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Tyler23

question for you engine builders

18 posts in this topic

okay so i think ive found a new project. iam going to(once i find one for a good price) buy a 350 4-bolt chevy and have it boreded and balance and stroked into a 383. i wanna make it be able to rev to around 6500 7000rpms. my question is what is a good set of heads that are reasonably priced that can handle this? thanks

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why not?.. i got a light car that it will be going in and i want it to be a fast high reving motor. the one i got in it now will rev to 6,000 no problem

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(6 to 7000 RPM is really not a problem for a 4 bolt small block)

Tyler, the engine choice you made is a very popular but more expensive one than doing a regular 350, but the finished motor is very impressive. I assume that you are aware that the small block 350 uses a smaller main bearing diameter than the Small block 400. To run a 400 crank in a 350 the crank has to be machined to fit the 350 bearing diameters. Piston height will need to be matched to which ever rods you are using (350 or 400). If you use the 400 connecting rods, then you can use regular 350 pistons. The longer stroke 400 crank also requires that you machine additional clearance inside the block, by grinding notches to eliminate the crank hitting the block and other parts. The entire engine must be re-balanced because the 400 is externally balanced and the 350 is internally balenced so you need to use 400 flywheel and 400 harmonic balancer.

Machining and setting up a bare or used set of heads, is very expensive. Your best bet, if you are willing to spend the money would be a good set of aluminum heads fully asembled and ready to go out of the box. There are several brands out there so check the catalogs and choose the best you can afford.

Be prepared to spend some bucks on this combo....

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macgyver-thanks a bunch. as for the heads i got a set of camalback heads and a set of corvette heads from 1971. the corvette heads have 75cc combustion chambers according to the code breakdown on the net. would those be good heads if i have them machined and valve job done? i wasnt sure about the aluminum heads because of the expansion and contraction comparded to a cast block? will it go threw head gaskets?... maybe i should get a 4-bolt main bare block and a complete 400?

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The older 64cc "Camelback" heads you have will do well. Look for casting number "461" Those were the standard head on a 327 4bbl. They lack the accesory bolt holes for the alternator,etc.

The next step up would be the 68cc "186" casting heads. These came on the 300h.p. 350 4bbl's from '69-'70 these have the accesory holes in the ends.

Either of these heads will yield 10.5 to 1 compression with flat top pistons-about 11.5 to 1 with domed pistons. Both have 1.94" intake valves. The best stock iron is the one's I have on the shelf-the angle plug 2.02's. They came on the high h.p. 350's in vettes and Camaros.

Unless you're running turbos or a supercharger,75cc is too much of a cavity.

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ok the casting numbers on the engine i got in my camaro now are 3973 487 could you tell me anything about these? he claims they are off a early 70's corvette.

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if i put aluminum heads on a cast block with this cause head gasket failure or will it be fine?

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Putting aluminum heads on a cast block is very common, even standard practice for production motors. A head gasket failure is possible on ANY engine, but probably not any more likely on your setup than any other.

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ok well any idea how much get a set of cast head redone will cost ballpark? or should i be better off buying a set from like edelbrock or something

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ok well any idea how much get a set of cast head redone will cost ballpark?

As you will find out as you get deeper into performance engines, there is no real "ballpark" number. Its basically limited to whatever you can afford and how "fast" you want to go. If I were to guess, as far as a good "street" motor you should be able to get a set done decently in the 750 range, but a decent set of Edelbrock aluminum for street use is under a grand. If you want to go better you can get into a set of Dart heads for 1500 or so. Like I said its a money game and there is no limit to what you could spend. Once you are "hooked" you'll find yourself wondering what you could do to make it just a little faster. And the game goes on.....

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haha yep im finding that out. i thought the 355 thats in it would be fast and it is. but i wanna go faster lol... if i get a set of camalback heads redone so there basically new are they going to be much different that like edelbrock heads or dart heads? am i going to gain much

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This is an interesting thread since it involves my favorite engine. I have built a ton of them. Mostly for racing, but some for street use as well. The cost quoted above to do stock heads is about right. But you can buy new heads for the same money that will flow much better. Dart has a cast iron street head with 170cc intake runners that will add 30hp over a double hump. And you don't have something 40 years old to start with. The 487's you have is one of the better castings for a smog head. But still do not have the flow you can get with new heads.

The days of machining 400 cranks to fit a 350 block are long gone. The 400 crank is junk to begin with. You can buy a new Eagle crank that will fit right in for around $300 that is internally balanced. So you can still use your 350 balancer and flywheel. Nobody can tell by looking that you have a 383.

Better yet you can buy a complete rotating assembly including an Eagle crank and rods, SRP pistons, moly rings, clevite bearings, and internally balanced. Just get your block machined and assemble it.

Going about your project in this manner would greatly simplify it for you. And you can turn this motor 7,000rpm all day if you want. It would end out around 425-450hp.

Hope this info helps.

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You have mentioned cost repeatedly, and I'm going to tell you that if your looking for a 7000 RPM 383 you are going to have several thousand dollars in this motor if you want it done right.

You would be better off getting a crate 350 from GM and a blue bottle.

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im aware of the cost... DR Thunder- thanks a ton for the info i was thinking i was going to have to get a 400 crank and have a bunch of work done to it but im thinking now if i do it im just gunna get a eagle rotating assembly and a set of new heads... this motor will be in a 79 camaro thats been restored so it doesnt get driven more than a few times a week. id like to get max horsepower but still drivable any idea of a get cam spec. for this? Thanks abunch!!

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You should be able to call just about any cam company and they should be able to recommend one for you based on the the specs of the motor and how you plan to use it. We have good luck with Comp, crane, and isky in our race motors im sure they all make something that will work for you application.

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im aware of the cost... DR Thunder- thanks a ton for the info i was thinking i was going to have to get a 400 crank and have a bunch of work done to it but im thinking now if i do it im just gunna get a eagle rotating assembly and a set of new heads... this motor will be in a 79 camaro thats been restored so it doesnt get driven more than a few times a week. id like to get max horsepower but still drivable any idea of a get cam spec. for this? Thanks abunch!!

Before you can decide the right cam, you have to have established several things...

Compression ratio

Displacement

Power band/power range

Torque converter stall speed (if auto)

Rear end gear ratio

etc..etc..etc..

I've considered doing the 383 thing or maybe even a 427 smallblock (yes, 427 smallblock) for my 1991 Z-28, but to do it right is very expensive. Once you start getting up there in power it's not just the engine. It's the transmission, driveline, rear end, etc. too.

By the time it's all said and done, the preassembled engines from reputable places aren't too bad of deals. I had been sort of leaning towards the GM 383 "fastburn" package with a TPIS Miniram intake, cam, and matching chip. Not cheap though....I've decided to hold on to my money for now.

That new Camaro with a 425hp engine is only $20k more, and a lot less work, than trying to beef up mine. wink

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