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Custom Rusch Motorsports P-90a head


BRAAP

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I'll throw into the mix that I just changed divisions at work, and no longer have access to the five-axis tracer machine back in Kentucky.

Originally the plan was to trace out a BCG head from JeffP's engine, since Nathan is not doing them any more, having the ability to five axis a port to exactly what it was before (within reason) on another head, or after a repair on the Bonneville car was the primary reason for this---but it would have given a nice model to reverse engineer what others are doing compared to one of the premier head porters in L-Engine History.

 

What I will do now is up in the air. I wanted to check the ports done by RS Okinawa back in the mid 80's and see how they compared, as they look very different, and obstensibly came from similar applications.

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Not much to update tonight. This last week and last weekend has been hectic so we fell behind again, (seems to be a common theme around here lately).

 

Any how Ian’s cylinder head has been surfaced top and bottom and being as my die grinder got away from me while working the port entrances and left “cutter tracks” across the intake/exhaust manifold mating surface, I surfaced that as well at no additional charge, (I love how the L-6 looks when all 3 surfaces have been cut and all the threaded holes have been tapped and chamfered…)

 

As for lash pads, .190, .180, .170, and .160 all worked well with this Rebello cam keeping the wipe pattern safely on the rocker arm. I chose the .170 pads as that cheated the wipe pattern slightly rearward from the middle without being real aggressive. Those lash pads are on order, and if they are in stock, (fingers crossed), your head could ship as early as Aug 28th, or sometime during that week.

 

I’ll have Chamber volumes Saturday and hopefully some updated pics of the CC’ing process as well as the clean surfaced head.

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no biggie man. i'll be sure to contact ya at some point in the next week

 

 

Silent,

 

Your custom N-47 head is in process as I mentioned previously and I will be posting pics of the progress within the next week or so.

 

 

BTW, how’s that new LS powered toy treating you? You may want to consider at least a little squeeze for the Z if you want it to be quicker than the new toy… At least wit the Z you’ll be able to steer with the throttle… YEE HAA….

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Ian,

Your head is finished and yes we did find you that piston stop, identical to the one pictured in “how to degree your cam” thread.

 

Being as your cam is a Rebello cam, the lash adjustment is checked at the valve, not under the cam lobe. Here is a picture of a modified .008” feeler gauge while I was “cold setting” your vale lash prior to bagging the cylinder head. If you don’t mind, I would like to use the pics I took of your head to update the “How to Degree your cam” thread referencing Rebellos lash adjustment procedure.

 

 

DSC_1225Large.jpg

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Excellent Paul. I will be on the phone very shortly to sort out whats needed to get this to the UK. Hopefully we can have a quick chat when I call.

 

No probs about using any images of my head/cam., I as others who read your input no doubt find it very helpful/informative.

Thank you.

 

Ian

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hey braap, my bro has told me that roughing the intake before fuel gose in keeps the gas from beeding on the surface. I guess from small vortecs. Not to rain on the parade.

 

Yes that is true. You aren’t raining on any parade here. As you stated, a slight texture on the port walls offers slight turbulence in the boundary layer along the port walls themselves keeping the fuel from falling OUT of suspension and accumulating on the port walls. For that reason, I do not polish the intake ports to a mirror finish. The finish is either 120 grit or 240 grit, sometimes bead blast finish just for that reason.

 

 

That is a 240 grit finish in Ians ports with a light buff using the scotchbrite buffing pad to give it that sheen.

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Is checking lash at the valve common practice for most aftermarket cams? I just installed a new Delta cam, but haven't adjusted anything or degreed the cam yet. By the way, their service is awsome, as are their prices.

 

Different lash measuring locations for specific cams is mentioned in the degreeing your cam FAQ linked here….

 

http://forums.hybridz.org/showthread.php?t=111523

 

 

If you are not sure where to take your lash measurement with a particular cam, just get in touch with the cam manufacturer/grinder and they will have the lash spec and where the lash needs to be measured at.

 

 

Hope that helps,

Paul

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That is a VERY nice L-6 indeed. One to be very proud of for sure. The chambers look VERY nice from a performance standpoint, and from an aesthetic stand point as well. I take it this is a true Bob Sharp engine?

 

 

As for that being a P-90 head… Hmmmm. That chamber looks more like a welded N-42 than a P-90. Notice the porosity around the intake seat, (definitely built up), and the shape of the spark bolt boss, ala N-42/N-47, (I doubt Mr. Sharp used the N-47)… I’m 99% sure that is no P-90.

 

The interior of the block is very pretty to look at. You can be sure there are no stress risers from sharp edges in that crank case, (not that the L-6 block suffers from crank case failures due to stress risers).

 

I LIKE IT!!! And who wouldn’t, it’s a Bob Sharp engine!?!?! :hail: Nuff said. :rockon:

 

BTW, OTM, as for your signature… :lmao:

 

Loudmouth Z: L40DETTTS, tripple T3/T4 turbos from turbonetics, M62 Supercharger, twin 3.5" exhaust, Dual Megasquirt, 12 1500cc injectors, 5LB 300mm flywheel, 10 disc clutch, Air-liquid intercooler the size of texas, tripple 60mm custom wastegates from HKS, 80mm custom HKS BOV,

Custom built transmission, one off rear end,

Just dyno'ed 1500hp

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