PRW 1.6 rockers on J heads 360 Mopar pushrod clearances?

[67cuda360]

I have done a bunch of reading on the forum regarding the use of 1.5 vs 1.6 ratio roller rockers and see some members advice to stay with the 1.5 since the 1.6 may cause issues on already higher lift cams.

My mechanical/solid lifter cam specs are pretty mild and I can get the PRW 1.6 ratio a fair bit cheaper than the stock 1.5 PRW at the moment. Current lift as measured with the 273 rockers I have currently on the car, is .410/.425 with dial indicator on valve spring top, so adding the .020 - .030 lift with the 1.6 ratio is probably not over the limit of the Mopar performance springs (Looks to be 1.497” OD MP valve springs (single with damper) P4120249 I think rated at .430 - .500 lift).

Main concern is the pushrods to head clearance I assume? Anyone have any experience with the 1.6 ratio PRW on J heads? Hoping to change to Promaxx 171 heads in the year or so as well.

I know I should contact Mike at B3 racing but don't want to waste his time with basic questions LOL, so trying to get educated here first before calling him.

 

[Earlie A]

Here's PRW 1.6 rockers on a stock J head sitting on a 340 block with a stock 340 cam. I rotated the cam 360 degrees and there are no clearance issues with a 5/16 pushrod. 3/8 pushrod would still be OK on my mock-up.

That being said, 1.6 vs 1.5 rockers are a 7% increase in lift, a 14% increase in valve side system velocity, a potential 21% increase in acceleration and a potential 29% increase in jerk. Are the springs up to the task?

 

[RustyRatRod]

I have done a bunch of reading on the forum regarding the use of 1.5 vs 1.6 ratio roller rockers and see some members advice to stay with the 1.5 since the 1.6 may cause issues on already higher lift cams.

My mechanical/solid lifter cam specs are pretty mild and I can get the PRW 1.6 ratio a fair bit cheaper than the stock 1.5 PRW at the moment. Current lift as measured with the 273 rockers I have currently on the car, is .410/.425 with dial indicator on valve spring top, so adding the .020 - .030 lift with the 1.6 ratio is probably not over the limit of the Mopar performance springs (Looks to be 1.497” OD MP valve springs (single with damper) P4120249 I think rated at .430 - .500 lift).

Main concern is the pushrods to head clearance I assume? Anyone have any experience with the 1.6 ratio PRW on J heads? Hoping to change to Promaxx 171 heads in the year or so as well.

I know I should contact Mike at B3 racing but don't want to waste his time with basic questions LOL, so trying to get educated here first before calling him.

Mike would probably tell you to properly relocate the rocker shafts and potential pushrod interference would no longer be an issue. All you have to do to see if it's out is take ONE measurement that he asks for ONE. I don't know what's a waste of time about that? He's glad to do it. He helped me get the shaft location on my slant 6 head just right.

 

[gzig5]

Hoping to change to Promaxx 171 heads in the year or so as well.

I have a set of ProMaxx 171 heads and my PRW 1.6 rockers had interference with the valve spring retainer. The rocker needs to to be raised and/or moved back to clear the stock retainer. I didn't want to grind on the rockers so we subbed in 273 rockers temporarily. Now mine are an older design of the PRW rocker. I guess they made a design change in recent years. @Earlie A had a post a while back that showed the difference. Don't know of the new design would fit better on the PM head or not. I've already done the preliminary work with B3 to get a relocation kit, just haven't pulled the trigger yet.

 

[Earlie A]

The new style PRW rockers will work on the ProMaxx, Speedmaster and Edelbrock heads with no clearance issues.

 

[George Jets]

Just an interesting comparison between the J Heads and the 318 roller cam engine 302 heads.

Factory roller cam heads have the pushrod holes opened up quite large for added clearance.

Kind of makes a person wonder about the 302 headed 318s with putting the 1.6 roller rocker upgrade on them?

Or how much you can hog out the J Head pushrod holes to gain the extra clearance?


.

 

[67cuda360]

WOW, great info. Thanks for mocking them up on your 340 with j heads Earlie A, really appreciate it.

 

[CrowkillerDC]

"The new style PRW rockers will work on the ProMaxx, Speedmaster and Edelbrock heads with no clearance issues."

Since they work with the above listed heads, I am going to assume they will work the new heads AFR dropped. I will check them as well though. Thanks

 

[Earlie A]

"The new style PRW rockers will work on the ProMaxx, Speedmaster and Edelbrock heads with no clearance issues."

Since they work with the above listed heads, I am going to assume they will work the new heads AFR dropped. I will check them as well though. Thanks

Although I have not had the PRW rockers on the AFR, I think that would be correct. I have an AFR head beside me right now. It is almost a direct copy of the ProMaxx. Deck to rocker stand height is within a couple of thousandths between the two.

 

[CrowkillerDC]

Thank You Earlie A, I appreciate the update. Have not checked on reviews on the heads themselves yet?

 

[Earlie A]

Thank You Earlie A, I appreciate the update. Have not checked on reviews on the heads themselves yet?

It’s as good a casting as any of the imports. The valve job is a little nicer than the others and flow is a touch higher.

 

[CrowkillerDC]

That is good to hear. I will get them bare anyway and put the Ferrea 6000 series valves and beehives springs on them anyway. This one is just getting a small cam and getting the car running motor.

 

[Earlie A]

That is good to hear. I will get them bare anyway and put the Ferrea 6000 series valves and beehives springs on them anyway. This one is just getting a small cam and getting the car running motor.

Good choice on the valves. Excellent choice.