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Old 11-07-2012, 10:29 AM
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sbc 400 heads

Hey guys, I am new to this forum and have a question. first some background,I have a 1983 chevy elcamino with a 305 engine with 226,000 miles and only has 145hp. I want to have a little more power but dont have plenty money to spend right now. I have a 1971 400 with matching heads that my brother law pulled out of a 68 camaro It was running great when he pulled it to put in a zz4 crate engine. he gave me the 400..I have researched and everyone says throw the heads away they are useless but it seems there all looking for 400 plus horsepower, I am not I want to drive this baby everyday and if I can get 300 to 325 that would be great..What do you guys recommend?

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Old 11-07-2012, 12:04 PM
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Originally Posted by gmtony55 View Post
Hey guys, I am new to this forum and have a question. first some background,I have a 1983 chevy elcamino with a 305 engine with 226,000 miles and only has 145hp. I want to have a little more power but dont have plenty money to spend right now. I have a 1971 400 with matching heads that my brother law pulled out of a 68 camaro It was running great when he pulled it to put in a zz4 crate engine. he gave me the 400..I have researched and everyone says throw the heads away they are useless but it seems there all looking for 400 plus horsepower, I am not I want to drive this baby everyday and if I can get 300 to 325 that would be great..What do you guys recommend?
If its working then dont mess with it. Just swap em. If it needs head work I would not spend to much cash on the stock heads but they may not be the bad ones. best to have machine shop check them out if questionable. I do not think all the heads for the 400 had the cracking issue. I could be wrong on that one tho.....
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Old 11-07-2012, 12:32 PM
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Quote:
Originally Posted by gmtony55 View Post
Hey guys, I am new to this forum and have a question. first some background,I have a 1983 chevy elcamino with a 305 engine with 226,000 miles and only has 145hp. I want to have a little more power but dont have plenty money to spend right now. I have a 1971 400 with matching heads that my brother law pulled out of a 68 camaro It was running great when he pulled it to put in a zz4 crate engine. he gave me the 400..I have researched and everyone says throw the heads away they are useless but it seems there all looking for 400 plus horsepower, I am not I want to drive this baby everyday and if I can get 300 to 325 that would be great..What do you guys recommend?
The early 400's used a 2-bbl carb and were rated at 265 hp (gross hp from 1971 and previous years of production. As of 1972, hp ratings were based on net output, so that 265 hp figure would be lowered to 170. That would be the number that you would compare to the 305 hp from the factory) That would be a step up from your 305 motor, but of course, we don't know if that would satisfy you.
Are you capable of disassembling the motor, buying different parts, having machine work done (align bore or align hone the main bearing bore, bore and hone the cylinders for +0.030" pistons using a torque plate, cutting the block deck height to arrive at a close squish) and then re-assembling the motor with new parts? If not, install the 400 as is and enjoy.

Last edited by techinspector1; 11-07-2012 at 12:44 PM.
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Old 11-07-2012, 01:02 PM
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Quote:
Originally Posted by gmtony55 View Post
Hey guys, I am new to this forum and have a question. first some background,I have a 1983 chevy elcamino with a 305 engine with 226,000 miles and only has 145hp. I want to have a little more power but dont have plenty money to spend right now. I have a 1971 400 with matching heads that my brother law pulled out of a 68 camaro It was running great when he pulled it to put in a zz4 crate engine. he gave me the 400..I have researched and everyone says throw the heads away they are useless but it seems there all looking for 400 plus horsepower, I am not I want to drive this baby everyday and if I can get 300 to 325 that would be great..What do you guys recommend?
Even a stock 2 barrel 400 will bring a massive injection of torque without necessarily bringing big horsepower numbers, so you will feel this right out the first stop sign you meet.

The 400 is an externally balanced engine where your 305 is internal. The difference being the 400 needs a 400 offset balance damper on the front of crankshaft and it needs a 400 offset balance flywheel or flexplate depending on whether your El Camino is a stick or automatic. Beyond that it's a bolt in.

Unless you're looking for some fantastic level of performance I wouldn't start by replacing anything especially the heads as heads, cam, pistons, intake and exhaust systems are really integrated parts of the whole, when you change one of these all should be touched if optimal power solutions are the goal.

Bogie
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Old 11-07-2012, 01:41 PM
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A lot of great info thats for sure. I did leave out that the previous owner installed a cam, too big in my opinion i was told 282 and an edelbrock performer rpm intake. this engine has the heads off of it and the oil pan off as well. I do have the dampner and flywheel also. The short block is all assembled and I would like to just put it all back together and install it. But something keeps telling me, You all ready have it out and down and the 305 is running fine "save up some money and build it up right". With that said I do not want to bore this engine anyway as it will get expensive. with the right cam, headers and carb I should be ok. Thanks guys
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Old 11-07-2012, 02:43 PM
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I do have another part to this question. Is the stock carb on my 83 elco something I can transfer over or not?

It is a 4 barrel Q-jet
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Old 11-07-2012, 02:59 PM
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Originally Posted by gmtony55 View Post
A lot of great info thats for sure. I did leave out that the previous owner installed a cam, too big in my opinion i was told 282 and an edelbrock performer rpm intake. this engine has the heads off of it and the oil pan off as well. I do have the dampner and flywheel also. The short block is all assembled and I would like to just put it all back together and install it. But something keeps telling me, You all ready have it out and down and the 305 is running fine "save up some money and build it up right". With that said I do not want to bore this engine anyway as it will get expensive. with the right cam, headers and carb I should be ok. Thanks guys
Cam can be an issue but may work out if your looking for some power. My friend stuffed a giant cam in his stock 400 and it was awesome. You had to aim the car before you punched it. So it was massive upgrade. Was it right nope! Did it work yep! But as we all know too big a cam can cause some issue that require gear change and stall converter. If the cam is small enpugh not tp require major upgrades run it. Changing the cam can lead tp all kinds of issues with breakin and Tuning. Unless its massive or wiped i would go for it. But i got no issue pulling it if then cam is wrong. If its your dd then you will have to make a choice based on use of the car. For me big cams are the only way to go. But other have much different ideas.

Without specs its hard to say. Also with it taken apart you may have some other issues. But if you not prepared to bore it leave it alone unless you know it may need some work. The 400 over the 305 will be amazing difference.
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Old 11-08-2012, 07:08 AM
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Its very hard to overcam a 400. If you just want a 350hp torque monster
just throw it in as is.. The stock 400 heads can be street ported for power
if you re willing. Add a simple mild torquey cam, headers, 4bbl and you are all set.
When you are ready to up the anty, find some vortec heads for it.
"282" don;t tell you much. If its 224@.050" or less you are good to go.
Replace the timing chain and the radiator with a new stock rad, in your camino.

Your lil El Sho-velle will GLH.
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Old 11-08-2012, 08:52 AM
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Street ported?? Is this expensive? the cam is out of engine and was not put up with oil or grease on it so I think I better get a new one anyway, It has some surface rust on it..
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Old 11-08-2012, 10:36 AM
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Street ported?? Is this expensive? the cam is out of engine and was not put up with oil or grease on it so I think I better get a new one anyway, It has some surface rust on it..
Yep its trash toss it out and start over. If the lifters are not marked dont bother even looking at it.
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Old 11-08-2012, 10:56 AM
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the lifters are not marked..but you mean dont look at cam right? not the engine?
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Old 11-08-2012, 03:18 PM
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the lifters are not marked..but you mean dont look at cam right? not the engine?

Yes just the cam. The lifters get broke into a lobe if you put that same lifter on another lobe it has a very high chance of failure. Even with new lifters if its rusty dont run it. Cam is so cheap its not worth the trobule unless its a roller. But flat tappet can be repalce with summit or sealed power cam for less than 150 bucks with lifters. Also you get the cam of your choice.

If it was installed in a sealed motor i would say run it but since its out and not marked to be reinstalled its not worth the effort to re install and get right. You want the engine to go another 50-100K miles before your back under the hood best to get a new one.
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Old 11-08-2012, 03:38 PM
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Thanks! One last thing, do you think I will be ok with my quadrajet carb? what size cam would you recommend? oops that's two things.lol
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Old 11-08-2012, 03:39 PM
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Quote:
Originally Posted by gmtony55 View Post
I do have another part to this question. Is the stock carb on my 83 elco something I can transfer over or not?
It is a 4 barrel Q-jet
To the best of my knowledge, Q-jets came in 750 and 850 cfm varieties, so yeah, a 750 is plenty of carb for a street-driver 400. In my opinion, it's the finest OEM fuel/air mixer ever bolted to a manifold and is nearly as good as EFI when properly set up. Get the proper manual to rebuild it yourself or have Cliff Ruggles or one of the other professionals set it up for your particular application. If you're gonna do it yourself, get Cliff's book....
Cliffs High Performance Quadrajets :: Qjet Carburetor Rebuild Kits, Parts, Quadrajet Rebuilding, Quadrajet Parts, Bushing Kits, Carb Tuning
I would bolt it to an Edelbrock Performer RPM #7104 intake manifold.

As far as cam, stay very conservative with a near-stock unit. If the motor is stock, then it's a low-compression motor and you will kill off all the low-end grunt if you use too much cam. I'd stay under 200 degrees duration @0.050" tappet lift. Resist the urge to use an extreme type of grind, choosing instead a reasonable rate of lift. Subtract the 0.050" duration from the advertised duration. If the result is a "hydraulic intensity" of 56 or larger, you'll have a nice, easy grind. The larger the difference, the easier the cam will be on the lifters. The smaller the difference, the more violent the cam/lifter interaction, with a better chance of roaching a lifter.

Last edited by techinspector1; 11-08-2012 at 04:08 PM.
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Old 11-08-2012, 05:30 PM
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Have to disagree with its hard to over cam a 400, you can over cam ANY engine, I over cammed my 406 & it had iron eagle heads & 10.4.1 compression, It was a bear to tune, sure it would rev too the moon, but it ETs & MPHs exactly the same with the mild cam that i had originally put in it & i shift it at 5000, not 62-6300, So if you choose a cam, choose wisely, I'd just keep it on the cheap, you could re-ring it, clean up the heads, all new gaskets/chain/oil pump, mild cam, then just install headers/intake/carb, It'll run very strong, even with the stock heads. This was the cam that i installed that hurt my 406.

510/510, 245/245 @50, 108 LSA, installed at 104*, even tried 102*

I have 4.11 gears & a 4200 stall.
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