Even-ing up the mixture and other thoughts

[Area 51%]

Do you have the 1/4in spacers installed under the manifolds? The Great Plains units allow plug removal without the spacers.

[Bryan Cotton]

I have spacers.

[GraemeSmith]

Well I'm not thinking much good about these Great Plains inlet manifolds. The laser cut spacers are gorgeous. The castings are beyond rough and the machining of the bolt holes is off. They would be going back except that I was planning on porting and polishing them anyway. But these are not remotely ready for prime time out the box. Dimensionally the left and right side are quite different.

Now if these were marked "rough castings require finishing" then it would be OK. But they are sorta machined and sold as ready to go.

I'll let you know what GP say.

[bvolcko38]

Agreed, not very pretty, but the proof is in the pudding. Temps will become much more even front to back.

[Bryan Cotton]

It would be interesting to see how they run out of the box vs after cleanup.

[Area 51%]

Wow! Their quality control has slipped a few notches since I got mine.

[GraemeSmith]

Great Plains response on the quality of the inlet manifolds was a little disappointing. Basically "Well if you had said you wanted them polished - we could have". Which was not really my point. They should be at least somewhat usable as supplied. Here one cleaned up and ported to gasket size and polished inside (and out).

Great Plains Inlet - dimensioned, ported and polished.

[GraemeSmith]

Now to a head. I ordered a "spare" from the factory. So I could have it ready to go. They set an EMPI with the second plug drilled.

This head is SUBSTANTIALLY better than the last EMPI one supplied to the builder.

Cooling fins are evenly cast - no need to file overlaps to get airflow.

Inlet ports are smooth enough to not really need a polish.

Exhaust ports have very minor casting slag. You could let these go as it.

Still I did polish the ports anyways - all polished up in about 30 mins. Nice and smooth.

That said - one of the plugs drilling left small ends of fine aluminum (red circle) that I don't fancy having create a point hot spot with risk of detonation - and I have filed this off.

And the head was not COMPLETELY clean. There was still machining dust and small chips in the head. So while I will have to clean it because I polished the inlets - even if I was not polishing ports - I would still drop the valves and wash the whole head out thoroughly before use. Good excuse to make sure the valves are lapped in correctly from the get go anyway.

Long and the short. This head is MUCH better than the previous supplied to the builder. But it still needs some work before use.