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See also: CCing
Overview
Quote by sagemanone:
Port and polish will yeild power gains and 3 or 5 angle valve grinds help also hand grinding the sharp lips in the valve pocket helps the flow into the combustion chamber. Any reputable high performance machine shop should be able to do any of the work to your head you ask them to do if you ask them for spacific items to be done. If they seem puzzled or can't answer ALL your questions real easily take your head and run the other way. Don't be discouraged and don't be afraid to try to be creative . I heard of guys cutting down L16 valves after modifying the ports and installing the matching seats in an A14 to get marvelous increases in flow .So let your pocket book and imagination guide you.
One other thing ,Look for the factory goodies like the GX option stuff that could be ordered like the GX duel SU intake ( Iam looking for one myself) And NISMO still has some neat stuff they sell right out of a catalog . Iam hoping to put a list togather that will be on My web page as to the sources for all the places for the parts we Datsun A/nuts need . I hope to Launch that web page soon and you will all be invited!!!
All Datsun A-series engines come from the factory with a 3-angle valve job. So certainly don't do anything less!
H89 (A14/A15 oval port) casting thickness
album
| Ports | Size (mm) | Exhaust | Raised | Note |
| round | 28 | ? * | no | 1971 A12 |
| round | 28 | ? | lowered | 1977 GFU |
| Oval - small | 28x30 | ? * | no | 1973 A13 |
| Oval - large | 28x34 | ? | no | Many A14s |
| Oval - GX | 30x34.5 | 27x29 | Yes | A12Gx (1971-1973) |
Quote by azza_bijan:
Go for the high comp. head (not dished out). These have 9.5:1 compression. A15s in AUS are mainly high comp Don't enlarge the ports matching to the inlet, they are already large enough. Enlarge around the exhaust valve area and out and get some cut down 1600 valves to fit. The exhaust porting hugely boosts better flow and power. If you are rich or race, do the inlets. I got my head done for $300AUS. Then get good manifolds (handmade steel inlets $200AUS are as cheap as new aluminiums but are port matched to the head and work heaps better).
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A14 oval port head cross profile:
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