BBC Valve Train Geometry??

[kc0000]

did I get this right? tight sweep though a bit off center
Dart Pro-1 310, 454 Gen VI, GM lifters with comp cams stainless 1:73 roller rockers and push rods +5/16 over stock.
Thanks, KC
http://www.boatbays.com/images/DSC00851_70.JPG

[Fiat48]

Good Photography. Narrowest pattern you can get in the center of the valve stem is best. Try a shorter pushrod and check again.

[kc0000]

any shorter push rod send the pattern wider without getting much closer to center, longer pushrod really gets closer to the edge of the valve stem. seems the valve is a touch long or short. either way, I'm looking at a 5400rpm rev-limiter and a max lift of .540, I hope it will be fine.
Thanks, KC

[gg10]

try ford rocker arm pn1130-16,it has a shorter stud to roller tip leg,they have worked good for me on dartpro1 heads

[DetroitJim]

KC, I had the same problem, I tried every length there is. I live 5 miles from Dart, went over and talked to them. Could not get a straight answer. I ended up with exhaust pushrods .150 long and intake pushrods stock length. This puts the rocker lower on the stud than looks right, but it gave the best sweep pattern and was the most centered at max lift. I have had no problems at 6400 rpm 130 lbs., .570 lift. At your lift and rpm you wil be fine. My theory on this is that the longer valves move the valve tip closer to the stud axis and pushrod length cannot change this. A longer pushrod probably gives the best lift profile throughout the travel, but ends up too far outboard for me. I want to avoid guide wear and if less lift is the price then so be it. I am going to do a study this winter with 3 different cams, .570 to .700 lift and post the results.
DJ

[kc0000]

Thanks for the responses! Sounds like I'll leave it be and things will be fine. Onto other challenges! KC

[gg10]

If you use 250 long intake valves on the dart head the distance from center of stud to center of valve is less than with a stock length valve because the axis's are not parallel.I did alot of work on this with two engines,giving up correct valve train geometry could cost you lift at the valve plus premature guide wear. With help from Reed at Crowler cams I started to used Ford rocker arms on the dart head,they have a leg that is 1.554" verse the chevy at 1.610,this will move your pattern closer to valve center and let you run the correct length pushrods.I have used this setup on two engines with springs that are 185lb @ 1.970"seat & 470lb @ .630" lift, 5500 rpm,130hrs use,no guide wear problems.

[kc0000]

darn..... now what do I do with the BBC rockers I bought four months ago..... Ford parts in my ride, that will take time to get used to! Will I need to carry a Fix Or Repair Daily emergency tool kit????? :)
That is two votes for ford parts, you guys have more experience than me.... more money.... guna hurt....
:) KC

[wideopen545]

i need a set of roller rockers 1.7 if you have then
just thought i'd ask tim