Here's the deal. I have a Super Duty head getting prepped to go into my Indy. I believe it's already setup to use 7/16" studs (I'll go measure and make sure tomorrow). I've been looking at 1.7:1 big block chevy rockers. These will work, won't they?
Thanks in advance, Nate
Posts: 1952 From: Red Deer, Alberta, Canada Registered: Mar 2003
Donk, the place I got my head from has another one up for sale. I can PM you the details if you want!
EDIT: T-top, how would you rate the quality of those Crane rockers? I can't be using something that will be shedding chunks of aluminum into my engine. I've been looking at the Harland Sharp rockers also...
[This message has been edited by FastIndyFiero (edited 12-30-2003).]
Yes 1.7:1 ratio will work . The stock head uses 1.75:1 ratio. If you increase the intake ratio or decress the exhaust ratio you will incress torque. Please check for the recomended ratio for the SD head. It may be the same as stock. Especially if the rest of the block and componants are stock. Also longer push rods may be nessesary.
You have a head the "breathes" wonderfully. Don't cramp it's style with the wrong ratio rockers. Frank
I've had the Crane rockers installed since July with no problems. As Frank says, the stock ratio is 1.75:1, so if you go with the 1.7:1 rockers you will be loosing a little lift at the valves if you keep the same camshaft. I am using a higher lift camshaft with my 1.7:1 rockers. The SD build ups in the Pontiac Performance Plus magazines used 1.55:1 & 1.6:1 rockers with high lift camshafts.
[This message has been edited by T-top Fiero (edited 12-30-2003).]
When I converted to the roller rockers I needed a longer pushrod. The stock length for the '84 2.5 is 8.976". After using an adjustable pushrod length checker I found that I needed a pushrod of around 9.2" for the roller rockers.
Dec 31st, 2003
Posts: 2541 From: Wichita, KS Registered: Aug 2002
The pushrod length info in the Haynes manual is wrong. I saw that too, but after looking at the specs in the factory service manual and actually measuring one the 8.976" listed in the factory manual is correct. I have all the Pontiac Performance Plus magazines, but have no way to scan them. If you need any info just let me know.