the angle at full lift.
[img]https://photos.app.goo.gl/QsoK2NMA8jdLRYGN7[/img]

All that said, my main question is whether I'm doing this right and the reasoning is sound. If I'm wrong on any of this, please let me know how and what I need to do to get the correct length. hopefully the pics show up but if they don't just click on the links and they will take you to my Google album. Thanks for any input.

- Greg

I think i run that same Bullet cam it's .016I/.018E

You know I always try to simplify things so just using "street math" on aluminum heads,

My adjusters are 20 threads per inch so each full turn is.050", So I crank the opposing valve all the way down (IC,EO and IO, EC) to full lift and set my rocker to zero lash on the base circle and mark the adjuster screw at 2:00,

Then I back it off until I get the mark to 12:00 (1/6 of a turn) which corresponds to ~.080 at the pushrod which (assuming 1.5" would correlate to .0125 at the valve), but with a small blocks geometry the true ratio (at best) is 1.45 (probably closer to 1.4) so that's right around .018" HOT and that always comes up right on feeler gauge at the valve, and when I tighten it I can see the 12:00 mark so I know I'm good.

Mopar 59's have horrible geometry to begin with and (IMO) it only makes it worse when you have 2 to 3 threads showing below the rocker. my logic is the further away from the fulcrum point the more the side loading and again, the 59's are already pretty bad geometry to start with so tighter is probably better than looser.

FWIW I like to run the cup type rocker adjusters and use conventional ball -ball or tapered end Comp pushrods as opposed to a cup type pushrod.

I also run the BAM lifters which are really light and they allow for a fairly long straight pushrod as compared to some of the longer body Morels.

The advantage to using a cup screw is you don't have to worry about a pushrod cup digging into the rocker from underneath if you run the threads close.

There's a lot of differing opinions but this way has always worked for me.

Thanks. I've thought about switching to cup adjusters for the reason you stated. It became pretty obvious I might need them when I made the checking pushrod longer. The adjuster had to go pretty far up into the rocker body to get any lash at all and by that point the cup hits the rocker like you said.

Is having two adjuster threads showing really going to cause problems? It seems OK to me but that's why I'm asking. I still have plenty of adjustment either way.

Regardless of the adjuster threads, the rest of my observations make it seem like I don't need to shim the shafts since the valve tip pattern looked better without them. And again, the pushrod at half lift was straight in line with the adjuster without shims. I do think my rocker ratio is a little better than 1.45. I don't think it's actually 1.6 either but it's at least 1.55.

I will try your method though and see what I come up with.