My neighbor has an ASC McLaren fox-body Mustang with a 5.0 in it. He's a retired guy & definitely a waxer/cruiser, not a racer.
A couple weeks ago he was driving through town when the car made a pop & started running like crap. After troubleshooting & dissasembly he found one of the pushrods punctured a rocker. I was telling a friend about this & he told me that's pretty common with a hot cam.
In the mean time my neighbor & his son(a Mustang drag racer) decided to instal some roller-rockers while it was apart - 1.72 ratio SVO E351's vs. stock 1.62. He said that it's firing with the valves open, even after shimming the rockers. He put stock rockers in & it runs fine.
The guy he bought the car from said it has a
303f cam, but his son keeps telling him it
sounds stock.
Any ideas why the roller rockers aren't working? This is all obscure caveman tech to me. Lol!
I asked him about that & he'd never heard of having different length pushrods. Think it's that simple?
oldtin
New Reader
8/3/09 9:23 p.m.
What year motor? - clearances are really close with an f cam - 86s have flat top pistons - need mods for most cams - 85 and 87 & up have valve reliefs. Roller rockers will increase the lift of the cam - leaving even tighter clearances. That's all I got from my cave.
Opus
Dork
8/3/09 11:37 p.m.
RossD wrote:
wrong length push rods?
351 pushrods are longer than 302. If he used the 351s that came with the rockers, they were wrong.
Thanks guys, I'll let him know tonight!
Running 1.72s with an F303 cam would give you .550" lift. Bad news for both the springs and valves.
The McLaren came with a B303 cam from the factory. If it still has this cam then with 1.72s it would have .516 lift.
http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=2029
You need to use the correct pushrods for the cam, rockers and engine. Personally I would replace the springs while you are in there. Something tells me they are the real culprit in wasting a rocker arm.
