Valvetrain choices

[SixFoFalcon]

I'm getting together a list of the valvetrain components I plan on using when I build the US250-Crossflow hybrid. Here are my preliminary selections:

*Crow Cams camshaft part #14776 or 14892 (hot but streetable)
*Speed Pro lifters, Summit catalog part #SLP-HT-900
*Comp Cams Magnum Steel Roller Tip Rockers, 1.72 ratio, Summit catalog part #CCA-1411-1

I will be using stock valves. The pushrods will be OEM parts for the GM 3.8L (non-roller) as spec'ed out on the "200 Crossflow" page.

I also considered Rhoads lifters (Summit catalog part #RHL-RL9008). They supposedly decrease valve lift at low rpms for better low-end power and overall economy. The problem is, when I do a clearance test by hand-turning the crank, I won't be getting full lift on the valves. I'd have to crank the engine at 2000rpms or so to see full valve lift.

Also, I'm not sure what to do about valve springs and retainers, yet. Crow Cams sells the "parts kit," but that includes a timing set, which I don't know if I can use on the US200 or US250. Any ideas?

Also, does anyone know of an online source for Crow Cams products, so I can price out the cams and other stuff? So far, I'll I've been able to find is the Crow Cams catalog, which has no prices.

 

[MustangSix]

The Buick 3.8 pushrods will be too short for a 250 and because the US 250 is about .080" taller than an Oz 250, the Oz pushrods won't fit either. You'll probably have to have them cu$tom made. After you get the head installed, measure and see if any other engine pushrods come close.

When you are in the process of blueprinting the engine you should use a solid lifter to check piston to valve clearance. This has nothing to do with how a Rhodes lifter works, but with the way a hydraulic lifter will collapse for preload. This means pulling the head multiple times, but blueprinting is a task that requires multiple assembly/reassembly. It's also the time to degree the cam, so get two of them.

Retainers from a small block ford will fit, but the keepers are multi groove items that are unique, so don't lose any.

 

[addo]

Pushrods won't be too dear, but that's if you're used to paying for stuff as we do down here. See if you can get a length checking tool. They (Crow) do recommend antipump lifters for a lot of their higher performance cams.

Crow don't do online; if you find anyone chances are it'll be on a high margin basis. Email them for RRP and get a parts store to mail it over. The timing set won't fit because of crank schnoz sizing, I believe.

Buy the Crow distributor gear! You'll need it.

Adam.

 

[Anonymous]

Couldn't you fit a set of lash caps to take up the 80#?

 

[Anonymous]

Depending on what you are trying to achieve there are options to play with rocker arm ratios also.

I have not done this myself and would be keen to hear from someone who has?

The Ford 250 crossflow has harmonic problems with the valvetrain and shortening the rocker ratio by using Chev or Holden rockers is supposed to help with this. Obviously a chev or Holden cam profile needs to be selected to suit and ground onto the Ford Billet also.