400 small block !!!!! having some head issues and need some advice

I recently purchased a 1987 monte carlo ss with a 400 cid sbc for me and my son to build together... I pulled the motor to rebuild and repaint etc. and I realized it has two different heads on it casting numbers

468642
462624

I checked on mortec and all they tell me is they are from 75- up 350-400 heads !
they look totally different to the eye right next to each other as for casting design , that's what caught my attention ! but bolted to the motor its not very noticeable
so my question would be are these heads ok to use together ,(they both have 1.94 intake and 1.5 exhaust valves) the car ran fine before I took it apart , or should I get a new set of matching heads , and which ones... its just a nice cruiser car with a little get up smoke the tires kinda deal... my son is 15 almost 16 and its his favorite car and going to be his driver... which heads should I go with 305, 350, or 400 ? I know about drilling the water jets on the 350s etc but I have not much experience building 400 motors just looking for some advice and direction so I get the best bang for my buck but want to keep it mainly close to stock it being his first car ! I have a 383 stoker sitting on my motor stand but he is not getting that !!! the block number is #3951509 400 sbc 2 bolt main( eldebrock intake with eldebrock 4 b carb normal distributor shorty headers) so keeping it close to stock with the basic pretty up visual stuff and performance upgrades .... which would be the best bet for my heads ? use what I got or ???? find new set and which ones?? thank you in advance for your advice and thoughts ....

I'd suggest a set of Aluminum Heads if the wallet can stand it..

If you're concerned over finding a head to match one of the existing, then you'll probably need / want to at least investigate the condition of both heads... you're going to lay out some cash anyway.. the alloy heads won't be so expensive when compared apples to apples.

Something to consider..

OH, and welcome to the club. It's good to see you here!

both heads look to be 76 cc so if engine was rebuilt one head could of been crack so then other casting would be put to use . this is a common deal long as valves size is matched not to big of a deal. i just did two sets of boat engine one had busted heads so i mached with head chamber cc and valves size . casting numbers told me the new heads for the engine were same valve and cc . some heads came with 3/8 ex stem but will work fine gm over the years cut the casting weight by the out side of the head is more scalped out and more open deck . but if all size i posted engine just will not know

In my opinion ,the money that it takes to make a set of factory heads decent ,you can buy aftermarket for the same or a little more.I use Iron Eagles a lot ,I can get them really reasonable from a local Dirt Track dealer and I have never had any problems with them.
If you take a set of stock GMs Hot tank and surface them ,install guides , three angle valve job, springs and retainers , maybe replace some valves. Well around here that usually means a shop bill in the $600 range.
Like I said just my opinion, I could be wrong.

If a set of factry heads are from the later 1970s(after cat converters/lead free gas) they will have induction hardened seats and won't be expensive to refresh---if its for a driver that has been running good but you just want to freshen it for driving (not racing) there isn't any reason to go and spend thousands on aftermarket late model aluminum or spec type iron heads.


If you are going to race the car its a little different story--but also keep in mind the thousands you'll also spent on suspension and wiheels /tires/brakes------------

my read on this was he has a 15 year old son that wants to get has feet wet with out a lot of $$$$$$$ so he as two head cast that work fine but numbers do not match so i said it happens alot if the chamber and valve size is the same then there be ok . ? is this rigth?? so that went from two heads out side miss match to hell DAD buy new heads ?? as jerry said they do not cost that much to rebuild and i would concur .if the heads need work then see if the machine shop can match the head if in good shape . then ask the guy whats the cost of a stander valve job and you have a budget . he may throw you a deal i know a guy that has done that were all machines are all set up for small blocks and as a surplus of parts. i am not going to say on here the time it takes.other then this it is very fast moving forward job :) i keep most all parts in the shop for small jobs like this seats .valve .guides.seal. in the shop. so there no stopping . the mag/ cleaning of heads they will be in the hot tank and jet wash longer that it takes all the time. to put all new guides in and a valve job and deck the sbc heads are easy as pie with the machines set up. i roll threw sbc heads . now bbc with iron head beat the hell out of me

As has been said, it all depends on the machine shops that you have to choose from, their ability to do quality work and how they price this specific job. If they're pricing high then you might buy a set of new, matched heads for about the same as you'll pay to have yours re-done, but if they're already set up for the job and want to toss you a good deal you might get it done for a song and be ready to go again. I think Pat's point that sometime in the past one head got replaced is likely the case, and can't see that it would be any problem, but I'm not a machinist.
If you're not in a hurry you might see if a shop is willing to hold your heads until they have a "run" of SBC heads, and take advantage of someone else paying the setup time, or at least sharing. Sometimes a flexible schedule can be of value.

to embellish on what Pat said about being set up to do work----I also will do whatever BBC, SBC, Ford,etc that are here for work while the machines are set up for that brand work as the set up time quite often is lengthy and we can be much more effienct/accurate doing jobs that are similar compared to strict in and out times---------

guy get that glazed over look when i tell them it the same guy running the machings for a oem valve job 185hp v8 to 1000hp+. the work is held to the same spec as if it 2.500 intake valve or 1.950 intake valve . i can take more brakes take a longer lunch but when the machine is set up it running it clips right along and is right as i can make it .i could do head work all day .but boring engine blocks brakes up the week . hey jerry i have a new 351 ford iron boss block ford claim it made out very strong iron? i deck it cut much the same as all Dart stuff i think dart use the same fourndy as ford see alot of McC on iron castings ? .honing blocks out realy is starting to beat me up that about the only job if v8 i save to the end of the week i have two days for rest

that's the reason I got a CK10-------


the decking process is where it is especially benefitial to do common engines ----with BHJ plate and main supports it can take more time to change setup than it does to cut the decks

Quote:

---

Originally Posted by jerry clayton

that's the reason I got a CK10-------


the decking process is where it is especially benefitial to do common engines ----with BHJ plate and main supports it can take more time to change setup than it does to cut the decks

---

yes well i keep going with my hone works just fine if i was boring 4 blocks a week i would spring for the11000. 14000. for a used ck10 . as for bhj deck tru had it for many years now. i make my set up rings but the bbc 2.937 ring works on the 351c .bore and FE blocks the 460 work on the 351w have the BHJ bore tru.there piston vice. there stuff deck plates iron and aluminum and some . i still deck blocks on the Storm vulcan with speed contol and run CBN with the Berco

The heads are proven to work in the application.

Let the budget decide if they get scrapped, not the cosmetic differences.