I am thinking of doing this over the winter (while the Z is in storage) but, before i do i'm wondering if i get a 350 block can i use most of the stuff off my old 305 or would i have to go buy NEW everything for the 350? also do i need a new computer or just a ecm?
if i don't do a 350 swap i also am looking at supercharging the 305. What would u guys do, and is a 350 swap that hard?
thx
-Abe

well i cant help you because im in the same boat you are but i am going from v6 to v8 super charged so if you learn any interesting facts let me know

Just about everything will convert over, but you will have to get a new chip for the ECM. I am not sure if there are any other differences in the 305. (possibily the injectors.) I have heard that the 305 tpi has smaller runners, but I am not sure. If anyone knows if the 305 tpi has any physical differences over the 350, I would really like to know.

Everything on the 305 TPI is identical to the 350 TPI except the injectors, chip and knock sensor. (assuming we are talking about the same year and vehicle application)



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Edwin
1986 IROC, 1992 Body Kit, 1989 5.7 IROC Engine, Crane Cam, 3" CVX Exhaust, ADS Superchip, 24# FoMoCo Injectors, Gutted Cat, AFPR (45 psi), Airfoil, 3.42 Gears, MAF Screens removed, Gutted Airbox, K&N Filters

If you go with the 350(which I highly recommend), you are going to need an adjustable fuel pressure regulator. With 305 injectors you will starve the engine. The 305 had 19/lb injectors, and the 350 had 22/lb injectors. If you bump up the fuel pressure to 48-50 psi you'll be fine. I didn't put one on when I did my swap and I noticed that I started to lose power at about 3,700 RPM. IT SUCKED! When I put one on, it was a whole new car! I hope this helps.

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1988 Trans Am
350 TPI
Hypertech Thermomaster
160 Deg. Thermostat
cool fan switch
B&M Shift Kit
Richmond 3.73 rear

I just did a 350 swap into my 305. I used everything from the 305. I used 19 lbs injectors from the 305 but bought the adj. fuel regulator. you're gonna need one. Also, don't change the injector size cause you will be forced to change the computer. you'll be fine with 19 lb injectors and a regulator.

I had to get a custom chip for mine because i upgraded the cam in the 350, so my car wouldn't idle.

but everything exhaust manifolds, tpi unit, everything is the same..

i suggest this swap, my car hauls, and i beat a new z28 yesterday.

hope this helps..

gary mann

Ok, so if i get a 350 here i can just yank out my old 305 and start swapping the parts onto the 350 right?(heh it all sounds easy on paper) Also would i need new heads for the 350? And does it matter if the 350 is the same year as my 305 (91)? or would a 350 from almost anywhere work? I don't plan on doing this in one weekend, but i have ALL winter to screw things up the only reason im asking about the age of the motor is because one of my bros friends said that i can't use an old motor because of where all the sensors are located in the newer ones? (i don't know if that made sense) but anyways thx for all the info already and keep it comming! =D now that i found out that i don't need to switch EVERYTHING out its really making this swap more reasonable in my eyes
THX for all the help and info!
-Abe

EDIT: BTW what is a fair price for a 350 block?

EDIT#2: Also when buying a motor what should come with it? (and what should i look out for?)

[This message has been edited by Abe91Z28 (edited October 08, 2000).]

[This message has been edited by Abe91Z28 (edited October 08, 2000).]

The only thing I changed was the injectors. I did my swap almost a year ago and I've been using my original ecm and 305 chip ever since. Also up until a few months ago I was using my original 305 knock sensor. I decided to replace it while I was doing my cam/head swap.

Replacing the chip is definitely something that should be done if you want to get the most out of your 350, but if you can't afford it at the time of the swap you should be fine with your 305 chip until you can. I drive my car everyday and I haven't experienced any drivability problems. It's slower than hell, but it drives nice. I'm supposed to get my custom chip this week so hopefully that and a little tuning will solve my problem. Also, since the knock sensor isn't very expensive it would be a good idea to replace that as well.

[Edit] I just noticed you have a 91 with Speed Density. My car has a MAF setup which from what I hear takes better to mods than SD. You may not be able to get away with using your 305 chip like I did.

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87 IROC
350 TPI 5-speed
- Edelbrock Aluminum Heads, LPE 219 Cam, Super Ram, SS Wheels, Graphite Leather, etc. Click here to see the rest.

-=ICON Motorsports=-

[This message has been edited by Jarod87IROC (edited October 08, 2000).]

jarod AWESOME ride man, i checked out ur page i have a few questions.. when u got the new 4th gen seats did they bolt in or did u have to putz around with em to get them to fit? Also you bring up a good point that i was thinking myself about the SD now does my new motor have to be an old SD engine?( that might be a retarted question) or does it matter? And that quote about all bark and no bite? Come on now, 305s aren't all that bad Anyways i'll kinda try and keep everyone updated on whats going on over here. The people who are going to do the swap with me are all mechanics at a GM dealer, but they are in training(they have been in traning for about 2months) but, i think if i can get them to help me that us three newbies could get a swap in over winter and if anything really goes wrong we could have some guys from their work come over

Thx again!
-Abe

Abe91Z28,
When you begin swapping your engine, can you take pictures of the process..for your documents and perhaps for people like me. I also wanna do the an engine swap but I don't have the money yet. I'd like to see what goes on step-by-step. If not, thats cool. Hope everything goes well.

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1992 Z28 (305) TPI.
160' stat, Accel 8mm, Flowmaster high-flow cat-back.

Yes, i will try and take pictures if i decied to do the swap this winter, my friends and i will be doing the swap, so if i can convince them to help me, then a 350 swap is very likely, but, lately we've been talking about a supercharger project for my car and a turbo for my frien's 00' cavalier.
But, as for the 350 swap its almost more likely then a supercharger (although i've always wanted a turbo or supercharged car) so, i'm trying to get all the info i can on a305 to 350 swap

Abe, the seats bolted right in. Took me about 20 minutes or less. As for your question, SD has nothing to do with the motor itself it only refers to the intake. You can put a SD TPI on a car that originally had a MAF setup and vice versa. I would recommend you find a good L98 block since it's already setup for a hydraulic cam and lifters.

I remember someone here (maybe it was GMTech) saying that the fuel pump is different between 305TPI and 350TPI. So you guys used your stock 305 fuel pump on the 350 and it worked ok? I hope so, I'm going to do the same thing and I don't want to mess with the gas tank if I don't have to!

Jarod87IROC,, what's your idle quality with the stock 305 chip and the ADS 24# injectors? I'm running a similar set up with the 24# SVOs,, and my idle is way rich. Part throttle and WOT is not bad,, in fact it feels pretty good. Any secrets you care to share on cleaning the idle up?

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86 IROC - 9.8:1 - 355, TFS twisted wedge heads, 218/228-110, fully ported GM base and plenum, SLP runners, 52mm BBK, 24# SVO, 1 5/8" Headman headers, 3" Dyno-max, TH350, B&M Megashifter, 245/45ZR17s on 212 Eagles

Man nobody has told you alot of the little bs about this swap. Ill try to help some. Make sure the block you get is one from late 87 up. You could get somthing older but if you have a stick you have to change the flywheel(same for auto),and the oil pan will be different. All the intake pieces are the same 305, 350 except for the injectors(change them if you go with a 350 to 24lbs). Also change the prom. If its going to be a mild 350(cam under 220@.050 dur) you can get a chip from hypercrap for the same year w/ 350. Change to afpr and bump it up to 43psi. Fuel pump is the same 305-350. If your going with stock heads get them from 87 up 350, not 305's. The center intake bolts are at a diff angle than older models. Or you can drill the intake base to work with the older style. These are just a few little things, oh and if you dont keep a roller cam remember to get longer pushrods.

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87z 383. mini ram 5spd, 150hpfunny gas, 1,3/4"headers. other stealth goodies.