I have an 87 IROC i'd like to put a ZZ4 350 in. Can the current 305 TPI unit and accessories be directly swapped onto the new ZZ4? Or is it more involved than that? Thanks.

 

Not exactly. The center two intake bolts on each side of your engine are at a different angle than the others, whereas the ZZ4 has them all the same ('86-earlier style). Either elogate those holes in or intake or get an '86-earlier style base.

Also, the ZZ4 heads do not have the exhaust crossover passage, so your TPI EGR will not work. That can either be solved with a Vette TPI base or by plumbing a tube from the exhaust manifold/header to the intake.

You may have to use an adapter or two for coolant sensors, but I'm not completely sure about that. Otherwise, it will all bolt up.

------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Edelbrock 1901 Q-Jet, 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).

 

All the sensors will work ok. If you want to keep you AC you will have to drill and tap a new hole in the pass. side head or the bracket will shake like crazy. Also don't bother drilling the manifold, get a new high flow base with the holes done for you. The power is worth the price.

------------------
1991 Z28 ZZ4 with LPE superram base, SLP runners, LPE 58mm T-body,Random Technology ramair,TES headers,24#svo injectors,ZEX nitrous,Walbro 255lph f-pump,Accel AFPR,Flowmaster catback,!cats,and mutch more.

 

Isn't the AC on the driver's side on an '87?

I agree with the intake suggestion. You can kill the bolt angle and EGR birds with one stone, and get a better flowing piece for free.

 

Glad to hear someone else is doing the 305 TPI switch to the ZZ4. I am currently in the middle of this task with my 88 IROCZ convertible. It's pretty much as everyone has said. I have the serpentine belt system so I had to switch to a reverse rotating water pump. I bought an Edelbrock #8881 - real nice but expensive. For the EGR I used Edelbrock 50 states legal headers with a TPIS big mouth manifold. I welded a fitting to the headers and used the Corvette style tube to connect to the manifold. For the air conditioning, mine is on the passenger side. The ZZ4 heads do not have the hole for the upper part of the bracker so I fabbed a short bracket from 1/4" steel plate and welded a 3/8" NC stud to
go through the AC bracket. Remaining fab items are a new coil mount and some spacers on the header bolts for mounting of miscellaneous braces.

If all goes right, I'll be installing the new motor in the car in about 2 weeks and hope to finish the shift kit (TRANSGO) and B&M megashifter soon after that. I then need to pass California smog in about 14 months. I'm hoping I've got it all figured out by then.

Hope this helps -- good luck!

------------------