Just what the subject line says.

Will 400 small block heads work well on a streetable 383 application?

I am looking for between 400-500 HP and torque. I haven't done anything yet except purchase the 4 bolt 350 that will be machined. I have a friend who's got a friend who's shop is closing down and the guy wants $300 for them.

I obviously need to find out if they are stock heads, or aftermarket and what kind of condition they are in. But in general... how well would 400 heads work on a 383?

 

factory 400s, and the heads that came on them, were very low preformance packages. i'd look for another et of heads.

 

What if I find that they are aftermarket heads that have better flow?

 

Thats gonna be hard to do with any stock heads. You will need some good aftermarket heads and some money to get 500hp. I have some PRO Topline heads that will work perfect for your application and will make plenty of power.

https://www.thirdgen.org/classifieds...tgo?adid=54152

 

400s, as they came stock, had 180 HP or thereabouts.

HP comes from the heads, above all else.

So: can you take 180 HP heads and get 500 HP out of them? What would you think?

500 ft-lbs of torque is fairly easy. Get anywhere near 100% cyl fill (volumetric efficiency) at any given RPM and anywhere near 10:1 compression with 383 inches, you'll have that, at that RPM. The question becomes, at what RPM. Will it be at about 2800 or something, like a stock LG4 or L03, and all downhill from there? That's what poor flowing heads will give you.

For 500 HP, you need to make your 500 ft-lbs at 5252 RPM; or somewhere close to that torque, at some higher RPM. You need heads with flow to get that kind of volumetric efficiency at that kind of RPM. Just as a rough rule of thumb, you're going to need heads that flow around 250 CFM in the intake ports, and a well-matched combo of cam, exhaust and intake, to get to 500 HP.

Stock heads, even the best of them, are really tough to get to flow much above about 220 or 230 CFM. That's low-mid 400 HP territory, assuming the best of everything around them. 400 heads (882 or 624 casting) will flow just over 200 with a good port job. Not really in the ball park.

If you find that "they" (whatever "they" are) are aftermarket heads, and they happen to be or to have been on a 400, then they're not "400 heads"; they're aftermarket heads that might happen to be, or to have been at some time in their life, installed on a 400. No magic will be found to have rubbed off of the 400 block and lodged itself in the heads.

 

RB what if the 400 with the heads still attached were in a VETT?

 

I think what the poster is asking is "Will heads intended for the siamesed-bore 400 (like AFRs with the steam holes drilled) work on a traditional 4" bore SBC which don't use steam holes in the heads - or will cause problems"?

Unfortunately, I don't know that answer as I have never seen anyone do that (yet).

 

The steam holes do not matter if used on a block that doesn't have them. They do nothing.

 

Thanks RB. I didn't think it mattered. But I wasn't sure.

But since I just hate people who say things they REALLY don't know the answer to and guess (hoping they are right), I practice what I preach. I have never installed heads drilled with steam holes from a 400 and installed them on a non-400 block.

So rather than guess (and hope I got the right answer) I would say "I don't know" and ask someone who has done it. People need to realize that if you guess and give the wrong answer, you might just cause someone to do something they really shouldn't.

TGO does not give prizes out for the person who gives out the most correct answers. But we sure do give loud laughter at fools who pretend to know the answer (and don't).

 

So here's the (kinda) funny ending to my story.

I get a call from my friend today telling me that this kid really needs to get rid of these heads and that he's willing to let them go for $250 if I can take them ASAP. Well, I hemmed and hawed with him for about 15 minutes, going through everything that I learned in the last couple of days on TGO about stock small block heads on a 383 application. I told him what you guys told me and that I was really leery of buying anything that wasn't aftermarket because I know that even with port work, they will probably not flow very well on the 383.

Well he finally tells me that they were off of an older truck, but that he had used them on a 350 that he was building a few months ago. He drove it for like 1,500 miles and screwed up his flex-plate. He gave me the name of the place that he had do the machining and told me that the heads have brass guides and that the valves were decked .5000. So I figured that for $250 it was probably worth it to at least pick them up and then sell them if they're not what I want. I told him that I would take them from him tomorrow and that he'd get a check from me at that time. I shouldn't have went against what you guys told me, but I figured that I'd take a chance.

Anyways, I got my buddy back on the phone and asked him to give me the casting number off one of the heads. He gives me 14022801. It didn't ring a bell of the top of my head, so I thanked him and told him that I would talk to him tomorrow. I got online about 2 hours ago, looked up the number and find from at least 10 different sites (including a search here that turned up 5 threads) that these are 305 heads off of a 1980-1986 block.

I called my buddy up and told him what I found. I could hear the guy in the background getting pissed off at me. I told him that I appreciate the offer, but I'd rather spend the extra money on good aftermarket heads than take a chance at buying something from someone who obviously has no clue what he's talking about.

Anyways, I gotta run cause I'm at work... I just figured that I would give you an update...

P.S. Thanks to all who replied, you saved me a lot of time and money by pointing me in the right direction.

 

You did good, i'm proud of you. You do not want those heads. Always get the casting # first and find out if they are any good. People try to pawn off all sorts of crap to unsuspecting people.

 

I can hear it now...
"Hey!! **** that stupid guy! Chevy parts are Chevy parts... Doesn't he know anything!!?? Tell him they'll fit on any Chevy... That guy doesn't know a good deal when he sees one"!!!

 

hahaha. Yeah that's almost word for word what he was said. I also got a "don't listen to a bunch of people on a computer, I've been a mechanic for 20 years and I promise you that those heads will be more than enough for what you're trying to do."

When he started making out like people who know and use computers are clueless, I relaized what a moron he is.

On a side note... it's amazing how many mechanics and car guys I've talk to think that people on boards like this are worthless. It's pretty insulting sometimes...

 

Once when Iwas in college I had an automotive student trying to talk down to me. We were talking about cams. And since I was a computer science major, I couldnt possibly know anything about cars (thats the general consensus at most colleges). When we were done, he realized I knew more than he did. Quite funny really.

 

There are some sites such as TGO, where you can supplement your education quite well.
It's just a bunch of guys here, sharing experiences and information. It depends what you pay attention to and who you choose to believe.
I've been a DIY car guy since the 70s and never had any actual professional training. And with the information I've gathered here, I can honestly say that my skills are much more honed. I've learned some of the finer points of working on SBC cars and engines.
There are a lot of conflicting beliefs, misinformation, and BS circulating out there. Even among guys who are supposedly professionals.
Who are you supposed to believe? The guy at the parts store?
You might get 20 opinions and one of them might be from a guy who's an actual specialist who knows what he's talking about.
The thing that's most useful in separating the facts from the BS is to expose yourself to as many opinions as you can. If you're open minded, it's not long then, before it becomes apparent what the truth is.
That's the strength of educating yourself online.

 

Bingo. Goes hand in hand with learning. Best way to learn is to watch someone that knows what they are doing. Watch, listen, and get dirty when you can!

 

I am a student at the Rochester Institute of Technology and I find it very rare to get a hold of anyone who knows anything about cars around here... let alone, anything about muscle cars. Most people find it hard to believe that someone who writes computer code during the day turns into a mechanic at night.

I tell everyone that being a programmer is the reason that I want to rip the computer out of my car and carburate it. If I started prom burning and writing code in the camaro, I might just go insane.

So now that all of this 305 B.S. is out of way, I wonder where I should start looking for a set of heads.

 

Same for me. After years of college and a future entirely dedicated to computers, I put a carb on my car. Cause I dont like computers!

 

I'm with you on that one, I'm not a computer programmer and it makes me want to go the low tech route even more. Or at least have a carb system on standby as a backup, in case something goes haywire that I can't afford to have repaired.

I wanted to suggest those heads that MELeigh is selling.
He had a cam for sale too and I'm getting that from him. He was was willing to work with me on the payments.
I wish I could get those heads, to go with my cam.

 

If I had the money to buy them off him right now I would. I would be about half short.

College drains ones pockets quickly. Thank goodness for work.

 

If you're looking for an inexpensive set of heads that can later be swapped for a better set, then maybe a set of the 76cc factory heads are the answer. They can be found ready to bolt on for about $300.
But you won't get that 450hp you were looking for til you get some good heads. Still, you might get 1 hp/ci if the rest of your combo is right. Those heads will give you about 9.5/1 CR with flattop pistons. Then later when you have the money, you could get some higher compression heads with a smaller chamber and really wake your motor up.

 

I definately want to make sure that I build the motor right. I am going to get the best parts I can for this motor. (within reason of course) I am currently researching TrickFlow, AFR, and World Heads. Any opinions on those?

I've been trying to decide where I want my compression to be when everything is all said and done. I'm not sure exactly where a streetable 383 should be. I was thinking maybe 11/1 ?

 

I'm not a big fan of World heads at all. I wouldn't ever waste my money on those crappers that barely flow more than stock. They however do port up pretty nice, but still i wouldn't waste my money when i could port a stock head. Now trickflow's are a little better, but they still don't flow that well. The ProToplines are next they flow really well and are reasonably cheap. The AFR's are pretty much the best head available but they cost alot.

 

With friends like that, who needs to wait and get screwed over the 'net?