As far as the shape and size of the exhaust ports, are they similar?

 

The shape is the same but that is it. The L98 heads are not swirl ports and do not have massivre amounts of material around the pushrod slots.

 

yeap, I knew that, but I've never seen a pair of L98 heads up close. I was just wondering about the actual shape/size. Got any pics of stock L98 heads to compare with my L03 heads?

 

The only small block heads that will have a different shape will be ones with D ports, or raised runners. Vortecs have raised runners and LT1's have D ports but the L98 heads should be identical to the LO3 heads. Now the insides of the heads are completely different.

 

The aluminum L98 heads have D-ports as well, but the iron version look exactly the same as the 187 L03 heads (as mentioned above) but I'd say they more closely resemble a 081 head or 416, except with larger intake runners.

 

Exhaust ports on aluminum L98s

 

Can the L98's be directly swapped to an L03? What else would have to change-- the exhaust manifolds?

 

They are a direct bolt on excpet the combustion chambers are a bit big. You would either want to run a thinner head gasket or have them milled a little. You can use the exhuast of your choice.

 

you woudl want to mill the l98 heads some to use on a 305.. you would be loosing put much compression to amke it worth the swap. you could prob get awa with either 60 or 61 cc;s with a thin head gastet and be ok.. i have l98 heads at home i take a pic for you to sso the exhaust ports on them.

 

I can pick up a used L98 aluminum set for $130 is why I am asking. I have been told by some others that it isn't worth the swap (performance wise).

So I can use my stock ex manifolds on these as well until I get headers?

What thickness gasket or how much should be milled?? 15 thou? 30 thou?

 

$130?!?! Yeah, I'd say that they would be worth that. The stock manifolds will work, but headers would be better (but you probably already know that). Technically, you won't have to mill the aluminum L98's, they've got 58cc combustion chambers. Since they're aluminum, however, you can run higher than stock compression. I'd shoot for somewhere between 52-55cc. Not sure how much off the bottom to get that, though.

 

For a 64cc head you can usually mill .020" and use a thin head gakset and come out right around 9.3:1. You can use the aluminum L98 heads that have 58cc chambers but you still want to mill them. You are going to want a little more compression with those heads. I would shoot for 10:1.

 

How much of a performance gain should I expect? I know they are quite a bit lighter and flow better, but from a HP standpoint? 10, 15, 20?

I am thinking I am going to jump on this and just want to make sure it is going to be worth the time.

Thanks

 

It all depends on tuning, cam selection and any other mods you have.

 

Also, is it necessary to upgrade the cam? If so, other than the LT1 cam, what should I go with? Would the LT1 be the best for this combination? I am running the 163K mile original stocker.

Do these need to be '87 up? Well I guess that is a dumb question, but just for confirmation.

Thanks

 

well, I just found out the heads are IRON off a Formula

Is it still worth the swap??

 

It is pointless to do a head swap and keep the same cam. When the heads are off only a few bolts are left that keep the cam in. You might as well change it while you are in there. I would hold out for a pair of 305 TPI heads. The L98 heads are good but much better suited to a 350.

 

Where can I find the casting numbers for the 305 TPI heads so I know what I am looking for??

Thanks for the help!

 

What are the casting numbers for the iron l98 heads?

 

the last 3 digits are 083. I can find the whole number tonight and let you know.

 

Thats what I thought. I was trying to buy a set of l98 heads off a guy in the classifieds. We had arrangements and everything. Asked him what the serial number is and he replies with 193's. I was angry considering 193's are lo5 swirl ports and I already have them...

 

14011083 350-300HP, Crate Motor, 64cc, 90º manifold bolt, hard seats
14011083 350, 87-up, 64cc, center bolt VC, 72º manifold bolt


check this out too:

http://chevyhiperformance.com/techar...98/index4.html

 

SBC Cast Iron L98 Center Bolt Valve Cover Head.
This is a cast iron cylinder head assembly used on 285 hp 350 engine. Includes 1.94” intake valves, 1.50” exhaust valves.
64cc chambers. The cast number for this head is P/N 14101083 or 14096217. This cylinder head has 1987 and later intake manifold bolt pattern. The center two bolts are at a 72° angle.