Fred, thank you for all the helpful information! I just picked up a motor with a set of "291" heads. The entire casting number is 39171291. Is there any way to tell if these heads have 1.94/1.50 or 2.02/1.60 valves without removing them? Searching the net it looks like these are from a '67-'69 302, 327, or 350. I would love to narrow this down and determine what the came from to know exactly what I have. Is removing them the only way? FYI, the engine block code (V0306TJZ) looks to identify it as a '73 truck 350 so it looks like the heads were added later. I'd appreciate any info. you may be able to share. I'll attach a few pics of the heads. Thanks, Tommy
Great thread!! I'm building a mostly stock 327/275 HP engine. It currently has small valve (1.71 intake valves) 290 heads. Factory QJet and cast iron manifold and stock ram horns. I'm going to use a different cam. The correct 275 HP head casting calls for the 462 casting. I friend of mine gave me a set of 461 heads w/1.94 intake valves. My goal is for the car to be street driven on 91 octane gasoline. Does anyone see a problem using the free 461 heads or should I find some 462 heads? Can the 461 combustion chamber be messaged to look/act like the 462 chamber? I'm concerned about compression ratio being too high. Thoughts? Thanks.
Usually I bitch about 900 year old posts being bumped but like as has been said this is good info and should be someplace that it is easy to find. I am not the world's biggest camel hump fan but they are good heads if you can find a good pair and they are old school which makes them a double blessing.
For those who give a rat's ass about fueler heads--- Nothing wrong with bringing back old posts as long as they stay relevant and informative. Have not reread the whole Marryann here but someone brought up the "291" heads, they may be on the edge of traditional here for some but these were kind of a transition head. They were a mid to late 67 casting for the 68 product line, replacing the 462's, they look just like the "fueler" heads of the past with the large camel hump, but do have one slight physical external giveaway as they had the new water temp. sender location between the exhaust ports, these were the last castings prior to the 69 and up "186" style castings that got the accessory bolt holes. Years ago I acquired a pair of NOS castings in GM boxes labeled "initial Corvette stock", as well as 2.02 valves, springs,retainers, keepers, and rocker arms (O stamped). These heads were also used on the 68 Z28 Camaro's (302). These heads did not have screw in studs and guide plates as many people have thought. I have often heard of these referred to as the predecessor to the 292 "turbo" heads that were available across the counter around 1970.
Double-hump heads will fit the small bore SBC engines IF you use lift-limited cams!! I think around .440" lift is about it before the valve start hitting the tops of the cylinders. BUT check here for sure. I have an old TRW hy-cam PN TP-146 that is spec'd at 308/244, 108/106.5, .429" lift that came out of my Nephew's '66, 283 that I now have. Engine had flat-top rebuilder pistons in it, thick composite head gaskets, the blue jobbers, along with a good pair of big valve -291's. I figure the reason he had it was because whoever put it together dumped it off on him after finding out that it wouldn't pull a fat whore off the throne!! My pretty-much virgin big valve -461's cc'd at 66 and 66+ cc chamber-wise and have right at 160 cc intake ports. You can see/feel the factory plunge cuts around both valves. BUT it is way more noticeable around the intake valves. Maybe around the exhaust valves is just a roof dress-up and not really a plunge-cut?? Remember, the old -461's are the original fuelie heads and have a double-quench chamber design. They are not laid back by the sparkplug. I think the 360Hp-FI/327 engines got the 1.94"/1.50" valves and the later 375Hp-FI/327 engines got the 2.02"/1.60" valves.. Fwiw, I have an old pair of '56, 265, -306 trough sparkplug heads just to have. I measured them and they have 60 cc chambers and 118 to 120 cc intake ports!!!! Talk about SMALL ports!! These are the heads that have the plugs in a "trough or notch".... Also have an old pair of 305HO, -601 heads! Now these are jewels IF your CR won't be too high.. They cc'd at 53 and 55 cc's chamber-wise and right at 160 cc intake ports. They have the 1.84"/1.5" valves and hardened seats. They look very much like the old -461 heads because they are a "double-quench" chamber design like the fuelie heads. The 305HO, -416 heads have more squared-off chambers like smog heads....... Not double quench.. Hope this is of interest. pdq67 PS., original 283 power-pack heads have a triangle on the top of the flat on the end of their heads and they have right at 137 to maybe 140 cc intake ports. This is why those old engine ran so good, imho...
Like Roothawk said : I put a pair of 1.94 on a stock 283 with a 097 cam. It wouldn't get out of it's on way. My C/R probably was 6.5 to 1. I learned from that. But with the right pistons they will scoot.
Right, had to have the CR up there. My old junk301 that I made out of a wore out SJ 327 standard bore block, a '55, 265", 3" crank, unknown heavier 283" rods, not the skinny stock 265" jobbers that are like the lo-po 305" rods. Heads were '55, 265" ones with little valves that I ground hell out of. .020" thick MrG steel shim head gaskets. A junk engine -097 cam that I coffee canned the solid lifters. A new $39.95 set of W/JCW 1/8" over, 283 cast pistons with 1/8" tall, 1/2 round domes on them, my 350's Q-Jet intake and exhaust manifolds. These were like the old 283FI pistons. My engine was unbalanced to boot and I could tell my rpm by the harmonics as I went up to above 7,000 rpm with new points! He, He!! It threw two dampers off running like 55 to 60 mph down the Hwy!! I had 3.31 reg's so I just rolled her out easy and once she hit 3,000 rpm nailed her up to above 7,000 and repeated through my M-20 Muncie! What a hoot, not much power but oh so fun!! I figure I was making like 325hp back then before I knew anything much about how to really produce power. pdq67
The OP seems very knowledgeable but this info^^^ is wrong. Copied from elsewhere. This guy is correct. You can't tell a 461x head from the top side. There is no "X" under the valve cover. The x in 461x heads is cast in the under side of the head under the water passage. "...461x heads were mostly 1.94,1.5 valves with some 2.02s the X was never in the cast # under the valve covers between the rocker studs but was cast on the under side of the water jackets on the intake side on the ends of the heads they do have 170cc intake runners and were the best factory heads in the early 60s(most were cast in 63-64,65, with some 62 66 date codes, they were The head to have in stock and super stock classes and came mostly on the hp corvette 327s with and without the Rochester FI but could be found in other models with hp 327(ss chevelles ,ss impalas and are highly sought after by collectors for restorations and by street stock roundy round racers. check out the ebay listings for original un modified 461x and most are getting well over $1,000 for them compared to $200-$500 for the other (461,462,186,ect.. )camel hump hp small block heads. one last thing they will support370-400 horse power even in 1.94 valve sizes, proper porting with 2.02s(attn.to un shrouding) will support 450+ and maxed out welding by a few elite porting gurus have gotten 600+ out of these suckers and if you think i am wrong check out some of the NHRA records that still stand today with these heads
Got a set of 492 factory 2.02's. Old scrapper claimed to have pulled them from a wrecked 70 Z28 in 1972. Hmm, story sounds good but the heads look great, the dates check out and the hardware is all GM, so maybe. I'll get a pic of them for this thread next time i'm at that shop. Also got a pile of 186's and 462's that need machine work, not worth putting the money into at current machine shop costs. Got a giant pile of 882 smoggers, some have decent seats with valves riding high, can't bring myself to scrap them. I'm still gonna run vortecs, unless I get into a period correct build.
"Double humps, an AFB, an 097 Duntov and a .125 over 283---recipe for revving'." I agree as long as your compression ratio is up there and not like I did. Mine sounded great but no power.
Some great info here and I had forgot that I subscribed to this thread until it was bumped. I have been messing with some of these heads again lately and good to brush up on what I knew or didn't know.
Several aftermarket aluminum heads are now available that look identical on the outside to 461 heads but have the the better flowing Vortec ports and high turbulence combustion chambers. These support higher compression without detonation than the old heads. They cost about 1400 bucks a pair. ready to go.. some might bitch about modern heads but do the same bitch about 5 speeds and better brakes?
If I ever get around to building a car with no hood I will be giving those aluminum humps some serious consideration...
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