1987 305 Heads

[NCali]

  87 305 TBI
   I knew the intake is alumn but the heads , Are they aluminum to?

I started reading all of the info on the different heads used and all I got was confused .   center bolt? angle intake bolt holes ? swirl heads? car /truck heads are different , good heads /what do I need?

[Irish_Alley]

would have to know more about the engine/head numbers. but even a picture should tell you if theyre aluminium or not. aluminium wont rust and unless they are covered in oil and grease they should still be aluminium in color. but more than likley they wont be unless they been swapped. i know my 91 tbi had cast heads, theyre a better "flowing" head and some refer to them as vortec but they aren't the true vortec you would find in 96+.

[AZ87V10]

Every factory TBI application I've ever seen has cast iron heads. I know my 87 TBI has cast heads. So did my dad's 89 K2500 350 TBI and so did my 91 S10 4.3 TBI. Yes, you can get aluminum heads for those engines, but they were an aftermarket thing and not very common. Tim is right, look for rust showing on the machined parts of the heads, like where the exhaust manifolds bolt on. All fuel injected small blocks had center bolt valve covers starting in 1987 and had them through the end of the traditional small block design which was the end of the Vortec style engines in about 1999 or 2000. I'm not sure on the newer style LS engines like a 5.3, but that's an entirely different animal! Straight plug applications are usually more like what the factory installed. Whereas angled plug are for engines that have headers on them instead of exhaust manifolds. All 87 to 95 small block engines used the same style heads, they changed in 96 to a different style intake design and are not interchangeable with your stock TBI intake unless you get one that accepts Vortec heads. The bolt pattern is different. I would just get a new set of stock heads for your 305 or have your existing ones rebuilt if they're not warped.

[Jason S]

On a truck the heads should be cast iron.

 - Center bolt:  The valve covers have retaining bolts in the center versus earlier style which had bolts or studs around the valve cover perimeter.

 - Angle intake bolts:  The TBI heads differed from earlier heads in that the middle intake manifold bolts were at a more vertical angle than the outer bolts. This differed from earlier heads where the intake manifold bolt holes were all at the same angle.

 - Swirl port:  The TBI heads had a small ramp that was supposed to introduce a 'swirl' to better mix the air and fuel.

 - Car/Truck heads:  The heads can/will be different depending upon application. 

As for the TBI heads, I have heads off a truck TBI 350 on my '74.  They are pretty good for low end torque.  The main reason I went with those is I wanted hardened valve seats, knew who rebuilt them and the price was right.

[NCali]

well what I know now is that the heads are cast iron heads(they rust) and there is a crack  in the # 6 cylinder position. Its a long crack next to but not in the egr port going to the exhaust valve. It is in the machine shop now and they will let me know tomorrow if it can be fixed. They said that if the crack goes into the egr port it is junk, but he will have to mag the head to know for sure