![[Datsun 1200 encyclopedia]](/wiki/upload/wiki.png)
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| - | Stock valves for A12 engine are 35 mm intake, 29 mm exhaust. You can fit the A14-size 37mm inlet/30mm exhaust. And valves up to 40mm have been fitted for ultra high-RPM use. | + | Stock valves for A12 engine are 35 mm intake, 29 mm exhaust. You can fit the A14-size 37mm inlet/30mm exhaust. And valves up to 42mm have been fitted for ultra high-RPM use. |
| = Overview = | = Overview = | ||
| - | The stock A12 valves (35/29) are good for small-bore (1200cc) use below for up to 6000 RPM. For larger bore engines (or higher RPM) the 37/30 valves from an A14 are better. | + | The stock A12 valves (35/29) are good for small-bore (1200cc) use below for up to 6000 RPM. For larger bore engines -- or higher RPM -- the 37/30 valves from an A14 are better. |
| For racing at high RPMs, more power can be made with larger valves, but care must be taken for proper valve flow. | For racing at high RPMs, more power can be made with larger valves, but care must be taken for proper valve flow. | ||
| Line 10: | Line 10: | ||
| The 40s may require relief/flow notch in the side of the cylinder wall? | The 40s may require relief/flow notch in the side of the cylinder wall? | ||
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=20353 http://datsun1200.com/uploads/thumbs/20353.jpg] | + | {{AlbumH|20353}} {{AlbumH|20747}} {{AlbumH|700}} {{AlbumH|6691}} {{AlbumH|9027}} {{AlbumH|12142}} {{AlbumH|15324}} {{AlbumH|20264}} |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=20747 http://datsun1200.com/uploads/thumbs/20747.jpg] | + | |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=700 http://datsun1200.com/uploads/thumbs/700.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=6691 http://datsun1200.com/uploads/thumbs/6691.jpg] | + | <blockquote>[{{Post|87257}} COUP1200]: My A14 makes 140hp & its not EFI or turbo. I have twin 40mm webers, good extractors the head flowes 141hp. All your power gain is in the head big valves extencive amounts of porting good spark ... I dont run roller rockers & have not had a problem.you dont need to go to big with the cam mine about 74deg ... Mine makes power to 7500rpm. |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=9027 http://datsun1200.com/uploads/thumbs/9027.jpg] | + | |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=12142 http://datsun1200.com/uploads/thumbs/12142.jpg] | + | |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=15324 http://datsun1200.com/uploads/thumbs/15324.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=20264 http://datsun1200.com/uploads/thumbs/20264.jpg] | + | |
| - | + | ||
| - | <blockquote>[http://datsun1200.com/modules/newbb/viewtopic.php?post_id=87257#forumpost87257 COUP1200]: My A14 makes 140hp & its not EFI or turbo. I have twin 40mm webers, good extractors the head flowes 141hp. All your power gain is in the head big valves extencive amounts of porting good spark ... I dont run roller rockers & have not had a problem.you dont need to go to big with the cam mine about 74deg ... Mine makes power to 7500rpm. | + | |
| <br> | <br> | ||
| <br>[http://datsun1200.com/modules/myalbum/photo.php?lid=7240 feral]: COOPS 1200 SEDAN AFTER RUNNING A 2:11 AT PHILLIP ISLAND CIRCUIT ... The car sounded awesome and handled very well. In typical 1200 fashion showed alot of more exotic machinery including a Porsche 924 turbo and a lotus elite a clean pair of tailights :-) | <br>[http://datsun1200.com/modules/myalbum/photo.php?lid=7240 feral]: COOPS 1200 SEDAN AFTER RUNNING A 2:11 AT PHILLIP ISLAND CIRCUIT ... The car sounded awesome and handled very well. In typical 1200 fashion showed alot of more exotic machinery including a Porsche 924 turbo and a lotus elite a clean pair of tailights :-) | ||
| - | <br>[http://datsun1200.com/modules/myalbum/photo.php?lid=7240 http://datsun1200.com/uploads/thumbs/7240.jpg]</blockquote> | + | <br>{{Album|7240}}</blockquote> |
| = Feral = | = Feral = | ||
| Feral used 40mm steel Inlet valves, tuliped and swirl polished, with 35mm Exhausts steel polished. | Feral used 40mm steel Inlet valves, tuliped and swirl polished, with 35mm Exhausts steel polished. | ||
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=1501 http://datsun1200.com/uploads/thumbs/1501.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=1245 http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/album/th_1245.gif] [http://datsun1200.com/modules/myalbum/photo.php?lid=1498 http://datsun1200.com/uploads/thumbs/1498.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=1499 http://datsun1200.com/uploads/thumbs/1499.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=1500 http://datsun1200.com/uploads/thumbs/1500.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=1502 http://datsun1200.com/uploads/thumbs/1502.jpg] | + | {{Album|1501}} {{AlbumPhoto|1245|gif}} {{Album|1498}} {{Album|1499}} {{Album|1500}} {{Album|1502}} |
| And don't forget to dial in the camshaft timing | And don't forget to dial in the camshaft timing | ||
| - | <br>[http://datsun1200.com/modules/myalbum/photo.php?lid=3639 http://datsun1200.com/uploads/thumbs/3639.jpg] | + | <br>{{Album|3639}} |
| = 41mm = | = 41mm = | ||
| GX head with 41 mm intake valves & 32 mm exhaust valves | GX head with 41 mm intake valves & 32 mm exhaust valves | ||
| - | <br>[http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/IN41EX32-1.jpg http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/th_IN41EX32-1.jpg] [http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/IN41EX32-2.jpg http://i297.photobucket.com/albums/mm219/ddgonzal/Datsun%201200/wiki/th_IN41EX32-2.jpg] | + | <br>{{Photo|IN41EX32-1.jpg}} {{Photo|IN41EX32-2.jpg}} |
| = 42mm Valves = | = 42mm Valves = | ||
| 42 mm intakes are perhaps the limit for A-series cylinder heads. | 42 mm intakes are perhaps the limit for A-series cylinder heads. | ||
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=20264 http://datsun1200.com/uploads/thumbs/20264.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=12142 http://datsun1200.com/uploads/thumbs/12142.jpg] | + | {{Album|20264}} {{Album|12142}} |
| - | + | ||
| - | = Dual Valve Springs = | + | |
| - | Large valves work best at high RPM. When revving over 6000 RPM, dual valve springs are called for. The stock A12GX springs are good for 6600 RPM. | + | |
| - | + | ||
| - | Racing/aftermarket dual springs are usually good for 9000 RPM and shouldn't be used in a street engine as they cause accelerated wear on the valve guides. | + | |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=19821 http://datsun1200.com/uploads/thumbs/19821.jpg] | + | = Dual & Triple Valve Springs = |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=21686 http://datsun1200.com/uploads/thumbs/21686.jpg] | + | Large valves work best at high RPM. When revving over 6000 RPM, dual valve springs are called for. The stock A12GX springs are good for 6600 RPM (and some report higher RPMs). |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=21687 http://datsun1200.com/uploads/thumbs/21687.jpg] | + | |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=23378 http://datsun1200.com/uploads/thumbs/23378.jpg] | + | |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=23647 http://datsun1200.com/uploads/thumbs/23647.jpg] | + | |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=23648 http://datsun1200.com/uploads/thumbs/23648.jpg] | + | |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=23649 http://datsun1200.com/uploads/thumbs/23649.jpg] | + | |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=23734 http://datsun1200.com/uploads/thumbs/23734.jpg] | + | |
| - | = Triple Valve Springs = | + | {{Main|Valve_springs#Racing_Valve_Springs}} |
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=18703 http://datsun1200.com/uploads/thumbs/18703.jpg] | + | |
| = Tomei Valves = | = Tomei Valves = | ||
| Tomei valves Fitted to A12 GX head. Tomei valves with 7mm stems. Intake valves 40mm, exhaust valves 33mm. The stems have a thinner design for maximizing air flow rate within the port with the reduced air flow resistance. The cylinders need extra notching at the top of the bore to accommodate these large valves. | Tomei valves Fitted to A12 GX head. Tomei valves with 7mm stems. Intake valves 40mm, exhaust valves 33mm. The stems have a thinner design for maximizing air flow rate within the port with the reduced air flow resistance. The cylinders need extra notching at the top of the bore to accommodate these large valves. | ||
| - | [http://datsun1200.com/modules/myalbum/photo.php?lid=23472 http://datsun1200.com/uploads/thumbs/23472.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=23473 http://datsun1200.com/uploads/thumbs/23473.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=25142 http://datsun1200.com/uploads/thumbs/25142.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=25143 http://datsun1200.com/uploads/thumbs/25143.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=25144 http://datsun1200.com/uploads/thumbs/25144.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=25145 http://datsun1200.com/uploads/thumbs/25145.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=25146 http://datsun1200.com/uploads/thumbs/25146.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=25147 http://datsun1200.com/uploads/thumbs/25147.jpg] [http://datsun1200.com/modules/myalbum/photo.php?lid=25148 http://datsun1200.com/uploads/thumbs/25148.jpg] | + | {{Album|23472}} {{Album|23473}} {{Album|25142}} {{Album|25143}} {{Album|25144}} {{Album|25145}} {{Album|25146}} {{Album|25147}} {{Album|25148}} |
| = Photo Index = | = Photo Index = | ||
Revision as of 21:40, 24 July 2018
Stock valves for A12 engine are 35 mm intake, 29 mm exhaust. You can fit the A14-size 37mm inlet/30mm exhaust. And valves up to 42mm have been fitted for ultra high-RPM use.
Contents |
Overview
The stock A12 valves (35/29) are good for small-bore (1200cc) use below for up to 6000 RPM. For larger bore engines -- or higher RPM -- the 37/30 valves from an A14 are better.
For racing at high RPMs, more power can be made with larger valves, but care must be taken for proper valve flow.
The 40s may require relief/flow notch in the side of the cylinder wall?
POST COUP1200: My A14 makes 140hp & its not EFI or turbo. I have twin 40mm webers, good extractors the head flowes 141hp. All your power gain is in the head big valves extencive amounts of porting good spark ... I dont run roller rockers & have not had a problem.you dont need to go to big with the cam mine about 74deg ... Mine makes power to 7500rpm.
feral: COOPS 1200 SEDAN AFTER RUNNING A 2:11 AT PHILLIP ISLAND CIRCUIT ... The car sounded awesome and handled very well. In typical 1200 fashion showed alot of more exotic machinery including a Porsche 924 turbo and a lotus elite a clean pair of tailights :-)
Feral
Feral used 40mm steel Inlet valves, tuliped and swirl polished, with 35mm Exhausts steel polished.
And don't forget to dial in the camshaft timing
41mm
GX head with 41 mm intake valves & 32 mm exhaust valves
42mm Valves
42 mm intakes are perhaps the limit for A-series cylinder heads.
Dual & Triple Valve Springs
Large valves work best at high RPM. When revving over 6000 RPM, dual valve springs are called for. The stock A12GX springs are good for 6600 RPM (and some report higher RPMs).
Tomei Valves
Tomei valves Fitted to A12 GX head. Tomei valves with 7mm stems. Intake valves 40mm, exhaust valves 33mm. The stems have a thinner design for maximizing air flow rate within the port with the reduced air flow resistance. The cylinders need extra notching at the top of the bore to accommodate these large valves.
Photo Index
Big Valve
Valve Spring
