ok so I have a 87 iroc-z with the 305 tpi and auto trans the motor is in almost good running condition, it starts fine runs fine but burns a little oil I was told the valve seals are bad.


my body on the other hand has seen better days so last fall I picked up a near mint 86 iroc z that needed a drive train. my plan is to swap my motor and trans over to the 86 but I would like to rebuild my 305 before I put all the time into swaping them.


I plan on tearing the motor down and cleaning everything and honing the block out and putting new pistons and rings and all new seals and that's it for the bottom end as for the top end I would like to swap in a slightly larger more aggressive cam one with a slightly bigger opening and slightly longer duration, now I know some would say its a waste but I can get a kit that has new valve springs and seals for not mutch more than just the valve springs and seals. I just need to know what size my stock cam is and what is a safe size to go.

 

If you are going to go thru the trouble of swapping the drivetrain and doing a rebuild why bother with rebuilding 305 at all?

You will spend same on a 350 short block rebuild. The only additional cost would be for an OEM 350 block and heads which are a dime a dozen for good cores. for a little extra cash you can get better aftermarket heads.

Everything else will bolt right on including the OEM TPI.
With a slightly more aggressive cam than oem you will make more TQ and HP than an equally rebuilt 305.

Otherwise just replace the valve stem seals on the 305 and call it a day. I would not waste money on a full rebuild, cam swap, etc,... save it for a 350.

 

In my case with wanting to keep my car #'s matching with the original 305 and 700R4, call Jegs and tell them what you have and what you're wanting to do and they will get you going in the right direction. I think they hooked me up with a mild cam and roller lifters, springs, seals and retainers for around $350 or so.

 

In this case he is swapping the complete drivetrain from one body to another..

"numbers matching" means nothing at that point because the date codes will be off from the original "numbers matching" body versus the donor car.

They made this body style for 10 years, they will never be worth what the 1st and 2nd gen models fetch for a "numbers matching" car.

but if that is the game you want to play have at it... LOL

 

If you insist on keeping the 305.

Put 1.94 valves in the heads
Hooker or Dyno Don Shorty headers
3" catback
Lunati 60102 or Equivilent cam
Since you are honing it, you will need new pistons as well. have the crank and rods inspected but they should be good.
You will need new springs for a new cam. Call the Cam companies, Lunati, Isky, Comp etc and let them help you pick the cam. WIth an 87 you have a roller block so you can get a roller cam. Good deal.
Call Precision industries and get a new torque converter. 2200 stall should be just about right.
Call Dana at pro-built for a rebuild kit for your transmission.

This will give you a good running 250+hp 305 that will be fun on the street.

 

All that said, I agree with FRMULA88, if you are pulling the motor and spending the money to rebuild it, you're better off getting a 350 because with the same money, you'll get more out of it. For the money needed for the mods I just mentioned, you can get a 350 and make it 300+ hp.

 

Okay I understand what your saying I was just giving the guy options! No need to get an attitude about it! So with that being said, I didn't know you could use the original 305 tpi on a 350 so what if any other mods need to be done to drop a 350 into a 305 car? Will the 700r4 tranny still work? Need to reprogram the computer? Can you use a newer vortec engine with the old tpi or do you need a 80's 350?

 

i was thinking of going the 350 route but it all depends on what the block looks like on my 305 if my motors good It money I don't have to spend and if I was to do the swap to a 350 I would look into doing a the 5.7 vortec with matching auto tranny and computer if the wiring would still plug into the wall but I highly doubt it would


im not looking to build the 305 to be a race motor I just thought that while I had it out why not make it basicly a brand new motor the cam swap would just be to give it a lil more pep I am actually really happy with the stock cam but I have to take the heads off to replace the valves so y not bump up the cam a step


as for exhaust I was looking at hooker shortys and running my stock y pipe and a hollow cat then a mor e open muffler intake wise I was planning on running the hawks intake boxes

 

Your hooker shorties will not match up with your factory Y-pipe. It's why they come with their own.

Don't need to get a "vortec" motor with matching tranny etc. Find a running L98, put your intake on it, bolt it to your transmission and go (Dont' forget to take the injectors). You will also need a new ECM with the vortec's motor. Get a hold of John Wayne or Tuned Performance or Rbob and have them get you a good tuned ECM chip for it. If you install the motor and do the labor part yourself, all can be had for under $1000.

 

No mods needed, it'll drop right in. You ened bigger injectors, a 350 knock sensor and that's it. 700R4 will bolt right up. You will probably need to retune your ECM for the bigger motor since you need the bigger injectors. John Wayne, Tuned Performance, Rbob can do this for you.

Newer Vortec heads will not bolt up to the old TPI intake. The only thing different about a "Vortec" motor vs the "80's" 350, is the heads and intake.

Unless your taking the 2000+ truck vortec's which are actually LS motors.

 

Here is my biggest question, just how bad is your 87? Instead of basically scrapping it by removing the drivetrain and swapping to the 86, could you sell it as is for enough to get a good drivetrain to put in the 86?

 

The front subframe and rear frame/subframe? Are rotted and i have 3 or 4 spots on each side on the main body that are rotted unser neith plus the regular panel rust behind the doors and on the fenders

When i take the heads off what should i look for to see if there is any damage to the block and or rings/pistons? Im just at the point of finally pulling the whole drive train so it will be soon that i tear into the motor