well guys i have a realy good deal on a set of 91 5.7 tpi heads.i was wondering if these can be installed on my 89 5.0 tbi motor.wat are the diffrences like cc vavles exc.also i have the lt1 cam that may help seens there 350 motor parts

 

Vette L-98 heads (the aluminum ones)? Or cast iron f-body L-98 heads?

 

Iron L98 heads are 64cc chambers, yours are 58cc. If its a great deal, take the L98 heads, sell them and buy some 305 TPI heads, '081's or 416's. Those heads have 58cc chambers keeping your compression up, and they flow just as well as L98 heads. If you really want to wake the motor up, pick up some 305 tpi heads and work them over a little, you can get great flow out of them.

 

well they are the cast iron ones,and can u just milled them down to my cc?and they will benifit me because of the bigger vavles

 

It's definitely not worth the machine work to mill them down. The valves may be ok, but I thought 081's had 1.94 intakes and 1.50's just like L98's. I could be wrong there though, they could be 1.84.

If I were you, I"d pick up a set of 081's do a little self porting on them, make sure they have 1.94 1.50 valves and throw them on for a big improvement. Don't bother messing with the 64cc 350 heads when the 58cc heads have the same flow characteristics.

 

Agreed. The only heads I that would be worth spending the money on to mill are vortecs. I would look for 081's or consider the worlds.

 

Yeah, 305 heads from a TPI motor (without the nasty swirl ramp clogging up 1/2 the intake port) would be a better choice over the weak-kneed TBI heads. But I wouldn't bolt on the L-98 heads as your first choice.

If you have no other choice and have to choose between the stock TBI heads and the lower-compression L-98 heads, I would choose the L-98 heads. But there are better choices out there for not much money. Find anyone with an 87-up 5.0L TPI engine and swipe the heads off it. Unwanted 305 parts litter the landscape looking for a good home. They're the pound puppies of the small block Chevy line.