Stock Rocker Ratio?

JMSII

I knew this once, but I am getting old and feeble-minded! Anybody know the ratio for stock 401 rockers? (Bridged) Thanks!

BREK

I think all amc's are 1.6?

amundaza

Yes, all AMC V8's are 1.6 ratio. I have read of someone installing Harland Sharp 1.65 PONTIAC rockers ... anyone else heard of this? Sincerely, GregTaylor Oxford, MI 1989 Grand Wagoneer : Water/Hydrogen Injection 360-V8. 4.5" lift 31" BFG A/T's. Killer32 front bumper

ol' school power

amundaza wrote
Yes, all AMC V8's are 1.6 ratio.

I have read of someone installing Harland Sharp 1.65 PONTIAC rockers ... anyone else heard of this?

Sincerely,
GregTaylor
Oxford, MI
1989 Grand Wagoneer : Water/Hydrogen Injection 360-V8. 4.5" lift 31" BFG A/T's. Killer32 front bumper

I've been using them on my Ambassador for several years.

amundaza

ol' school power wrote
I've been using them on my Ambassador for several years.

Was there anything special you needed to do to install them? Do you remember the Pontiac P/N's you installed? Lastly, do you like them ... how do they perform for you?

I'm also wondering if there might be any special benefit to running a 1.6 on the exhaust and a 1.65 on the intake, or vice versa, of someone is wanting to custom tailor head flow for optimum power.

Sincerely,
GregTaylor
Oxford, MI
1989 Grand Wagoneer : Water/Hydrogen Injection 360-V8. 4.5" lift 31" BFG A/T's. Killer32 front bumper

ol' school power

Greg I don't remember the p/n. They were just off the shelf Harland Sharp Pontiac. You have to switch the studs to 7/16 stem instead of the AMC 3/8" top. Never tried the cam without them. It was spec'd at .490 lift with a stock ratio so I wanted to bump it up a bit. In mine, I had to use a longer pushrod probably due to how the cam was ground. for anyone on a budget with early heads, you can use stock steel replacements for the Pontiac Ram Air IV engine (1.65) also if you use the stock 3/8 AMC rocker ball. You can also get 1.7's, but the only problem is that the pushrod slots in the heads are a little inconsistent and may need to be machined a little further inboard.

jeepsr4ever

The whole reason for changing rocker ratios like that is to get that 92% or close to it for the intake/exhaust efficiency ratio.

fifesjeep

I have the 1.7:1 Harland Sharp Rollers on my 360...
S4004-77 is 1.7:1 and 7/16" stud... the S4004 is the 1.6:1 and 3/8" stud...
If you bump up to the 1.65's and the 1.7's with the 7/16" stud the bottom of the rocker needs to be relieved...

jeepsr4ever

No, they actually relieve those for the factory stud shoulders otherwise they would share the same part number as the Ford small block rockers.

fifesjeep

jeepsr4ever wrote
No, they actually relieve those for the factory stud shoulders otherwise they would share the same part number as the Ford small block rockers.

Hmmm, I don't see how they would be relieved for the factory stud shoulders when these and the new studs are 7/16" and the bosses need to be machined in-order to achieve the proper geometry. Do the 3/8" studs and 7/16" studs use the same shoulders? I'm having a serious mental block (Brain fart)... :oops:

jeepsr4ever

Hmm good point! You got me! The relief is for the hex on the stud? :idea: #-o

ol' school power

Bottleneck studs