i have a 73 chevy 400 in my 89 firebird-they have got the stock 1.96/1.5 76cc heads on it right now and i just got a set of 3890462 camel hump corvette heads (66-68) i know they have no accesory holes but would these be worth building up-they are 2.02;s and i recently read on a website that they were "the best flowing head gm ever made"

 

Best flowing head made by "GM" back in 1968. Lots of better choices available now.

They already have 2.02/1.60 valves. That's a good start however:

Does it need a valve job (regrind)?
Does it need new guides?
Does it already have screw in rocker studs?
Has it been cut for larger valve springs?
How old are the valve springs?
Have the heads ever been resurfaced?

If you need to invest a lot of money into these 30+ year old heads, it would be cheaper to buy a set of aftermarket heads. They'll be better right out of the box than what you'll end up with with the old heads.

With all the good aftermarket choices available now, using old technology heads isn't really worth it unless you can do all the machining work yourself to save money.

Sell the heads to someone building a numbers matching car or to someone who races in a class where they need the old castings.

 

yup, what he said.

 

Without the accessory holes, you'll have to find a way to mount an alternator and a PS pump without bolting them to the heads. That would be interesting, to say the least. Those heads also won't work well with modern fuel, as it doesn't have any lead in it anymore, like it did back in 1969.

Put 'em on Ebay, and use the money to find some 083 heads, or something else that DOES have the holes, and is compatible with modern fuels.

 

i know ill have problem keeping the power steering and alternator problems but im just wondering about power right now-the cars best time was a 12.87 @ 109.mph(yeah high mph due to the stock gear 3.42) im just wondering how much these heads would pick me up compared to my stock 1.94's i have now

 

Those heads could make a pretty good deal more power than the 993 or 882 heads you probably have on there now. The CR would be much higher, and they are better flowing heads. But if you can't use them in your car anyway, what does it really matter?

 

just curious

 

...What they said, the older heads are better than what you have, but quite honestly they are boat anchors. For what it would cost to be gone through and ported you could get a set of Vortec, port match/hit the bowls and have a great flowing street head. May have to use a vortec base though.

 

Personally I feel the same way about the vortecs. By the time you pay to have the machine work done on them, and buy the cores, and replace the valvesprings, etc., you should have just bought aftermarket.

 

ok i really dont know much about heads-so i was wondering is there anyway you can make 1.94 into 2.02's---and you guys keep talking about these vortecs-how much would they cost me?-and do you any of you guys have a set of sbc 2.02's for sale?

 

Yes you can jam a set of 2.02" intakes into just about anything. Even a set of 305 heads with 1.72" intakes. Big deal. If the valve isn't the limit to the total flow, then you could put 6" valves in it, and it won't make any more power. It would be a waste of time and money.

Why are you so fixated on the intake valve diameter? It's only one piece - and often, not even the most important piece - of what makes a head good.

A better way to approach this, is to first identify a set of heads that FITS YOUR CAR. Forget all heads that don't, because no matter how curious you are, they won't do you any good. Concentrate on ones you can actually use.

The next thing to do, is to look at your overall goals. A fast street car? A reliable daily driver? Occasional bracket racing? Get yourself a new Sunday afternoon job wearing a fire suit uniform? Each of these things requires something different.

A set of Vortecs with 1.94" intakes, will mop up the floor with a set of 462s with 2.02" valves in them. Likewise, a set of 462s with undercut-stem 1.94" valves and a good port job (NOT yerbasic backyard hilljack "hogging out") will flow at least 20% more (make 20% more power) than a set of stock ones that somebody has just jammed some 2.02" stock (straight-stem) intakes into.

What do you expect out of this car? What kind of money are you willing to spend? What is the rest of the car; cam, pistons, bottom end of the motor, transmission, gears, suspension, weight? How much is it driven?

 

well i only ask these questions because i actually have a set of these heads adn im not really in the money if ya know what i mean-the heads need work and i called around and it would cost about 2-300 dollars having all new valves/springs- 3 angle valve job and all those other little things-\

the motor is a 73 chevy 400-292/501 cam , stock pistons -vitor jr intake -holley 750 carb -accel 8.8mm wires-hei super coil- turbo 350 trans and the stock 3.42 open rear end.--the best time this car has ever ran was a 12.87 but that was in good weather -on average it runs about 13.00--my main goal of this car is to still be streetable and possibly crack 11's but would settle with low 12's--i also i plan on gettign an electric water pump and a bigger cam---pretty much the only thing on the motor stock is the heads and pistons-so thats why im looking into good heads and ive heard good thigns about 64 cc 2.02's (the camel humps were taklign about) adn bad things about the ones i have on here now (76 cc truck heads -1.94) adn ive had multiple people tell me 400's love 2.02's and that it would pick me up a bunch--but either way id just like to get a set of heads that would pick me up at least 4 tenths-adn if these heads would do that its all im worried about-i would much rather go out and buy a set of new ones but i aint got much money =the accesory hole thing is a problem but ive read elsewhere that i can drill the new holes--and yes i can get the work done cheaper because most of family races adn they knjow how to do most of the work------but on top all of this lol ive read that gm made two different size 3890462's they came in 1.94 and 2.02's with the same #--so maybe all this time ive been arguing abotu em for nothign lol

 

the car really is fast enough for the street considering im an 18 yr old in high school-i mainly just want to race it and like i said run low 12's or high 11's =i never plan on driving it far on the street-all i pretty much would like to do is drive it to school every once in awhile and show it off-ive always got kids talking about there cars and how fast they are and say they could beat me-i never street race and prolly never will but its still fun to start it up and shut all the **** burner kids up about whose car is faster

 

You can't drill the holes. There's no metal there to drill. Did you read the other post? Look at the pictures? They kind of tell the story. In heads with bolt holes, they added a big boss of metal back there behind the hole, so there's something to drill. Without that, all you have to put the bolt in, is a "sheet" of cast iron about 1/8" thick (2 threads) that goes RIGHT STRAIGHT INTO the water jacket. So, please try to understand: there's a reason you got them for super-cheap. And the reason is, THEY DON'T FIT ANYTHING that's been made in the last 35 years, including your car, and nobody wants them because of that. PLEASE DON'T ruin them, like SO MANY people have destroyed SO MANY sets of those heads over the last 3½ decades, by attempting to drill them. It won't work, and all you'll end up with, is some scrap. The heads will no longer be any good for anything at all.

400s don't care what the valve diameter is. The short block doesn't look up at the valves and whup out its micrometer and say, "OK, these are 2.02 inch, I'll run good now" or "Yuck these are only 1.94s, I'll just be a slug". All they care about, is FLOW. Which is, how much air gets into and out of the motor. In a nutshell, the amount of work you get out of each cylinder, is proportional to the number of gasoline molecules you burn in it, which in turn is proportional to the amount of air in it, which in turn is proportional to the size (cubic inches) of the cylinder. Then, since the definition of power is the time rate of doing work, the more times per second you can fill and empty that cylinder, the more horsepower you get. And that is ultimately determined by FLOW.... and NOT NECESSARILY by the measured diameter of the intake valve.

That's what makes the Vortec heads so good. GM moved the whole intake port upwards on the intake surface, like over a quarter of an inch; which gives the air a MUCH straighter shot down the port and into the cylinder; which means the port FLOWS more, with the same 1.94" valve and the same port volume as any other stock 350 head. That's yet another good example, besides the undercut stem technique, of increasing the FLOW, besides just increasing the valve diameter. Which won't increase the flow of crappy heads anyway.

So, rather than destroy those old heads, go to the junkyard, and ask them for a set of heads for a 97 Chevy pickup. The casting numbers you want will end in 062 or 906. Don't utter the word "Vortec" (because if you do, they'll know you're a hot-rodder and not some grunttrying to fix his broken work truck), and don't mention the casting number; and don't settle for "almost as good", "early Vortec", "Vortec 305", "87-95 heads", "same thing just looks different", etc. If they bring you ANY OTHER casting number, tell them they're the wrong ones; but DON'T tell them how you know, just tell them they're different from the ones in your construction company pickup, and you want to make sure you get the right ones.

Those heads are 64cc chambers, and will outrun just about anything you can do to those old ones. You should be able to get a pair in running condition for something in the $250-300 range.

The only work you'll need to do to them, is to get a set of replacement valve springs, from the speed shop not the parts store; and a set of .050" offset valve keepers. DO NOT attempt to run them without those parts, or YOU WILL SURELY bend or break or otherwise destroy parts. You will also need an intake manifold, which if you sell the one you've got, you'll be able to get at least half of what it will take to trade up.

 

listen to these guys ^^ , some of them have been building engines and racing since before you were alive.

i'm curious to know how on earth you got those stock, 185hp rated, boat anchors, with probably 8:1 compression to pull your car into the 12's @ 109mph? did you personally do this, or did the guy who sold it to you tell you it would go this fast? was it REALLY windy that day?

with that cam and those stock smogger heads you may actually be making less average HP then the engine did when it was stock in 73.

vortecs are nice, but only if you get a really good deal on them, in my opinion. once you've paid to have all the machine work done to make them a reliable performance head (dont forget the 160$ intake manifold too) you're in aftermarket territory. but to each his own i guess, they'll certainly get the job done.

 

i personally ran this myself -it ran 12's many times-and the average mph was about 106- -- and your not the first person to scratch your head about this-its one hell of a bracket car-people try to judge my car at thousand foot mark then i hit 3 rd gear and it just takes off -you wouldnt believe how bad it messes guys up-and theyre always asking me how it runs so fast

 

i just found a set of those 906 vortec heads on ebay for 250 and i could pick them up because its only 10 miles away--do these sound like they would be worth it and do i really have to get a new intake? cuz i personally like my victor jr.

 

What track do you race at? just curious, im in ohio too..

I would pull them valve covers and check the head casting numbers to see what you have. You wont be trapping that high with any stock 70's smogger head. Just for future reference, the stock diameter intake valve for "most" 350/400 heads is 1.94, not 1.96, not sure if you were just mislead, or if it was a typo.


If your trapping 109, you dont need new heads, you more then likely need a new rear-end, stall converter and tires.

 

i race at national trails-and i found out what kind of heads they were from tearing the valve covers off-and yeah 1.94 was a typo sorry-yeah my stall convertor and rear end do suck which also prolly made a difference..but tires were good size--the heads are stock but they have roller rockers and all new parts -you wouldnt believe the deal i got on the motor-

chevy 400
victor jr intake
292 /501 cam
stock heads with roller rockers
double roller timing chain
and nice set of valve covers
block was freshly rebuilt from bottom and had only been ran for 15 minutes-250$

 

Half tempted to change my opinion, didnt realize the size cam you are running, assuming its the Comp 292 Magnum cam?

IMO a 190-195 head would be perfect, but you are limited on funds, understandable. Fwiw, you can buy upgraded Vortecs brand new from Chevy with sufficient vavespring, but the price does creep up a bit.

The motor you have is the old recipe for a 400hp motor-9.5/10:1, ported camel humps, Victor Jr, etc. Lots of alternatives to make more power with smaller heads/cams. Not shooting you down at all, just letting ya know.

 

YES it is the comp magnum cam--and dont worry about shooting me down as long as ill benefit from your advise im glad to take it-i know a little more then the basics of motor/building them up and i know you guys know alot more -thats why i ask lol--but from what im hearing form everyone is pretty much go with vortec heads as long as they re 96 and up -and money wise i think i can handle that-now with getting a vortec intake makes it questionable -more so because it makes me feel kind of stupid to buy another intake when ive already got a good one-but im gonna look into it -but like i said i dont care what i get i would just like my car to pick up say half a second with touchign rear end or transmission/ although i am looking into a posi unit because i have had trouble hooking up

 

type o-- * without touching rearend or transmission*

 

What is the casting number on the heads that are on the motor now? If you're trapping at 109mph they probabily have been worked over a bit. Some of the smogger heads are not bad when ported. Such as 487x 441(X) 920 336 etc
while 624's and 882's leave more than a bit to be desired.

You would knock off a good .5 sec or more with a high stall
3500rpm +converter and 4.10's and slicks.

You can try advancing the 292magnum cam a bit in the motor to increase average torque. (advance it 4deg)

 

well since im prolly screwed on the camel humps and vortec sounds good but im not into having to buy the heads and intake- either way im looking at these 14011034 bowtie heads -they are 64 cc 2.02 / 1.6 and have been ported and polished adn the correct valve springs for my cam -does this sound like a better idea?--i figure the 64 cc could boost my compression up considering i got the 76cc now and stock pistons

 

Bowties are nice heads. Very nice when properly ported.

Many 034 bowties that are offered for sale are from circle track motors. Many have been milled or angle milled to increase compression. That often makes them not usable for a street motor unless dished pistons are used.
Just be sure of what you're buying. Check for cracks and excessive milling beore you lay down the $$$'s.

What heads are on the motor now? I'll bet they have been shaved to 68cc and ported if you're trapping 109mph.

 

ill look into the heads some more to make sure--ill have to go check and make sure what heads are on mine now-i know for a fact they were 76 cc from the day i brough em home and ran the#-and the guy told us the heads had all new parts on em but not performance upgrades

 

the bowtie heads have been flat milled and they have 200cc intake ports (isnt that pretty big?) and a mild port job--he said with my stock pistons the valves could hit the pistons-and that the valve reliefs might not be able to accomodate 2.02 valves-does this sound right--and in order to fix that he said to fly cut the intake valve reliefs

 

Actually, if you look here, you can get custom brackets to use the no-accessory-hole heads on a modern car. I only saw for the alternator, but there might be other brackets as well.

http://www.alangrovecomponents.com/index.htm

 

http://marchperf.com/

check this place out the brackets are crome and the dress up value is great, i am not sure of the pricing since i havent been to the site in a while

 

Bowties have 184cc ports as cast. Porting would make them larger. Wether they are too big depens on your engines specifics. The only way to tell how big the ports are now is to cc them. Milling will move the valves closer to the pistons.
usually not an issue until block is decked and lot and heads are milled a lot and cam duration exceeds 255@.050.
The only way to tell for sure is to check and verify valve to piston clearance on your motor. That is ultimately up to you.
is your block decked? what cam? what gasket? what pistons? I would cc these heads before purchase.
If the seller bocs, pass.

 

i finally took the valve covers off and checked out the head numbers -3998920-

 

920's are some of the better of the early smog era heads.
They are pre 1975 heavy castings 76cc like 441's and 487. usually from 350 truck engines.

I have a set that I've been working on porting off and on here.

They are prefered not because they flow more ( they don't) but they port up pretty good. They were never installed on hi perf motors or came with 2.02 x 1.60 valves. I'd say if you're trapping at 109mph these head definatly have been played with. They are not stock. You're actually doing pretty good.
Ultimatly the bowties are better heads.

 

well im not gonna argue with you about them being worked on although i was told nothign special was done-all they really have extra is comp roller rockers-yeah i know the bowties are much better but those went too high on ebay-im actually looking around for some vortec heads

 

hey i noticed youve got a 406 with vortec heads on it-have you ran it in the 1/4 mile and if so whatd ya run

 

check out buckeye steel, in columbus. last time i saw they had a set of used vortecs for $250.

you also have to factor in machine work so they'll work with that cam. and you may aswell get hardend retainers and locks too while you got it apart, and the springs aswell which goes with-out saying i guess.

i seriously dont think heads are your bottle-kneck though. you're in suspension/traction territory IMO.

You never said or i missed it, what exhaust setup do you have?

 

the worst kind of exhaust lol-that being the kind you have to take off everytime you get to the track and put it back on when ya leave--for street driving i just have the y pipe and a bullet muffler connected on the end-when racing its just shorty headers

 

1st off: Not all 462's had 2.02 intake valves. Most had 1.94's. 462's have a 68 cc combustion chamber. 2nd: the best flowing head from that "era" were casting number (last 3 #'s) 461. They had 160 cc intake ports and a 64 cc combustion chamber. The ultimate heads (read "rare") were 461X's. These all had 2.02's with a 165 cc port and 64 cc combustion chamber. As you've heard, these all are really "old school" and, although they can make some good power, they are 40 year old tech. Most of them have been whored out and used up long ago. If you have a good set they would be worth more $$$ to a restorer.

I wrote the above so every one knows what's up. I'm in my 50's now, so I was playing with these heads "back in the day".

FWIW: I had a set ot the 034 Bow Tie heads you spoke of. I put them on a .030 over 327 that I built back in the early 80's. They worked great, but I also had 11.5 to 1 compression (.100 high dome with milled valve reliefs) and ran a roller valve train (.585/270 Intake and .590/270 exhaust - both @ .050). This was good to about 7500 rpm and I was running a TH350 with a 3500 stall and 4.56 gears so I was right at 7200-7300 at the end of the 1/4. I'm thinking that these would be some good heads for your 400 if they are not used up too much (angle milled, excessive grinding on the seat, etc). Good luck and have fun.

 

No et slips yet. new combo. A cam bolt issue and no time keeped me from testing it last year. The local track opens in April, here.
Street testing--- . "the butt dyno" indicates its a very strong runner. The new motor now drains the carb's fuel bowls requireing a stronger upgraded fuel system than before (vortec 350) expecting mid to low 12's @110...

 

fbird-88-- i just picked up a set of 906 complete vortec heads for 175-i guess they just pulled em off the motor-im just wondering what all im going to need done to these heads to fit a carburated 400-i see you got a pair of these heads yourself and figure you know what ill have to do-
i know ill need new valve springs but i guess i have to have a certain kind-i plan on putting new valves in other then that i know i need things but not sure what(excluding intake and valve covers)

 

You'll need the valve guide boss where the valve seal sits shortened (about .200") ( high cam lift) You'll need the spring seats machined to match what ever springs you use. The inner seat diameter is larger than on the old SBC heads so most stock diameter "drop on springs" will not fit without machining.
Crane makes one set that does "drop on". But the guide boss still needs shortening. You'll need to either drill and pin the rocker studs, or remove them and machine and tap for screw in studs (and guide plates). If no guide plates use self aligning rockers (hyd cams only).

Why new valves? Are they shot?
You will not see a power gain with larger valves unless the heads are fully ported.
I'd just do a new valve job, pocket port the exhaust side, do the valvetrain mods and bolt them on.

For a factory stock torque converter and mid 3gear use Crane Cam #113801 (HMV278-2)

For a mild high stall 2600 and mid 3gear to 3.73 use
Comp cams XE-274h10

For a 3.73-4.10 gear and 3000+ stall use Comp cams
XE-284H10
or Comp cams Mechanical XS 282s

Your current cam 292 magnum is good but needs a converter 10" 3500 stall minimum and could use more rear gear. use Comp cams 986 or 987 springs. I'd use screw in studs and guide plates with this cam.
Will require machining the spring seats. 1.44"
You can buy the machining cutters and arbor and do it all yourself.

 

well it turns out i just got a 3500 stall-how much money do ya think all of this is going to cost me?

 

now will all .550 lift springs work as long as i have that work done for them to fit?-

 

You mean for the required cylinder head maching mods and parts?

How much of the work can/ will you do yourself?
What stuff from you present heads can u reuse? ( valvesprings etc)

For a qualified automotive machine shop to do the machining
is nothing special. Its routine for a good shop and should not be exessive$$$.
Know what needs to be done and get a $$$ quote $$$.
Some of it you can do for yourself if you buy the tooling and have a good drill.

 

ok so what your saying is the old springs will work they (they have a .535 lift-as long as the machining work is done---adn as for the machining-which of it are you talking that can be done at home-sorry i ask so much-im in high school adn i aint got a job and my dad has to support between my race car and my brothers race car and his is in the middle of being rebuilt so im on my own on alot so yeah anythign that can be done in our garage is helpful to know

 

Most will as long as the pressure is not exessive for a hyd lifter. Comp recomends a pn 986 spring for your 292H magnum cam 1.44" dia. Anything simular will work.
Any thing around 110 to 120seat pressure at 1.75" and 300 to 330 open (.500") is good.
What is on your present heads for springs?

You can do the spring seats and valveguide boss's at home
using Comp cams cutters #4718,4732,4726. You'll need new .530" seals now. You make the spring seats bigger, not deeper. pretty straight forward will a drill.
Then you shorten the gudie boss height with the other cutter. (about .200" is good) Best to get the new seals and measure first. You need a minimum of .060"++ additiional space between the new seal and what ever retainer you use.

For the studs you need to pull them and then machine down the stud boss pad flat for guide plates and then drill and tap for screwin studs. You want the end of the new stud to be the same height as the stock pressed in ones are now.
So do 1 stud boss first completely, then do all the rest to match. You have to flat mill the stud boss to allow for the additional assembled height of the guide plate and rocker stud nut so that the tip of the new setup end up the same height as the old pressed in stud set up. Thats why you do 1 first before pulling all the other studs out.
You don't want the rocker stud boss too short nore do you want the rocker stud sticking way up in the air. you want to maintain the stock geometry.
You may be able to use the screwin studs and guide plates off your old heads
Comp rocker stud puller and tap guide tool #5306

Comp Stud boss cutter #4729

Note: On Vortec heads the exhaust rocker stud goes into the water jacket. Apply silicone sealer to the rocker stud bottom threads before installing them. Torque them down when you have the guide plates aligned properly with the pushrods.

All that is left is the new valve job and maybe religning the valve guides ( bronze liners) if they are worn too much. Let a machine shop do this for ya.
if they need resurfacing cut .005" off the decks to straighten them. (routine stuff)

Stock vortecs flow 228 intake and about 150ex with the stock valves. Stock vortecs work nice out of the box, but.... You can increase that nicely to about 240+ and 180+ cfm while still using stock 1.94x 1.50" valves with a general *complete port job*. Do a 30deg back cut on all the valves too. You can do all this yourself at home. You want to completely port them but you do not want or need to make big huge ports. With the stock size valves you do not need to touch the chambers but can polish them if you want to.
You cannot turn a vortec head into a AFR 227 so don't try.
But you can make a spankin good small port head out of them.
you can price the machining tools yourself online at Summit
to get an$$ idea $$

Do a few head for friends and you make your $$$'s back and more.

If all this scares ya get an old set of heads to practice on but all this can be done at home with an electric drill and a die grinder. A drill press is nice too.

 

i was also wondering about the rocker arms-i have comp magnum roller rocker arms-but i dont know if they are self aligning-and do they HAVE to be self alignign rocker arms?

 

i really dont know -we bought the motor that way-all i know is theyre brand new and theyve ran on my car all year wiht the 292 cam in there-the engine builder seemed to know what he was doing so i imagine theyre the right ones for the cam

 

measure the diameter of the springs. Even a stock diameter high perf spring will not bolt onto a vortec head.
Inner spring seat interferience.
Are they 1.44" diameter or 1.26"("stock")??

self aligning rockers don't need guide plates ( just drill and pin the stud bosses as long as your rollers are 3/8" stud versions. if they are 7/16" version you will need new studs. or use the old ones of your heads.

non self aligning rocker will need guide plates.

self aligning rockers "align the rocker by two tabs or washers in either side of the roller tip. Non self aligning ones do not have these, just a roller tip. they must use guide plates. It's more than likley that you have non self aligning rockers now.
Before ya fire it up be sure yu've oiled up the rocker *****.
may people forget this and then blame the rocker arm for failing.

 

Read this There will be a test...


and this too

 

ok let me make sure i got this right-its ok to use my old roller rockers as long as i get guideplates-adn i need to replace the stud to a a screw in one-and from the article you showed me all it really looks like is just drilling here and there so it really shouldnt cost too much to have done professionaly-id rather not risk us doing it at home considering were amateurs when it comes to heads.-and you advise just pocket porting adn keeping the same 1.94 valves unless i decide to have a complete port job done-am i missing anythign else?