289's compared GT-40P's???

mustanger82 · 09-13-2001, 12:10 AM

the 289 castings you have have their advantages they are in your posesion they use "normal" sized hedders and they have the smaller combustion chambers which are great for compression they can be ported and flow well but the largest valve you can fit in the 289 head is 1.88 intake and 1.55 exhaust with out modifying your chamber. Modifying your chamber include clearancing the side of the chamber so the valve can make full travel without making contact with the side of the chamber; this takes away material and some valuable compression is lost, secondly they wont flow as well as the the gt-40ps no matter how good the port job. as well the heads need machining to accept any kind of performance rocker. unless you have the 289 hi-po head.
The gt-40 p has many bonuses it has a revised combustion chamber with places the sparkplug closer to the center of the chamber, which gives a better burn, as well as the shape decreases th equench zone reducing the likely hood of dedonation due to combustion temp. secondly the valve placement is better; the 58 cc head allows for the much larger 1.94 int and 1.60 exh valves and the ports are larger as cast and will flow extreamly well after porting prolly in the 240 cfm range for intake and 175 for exhast which is excellent
the heads are more expensive than the cast heads you have. The pedistals are machined to accept roller rocker, and you need special hedder to fit the wider exhast manifold bolt pattern.
In my opinion the gt-40p head is superior but depending on your performance goal the 289 heads my be adequate anywho thats my 2 cents
sean kisch
hardac12@hotmail.com

89 mustang 1977 351w w/1970 61 cc 302 heads with full port and polish job 1.94 int 1.60 exh eagle h beam rods, stock crank, tfs main stud girdle, tfs forged pistons and edlbrock victor portmatched intake tranny and rear end on the way!!!

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09-13-2001, 12:10 AM	#9
mustanger82 Registered Member Join Date: Jun 2001 Location: chilliwack b.c. canada Posts: 25	the 289 castings you have have their advantages they are in your posesion they use "normal" sized hedders and they have the smaller combustion chambers which are great for compression they can be ported and flow well but the largest valve you can fit in the 289 head is 1.88 intake and 1.55 exhaust with out modifying your chamber. Modifying your chamber include clearancing the side of the chamber so the valve can make full travel without making contact with the side of the chamber; this takes away material and some valuable compression is lost, secondly they wont flow as well as the the gt-40ps no matter how good the port job. as well the heads need machining to accept any kind of performance rocker. unless you have the 289 hi-po head. The gt-40 p has many bonuses it has a revised combustion chamber with places the sparkplug closer to the center of the chamber, which gives a better burn, as well as the shape decreases th equench zone reducing the likely hood of dedonation due to combustion temp. secondly the valve placement is better; the 58 cc head allows for the much larger 1.94 int and 1.60 exh valves and the ports are larger as cast and will flow extreamly well after porting prolly in the 240 cfm range for intake and 175 for exhast which is excellent the heads are more expensive than the cast heads you have. The pedistals are machined to accept roller rocker, and you need special hedder to fit the wider exhast manifold bolt pattern. In my opinion the gt-40p head is superior but depending on your performance goal the 289 heads my be adequate anywho thats my 2 cents sean kisch hardac12@hotmail.com 89 mustang 1977 351w w/1970 61 cc 302 heads with full port and polish job 1.94 int 1.60 exh eagle h beam rods, stock crank, tfs main stud girdle, tfs forged pistons and edlbrock victor portmatched intake tranny and rear end on the way!!!