Hey guys. I'm building my first 383 motor. I bought all the stuff off my brother in law. The block is all done. Bored 40 over, clearanced, ready to go. The pistons he gave me with it are Speed Pro 8KH860CP flat tops. Here are my questions. The heads I have are from my 350. They are casting 14102193. I've read a lot of threads on here and everyone seems to say something different, I need to know the CC of these heads. I've read anywhere from 64cc to 76cc. Anyone know for sure. According to Summit, with these pistons if they are 64cc heads, the CR would be about 10.4 to 1. Is that to high to be able to run just 93 octaine pump gas? I've never built a motor with that high of a CR, so I am unsure. I understand from what I've read that these are not great heads, but they have hardly any miles since they were redone, and theres not much left in my budget so I need to make them work if possible. Any thoughts? Thanks alot guys

 

Yes the cr is too high. What is the point of building a 383 if you're just going to run a crappy stock low perf head.
You have the heads there. Why don't you CC them yourself?
Its not hard to do or expensive to do yourself. Then, throw them in the corner and get some decent heads....

Unless you'll be running a big cam and aluminum heads or really nice vortecs along with proper detonation suppressing piston head quench clearance (and a big cam), the cr will be very likely be too high. What is the piston deck clearance @TDC?
If the block was decked the cr will be even higher with a 64cc head.
I would wait till you can buy some real hi performance heads to go with your new 383.
You don't mention what cam or induction you'll be using.
You do not want your street car to have such high compression that on the bad hot summer days and or on a bad tank of gas, or up a long steep hill, it rattles itself to death. Doesn't take long to wreck an motors ring seal quality from detonation and knock. We won't even get into pre-ignition. Makes a new fresh motor into a tired, old motor in a hurray. Then whats all that compression ratio worth to ya?
Excessive compression ratio in the real world (an imperfect world) is a very slippery slope in the long term on a street motor.
The cylinder heads should have been a high priority on your engine build budget plans.

A 350 with good heads will walk all over a 383 with junk restricted low perf heads.
I would look into a entry level 70cc aluminum head with 190-200cc ports for a 383.
Trick flow 23deg 195 ,,, brodix IK200 70cc come to mind. Its only money, you'll get more of that.
If money is that tight trade the 193's for some open chamber 441's or 920's or 336's milled to 70cc (about .050-.060") and do a home port brewed port job on them. Edelbrock performer RPM (70cc) heads work well also for low $$$s
So will a set of cheap 200cc 72cc WP Sportsman II's They make very very good power with some hand porting.

 

thanks for the reply. Yeah, I knew the heads would probably be an issue. This motor is an unexpected project. It came along cheap so I picked it up. Never had to cc a set of heads before. Don't know how. Probably should learn how I suppose. Also the block was not decked so that shouldnt affect anything. As for the other stuff, this is going to be a carb motor, need to figure out what size carb to run too. I need to get the cam card from my brother inlaw, forgot to grab it, but the cam is a lunati voodoo #60101LK. I'll look up the specs. I realize that the heads should have been high priority, but like I said this project wasn't planned, it just happened. And no heads were included with the motor. And like I said this is my first 383 so any advice would be greatly appreciated. Thanks

 

Well that cam is pretty mild/moderate as cams go. I would go easy on the compression ratio. I would plan on a 70cc head.
It will be well worth it in the long run to get some decent heads.
Even if that means delaying the completion of this project.
A Edelbrock 70cc RPM head would be just right. You want a torky 170-180ish cc port head with a high velocity- high flow intake port for a mild cam like that.
Use a 750cfm carb and a dual plane hi rise manifold. This wont be a hi reving motor.
the only 64cc cast head I would attempt to run on that motor would L-31 vortecs
With this cam you should be able to get away with a non upgraded stock 062 vortec head assembley using a Lunati 73943 spring minus the inner damper.
Summit #NAL-12558060 or Competition products #PCH353-DP-1
The stock pressed in rocker studs are fine with this cam.
the stock OEM valve springs are going to be border line but this motor will not need more than 5000-5200rpm with the mild cam. it would be worth it to try with the stock OEM vortec valve spring on this one.
if they are not enough its simple to swap on the Lunati 73943 replacements-damper
The lift of this cam is not too high with 1.5 rockers (87+ self aligning)
Worst case the vortec exhaust retainers will need minor if any clearance grinding off the bottoms for full lift clearance. (.468" lift). You can do that yourself with a bench grinder. GM Vortecs with their fast(er) combustion, often don't need much spark timing (29-32 total). This modest need for spark timing adds some detonation limit tolerance.
The motor will run very very good with them. A great torkie match for that cam.
You won't be dissapointed with the vortec heads.
Use a cheap(er) Professional products Crosswind manifold (vortec) they work and fit fine. You'll need a low hugging drop base air cleaner to fit it under a stock third gen hood.

 

I took a quick look in the garage. I have a set of 624 heads sittin on the shelf with 1.94 1.50 valves. Any opinions on these? Wow, I didnt think I would need that big of a carb, glad I asked. And thanks again.

 

that is a important thing to know when figuring your compression ratio. If its not decked, then those pistons could be anywhere from .025-.040 in the hole. Combine that with a thick gasket and your WELL over proper quench height.

Iron heads can run the .015 steel shim gaskets and the will seal well and with .025 in the hole, your looking at a great .040" quench. thats what you want, so you need to know how far those pistons will sit in the hole.

Most flat tops and non decked blocks will give anywhere from 10.5-11 to 1 compression with 64cc heads. you definately dont want that with Iron. You want 9.5-10 to be safer


UNLESS this car needs to run immediately, i'd seriously consider taking time off the build and save money for a GOOD set of heads that will give you the combination/compression you want

 

Thanks guys. This doesnt need to run immediately, just hoping to get on the road before summer. This will be my biggest build yet, so I appreciate the help. I would still like any info and opinions on the 624 heads I mentioned before, just for future reference. Thanks again.

 

The info and opinions in this thread about the 624 casting heads pretty much says it all. I would not even consider using them.
https://www.thirdgen.org/forums/tech...s-casting.html
they are the worst of the worst.

if you want to use a 76cc open chamber head, use a 441-487-920-336(x) pre 1974 heavy casting head. Avoid early 993-all 882 all 624 heads at all cost.
Don't fubar this 383 project with a crappy worst of the worst cylinder head.

A stock 350 TPI 083 L98 cast head is a work able solution. You could "deshroud" the combustion chambers to say 68cc to tame the finished cr. That would give you 10:1 even. With a home port job they can work well.
There are lots of ways to skin this cat on a tight budget and get very good reliable performance the first time. But not with 624 castings.

The best thing you can do with those 624 castings is strip the valves, springs and retainers out of them, give them a quick black spray paint and march them out to the curb and put a for sale sign on them (asking say $100) leave them in plane view out on the curb.
If you're lucky some sucker will steal them in the middle of the night and you'll be rid of them.

 

624 heads were truck heads i believe with 1.72/1.5 valves... probly the worst waste of a piece of iron ever!! Dont even think about those heads

EDIT: beat me to it

I'd run a set of 083's before i touch any of those other heads. A mild clean up 083 L98 Iron will work much better than those others. I just sold my set

 

Wow, that thread was brutal. Yeah, i already decided to put the 383 on hold till i find some good heads. I was just wondering if the 624 heads were worth keeping around for anything or if they had any value, but you guys more than answered that. Thanks guys.

 

those heads are great!! Me and my brother have used them, literally, thousands of times. I can still remember the last time too..........There we were, it was a dark and cloudy night. Rain was on the horizon. It was only a matter of time before the clouds would open up. We wondered what to do, as we had an 1987 camaro in front of the garage, and no way to get it inside tonite. And, aghast, we noticed that the hood was not on it. Wasting no time we dashed inside the garage and grabbed the nearest tarp. But, we had nothing to hold it down with, until, in a fit of brilliance my brother cried out "hark, brother of mine, I have found our saviour!" I looked in his direction, eager to see this being of deliverance, when I saw them. Sitting there, looking inconspicuous. They were perfect, gm 624 heads. Those were some of the best heads I ever had for that job. The tarp stayed on, and the car ran. All thanks to a set of 624's. And they also make great boat anchors!

 

Any opinions on 3998997 heads guys?

 

Read my above post. Everywhere you see 624, substitute 997.

 

i dont think there was any good heads worth using from those years. Way better stuff out there now for cheap prices like dart iron eagles/vortecs and even the 081/083's that Lb9/L98's have.

 

I came across a set of 441 heads. How do I tell if they are just 441's or if they are 441X's?

 

Seeing an X right after the 1 on the casting number, would be~~~ a clue.

 

just wondering, cuz there isnt a x after the number but there is one all by its self on the bottom of the head on one of the exhaust ports.

 

Just buy a set of assembled vortec heads if you want to save money. You can find many places on the internet that sell re-worked vortec heads for pretty cheap. At one time I looked at having a set of heads cleaned up and reworked and compared it to just buying a set of heads off the internet and it was much cheaper to buy. If you're willing to spend a little bit of money (around $1k) then you can get you can get some decent aluminum heads or good iron heads.

 

Ok guys. My brother gave me a set of 441 heads that he was running on his 69 camaro until last summer. He's building a 502. The heads are in good shape, but pretty much stock. Any suggestions on what I should or could do to these heads to make them perform well? Thanks again for all your help guys.

 

good port clean up job, and setup with screw in studs if not already equipped, and machine the spring pockets out to handle larger springs if you will need them.

Port work will be necessary and maybe a valve job. I dont know if any of that i worth it tho

 

You're at a fork in the road....

Do you want a motor that runs good, or do you want to use those free head cores? (that's what they are, cores)

Pick one.

There's a reason the heads are free.... not only because they're "in the family", but also, because there's nothing else to do with them. They'll just sit on a shefl somewhere gathering dust. Nobody else really wants them. There's a reason nobody else wants them. You'll find out what that is if you use them.

 

The heads are already set up with screw in studs, I pulled the valves and they pretty much look new. Only have about 8000 miles on them. Will have to look into the whole port and polish thing. Havent ever really done it. Most of my rebuilds have been pretty stock. I think these heads will be fine, I just want to "help" them out a little if possible. I'm not lookin to make monster power here. I just want a good, strong, reliable daily driver.

 

Do those heads have accesory holes in them?

 

yes they do have the accessory holes.
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Also, any opinions on using one piece rear main seal blocks for a 383? The one I'm using for mine is a older block, but a buddy was asking me about the newer style blocks.

 

i'm building a 1 piece RMS 383 using a newer style block. Shortblock should be here next week 1 pieces usually seal better than 2 piece.

Most 1 pc blocks are 2 bolts but you can get 4 bolt mains.

 

With a 383 build like your I would recommend ones with in intake at 2.08 and exhaust 1.60. I say a huge gain in power from my old edelbrock 2.02/1.60 to the dart 2.08/1.60's. MY CR is 10:8:1 and I run 92 octane all day and works perfect.

 

10.8 to 1 on 92 octaine? I didnt think that was even possible. Wow. And Orr89RocZ, is your block a 2 bolt main? How much power and how high of an rpm can you run a 2 bolt main block?

 

Yep, I use pump gas. I have a splayed 2 bolt main. The max rpm I go is around 5700. That is about max for the valve train

 

a 2 bolt main block splayed and converted to a 4 bolt main is stronger than a regular 4 bolt main they say

my block is a 4 bolt main block. I've heard guys taking 2 bolt mains to 7000 rpms no problem and making some good hp up there too.