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
smith9300
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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
you will need manifold and valve covers.you need to know what pistons are in the engine or static compression ratio
dont forget to have the steam holes drilled in them. and you will probably have detonation problems.
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.
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.
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.
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.
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.
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.
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.
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!!!
R O F L M B B O!!!
I had a guy thats been working with sbc engines for around 16 years tell me I would be good to run them he said the pistons I have are the stock 22 cc dish pistons and im not just throwing it together iv did so much reading on it and asked ppl many ?s everybody tells me I should be fine running the vortecs on it but I know I am going to have to be running premium but that's fine BC the engine im going to have is going to be a monster well for me anyways and thanks for all the help everybody I wasnt trying to be a Dick
Fair chance you'll need premium to keep it from pinging.
What you want to avoid is backing the timing off from the best power timing to stop the pinging. This is because lowering the timing kills the power and mileage.
The 256 Comp cam has a relatively early intake valve closing (IC) point (55° ABDC @ 0.006" lift). What that means to you is the static compression ratio (SCR) that I estimated to be about 9.6:1 on your last thread will make the dynamic compression ratio (DCR) to be about 8.25:1. This page (written by techinspector1) will give you an idea of what CR is needed for different durations.
BUT!!! Until you know the exact static compression ratio as well as the quench distance (and that brings you back to CC'ing the combustion chambers and measuring how far down the hole your piston sits and the dish volume), this is a ballpark guess ONLY!!! To use my figures w/o checking my math and using the correct SCR might cost you an engine or at the very least cause you to tear it back down to correct the CR or to run race gas or to retard the total timing.
Online Calculators (there are others):
• SCR calculator
• Wallace Racing DCR calculator
• Kelly DCR calculator
• KB/Silvolite DCR calculator
You also need to use a vacuum advance and set the ignition timing advance curve up correctly. There are MANY threads on this. After reading up on it if you still have questions, just ask and we'll try to sort it out for you. But first you need to research it for yo'self.
What you want to avoid is backing the timing off from the best power timing to stop the pinging. This is because lowering the timing kills the power and mileage.
The 256 Comp cam has a relatively early intake valve closing (IC) point (55° ABDC @ 0.006" lift). What that means to you is the static compression ratio (SCR) that I estimated to be about 9.6:1 on your last thread will make the dynamic compression ratio (DCR) to be about 8.25:1. This page (written by techinspector1) will give you an idea of what CR is needed for different durations.
BUT!!! Until you know the exact static compression ratio as well as the quench distance (and that brings you back to CC'ing the combustion chambers and measuring how far down the hole your piston sits and the dish volume), this is a ballpark guess ONLY!!! To use my figures w/o checking my math and using the correct SCR might cost you an engine or at the very least cause you to tear it back down to correct the CR or to run race gas or to retard the total timing.
Online Calculators (there are others):
• SCR calculator
• Wallace Racing DCR calculator
• Kelly DCR calculator
• KB/Silvolite DCR calculator
You also need to use a vacuum advance and set the ignition timing advance curve up correctly. There are MANY threads on this. After reading up on it if you still have questions, just ask and we'll try to sort it out for you. But first you need to research it for yo'self.
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