SBF 1.6 Rockers on Pontiac no clearance issues?
 

An old timer "Pontiac Guy" told me that the SBF rockers in 1.6 ratio will work on non-clearanced Pontiac heads so long as the pushrods are 5/16" and not 3/8" RAIV and lift does not exceed .550" with them in place.

Like they say, trust but verify. Any truth to that?

Yes here with some:

https://forums.maxperformanceinc.com...34#post3577934

I have "small-block Ford" roller rockers on an Olds 455. They "fit" and "work", but because the valve angles are different (Olds has 7 degree valve angle, SBF has...20 degree valves (?)) the geometry isn't perfect.

I'm thinking that Pontiac is closer to SBF than Olds is, but I haven't confirmed that.

As always, verify the width of the contact pattern, and the contact pattern's placement on the valve tip. Wouldn't hurt to verify the actual valve lift vs. the cam-card valve lift, too.

When I put Comp Cams roller-tip 1.6 rockers on my Father-In-Law's modified but mild-cam Pontiac 455, I had to grind the livin' pizz out of the pushrod holes to get clearance. The "book" said that the tops of the pushrod holes needed some grinding, but I had to grind all the way down.

Response was mixed but most said they still had to enlarge the pushrod holes using either Ford or Pontiac rockers above the 1.5 ratio. That's what I am trying to avoid.

I guess I will have to buy from a source with a "liberal return policy" and just try them out.

Try adding a lash cap and it may then clear the push rod hole depending on the lenght of the valves you have in the heads.

I forget if the 4.980" stock valve lenght of the late low comp heads get the needed clearance with a lash added, plus it's a easy try if you can borrow a cap from someone , or even just stuff.050"worth of feeler gauge in there to see how things change.

I have a Crower 1.6 SBF that is way too short to fit.

Paul C would be the guy to ask. He has built several Pontiacs for customers using the Ford rockers and has explained many times what is needed to make it work. There was a reason he liked going this route better but I can't remember why.

[QUOTE=Schurkey;6266247]I have "small-block Ford" roller rockers on an Olds 455. They "fit" and "work", but because the valve angles are different (Olds has 7 degree valve angle, SBF has...20 degree valves (?)) the geometry isn't perfect.

Same here. "Close enough" for a mild street engine.

Less than optimum, like Kennedy's trip thru Dallas.

Lol!
Less then optimum=Yamamoto's flight to the Solomons!

[QUOTE=Mr Anonymous;6266384]
So you're saying that the rockers could cause a hole in my head?
Sorry, I couldn't resist the temptation.

The Neck first, then skull!

I can send you my Crower for a mock up. I bought a bunch of singles of various types to see what would work. For those not wanting to cut pusrod holes in head(ie already assembled) look at Crower's 0.090 offset BBC rockers with a lashcap and short pushrod.

I appreciate the offer Skip, but Crowers are above my pay grade! I m looking into the 1.6's that FBPaul has on eBay as a candidate. They're abut $150 a set

So your 6X-8 heads are already on the motor?

If not, it’s a real simple 1/2 hour long job to just drill out the 8 intake push rod holes with a 1/2” drill bit to get a good amount of added clearance.
You need a decent size drill motor to power the 1/2” bit though!

I have 1.7 BBC on my 468

This may not be helpful info as this is not related to stock heads, but I tried Comp Ultra Magnum SBF 1.6 rockers on my 463 build using KRE D ports and the first version of the Stump Puller cam.

Spent a lot of time with an adjustable pushrod trying to get a decent pattern somewhere near the centre of the valve, and the only way to get the pattern halfass decent (width was "OK" but always too far to edge of valve) was with a pushrod length wayyy longer than ideal. The rocker geometry was just all wrong in this application using these Comp rockers. I have no idea if they are much different than other SBF rockers, but this was a waste of time and $$ for me.

Ended up going with 1.65 Crower Enduros and everything fell into place with what was a "normal" pushrod length for KRE's and the valve length they used. Pattern was nice and narrow, just slightly off centre.

Yes they are. I have been running the same 1.52 CompCams Magnum Rockers that came with the car (motor out and disassembled) when I bought it back in the late 80's. I have rebuilt the motor 2x since then and re-used the rockers after radiusing and smoothing the notches. Last time the heads were off was way before people were savvy about enlarging the pushrod holes.

I know the rockers aren't going to fail anytime soon based on experience, but I want to replace them with full rollers anyway and up the ratio via a bolt-on. If I take the heads off, you know what happens next ... credit card comes out and aluminum heads get purchased which I know I don't really need.