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Hi everyone, I bought a pair of flotek heads (Small Block Ford 180cc/58cc | FloTek - Evansville, IN) and I wanted to build a 302 with a good cam that can rev to 7000 RPM. I was reading the info on the website and it says the heads have a range up to 5500 RPM, does that mean the engine wont be able to rev to 7k? My goal is to make the car good on the track and the street, i'd love it if you guys can give some suggestions or advice on how to approach this. Thanks :).
 

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Typically what that means is the flow isn't enough to make hp at those rpms. Or valve float could be an issue. Making an engine that streets well but can make power at 7k is gonna be a tall order.
 

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There is so much more to making a 7k rpm engine. Do lots of research. The valve train and rotating parts are going to need lots of attention. Find someone local to guide you because you’ll get 100 different opinions here.
What do you plan on doing with that motor, what trans do you have, what gears? So many questions to ask and to get answered.


Mark
 

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The valve & spring package is often where money is saved with budget heads, that's probably what limits the RPM. An 180cc head should be capable, after all it's been done with ported stock heads. It's a shame you already bought them, it says they do offer PAC/custom valve spring packages. You'll end up replacing the ones that came with the head.
 

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I'd plan on replacing the valve springs immediately. A cam that makes peak power at 7000 RPM is going to have around .600 lift. You'll need around 150lbs+ on the seat and 450lbs+ open pressure. Also I would not just run something like Scorpion rocker arms that everyone (myself included) uses, I'd use the gold Comp rockers or something made of steel with a 7/16 stud.

Probably should have asked this question before you bought the heads. :confused:
 

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By the time you spend the money required to make those chinese heads work at 7000 rpm you could have bought some AFR or TFS heads.
 

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it says those springs are good to .550 lift, which is a fair amount of lift for a street engine. those heads flow roughly 220cfm @ .550 lift. that can easily get you in the 350h.p. range. those will easily rev to 6k+ or until you hit valve float which on a sbf engine is inevitable with hydraulic lifter setup. be happy with a 6krpm engine or sell those heads and buy better ones lol
 

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here is the deal, you could be happy with a little motor that makes power to 6k and you shift 6300-6500. or you dump a bunch of money into a better hydraulic roller setup and still you going to have valve float at 7k rpm. a better engine will be making power at 6500-6800 rpm but it is still going to float valves and you still are not reaching your goal. the only way to be happy at 7k is to switch to a solid lifter, then you are really stressing the block at that rpm. it really does not make much sense with a oem 302 block.
 

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Track and street, you’ll do much better picking a single application.

7K with good street manners?
 

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Chris, your heads can do this, but the rest of the engine has to be able to live at this rpm as well. And yes, the 302 can do it, but it is not a budget deal. Can I ask why 7K is the goal ? How much power are you trying to make, and what is the goal for this car ? What trans do you have ? what axle do you have ? Does 'the track' mean a dragstrip or a roadrace kinda thing. LSG
 

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By the time you spend the money required to make those chinese heads work at 7000 rpm you could have bought some AFR or TFS heads.
Those don't always come out of the box ready for 7k RPM either. I changed the springs in my TFS heads immediately and I'm not revving nearly that high. Chinese heads can be decent builder heads if you go into it armed with knowledge, especially since there's many options available for them from the vendor. It's not the way I would do it but it could work.

it says those springs are good to .550 lift, which is a fair amount of lift for a street engine. those heads flow roughly 220cfm @ .550 lift. that can easily get you in the 350h.p. range. those will easily rev to 6k+ or until you hit valve float which on a sbf engine is inevitable with hydraulic lifter setup. be happy with a 6krpm engine or sell those heads and buy better ones lol
I never trust those ratings. The lift rating is usually more about coil bind than valve float. Generally speaking a head with springs for a roller cam will be rated at .600 and flat tappet will be rated at .550, but at what RPM? 5500? 6000? Just cause they say .600 doesn't mean it won't experience valve float at .550 lift at 6500 RPM. It pays to be kinda familiar with what spring pressures are required so you can make your own judgement.
 

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I never trust those ratings. The lift rating is usually more about coil bind than valve float. Generally speaking a head with springs for a roller cam will be rated at .600 and flat tappet will be rated at .550, but at what RPM? 5500? 6000? Just cause they say .600 doesn't mean it won't experience valve float at .550 lift at 6500 RPM. It pays to be kinda familiar with what spring pressures are required so you can make your own judgement.
I agree, modern custom cams can have really high ramp rates. There's more to it than just lift and duration @ .050 numbers.
 

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Also, at high RPM valvetrain stability plays a huge role. If stuff starts flexing that can make things inconsistent. That's why people use stud girdles or shaft rockers. 7/16" studs can be helpful. Mine are only 3/8" which is probably an error on my part. The portion that threads into my TFS heads is 7/16" but I had already bought the 3/8" rockers before I knew enough about it. I thought my car would pull to 6500, and maybe at sea level it would, but power began dropping off after 6100. Who knows why. Could be valvetrain instability, or adjustment, could be the lazy 112 LSA, could be ignition, could be tuning, could be just what the airflow allows.
 

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Those don't always come out of the box ready for 7k RPM either. I changed the springs in my TFS heads immediately and I'm not revving nearly that high. Chinese heads can be decent builder heads if you go into it armed with knowledge, especially since there's many options available for them from the vendor. It's not the way I would do it but it could work.



I never trust those ratings. The lift rating is usually more about coil bind than valve float. Generally speaking a head with springs for a roller cam will be rated at .600 and flat tappet will be rated at .550, but at what RPM? 5500? 6000? Just cause they say .600 doesn't mean it won't experience valve float at .550 lift at 6500 RPM. It pays to be kinda familiar with what spring pressures are required so you can make your own judgement.
valve float will happen because of the lifters even with the best springs.. those springs have 130# closed at 1.75 height, 310# open at 1.250 height. coilbind at 1.160 it says it right on the website lol. they rated those springs at .550 lift, they have an additional .090 of margin before coil bind. small valves in those heads will help keep the springs happy a little.
 

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to the original poster, when you decide on your shortblock most importantly what pistons you will be using ( which is critical for valve to piston clearance) you can call some companies give them your info and they can help pick a cam that will be happy with your heads. or if you want a more radical engine, you are best off selling these heads and going with something on a higherprice shelf lol
 

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valve float will happen because of the lifters even with the best springs..
That's true. I have stock replacement 5.0 style lifters. That could be another reason it doesn't make power as high as I thought it would. I don't really want to deal with a solid roller cam, I wonder if better aftermarket hydraulic lifters would make a difference.
 

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That's true. I have stock replacement 5.0 style lifters. That could be another reason it doesn't make power as high as I thought it would. I don't really want to deal with a solid roller cam, I wonder if better aftermarket hydraulic lifters would make a difference.
there are a few that help get a couple hundred more rpms. my take is the best advantage is light weight everything, and just the right amount of spring pressure enough to control the lobe ramp rate, but not overload the lifter with too much pressure. the LS crowd is big into making hydraulic setups work cuz they are all afraid of adjusting lash lol... i joke
 

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there are a few that help get a couple hundred more rpms. my take is the best advantage is light weight everything, and just the right amount of spring pressure enough to control the lobe ramp rate, but not overload the lifter with too much pressure. the LS crowd is big into making hydraulic setups work cuz they are all afraid of adjusting lash lol... i joke
You can get more revs out of a 5.0 lifter buy swapping in ceramic check balls, or compete "high-rev" lifters.
 
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