Does anyone have the flowbench numbers for the LO3 heads? Yeah, I'm not expecting they flow a lot, but it'd be nice to have a baseline.

 

Whats the casting #? I don't bother with 305's
But I do mess with the 305 heads.

 

I'm not sure, haven't taken the covers off. It's a '92 with centerbolt covers if that's any help.

 

Well pull the covers off and get the # off the head and call me back. I'm not a magician.

if they are 081 or 083 or 217 they will port up real nice.
At least as good as my 416's (see my posts)

if they are swirl port heads 510 ,188 ,187 don't even bother
just put the covers back on.

Here's the Flow # for stock 081 castings. the others are real simular.

0.050 31 0.050 15 49
0.100 63 0.100 37 58
0.150 92 0.150 61 67
0.200 116 0.200 78 68
0.250 134 0.250 92 69
0.300 157 0.300 101 64
0.350 170 0.350 105 62
0.400 182 0.400 107 59
0.450 189 0.450 109 58
0.500 195 0.500 110 56

The last # is a ex to in flow ratio.

Expect to get 225@.450 intake and at least 140 @.500 ex
with a good port job and 1.94x1.50 valves.

A mild going over won't cut it here. Ya have to carve some meat out of 'em so don't be shy.

What casting are they?

 

F-bird '88:
Hey, thanks for the flow numbers. They're not real impressive in stock condition, but the post-port'em number look excellent!

:hail:

 

Those would be 187's

If you can't get those to flow at least 180 on the Ex. somethings wrong.

 

i'm using a set of 1987 416 castings.

do the have a fair amount of meat to them to accept a set of 1.94 valves, and a full porting? i'm looking to port these this winter.

i do have a set of 1979 or so castings from a 267 that have 52cc chambers, i'll grab the casting number sometime. i'd like to know if they're a junk head, or if they can be stuffed with 1.94's and e ported. i'd love the compression boost if they would flow worth the effort put into them.

 

The 416's can handle the 1.94 valves no problem.
And the porting. You should expect to match or exeed
my numbers with a good honest effort. I didn't write any books
on head porting so if I can do it, so can you/or better.
Don't even consider 2.02's in these heads. You'll just weaken
the castings.

I have no idea about the 267 heads. I'd have to see the castings. The late model centerbolt TPI heads look like good castings to start with as long as they are not the swirl port heads.
None of these heads will ever match a Camel-Back
or Bowties potential , but that's not the point here.

 

F-bird, what's so bad about the swirl port heads?

 

Chevy put a big up/down lump of a push rod casting in the intake port. It is way too big to grind away, and would expose the push rod long before you could remedy its bad effects anyway.

 

The swirl port heads also have a big "swirl vane" cast into the bowl that divides the flow and supposed to cause a big swirl. The bowl also seems to be cut deep with nearly straight walls.
This may enhance swirl and tumble but cuts into the raw flow
a lot. I suppose you could grid out the swirl vane but I'd rather start with a better common casting.