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Old 11-30-2012, 10:00 AM
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vortec heads on 400 sbc

Ok im thinking about vortec heads on my 400 I was just wondering what I would all have to change I know the intake and can some one give me some ideas on one of those to plz the motor is stock not looking to do anything to it I have a mild cam comp cam xe256 is the model just looking for a little help im 19 and this is pretty much my first motor

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Old 11-30-2012, 10:05 AM
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what do you want the heads to do that the old heads didnt do?
you will need manifold and valve covers.you need to know what pistons are in the engine or static compression ratio
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Old 11-30-2012, 12:26 PM
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Didn't we just do this on another thread??.Humm
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Old 12-01-2012, 06:54 AM
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dont forget to have the steam holes drilled in them. and you will probably have detonation problems.
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Old 12-01-2012, 10:59 AM
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Y would I have a problem with detonation
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Old 12-01-2012, 12:02 PM
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Quote:
Originally Posted by smith9300 View Post
Y would I have a problem with detonation
Compression ratio too high.
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Old 12-01-2012, 12:55 PM
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Y would I have a problem with detonation
because i did with a 4.030 bore and 3.562 stroke using vortecs. a 400 is i a bit more than that.
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Old 12-01-2012, 01:41 PM
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Smth, I'll say one thing for you, you're hard-headed.
What you may not understand is the fact that the last 400 rolled of the assembly line somewhere around 1980. The first one rolled off in 1970. So, that 400 of yours would be somewhere between 32 and 42 years old. Now, in that length of time, nobody knows how many owners the motor has been through and nobody knows what changes have been made to the motor. I said this in the other thread and I'll say it again here. You must know the piston crown configuration and the piston deck height before you make any decisions to change heads. Further, you must calculate your static compression ratio before you can make an intelligent camshaft choice. You can't just throw this together and that together and expect good results. It's no different than anything else, garbage in, garbage out. Is there any possibility of you taking some pics of the piston crowns and showing us what you're dealing with. If you can do that, I can explain how to find the piston deck height with simple tools. Run one of the pistons up to top dead center and take some pics.
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Old 12-02-2012, 02:47 PM
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Ok ? for you if your smart y would my motor be any different from anothet fully stock (means everything that came from factory) motor
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Old 12-02-2012, 02:57 PM
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Ok ? for you if your smart y would my motor be any different from anothet fully stock (means everything that came from factory) motor
OMG...
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Old 12-02-2012, 04:42 PM
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I think what tech was saying its rare to find a 400 that is competely stock. Many have at least been bored once with new pistons installed.

I have not seen too many older engines come apart and still be at the stock bore size. Most of the time they have been rebuilt once or still in tje original car they came in with low miles.

Where did you get the engine from that leads you to belive it is stock?
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Old 12-02-2012, 05:09 PM
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vortec heads on 400 sbc

For the young and..... The 400 engine was in production from 1970-1980. There were three different volume of dished pistons used in the 400 engine. The 400 heads had a 76cc combustion chamber. The reason you have to know the piston head volume is to figure your compression ratio. For an example an engine with 12cc dished pistons with 76cc heads will have 9.6 compression ratio. Another example is an engine with 22cc dished pistons and 76cc heads will have 8.8 compression ratio. Now take the engine with 12cc dish pistons and change the heads to 64cc chambers will have 10.8 compression ratio. With 22cc dish pistons and 64cc heads the compression ratio will be 9.8. To use pump gas with iron heads safely you would want the compression ratio to be around 9.6. Detonation destroys engines.
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Old 12-03-2012, 09:52 AM
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Not sure about your math.I didn't bother to check to be honest.I think about 9.5 SCR is pushing it with iron heads.But the real factor is which cam that is being used,what the cam timing is,and what the dynamic compression ratio is or how much is being bled off.You have to know the SCR before you can find the DCR.It is a safe limit if the DCR is about 8.5.

The Vortec's aren't too bad for a 350,but are a tad small being 170cc intake runner(180cc would be better) and are way too small for a 400 which should see around 195 o 225 cc runner.It's all about heads/camming in these SBC's.How much air/fuel in and how much out.The bigger raised runner Bowties would be the answer with the matched intake.
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Old 12-04-2012, 12:41 AM
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Quote:
Originally Posted by smith9300 View Post
Ok im thinking about vortec heads on my 400 I was just wondering what I would all have to change I know the intake and can some one give me some ideas on one of those to plz the motor is stock not looking to do anything to it I have a mild cam comp cam xe256 is the model just looking for a little help im 19 and this is pretty much my first motor
First, lose the 'tude. Ain't nobody here owes you anything.

Second, the laws of physics have not changed since your last thread on this.

So... you cannot use Vortec heads if you have FT pistons. If they're dished, you need to know the volume of the dish.

You have got to help us to get any useful feedback! What pistons are in the engine now? Describe what they look like (round dish w/4 valve reliefs, for example). If you measure the depth and diameter of the dish an estimate of the dish volume can be made using the formula pi x r squared x depth of the dish x 16.4 + 2 or 3cc for the valve reliefs.
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Old 12-04-2012, 12:52 AM
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If you measure the depth and diameter of the dish an estimate of the dish volume can be made using the formula pi x r squared x depth of the dish x 16.4 + 2 or 3cc for the valve reliefs.


R O F L M B B O!!!
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