TPI Intake bolt size location
Thread Starter
Joined: Sep 2005
Posts: 19
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Car: 1990 IROC-Z Convertible
Engine: 5.0
Transmission: Auto
TPI Intake bolt size location
Hello I recently took off my lower intake and in my ignorant excited stupidity I am unsure where the 4 longer torq head bolts go... I have a GM service manual, however the diagram is for a carbureted intake. I search the forums and best I could find is the four corners. please confirm or deny this. I know the passenger side near the firewall definitely is one of the longer bolts.
thanks in advance
thanks in advance
Thread Starter
Joined: Sep 2005
Posts: 19
Likes: 3
Car: 1990 IROC-Z Convertible
Engine: 5.0
Transmission: Auto
Re: TPI Intake bolt size location
It’s a 1990 305
six bolts on each side four of them, are just under an inch and a half.. ( 1 & 3/8’s maybe) …long…the other eight are an inch and a quarter long
six bolts on each side four of them, are just under an inch and a half.. ( 1 & 3/8’s maybe) …long…the other eight are an inch and a quarter long
Joined: Dec 2004
Posts: 16,754
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From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: TPI Intake bolt size location
Attachment 345925
Attachment 345926
Attachment 345927
Attachment 345928
Attachment 345929
Pictured above is the typical set up for a 1986-89 MAF based system. Speed density is similar. (A) Intake manifold. (B) EGR valve (C) EGR temp switch (maf only) (D) PCV fitting, to the left is orifice for cold start injector (maf only) (E) Thermostat housing neck and bolts (F) Bolts needed for top plenum and runners- 13- M8x1.25x30mm, 2- M8x1.25x40mm, 4- M8x1.25x50mm, 1- M8x1.25x30mm throttle bracket stud, 20 total, these use a T40 Torx head bit, NOTE these are metric. (G) Fuel rail typical for a "F" body, maf system, fuel lines for Corvette is on opposite side. Look at picture, as this is a complete system (H) cold start injector and fuel tube (maf only) (J) Fuel injectors-8 total (K) Intake runners, speed density will not have the cold start opening (L). (M) Intake air sensor (P) Intake plenum, with throttle body, be sure to get complete throttle body with no missing upper and lower cover plates, bottom plate has provisions for IAC and coolant tubes. (Q) Throttle bracket and bolts (R) Vacuum fittings for fuel regulator, heater control and brake booster, speed density will have a fitting for MAP sensor and mounting boss.
Attachment 345926
Attachment 345927
Attachment 345928
Attachment 345929
Pictured above is the typical set up for a 1986-89 MAF based system. Speed density is similar. (A) Intake manifold. (B) EGR valve (C) EGR temp switch (maf only) (D) PCV fitting, to the left is orifice for cold start injector (maf only) (E) Thermostat housing neck and bolts (F) Bolts needed for top plenum and runners- 13- M8x1.25x30mm, 2- M8x1.25x40mm, 4- M8x1.25x50mm, 1- M8x1.25x30mm throttle bracket stud, 20 total, these use a T40 Torx head bit, NOTE these are metric. (G) Fuel rail typical for a "F" body, maf system, fuel lines for Corvette is on opposite side. Look at picture, as this is a complete system (H) cold start injector and fuel tube (maf only) (J) Fuel injectors-8 total (K) Intake runners, speed density will not have the cold start opening (L). (M) Intake air sensor (P) Intake plenum, with throttle body, be sure to get complete throttle body with no missing upper and lower cover plates, bottom plate has provisions for IAC and coolant tubes. (Q) Throttle bracket and bolts (R) Vacuum fittings for fuel regulator, heater control and brake booster, speed density will have a fitting for MAP sensor and mounting boss.
Joined: Sep 2008
Posts: 355
Likes: 34
From: Accord NY
Car: 90 IROC original owner
Engine: 5.7
Transmission: 700R4
Axle/Gears: 3.73
Re: TPI Intake bolt size location
Shorter ones need to go on the inner holes otherwise they hit the push rods.
https://www.thirdgen.org/forums/tech...g-problem.html
https://www.thirdgen.org/forums/tech...g-problem.html
Last edited by BigBlock73; Mar 26, 2025 at 12:15 PM.
Thread Starter
Joined: Sep 2005
Posts: 19
Likes: 3
Car: 1990 IROC-Z Convertible
Engine: 5.0
Transmission: Auto
Re: TPI Intake bolt size location
Funny, I have heard that once or twice before lol. But I did not realize those were different sizes.
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Joined: Apr 2010
Posts: 513
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From: New Jersey
Car: 87 Monte Carlo SS
Engine: 89 350TPI Transplant
Transmission: 2004r
Axle/Gears: 3.73
Re: TPI Intake bolt size location
Darn, you guys have me wondering. When I did my TPI conversion, I did not know there were different length intake manifold bolts. Something I will have to check.
Fred
Fred
Joined: Dec 2004
Posts: 16,754
Likes: 996
From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: TPI Intake bolt size location
on 88-92 f body there we’re 2 longer ones for the coil bracket. Iirc 85-87 were all the same length. Or could of had the two longer ones a/c bracket front drivers side 2 bolt holes.
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