Cylinder heads factory-engineered to deliver performance for small-block engines. These cylinder heads are direct replacements for OEM heads on 1987 and newer GM Small-Block V-8 engines. Vortec Bowtie cylinder heads are the most powerful cast-iron heads offered by Chevrolet.
With a small CID engine like a 283 (.060 makes it a 292), I'd be looking for a pair of casting #601 305 heads. You can probably get them for next to nothing, if not free. 53cc chambers, some even came with 1.84 intake valves, the usual port/spring work, and you're set.
That's unless you have a wad of cash burning a hole in your pocket, if that's the case, one of the aftermarket head companies makes a SBC head with 49cc chambers. Dart or World Products, I forget which.
Any head with more than 60cc chambers, and you're going to lose compression. Click to expand.Not saying they didn't build any but I tore down several '63 and '64 250 HP 327's with 520 heads as a kid and never found a single one with 1.94 valves, they all had 1.72 intakes. In '65 the 250 HP was switched to the 461 heads with 1.94's.It's all about matching the flow to the engine, mixture velocity is the key and bigger is not always better. Somewhere I have a scan of an old article from Car Craft back in around '84 where they did a comparison between 461's and a set of well prepped 520's on a.030' over 283 in a '66 Chevelle with a 4 speed and 3.31 gears.
It was a real eye opener, I can e-mail it if you'd like. They didn't do anything radical to the 520's just a little mild port work and a 3 angle valve job on the 1.72 intake valves but they kicked the 461's butt. They maintained a higher mixture velocity on the little 287 than the 461's and it responded accordingly with better gas mileage and lower ET's. If you wanted to get a little more top end the 1.84 valves from a 305 fit nicely without having to modify the combustion chamber.Believe it. You can make most SB Chevy heads run well for what you want to use them for and considering the engine size. A SB Chevy will run with the big dogs. All it takes is a lot of long green rectangular money instead of a lot of cubic inches.In 1968, I installed a beautiful pair of slightly used '692' Power-Pack heads and some early style staggerd bolt Corvette valve covers on my '59 Impala 2-door H/T, 4-speed w/4.56:1 Positraction.
I installed a over-the-counter 1965 327/375HP FI factory short block using a factory 409/409 oil pump and the 1965 30/30 FI camshaft. In 1965, those '692' heads were sent to California and were ported and flow tested by Joe Mondello for $700. Mondello milled them to 58 CC chambers for 11.5:1 CR with the Corvette FI pistons. The heads were converted from the original 1.72/1.50 valves to 1.94/1.60 valves. The 2.02' intakes would not fit the combustion chambers. They were first used on a C/FD in 1965-1967 with a short wheelbase chassis by Vance Hunt / Ed Mabry before I purchased them in the summer of 1967.They were excellent heads and helped my 3800 lb.
'59 Iplala to a AHRA National Record at 13.10 ET in F1-E/HR at Odessa Raceway Park at Penwell. I traded the Impala for a 1967 Firebird 400 convertible with 4,500 miles on the clock. The new owner of the Impala blew the clutch and trashed the SB Chevy motor then installed a 396/375 HP engine, a real asshole.
Duntov knows of what he speaks, evidently those early heads had a bit of extra metal allowing some fine port work to be done. I remember the Jr. Fueler my friends ran in '66-'67 had the 2bbl marking on the end of the heads, is that what those are/were?Back to your question, I'd definitely get those power packs, but just do a bowl clean-up and remove any rough stuff in the ports that you can reach. Don't gasket match but do square up the intakes, and smooth the exhaust as much as you can. Also smooth over any sharp edges in the combustion chamber to prevent hot spots.
For valve seals I like to run those cheap umbrellas that came on smallblocks in the 80's and discard those oil shields, this saves valve train weight, but do use the square cut O-rings below the keepers. I also like aluminum retainers although many will argue the sanity of this, they've worked for me on the street for ages with no failures, but I run old style performance cams, and you most likely know the newer grinds have higher lifts and more agressive acceleration ramps that require higher valve spring rates and might be the death of anything short of steel or titanium retainers.
Not saying they didn't build any but I tore down several '63 and '64 250 HP 327's with 520 heads as a kid and never found a single one with 1.94 valves, they all had 1.72 intakes. In '65 the 250 HP was switched to the 461 heads with 1.94's.It's all about matching the flow to the engine, mixture velocity is the key and bigger is not always better. Somewhere I have a scan of an old article from Car Craft back in around '84 where they did a comparison between 461's and a set of well prepped 520's on a.030' over 283 in a '66 Chevelle with a 4 speed and 3.31 gears. It was a real eye opener, I can e-mail it if you'd like.
They didn't do anything radical to the 520's just a little mild port work and a 3 angle valve job on the 1.72 intake valves but they kicked the 461's butt. They maintained a higher mixture velocity on the little 287 than the 461's and it responded accordingly with better gas mileage and lower ET's. If you wanted to get a little more top end the 1.84 valves from a 305 fit nicely without having to modify the combustion chamber.Believe it.
I've been watching this and other threads trying to make up my mind for my 283' project but am fuzzy about the term POWER PACK HEADS. So far that term has been applied to #3731539, 283' (also called a 57' 'Fuelie' or 57' 4bbl head), #3748770 (58') 283', #3795896 (63'-65') 283', #3837064 (56'-62')265'/283' and now in this thread '520s'. The CAMEL HUMPERS (per MORTEC) are: #3890462 (62-67') 302'/327'/350',no acc. Holes,64cc., #3782461= (64'-66') 327' only,no acc. Holes,160/62cc., #3782461X (60'-63'),no acc.
For use on 283' or 327'. NOTE THE 'X' suffix to that one indicating that it is the only humper that will work on a 283' (per factory).Someone also said 'A 2bbl head with an Edlebrock 500 would yeild the best overallfuel mileage with suprisingly good low end torque due to high flow rate'. Is this the '520' head you all are speaking of? (the #3884520). Thanks to All.
I'm no expert but this is what i ran into. I just built up my 283 40 over fuelie pistons and i checked out two sets 896 520's and 461x's. One set (520) is box stock and the others ported 896-vortech 1.94 valves. Power Packs are both identical in the ports and pockets, lots of meat. The real trouble with converting to 1.94's is the careful grinding it will take to open up the bowls under the vlave. The chambers will also need unshrouding so I dont think there is any advantage unless you also do all the work for a better flow.
If you have a set of camel humps, then just bolt those on and go. I spent at least 2days grinding on my heads than compared them to 461x's and figured i shouldve just bolted on the 461 x's with a mill job and good bowl cleanup.Oh! And by the way in the process one head got screwed up when we were trying to open them up(hit water) in the bowl. Spent a few days looking for another matching head. Its a big step up from little valve to big ass valve -learning curve there However it can be done if you take it to someone who knows what theyre doing and it will cost you money.The heads you see on my motor are the stock 520's with a good wire brush cleaning to remove rough casting flash in the bowls/ports and 305 vortech valves are used. I have fully ported 2 1/4 rams and 30/30 solid to go along with it.
I've been watching this and other threads trying to make up my mind for my 283' project but am fuzzy about the term POWER PACK HEADS. So far that term has been applied to #3731539, 283' (also called a 57' 'Fuelie' or 57' 4bbl head), #3748770 (58') 283', #3795896 (63'-65') 283', #3837064 (56'-62')265'/283' and now in this thread '520s'.
The CAMEL HUMPERS (per MORTEC) are: #3890462 (62-67') 302'/327'/350',no acc. Holes,64cc., #3782461= (64'-66') 327' only,no acc. Holes,160/62cc., #3782461X (60'-63'),no acc. For use on 283' or 327'.
NOTE THE 'X' suffix to that one indicating that it is the only humper that will work on a 283' (per factory).Someone also said 'A 2bbl head with an Edlebrock 500 would yeild the best overallfuel mileage with suprisingly good low end torque due to high flow rate'. Is this the '520' head you all are speaking of?
(the #3884520). Thanks to All. Click to expand.Any of the 'pyramid' heads are commonly referred to as 'power pack' heads. Beginning in 1956, the 4 bbl. Engines got the cylinder head with the small 'pyramid' or 'point' on top of the rectanglular casting protrusion on the end of the head.
This practice continued (with half a dozen different casting numbers) through 1962. Beginning in 1963, every passenger car 283 got what was formerly the 'power pack' head, 2 and 4 barrel engines both. The 461, 462, and 291 casting numbered heads are commonly referred to as 'camel hump', 'double hump', or 'fuelie' heads, and have either 1.94/1.50 or 2.02/1.60 intake and exhaust valve sizes. The 'fuelie' moniker came from the fact that the first engine to get them was the 315hp 283 F.I. Corvette mill in 1960. A few of the early '60 fuelie heads were cast of aluminum, but porosity problems nixed that idea early on; I've seen two sets of aluminum fuelies in my life.
The 520s are part of the 'power pack' family.
GM's Ontario, Canada, plant-manufactured engines for some of its older-model pickups and for the Studebaker Corp., a South Bend, Indiana, automaker. Casting numbers 3731556 and 1816887 were used on the 1957 and 1963 Canadian-produced 283-ci GM trucks, respectively. Number 3884520 is stamped on 283 Chevy engines, which were also used in the Studebaker Lark passenger cars. Number 3884520 identified the 327 used in the 1962 to 1967 Chevys, the Studebaker Avanti and the independent Avanti II after Studebaker ceased production in 1967.