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Will a 87-95 tbi intake work on an 1986 tune port block (came out of a 305ci firebird) without slotting any holes. I bought a 1989 intake today casting # 14102182 Rebuilt the 1986 305 installed it in an 1989 silverado the original 89 305 froze and busted the block we towed it from and apartment complex as abandoned vehicle have no history of the vehicle. Rebuilt the 1986 305 and installed it in the Silverado. The original intake off the 1989 was cracked and bought a replacement from craigslist and found out it was slotted. Now I'm hearing that some of the the slotted intakes leak and are differnt angles mating on the flat surfaces (slight but differnt). Ran perfect in the beginning but then began to not idle and run rough. Heard from two people this a typical characteristic of slotted hole intakes at first they run fine then heat up and don't run fine. Haven't ran a air leak intake test yet because I went to Pull a Part and got a GM 1989 Silverado TBI intake today just because I don't trust the slotted one. Changed the map sensor, idle air, and am rebuilding the intake when I change the intake. Anybody seen or heard of this.
 

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Will a 87-95 tbi intake work on an 1986 tune port block (came out of a 305ci firebird) without slotting any holes. I bought a 1989 intake today casting # 14102182 Rebuilt the 1986 305 installed it in an 1989 silverado the original 89 305 froze and busted the block we towed it from and apartment complex as abandoned vehicle have no history of the vehicle. Rebuilt the 1986 305 and installed it in the Silverado. The original intake off the 1989 was cracked and bought a replacement from craigslist and found out it was slotted. Now I'm hearing that some of the the slotted intakes leak and are differnt angles mating on the flat surfaces (slight but differnt). Ran perfect in the beginning but then began to not idle and run rough. Heard from two people this a typical characteristic of slotted hole intakes at first they run fine then heat up and don't run fine. Haven't ran a air leak intake test yet because I went to Pull a Part and got a GM 1989 Silverado TBI intake today just because I don't trust the slotted one. Changed the map sensor, idle air, and am rebuilding the intake when I change the intake. Anybody seen or heard of this.
The 89 TBI will have the center bolts at 75 degrees to the plane of the port face of the head. The 86 TPI may use either the 75 or the older 90 degrees to the plane of the port face of the head as there is a transition phase for passenger car engines right in 1986 time period and either may appear on an engine. You should be able to see the angle of these bolts your heads use quite well, at 90 degrees they will come straight out of the port plane at 75 degrees they will angle up with respect to the port plane.

Bogie
 

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90 percent of the 86 tpi engines had the 90 deg face on the center bolts unless you are lucky enough to get a late model with factory aluminum heads which are rare in 86 about 40 percent were 70 deg however the tpi intakes were wired as a crossfire on the injectors just like the tbi injectors one set of the computor wires fires the right and one fires the left so with a little wiring skill you could run the tpi on your truck without that many mods other than cables (accelarator and detent) and a wiring diagram
 
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