im sure people have done this b4 using the older style block with new style heads and intake. but i have a couple questions. the motor is at the machine shop right now. its getting brand new heads and im trying to think what cam to use (any suggestions?) but there are different things about this block compared to mine like the dipstick is driverside it has a short style water pump but im assuming my water pump will bolt up?

now what all has to be changed to go from the 305 to the 350? will i have to change injectors? if so what size do i need to go to? will it run with the 305 injectors? i think the computer and all should be fine since it doesnt deal with the block but the intake and the intake will all be the same. i heard something about a knock sensor what will have to be done with that?

thanks in advance for the help guys.

 

How much lift can your springs handle? go with a zz4 type cam
When the block gets back, set the intake on there, you should have to route out the bolt holes a little and it should work.
As for the knock sensor issue, just dont run a gear drive timing setup, and it will be alright.
Your 350 will RUN on 19 lb injectors, but if you have built the motor any, its not a good idea. i would get 24# and get it tuned, which is a must have with any radical motor changes.

Got any pix?

 

The 305 and 350 knock sensors are different as well as the computer memcal.

Electrical pg. B

 

the intake isnt a problem b/c im using the newer style heads with accessory bolt holes and 87-up intake. i have to find out about the springs. everything in the heads is brand new and they have been reworked a little. idk anything about them really my dad got em.

i need some opinions on a cam though. i want to have a fairly good size cam but still have it not throw the computer off too much. if that is not possible then i want to have good size cam that will sound really good and preform good also.

also i heard of some people that flat out dont run the knock sensor... will that cause any problems? throw any codes? what would be advantages or disadvantages of not running a knock sensor? if i get a new chip they can erase the knock sensor though right?

 

I dont know about SBC cams out there, but what I can tell you is that if you want to run it with the computer, stay with a real mild LSA, we're talking 112-114 degrees, and take it easy with the duration. Don't want to lose too much manifold vacuum.

 

It wont cause any problems but it is a nice safety feature. It can be very useful in saving your engine for some reason if you run into a lean condition. Especially when doing any engine modifications these things could happen more frequently so its really on how comfortable you feel running without it.

 

You need the 350 PROM, knock sensor, Injectors would need to be larger also. As for the cam, I have a Comp Cam, not too big but noticable. .50 Duration 210 Intk, 215 Exht, .50 Lift .476 Itnk, .480 Exht., 114 Lobe Separtion.

The cam sounds good and runs smooth at 1700 so crusing in fourth gear is ok, not loping too much you know? If you go this route I suggest having custom chip burnt for your PROM. I swapped from a 305 TBI to a modified 350 TPI. Definatly worth it, even though I'm still working on a charging problem.

Water pump should be no problem too. I used the one I had on my 305, same radiator too.

 

I had a TPI 305 and has now been changed to a zz4 350 block with same tpi. The research i did showed that the prom, ecu, injectors, fuel pump, regulator, intake, and throttle bodies are all the same between 305 and 350. If you are going to the trouble or switching motors i'm sure that it not al your doing, this requires a new prom, (i still think that my aftermarket one is wrong). I put new 24 lb/hr injectors, 58 mm throttle body, vortec heads, cam(.500 lift), headers, no smog, no cat, roller tip rockers(1.52) . The cam is a little radical but the only problem is low vacum at idle. I had to change the push rods to longer ones so make sure you check that. I still have not got my car running perfect, 1. i can't find anyone to custom tune, 2. i found out the hard way about the longer rods. It still sounds like a small miss and some occasional popping. I was told it could be valve lash is to tight. Since we are attempting the same thing i figured some feedback both ways could help us both.

 

I did the same thing (305 to 350 in an 86) this is what I did:
NO work to the intake, 350 prom, 22lb injectors (to match the prom), knock sensor (for 350),and I also us a P.J. ''guiet'' gear drive with my TPI knock senser with no problems.
As for the cam I would not go bigger than 488* lift with pressed rocker studs.
I did alot of searching here at THIRDGEN.

 

my pressed in rocker studs pulled out so i had to put in screw in studs

 

well it looks like ive changed paths... im going carb i think. but we will see.

btw thanks for the help guys. i really appreciate it.