86 305 TPI to early model 350
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Joined: Oct 2000
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From: Gardner, KS
86 305 TPI to early model 350
My cousin's 305 in his Firebird went to crap this weekend. Our grandpa has a rebuilt 350 sitting in the garage, but it is a 4-bolt main that came out of a mid 70's truck. From what I understand, the TPI won't bolt up to the heads on the 350. Am I correct? From what little I know about doing this swap, we'll need to get 22lb injectors, 350 knock sensor and a 350 chip. How about things like cam and flywheel? Am I missing anything? Anything else we should know before we get started on the swap?
Joined: Mar 2000
Posts: 43,187
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
An '86 TPI will bolt to earlier 350 heads. An '87-later TPI will have different angles for the center two intake manifold bolts on each side, but the holes can be elongated to make it work. So, no problem bolting the TPI to the 350.
The '86 305 will have a one-piece rear main seal crank, so the flywheel/flex plate will not fit on the older engine. But, just get a 153-tooth piece for '85-older.
You can easily get by with the 19 lb injectors. Spend the money on an adjustable fuel pressure regulator or convert the stock piece instead. Buddy here runs quicker with 19 lb injectors in his highly modified ZZ3 SD TPI than he did with 24's.
Get a nice aftermarket flat tappet computer-compatible cam to put into it.
The knock sensor and module are optional, but not a bad idea. It will probably run fine with a stock 305 chip, but a 350 chip would probably help it as well. Those things: you could wait until after it's running to decide if you want to change them.
The 350 truck engine most likely has dished pistons and small valve heads. Not the best performance pieces, but it will probably still run better than the 305 did.
------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 CC system w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker 2055 headers, 3" Catco cat & 3" catback, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).
[This message has been edited by five7kid (edited October 02, 2001).]
The '86 305 will have a one-piece rear main seal crank, so the flywheel/flex plate will not fit on the older engine. But, just get a 153-tooth piece for '85-older.
You can easily get by with the 19 lb injectors. Spend the money on an adjustable fuel pressure regulator or convert the stock piece instead. Buddy here runs quicker with 19 lb injectors in his highly modified ZZ3 SD TPI than he did with 24's.
Get a nice aftermarket flat tappet computer-compatible cam to put into it.
The knock sensor and module are optional, but not a bad idea. It will probably run fine with a stock 305 chip, but a 350 chip would probably help it as well. Those things: you could wait until after it's running to decide if you want to change them.
The 350 truck engine most likely has dished pistons and small valve heads. Not the best performance pieces, but it will probably still run better than the 305 did.
------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 CC system w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker 2055 headers, 3" Catco cat & 3" catback, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).
[This message has been edited by five7kid (edited October 02, 2001).]
Junior Member
Joined: Aug 1999
Posts: 83
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From: Ridge, MD
yeah i just finished this this spring. everything this guys said is true.
i am still running 305 injectors and chip
you also need a starter nose cone to fit that flywheel.
frogot to mention the dipstick tube. it coem out where the stock manifolds dump. you either need headers, or a torch and some creative bending. i did it, but it wasnt easy and alot of people claim it cant be done, but it can.
[This message has been edited by GeneralHazzard (edited October 02, 2001).]
i am still running 305 injectors and chip
you also need a starter nose cone to fit that flywheel.
frogot to mention the dipstick tube. it coem out where the stock manifolds dump. you either need headers, or a torch and some creative bending. i did it, but it wasnt easy and alot of people claim it cant be done, but it can.
[This message has been edited by GeneralHazzard (edited October 02, 2001).]
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