[Skippy597]

Can anyone 100% confirm that speedmaster heads work wih 1.65 rockers?

[25stevem]

The first question that needs to be asked in terms of any head that had no clearance issues with 1.5 rockers being used is what is the base circle diameter and what is the lobe lift of the Cam your running?

The Cams base circle diameter and lobe lift greatly effects the angle of the push rod as does how tall the lifter may be in terms of its push rod cup.

The second question is will the spring pressure needed cause 5/16" push Rods to not be strong enough then making for the need to step up to bigger diameter push Rods.

The speedmaster heads being just a knock off of the Edelbrock heads should allow the use of .650". Lift by means of 1.65 rockers and 5/16" push Rods without dealing with clearance issues, this assumes that the push rod lenght if need be has been changed to attain the correct geometry for the 1.65 rockers.

Another factor that comes into play here in terms of push rod hole clearance issues is if the block or head have been decked.

If the heads are off and you want to get the set up done to not have to deal with any clearance issues down the road with other changes that may take place then drill all 8 holes out to 1/2" and sleeve the holes with 1/2" OD brass tubing and then your good to go .

If you sleeve it will also allow you to grind back the push rod bulge right up to the brass tube.

This should be done to any aftermarket head that is currently flowing over 300 cfm, or down the road will be doing such.

[slowbird]

Originally Posted by 25stevem

If the heads are off and you want to get the set up done to not have to deal with any clearance issues down the road with other changes that may take place then drill all 8 holes out to 1/2" and sleeve the holes with 1/2" OD brass tubing and then your good to go .

If you sleeve it will also allow you to grind back the push rod bulge right up to the brass tube.

This should be done to any aftermarket head that is currently flowing over 300 cfm, or down the road will be doing such.

That's just bad advice imo, by doing that you just limited the potential csa at the pushrod pinch and that area is already too small. Every little bit there matter!

[25stevem]

I think you mis-read what I posted in the above?

My suggestion will add to the CSA there by allowing you to have only the .030" wall thickness of the 1/2" OD brass tube.

In this photo of a iron D port head you can see in the left side Intake port how little intrusion is left when sleeving is done in this way.

[racegto65]

Got an out of the box set running 1.65 rockers with a cam with .571 int. and .576 ex lift.

[Skippy597]

Originally Posted by racegto65

Got an out of the box set running 1.65 rockers with a cam with .571 int. and .576 ex lift.

Thank you. Not a big deal if I had to slit them just making a pro cons list.

[blueghoast]

Someone on here made a tool to enlarge the top of the PR-hole
for 1:65 rockers. Don't remember who, it was a wile back

GT

[25stevem]

The tool has been around longer then there have been Pontiac V8s!
It’s called a die grinder and a Aluminum Burr😊

[Skip Fix]

Paul Spotts had a tool for iron heads.

[mysticmissle]

We are over 600 lift w 1.65 rockers out of the box hydraulic roller speed masters , no issues to date been running since February. Approx 400 miles on build. No track time yet

[74Grandville]

i'm running a Crower 60311 and 1.65 scorpion rockers. I needed to clearance the pushrod holes to ensure there was adequate clearance.

[Skippy597]

Originally Posted by 74Grandville

i'm running a Crower 60311 and 1.65 scorpion rockers. I needed to clearance the pushrod holes to ensure there was adequate clearance.

Thank you, I figured I might as well do it either way to be on the safe side.

[25stevem]

Also keep in mind that if your open spring pressure gets to over 600 you must run a 3/8” push rod with a .135” wall thickness if you don’t want to end up with S shaped push rods at some point in time, no less loosing the lift your shooting for due to unwanted flex.

[tom s]

I have one of Pauls tools,will run it through mine just for grins.Tom

[GoatZillaRacing]

They work fine out of the box with 1.65 ratio rockers. Had them well over .700 lift.

[chiefbigb]

I'm test fitting some on a 408. Will share the results.

[chiefbigb]

On my set 1.5 rockers are to close to the intake side. 1.65 is fine.