I just finished a swap. Put a TPI 350 into a '91 5-speed Z28. It's made an incredible difference in how the car feels, especially when leaving a stoplight. I had the heads reconditioned, and have new 21lb injectors

The car definately runs hotter now though. I put a meat thermometer on the outlet hose and wrapped a dish towel around it. The 305 ran at about 190*, and the 350 is now running at a steady 210*. The fan is working properly, thermo tested good in boiling water, and I have an aluminum edelbrock w/p. The gauge in the car is flipped out now, it reads between 220 and 260 (red zone) all the time.

I'm thinking of putting a switch in the car so that I can flip on the HD fan in traffic. I've also got a block switch that turns the HD fan on at 195*. Thing is, it tends to run all the time when that switch is in there.

I'm also considering swapping the radiator from the 350 in; Does the rad. from the 5.7 have more cooling power? I've never heard that it does, as far as I know it's identical.

 

Mine is just the opposite. I put a 160 stat in with the 355 TBI... my temp guage barely creeps 1/8 way up. And thats with the 305 radiator, 80 degree day, and the a/c on. In fact, I'm starting to wonder if its getting warm enough to go into closed loop operation (although, I have no reason to think it isn't..)

 

I wouldn't worry about it.... all of those temps are well within the normal range for one of these cars.

A new motor, specifically with freshly cleaned-up heads, will always tend to run hot. When a layer of soot builds up in the exhaust passages (by far the hottest part of the head) it will insulate the coolant from the heat, and your temp will come back down some.

I would especially not rush out and start modifying the cooling systems over that. Again, it's a normal temp, so nothing is broken, so resist the temptation to jack around with something that's working right.

 

Thanks, I won't sweat it then. I also saw there is a new tech article on the cooling system, so I'm checking that out.

 

I have the LT1 with a 160 hypertech thermo and NO issues what to ever. I'm running with the 305 radiator.

I wouldn't run a fan switch. What if something or one distracts you then what? that'll get real ugly real quick... I'd use the 160(be sides for the non lt1's auto-zone sells the 160's for $3.99 - part# 400-160)

 

Nothing will get ugly, because I would just be putting a manual switch option on the second fan. First and second fans will still come on automatically if I overlook the temp.

 

FYI, 305's and 350's used the same rad

 

yep, t-top guy is absolutly right. 305 and 350 radiators are the same. now there is a difference btw automatic and 5sp radiators. the 5sp doesnt have the passages for tranny fluid. not sure if this makes a difference though. i still have the stock radiator out of my 305/700R4 and i swapped in a 350 T-5. mine runs a steady 170-180 on a summer day with both fans on.

another thing to check, sometimes when you drain the system, esp if your block and heads are dry (ie- engine swap), then you can get pockets of air in your heads. this happened to me. get the car hot, then let it cool and check the water. my guess is it will be a little low and you will have to repeat this process several times. after my 350 swap when i initially filled up my system it was running at 230. i thought this was a little odd for a new motor so i checked it and guess what, it was low. ended up putting in close to a gallon in the space of a few days. good luck

 

tregnab, I didn't know you where using both options and two fans. That'll be sweet then - you should run into any issues.
I had the 700r4 in my camaro B 4 I swapped to the LT1. I'm using a Lincoln LS fan(it's about 2" taller then the radiator)...

 

Normally I would say "If it ain't broke, you're not trying hard enough" but this time its....

"if it ain't broke, which it isn't, don't fix it."