The heads are from a 350 engine they have had a 3 angle grind job on them, and had stronger over sized valves installed with bigger springs for a higher lift cam. Up to 540 lift. Manley valves 2.02 intake valves 1.60 exhaust valves. The cc of the head i believe are 68 which would make the compression ratio 9.7:1.

They have a casting number on them, you need to find it. But most any aftermarket head will get you more lunch. What you have sounds good as far as stock head parts - sounds like somebody spent a few bucks, probably close to some new heads. Find out what you have, for sure, and maybe you can fetch some dough for them for what they are to use toward new. In any case, aftermarket will put you miles ahead provided you don't opt for those el cheapos - what you have will more than likely outperform them knock off heads anyway. What kind of coin you looking to drop? If you went with a known power making head, you might pick up close to 100 HP+ everything else the same. Also, your 5.7 rods are not longer unless you had short 400 rods or are using like a 5.85.

 

With flat-top pistons and 68cc heads on a 383, your static compression ratio is around 10.4, not 9.7. That's ok, because you have enough cam to cover it, but if you go to 64cc heads, the static compression ratio will jump to 11.0 and you may not be able to feed the motor with pump gas without it detonating.

Your power numbers stink. Anyone who can't make 500 horsepower and 500 ft/lbs with a 383....ain't tryin' very hard.

Save up for a set of AFR180 heads with 65cc chambers. That will give you a 10.75:1 static compression ratio that will work better with the cam you have and the aluminum heads. With an 850 carb and the rest of what you have, the motor will make 522 hp @6000 and 511 ft/lbs @4500.

 

They have a casting number on them, you need to find it. But most any aftermarket head will get you more lunch. What you have sounds good as far as stock head parts - sounds like somebody spent a few bucks, probably close to some new heads. Find out what you have, for sure, and maybe you can fetch some dough for them for what they are to use toward new. In any case, aftermarket will put you miles ahead provided you don't opt for those el cheapos - what you have will more than likely outperform them knock off heads anyway. What kind of coin you looking to drop? If you went with a known power making head, you might pick up close to 100 HP+ everything else the same. Also, your 5.7 rods are not longer unless you had short 400 rods or are using like a 5.85.

the casting number on the heads is 3973487.

I am aware the aftermarket heads will give me an increase, but what i was wondering was what kind of numbers i should look at for the he heads. and with those heads what numbers could i expect.

I looking to spend under 1000.00

 

With flat-top pistons and 68cc heads on a 383, your static compression ratio is around 10.4, not 9.7. That's ok, because you have enough cam to cover it, but if you go to 64cc heads, the static compression ratio will jump to 11.0 and you may not be able to feed the motor with pump gas without it detonating.

Your power numbers stink. Anyone who can't make 500 horsepower and 500 ft/lbs with a 383....ain't tryin' very hard.

i know my power numbers stink, thats why i am here

i DO NOT want to have to run high octane in my car. I have already had that expierence and it is one i do not want to repeat.

 

I added another paragraph to post 3, but you won't buy 'em for $1000.

 

I added another paragraph to post 3, but you won't buy 'em for $1000.

thanks! so do i want to get 65cc heads is that what will make the difference. I am not to savy when it comes to numbers with heads.

if i find a name brand set of 65cc heads will that help? or are there other factors that contribute to the numbers you mentioned? to tell you the truth those numbers are what i would like achieve.

 

No, he'll buy 'em for more, and post back how happy he is. I'd go for the 195s because they'll work for when you're ready for more.

Dude, just don't cheap out on heads, it's where you'll find what's missing.

 

what brands are good? are there other numbers besides the chamber size i want to look at? i noticed the afr's on ebay for 1500 is that a good price? also they have the 195 cc/ 65cc heads what is the difference beteen those and the 180cc/ 65cc heads?

also this motor is going in a 68 el camino, i think i will have traction issues with the already low numbers i am running.

it has a turbo 350. and i set up the rear end up with a 1 inch sway bar and adjustable tubular upper control arms and tubular lower control arms. new springs, new air shocks and new poly urithane bushings.

i have 255's but i think i will have to go with more narrow tires.

i was raised working on old cars, but when it comes to specs i am dumb and need help. im in law school now so i dont have allot time to spend figuring out all the cool spec stuff. thats why i am here. thanks so much guys i appreciate it! but more detailed feedback would be appreciated.

 

You can do Brodix IKs for under $1000. The 200CC runners made 568 HP here:
http://brodix.com/heads/ikdyno.html

You can see the specs there.

They'd be a good head if you want more. They can grow with you.

Brodix is one of the oldest, most respected manufacturers in the business. They own their own foundry and have the best QC in the industry by many standards.

If you want to spend $500 more there's more choices, but for the $1000 mark, these are an excellent head.

 

Buy a bare set of heads and swap your parts over, if the springs aren't fatigued that can save you some coin right there.

For some good budget castings look at RHS, Dart, Brodix, even GMPP has some decent heads if you want to to that route. You'll want a 200cc intake runner or so, also a little port work goes a long way in most of these heads, you can get over 600 horses out of them if you have some skill.

 

Buy a bare set of heads and swap your parts over, if the springs aren't fatigued that can save you some coin right there.

For some good budget castings look at RHS, Dart, Brodix, even GMPP has some decent heads if you want to to that route. You'll want a 200cc intake runner or so, also a little port work goes a long way in most of these heads, you can get over 600 horses out of them if you have some skill.

Good idea on swapping the hardware. You can get the cost down to under $800 if you do that. Springs are cheap. Keep the vavles do the springs. A set of LT-4 springs which should be plenty is about $30. Springs are like sparkplugs, old ones don't run as nice as new ones.

Don't take this the wrong way, the castings mentioned may be cheaper, but they are not CHEAP. All of them have some very fine results in their castings.

You can pick up a set of any of those heads in the $5000 range. What you're getting if you do go this route, is top quality castings that you can build on. I guess my point is they may be budget, but that does not equate to poor quality, in this case. The more expensive solutions will not be better quality I guess is the point.

 

not to be nit picky, but I think Jsup meant $500, not $5000... most of us realize that but some new guys may not. And I would actaully say its about $800 or less for a good bare set but it all depends on what you're looking at, some can be had for $500.

 

not to be nit picky, but I think Jsup meant $500, not $5000... most of us realize that but some new guys may not. And I would actaully say its about $800 or less for a good bare set but it all depends on what you're looking at, some can be had for $500.

Sorry, AP, meant $5000. My point was that the castings your getting for $800 are the same quality as the ones you're getting for $5000 that there's no degradation of quality because of price. It's a matter of finish. The $5000 cantered valved fully ported version comes from the same factory, with the same QC procedures as the $800 bare castings.

I didn't want to leave the impression that any of those you mentioned were somehow inferior just because you choose the entry level product.

 

I thought you were speaking of the original bare castings, when you gave the price, not the fully worked over complete version.

But you are right, they start with the same castings.

 

Buy a bare set of heads and swap your parts over

NO NO NO.
They are worth $money$ a$$embled, and will fetch a FAR better price if sold as an assembled set. Plenty of people will buy I am sure. Then there is the issue of not checking, valve lengths etc etc etc etc, how do you know everything will be a simple swap? What about the VJ and so on an so forth? An assembled set of heads compared to bare, usually you won't be able to buy parts cheap enough to get one up on a vendor who sells a lot of heads. JMO but I wouldn't be wasting my time and/or money trying to save a dollar that way all the while letting them slip thru my fingers hoping my swap will be good. Not a good call IMHO

 

good suggestions, thanks.

just a fyi there are no miles on my current heads. they have only been used for the dyno test.

with the 200cc runners can i still run pump gas?

 

Runner size/port volume has notta to do with CR. Your chambers size is what will change your CR. You can figure for octane several ways, but if you shoot for less than 11:1 preferably not more than 10.5 you will be close depending on camshaft and other. Actual cranking psi is helpful too, if you really want to crunch numbers do the math LOL

 

200cc runners usually do not affect if you can run on pump gas, compression and cam are bigger factors. If you're serious about getting over the 500hp mark going with a 200cc runner is a great way to get started, though you may want more port work done from there. If you get them take a look at a set of RHS, or Darts or other good head compared to yours- you'll wonder why they didn't do it that way from the factory. The design makes more sense and is far better built. I like going with a set of bare heads and picking your componenets from there primarily because it gives a person the opportunity to clean up the port, bowl, chamber, etc before final assembly, and it allows you to use matched springs for your cam, not what the vendor bought in bulk. The price comes out about the same in the end but you end up with a head that has been tailored to your needs.

If I can find a reason to justify yet another set of heads I think I'll be picking up some RHS's.

 

NO NO NO.
They are worth $money$ a$$embled, and will fetch a FAR better price if sold as an assembled set. Plenty of people will buy I am sure. Then there is the issue of not checking, valve lengths etc etc etc etc, how do you know everything will be a simple swap? What about the VJ and so on an so forth? An assembled set of heads compared to bare, usually you won't be able to buy parts cheap enough to get one up on a vendor who sells a lot of heads. JMO but I wouldn't be wasting my time and/or money trying to save a dollar that way all the while letting them slip thru my fingers hoping my swap will be good. Not a good call IMHO

Another great point.. I didn't realize the heads were new, I was thinking the valves could cleaned and salvaged, but if they have so little use, you can get most of your money back on them assembled.

Plus, have the company hit the chamber size you want for your compression.

Any one of those companies will bring the chamber size to 58CC or whatever you spec for about $200.

 

Runner size/port volume has notta to do with CR. Your chambers size is what will change your CR. You can figure for octane several ways, but if you shoot for less than 11:1 preferably not more than 10.5 you will be close depending on camshaft and other. Actual cranking psi is helpful too, if you really want to crunch numbers do the math LOL

i don't know how

 

i don't know how

Static compression ratio is the mathematically computed ratio of the volume of fuel/air mixture which is theoretically drawn into a cylinder with the intake valve open and the piston descending in the cylinder as compared to the same volume of fuel/air mixture after it has been squeezed into the upper part of the cylinder and cylinder head by the ascending piston with the intake valve closed. If, for instance, you draw in 9 parts of mixture and squeeze it into 1 part mixture, then the static compression ratio is 9.0:1

To compute static compression ratio requires 5 values.
1. Cylinder volume in cc's. This can be found by using the following formula: (.7854 x bore x bore x stroke x 16.387)
Example for 350 Chevy with 0.030" overbore: (.7854 x 4.030 x 4.030 x 3.48 x 16.387 = 727.4 cc's)
2. Combustion chamber volume. Usually already given in cc's.
3. Piston deck height volume in cc's. This is the volume between the piston crown and the block deck where the heads bolt on with the piston at TDC (top dead center). For instance, if this is a 350 Chevy and the piston is down in the bore 0.010" (ten thousandths) at TDC, we would compute the volume thusly: (.7854 x 4.030 x 4.030 x .010 x 16.387) and would find 2.09 cc's.
4. Gasket volume in cc's. Use the same formula with the gasket inside diameter and thickness. Let's say we are using a gasket that measures 4.100" x 0.039". It would compute thusly: (.7854 x 4.100 x 4.100 x .039 x 16.387) and would find 8.43 cc's.
5. Piston crown volume. Usually given by the manufacturer in cc's.

Now, let's figure this motor out. It's a 350 Chevy with a 0.030" overbore, the piston is down in the bore by 0.010" at TDC, the gasket is 4.100" x 0.039" and the pistons are flat-tops with 7 cc's of eyebrows for valve relief. We'll be using heads with a combustion chamber volume of 64 cc's.

727.4 cc's in the cylinder
64 cc's in the combustion chamber
2.09 cc's in the piston deck height
8.43 cc's in the head gasket
7 cc's in the piston eyebrows

Adding these values together, we find that theoretically, we have packed 808.92 cc's of combustible fuel/air mixture into the available volumes.

Now, as the piston comes up in the bore to compress this mixture, the only thing that changes is the piston position in the bore. So, we will eliminate the cylinder volume from our computations and figure the other 4 volumes into which the mixture is going to be squeezed. 64 + 2.09 + 8.43 +7 = 81.52 cc's.

So, we have drawn in 808.92 cc's and squeezed it into 81.52 cc's. To find the SCR, we divide the larger by the smaller and find 9.92:1 static compression ratio.

Dynamic compression ratio uses static compression ratio plus rod length, stroke and intake closing point on the camshaft to give us a better idea of what the motor is going to do. With the piston ascending up the bore to compress the mixture, compression cannot begin until the intake valve closes. This makes camshaft choice critical. The motor may or may not operate on pump gas depending on the intake closing point and the resultant cylinder pressure generated.

I'm sure there are math gurus who can sit down with a calculator and figure it. I am not one of those people. I cheat by using a calculator provided by Keith Black Pistons.
http://kb-silvolite.com/calc.php?action=comp2
I use a value of between 8.0:1 and 8.5:1 as reasonable for a pump gas motor. For instance, with this 355 that we have just figured, let's say that we are using a cam that has an intake closing point of 45 degrees ABDC (after bottom dead center) measured at 0.050" tappet lift. We would add 15 degrees as directed in the instuctions on the calculator and enter 60.00 into the calculator along with the 9.92 static compression ratio, 3.480" stroke and 5.700" rod length. The calculator says the DCR of this combination is 8.21:1 and I know from experience that this will work well with pump gas, particularly because I'm using a sensible squish figure of 0.049" (piston deck height added to gasket thickness).

 

Static compression ratio is the mathematically computed ratio of the volume of fuel/air mixture which is theoretically drawn into a cylinder with the intake valve open and the piston descending in the cylinder as compared to the same volume of fuel/air mixture after it has been squeezed into the upper part of the cylinder and cylinder head by the ascending piston with the intake valve closed. If, for instance, you draw in 9 parts of mixture and squeeze it into 1 part mixture, then the static compression ratio is 9.0:1

To compute static compression ratio requires 5 values.
1. Cylinder volume in cc's. This can be found by using the following formula: (.7854 x bore x bore x stroke x 16.387)
Example for 350 Chevy with 0.030" overbore: (.7854 x 4.030 x 4.030 x 3.48 x 16.387 = 727.4 cc's)
2. Combustion chamber volume. Usually already given in cc's.
3. Piston deck height volume in cc's. This is the volume between the piston crown and the block deck where the heads bolt on with the piston at TDC (top dead center). For instance, if this is a 350 Chevy and the piston is down in the bore 0.010" (ten thousandths) at TDC, we would compute the volume thusly: (.7854 x 4.030 x 4.030 x .010 x 16.387) and would find 2.09 cc's.
4. Gasket volume in cc's. Use the same formula with the gasket inside diameter and thickness. Let's say we are using a gasket that measures 4.100" x 0.039". It would compute thusly: (.7854 x 4.100 x 4.100 x .039 x 16.387) and would find 8.43 cc's.
5. Piston crown volume. Usually given by the manufacturer in cc's.

Now, let's figure this motor out. It's a 350 Chevy with a 0.030" overbore, the piston is down in the bore by 0.010" at TDC, the gasket is 4.100" x 0.039" and the pistons are flat-tops with 7 cc's of eyebrows for valve relief. We'll be using heads with a combustion chamber volume of 64 cc's.

727.4 cc's in the cylinder
64 cc's in the combustion chamber
2.09 cc's in the piston deck height
8.43 cc's in the head gasket
7 cc's in the piston eyebrows

Adding these values together, we find that theoretically, we have packed 808.92 cc's of combustible fuel/air mixture into the available volumes.

Now, as the piston comes up in the bore to compress this mixture, the only thing that changes is the piston position in the bore. So, we will eliminate the cylinder volume from our computations and figure the other 4 volumes into which the mixture is going to be squeezed. 64 + 2.09 + 8.43 +7 = 81.52 cc's.

So, we have drawn in 808.92 cc's and squeezed it into 81.52 cc's. To find the SCR, we divide the larger by the smaller and find 9.92:1 static compression ratio.

Dynamic compression ratio uses static compression ratio plus rod length, stroke and intake closing point on the camshaft to give us a better idea of what the motor is going to do. With the piston ascending up the bore to compress the mixture, compression cannot begin until the intake valve closes. This makes camshaft choice critical. The motor may or may not operate on pump gas depending on the intake closing point and the resultant cylinder pressure generated.

I'm sure there are math gurus who can sit down with a calculator and figure it. I am not one of those people. I cheat by using a calculator provided by Keith Black Pistons.
http://kb-silvolite.com/calc.php?action=comp2
I use a value of between 8.0:1 and 8.5:1 as reasonable for a pump gas motor. For instance, with this 355 that we have just figured, let's say that we are using a cam that has an intake closing point of 45 degrees ABDC (after bottom dead center) measured at 0.050" tappet lift. We would add 15 degrees as directed in the instuctions on the calculator and enter 60.00 into the calculator along with the 9.92 static compression ratio, 3.480" stroke and 5.700" rod length. The calculator says the DCR of this combination is 8.21:1 and I know from experience that this will work well with pump gas, particularly because I'm using a sensible squish figure of 0.049" (piston deck height added to gasket thickness).

can you recomend someone in san diego, that i can get to help me out with my situation?

you just dropped some serious knowledge on me, which has me a bit more confused and frustrated with my situation. it would be nice to talk to someone about this and what i can do to get the most amount of efficentcy, hp, torque and powerband out of my motor, and of course still run on pump gas.

thanks for all the help!

 

can you recomend someone in san diego, that i can get to help me out with my situation?

you just dropped some serious knowledge on me, which has me a bit more confused and frustrated with my situation. it would be nice to talk to someone about this and what i can do to get the most amount of efficentcy, hp, torque and powerband out of my motor, and of course still run on pump gas.

thanks for all the help!

I have a friend in SD who owns 8 Corvettes, and has built many cars.

I'll see if he'll let me give out his number. He knows his stuff.

 

OK, I guys I have thought about it and think I am going to go with the Brodix IK200 heads.

Any suggestions on the sizes (of chamber etc.) I should use with my motor, and where I can buy them?

Should I call Brodix and see what they think would be the best heads for my motor?

I don't want to rush but would like to make the purchase within the next week or 2.

Thanks a bunch!

 

can you recomend someone in san diego, that i can get to help me out with my situation?

Joe Sherman Racing
2302 W. Second Street
Santa Ana, CA 92703


(714) 542-0515

email: joeshermanracing@joeshermanracing.com