Q: I've heard alot about using chevy inline six rocker arms for a cheap performance gain, what is this? How hard is it to do?
A: To do this with no additional parts, you need pedestal mount rockers and 3/8" studs (which engines can these be found in? '85 for the pedestal mount rockers, what 'bout the studs?) (what is needed to do this for an EFI head is below) Basically, using rockers from any 192/250/292 cubic inch chevy inline six (go to the store and ask for rockers for a '75 Chevy C-10 with a 250 I6),
broncr wrote:IF you have pedastal mount rockers AND 3/8" studs, this is a good, CHEAP shortcut. Unless you have a very high lift cam (in which case you MIGHT encounter problems), you can increase your rocker ratio from 1.6 to 1.7, for about $30 -$40. REMEMBER, Mr1ford said he did this swap with a .487/.462 lift cam - in his opening post.
ALL it involves is replacing the stock, pedastal style rocker with the chebby one, and using a lock nut to properly adjust the valve clearance. I ended up double-nutting ALL of the studs, as one lock nut had lost it's bite.
I think most any cam would provide more lift/duration, but it would take another $70 to $100+(for the cam) AND significantly more time. I did the rocker swap & readjusted the valve train in a bit over an hour.
IIRC, the lift for the stock cam is .400. By switching to the chebby 1.7, it should now be .425. Not a BIG deal but, as mentioned earlier, cheap, quick and effective.
Thanks again, Mr1ford
80broncoman wrote:A pedestal mount 300 head can use stud mount rockers if you use a pushrod guidplate conversion kit. I have intsalled it on my 90 cyl head and it all works just fine. Crane part number 36655-16 will give you 3/8 studs and guideplate for 5/16 pushrods. If you go this route hardened pushrods are not required becuse the kit has nylon inserts in the guidplates. I had to mix a couple of kits on mine cause I needed 7/16 studs for BBC rockers I already had. It is best for long life of the nylon inserts if you polish the pushrods to make sure there are no burrs on them. This is easy to do in a drill.
This conversion kit will also make your valvtrain adjustable.
broncr wrote:broncr wrote:...the link to the post on the Isky guideplates for our 300's?...
It took a while...(& courtesy of Tetraruby300 - )
www.iskycams.com/category_template.php? ... ory_id=167
Note the fine print on the larger pic's -" picture may not exactly match actual product" - they all show a SET of adjustable guideplates.
originating thread can be found here
more relevant info can be found over here
brocr wrote:Q: what screw in stud sizes should I consider, and why?
SuperMag wrote:Specifically, Big Block Chevrolet 7/16" studs. The shaft is 7/16", but the part that screws into the head is 3/8", thus enabling you to use the existing 3/8" hole. Helps in keeping the price down...
Q: Which heads have provisions that allow a direct bolt on of Chebby rockers?
82F100SWB wrote:This I think might be 84 and older with stud mount rockers, if there is any that allows it to be a direct bolt on, I seem to recall that there isn't.
Q: which rockers can i use for my BB6?
StrangeRanger wrote:SBF rockers will not fit a 300.
GMC I6 rockers will fit
BBC rockers can be made to fit
385 series rockers (429/460) can allegedly be made to fit, there has been some dispute.
Q: what was the year of the head change over to pedastal mount rockers
A: 1985 was the first year for pedistal mount rockers
Courtesy of a PM by Other Evan