hey I was wondering if anyone knew any more about 487 cast heads than the fact that they're..
75 cc chambers
came on 71-72 LT-1's
runners are 161cc intake 61 cc exhaust

I had a set machined with a 3 angle valve job put in 2.02 1.6 valves... and I'm having major issues in the revs in first i can pull hard to 6000 but second only 5000 and third not even.

i have a lot of engine specs but I was curious about the heads, do they just die up top?

 

I think the 71 - 72 LT-1's came with the "X" heads and not the regular 3973487. They read 3973487X which has the larger intake ports. The regular 71 and 72's came with 3973487 and no "X" notation and they had the smaller intake ports.

I also heard many base models came with the "X" heads and many LT-1's had the non "X" heads. I have seen it all different ways.

Im replacing mine with some newer model Corvette aluminum heads.

 

The heads are not keeping the rev's down. I would look at timing and fuel delivery. Please fill in your profile so we know what you are driving.

 

this is actually not in a corvette, but my buddy (who has an 80 vette) showed me the forum when i couldnt find info on the heads, but this is the combo. I've been working out the fuel delivery bugs the last week, but I think i've got it sorted out. Another friend has my timing light, once I get it back I'll check into timing, can't remember the last time i shot a timing light at it, thanks for the input!!!! EDIT: btw I can't begin to tell ya how big a relief it is that the heads will flow it, I'm in college so that's another $1000 + that i dont have to worry about :-D

and here's the combo, if ya see anything out of place let me know

1972 355ci
-newly rebuilt 487 heads upped to 2.02/1.6 SS valves + 3 angle valve job, roller 1.5 ratio lifters
-9.34-1 static compression (can't remember the cyl pressure but it was something in the mid 150s)
-hypereutectic aluminum flattop pistons
-lunati Bracket Master 00010 cam (230*/230* @ .050 .480"/.480" lift 109* CL 109* lobe seperation) 110 lb closed 325lb open valve springs
-summit timing chain
-stock crank and rods, turned the crank checked the rods
-Mallory 85 series stock replacement HEI distributor, Msd Super conducter plug wires
-Holley 3310-3 4150 vs carb (72 jets in the primaries 82 jets in the secondaries, white secondary spring)
-Weiand xcelerator high rise intake
-shorty small diameter headers, dual exhaust
-rebuilt th350 trans with 2400 stall, custom cut and balanced driveshaft

-3.23, or 3.43 (havent checked em) rear gears, 27" tall 255/60/15 rear rubber
-gabriel highjacker rear shocks

 

I actually went to the machine shop with some junk truck heads and i saw the 487s and recognized the number, but at the shop he opened them up to the 2.02/1.6 valves and did a bunch of other work for me too. he said they were off an old vette... but there is no X after the number.

so lower port volume?... eh, I guess I can't complain for the $450 rebuilt pricetag.

Thanks for the info, but if you dont mind my asking, any particular reason for the switch to aluminum?

 

I have had 2 1972's with the base 350 and both had correctly dated 487X heads...I heard the "X" heads were 170 cc intake with 75 cc chambers and 1.94 1.5 valves....The LT1'a had the larger valves but all had the same markings. A large chamber low compression mediocre head. I am going to mothball my set and go to new tech aluminum heads. as we all know the power is made in the heads and cam..best of luck Makr

 

I think that's alotta cam for street 355 & <9.5:1.

Right now, whatever's limiting your revs may be the best friend you have because I think you should replace those 34 year old stock rod bolts with new.

 

yea the cam was what i was told would run good with the combo at camaroz28.com apparently the guy meant all out drag cuz it has no torque....

rod bolts sounds like a good winter project lol