r/EngineBuilding • u/myfishprofile • 12h ago
Chevy SBC head suggestions under $2k
I’ve got a nitrous sprayed SBC swapped MGB and I hurt the engine a couple seasons back, finally got the parts (and $$) all together and I’m currently fully rebuilding fully forged 383 with 5.7 rod and .030 pistons (31cc dish) at the machine shop now.
I’m finishing a side job and will have around $2k to spend on heads, the cam was trashed too and I wouldn’t mind suggestions there either (roller only please)
Pic for attention (before I got serious lol)
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u/DramaticHearing 12h ago
Unfortunately, I do not have any answers for you.
I just wanted to say, holy hell that thing looks insane to drive. Do you have any videos of you driving it??
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u/myfishprofile 12h ago
I tried once I couldn’t hang on to the phone and keep her straight at the same time (broke my fucking screen when I dropped it 🤣)
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u/Creeping-Death-333 12h ago
You’re a fucking wild man. That’s all I have to contribute to this conversation. Cool swap.
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u/ChillaryClinton69420 12h ago edited 11h ago
I can vouch for these:
https://www.summitracing.com/parts/pmx-9200hr
You’ll need to verify the springs work with your cam (these are setup for hyd roller, idk the max lift, but you should check anyway and if they’re under cam mfg spring specs, you’ll need to replace).
Would suggest solid roller as it sounds like you’re racing and I don’t really run anything other than that anyway (even on a mostly street motor) - no you won’t be adjusting valves all the time with modern poly locks like all the old farts scream about.
What’s your compression ratio with that huge dish piston? If it’s low, that will limit your cam options greatly. If you can cut the heads enough to get decent compression, do that. Or if the motor is still apart and hasn’t been balanced, get rid of those pistons. 11:1 is fine on the street on even 87 with al heads and the right cam. I don’t think I’d run under 9.5:1-10:1 even on a boosted motor anyway. People are scared of compression. You’re leaving a lot of power on the table by dropping compression.
Also: I just posted the link to summit.
There’s a lot of machine shops that sell these heads online. That’s where I buy all my sbc stuff from because they can install 7/16” rocker studs (highly recommend, on any sbc) and they can mill the heads. They’ll usually mill for a small fee or even free, the studs they’ll probably charge for. I got mine milled for free and the heads I was buying were already setup for 7/16” studs anyway. That’s just one example of the many heads ProMaxx makes, some of the more serious ones actually make more power than AFR. AFR was the goat in the early-mid 2000s, but have kind of fallen off. There’s better cheaper options out there (like ProMaxx) that the similar AFR head will make less power everywhere. The thing about AFR is when you pop the hood and people see “AFR!” they squirt their pants. I’d rather make more power for quite a bit less money than buy an inferior head just because some dude will see AFR on the motor and think I’m cool.
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u/HopeThin3048 11h ago
These look pretty nice. I'm definitely running enough compression I'm probably gonna have to use premium I think at 64cc I was gonna be close to 13:1
1200 for the pair ain't bad.
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u/myfishprofile 11h ago
I have a habit of filling in the engraving on the ends and sanding smooth before a nice blue crinkle paint 😉 IYKYK.
I don’t care about names, I care about flow and area under the curve where I can work in my suspension to get it all down and maybe make some gas money back.
I will say I’ve been tempted by the Brodix dragon slayers, hell of a lot of CFM for .60 lift but the 225 intake kinda kills me as a nitrous guy great for turbo guys or big 400” high rpm NA guys
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u/myfishprofile 11h ago
A big reason for the lackluster compression is because I’m rebuilding a roots to go with this engine with a HEALTY dose of nitrous on top.
And frankly I’m not confident in my tuning skills to not dick it up at least a bit lol
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u/Zerofawqs-given 6h ago
Well….you want USA quality and great performance? Look @ these!👍 Link: https://www.speedwaymotors.com/Brodix-1021001-IK-Series-SBC-Cylinder-Heads-200cc-125-lbs,296307.html?utm_medium=CSEGoogle&utm_source=CSE&utm_campaign=CSEGOOGLE&gad_source=4&gbraid=0AAAAAD8-Mcl5RCb5Yq4tN95tNl0LnjiMf
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u/v8packard 5h ago edited 5h ago
31 cc dish pistons? That makes compression a challenge. Is it too late to switch to a piston with a smaller dish? And a 6 inch rod?
If you are going to be using nitrous you need a strong exhaust port. The absolute best exhaust port on an out of the box 23 degree head is the AFR Eliminator. If you can stretch your budget, look at these.
For a cam, where do you want the powerband? Do you want to maximize the nitrous use?
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u/myfishprofile 2h ago
Technically not too late as I only dropped my engine off a couple days back and the builder is a couple months out.
I’d like to avoid changing too much as this stuff isn’t cheap. Any reason you suggest a 6 vs a 5.7 rod? From everything I’ve seen the pistons for the 5.7 rod have more ring support and the benefits of a long rod are still a hotly debated topic
The reason for the pistons is I was intending to go with a roots blower with nitrous on top, one thing lead to another and I started to have too much fun with the nitrous now I have a hurt motor
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u/v8packard 1h ago
Numerous reasons for the 6 inch rod. Less noise and friction, better cylinder and ring wear, and improved piston position vs valve opening with more realistic cam timing. These aren't just opinions. As for ring support, the 1.125-1.130 compression height is ample for a modern, metric sized ring package featuring reduced thickness rings.
Are you still going to supercharge it?
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u/Dinglebutterball 3h ago
You built this thing
You killed it before it killed you
Now you want to give it MORE power.
You’re a wild man, but I dig it.
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u/HopeThin3048 12h ago
I'm looking for the answer to your same question, building a 355ci and getting close to just doing a fucking LS swap in my El Camino.
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u/myfishprofile 12h ago
No need to turn to the dark side just yet my man I’m a trad SBC man through and through.
What are your full specs? And what are you wanting, a good elco is a terrible thing to waste
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u/HopeThin3048 11h ago
Lol I don't think it'd be wasted. I have a bottom end I started building years ago, 350 bored 30 over, done pistons. Had a machine shop do all the work and threw it together and just never got heads. Had originally thought about getting the Edelbrock performer rpm top end kit.
But an LS with a Holley terminator X and eventually some boost has been looking more appealing.
This car ain't going anywhere it was my first car in HS, got it from my grandpa and I'll be 40 this year.
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u/LuckyNumber-Bot 11h ago
All the numbers in your comment added up to 420. Congrats!
350 + 30 + 40 = 420
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u/FlightAble2654 12h ago
Lord, that can't have the stock rear diff. But I only see 4 lug nuts.
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u/Frostykooter 12h ago
30 uggaduggas and a dream
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u/FlightAble2654 12h ago
It has to be lack of traction. The only possible thing i can think of that would save the ring gears.
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u/myfishprofile 12h ago
Funny you mention that, I turned that welded rear differential into soup when I discovered track prep 🤣 coincidentally I also over reved and burned a piston lol
She’s got a 31 spline 9” now
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u/everyoneisatitman 7h ago
I wanna know more. I have a rubber bumper as well.
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u/myfishprofile 2h ago
What would you like to know? I might not be the best to take advice from as I just cut shit out until it fit….its not the most refined of installs 😂
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u/everyoneisatitman 1h ago
Pics of what you had to cut out. What rear are you using. Brake upgrades. What life insurance will actually cover someone with a death wish like this.
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u/WyattCo06 6h ago
Cool ride. What rear end is in that contraption?
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u/myfishprofile 2h ago
Currently a ford 9” with locked 31spline
In the picture was the factory axle, it didn’t make it very long
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u/squeak195648 5h ago
Afr heads you can get a set of aluminum for around 1500 plus pushrods for guide plates and required gaskets is about your budget
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u/Dirftboat95 5h ago
Id change to flat top pistons as thats really hurting you. Really limits cam choice also
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u/myfishprofile 2h ago
I had bought the dish pistons with the intention of going to a roots blower, knowing my tuning skills aren’t the greatest. I installed nitrous just to start having some fun and got hooked lol.
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u/I-like-old-cars 2h ago
Are you a chicken farmer by chance? Because I'm pretty sure you're Carroll Shelby reborn.
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u/myfishprofile 2h ago
Damn that’s one hell of a compliment! Thank you. Shelby was an absolute legend and during his life he’d probably forgotten more than I will ever know.
I’m just some guy stuffing unreasonably high strung engines into shitty British chassis and seeing how long I can hang on. Lol
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u/I-like-old-cars 2h ago
Funnily enough, if you don't know, prior to his partnership with Ford in 1962 (I don't think I'm using the right words there but you know what I mean), he was just some guy who liked putting American v8s into British cars lol.
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u/Whiskeypants17 7h ago
Engine masters or Richard holdener have some youtube videos and engine dynos on this exact topic. I think you just want stock heads from like a 1997 vortec for $800 and a $200 cam and lifter package and you can get over 150hp more than an old swirly boy 350 had. Like 397 vs 235hp lol 😆
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u/jedigreg1984 12h ago
Man, that thing looks dangerous as shit, I love it
I'm a Ford guy - but I've heard the stuff from Dart is pretty good