Skip to main content

Closed12 replies

Engine blahs

FM Former Member
Engine is about to go back together with new CB Performance CNC wedge-ports, S/S valves, CB dual valve springs, and CB titanium spring retainers. Valves were floating with the original build, sinking the seats slightly into the head castings and wreaking havoc on the Manley S/S valve seating surfaces. At least the valves weren't bouncing off the pistons.

Strange to have valve float (and probably bounce, too) - the Scat dual racing valve springs I furnished must have been from a bad batch as they were cryo'd, properly installed, and red line was kept at 6,000 RPM. I was going to increase the red line to 7,000 RPM at 2,000 miles but noticed the problem before I rolled up that much mileage.

Oh well, I'll try to get it together in time for Carlisle...
Original Post

Replies sorted oldest to newest

FM Former Member
Engine is about to go back together with new CB Performance CNC wedge-ports, S/S valves, CB dual valve springs, and CB titanium spring retainers. Valves were floating with the original build, sinking the seats slightly into the head castings and wreaking havoc on the Manley S/S valve seating surfaces. At least the valves weren't bouncing off the pistons.

Strange to have valve float (and probably bounce, too) - the Scat dual racing valve springs I furnished must have been from a bad batch as they were cryo'd, properly installed, and red line was kept at 6,000 RPM. I was going to increase the red line to 7,000 RPM at 2,000 miles but noticed the problem before I rolled up that much mileage.

Oh well, I'll try to get it together in time for Carlisle...
FM Former Member
David,

Maybe you can help me out with a ball park push rod length!

I have an FK8 cam in one of my new engines along with 1:4:1 Pauter rockers, and those same heads. What length did you cut you push rods down to in order to work with the high ratio rockers?

I just need something to start with, after than I can continue to "adjust" the length until the geometry is correct.

Thanks !

TC
FM Former Member
And THANKS from me, as well, George.

I have a dial indicator and an adjustable push rod. Off hand, would I need to do each individual rocker/push rod assembly as a separate entity, or would a single push rod measurement be sufficient and the remainder cut and assembled to the same specs.

If one is correct, would they all be the same length? Stock ones all seem to be, but I'm running nearly all non-VW factory parts, so there could be variances everywhere.

Any experience, any help?

Thanks,

TC
FM Former Member
TC, pushrod length should be such that at full lift the adjuster and pushrod are in a straight line through their centers. Measure with the adjuster lock nut set to allow maybe two turns of adjustment both ways (about centered on the adjuster) before you measure.

An imaginary line through the rocker arm "arms" should be more or less paralell to the gasket sealing surface of the head.

You'll need a dial indicator to determine max lift, and may need to shim the rocker mounts to get the "paralellism" and/or eliminate any rocker arm to spring retainer interference.
FM Former Member
TC, assuming the cast rocker mounting bosses in the heads are the same height from the cylinder mating surfaces (they may not be) and the cylinder shimming is about equal on each side of the engine to get equal deck heights, you probably should only have to measure one side.

If there seems to be variances in boss heights and/or cylinder shimming (for correct deck heights) measure both sides - if they're a lot different you may need to shim the rocker mounts a bit differently on one head so that same length PR's work on both sides.

I've seen engines with one length PR's on the 1-2 side and a slightly different length on the 3-4 side to get the right geometry spot-on, but that's usually not necesary for a street engine.
Post Content
Remove This Ad

Membership Required

We're sorry. You must be signed in to continue. Sign In or Register
×
Are you sure you want to remove from your Block List?
×
Loading...
×
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .
×
Link copied to your clipboard.
×

Access to this requires a premium membership.

Supporting Member

Please help keep us running!

Supporting members have donated about $4.00 a month ($49.00 US per year) paid annually.

  • Priority support
  • Removal of inter-page (between thread) advertisements.
  • Access to Build Manuals
  • Access to Knowledge Base
  • Access to Supporting Members events.
  • Access to Leveraged Group Buying from site Merchants.

AUTO RENEW: You membership will auto-renew after 12 months. If you prefer not to auto-renew, you can cancel your premium membership at any time and it will remain in effect until the end of the 12 months. To cancel, sign in at SpeedsterOwners.com and navigate to: (Your User Name)  > Premium Membership.

PLEASE NOTE: Your credit card will receive a charge from CROWDSTACK PAY, the payment processor, not SpeedsterOwners.com.

$49.00 per 12 Months (plus tax if applicable)
×