i have a 396 for my 70 camaro which was the original motor for my car. this is the reason for building it. the casting number on the block is 3955272 which is a 2 bolt main. i also have a steel crank #6223. the heads that i have are 3872702 and they are large oval ports. also i am using a muncie 4 speed behind it.
my questions are what is the best way to build this motor? cam,head porting, intake, pistons exc. what kind of horse power should i expect?
ive read many post about the 396 builds with everyone saying to build a 454 instead. but this is the correct motor for my car is the 396.
machine work and balancing $1,000
so how do we spend the next 1000?
gaskets/pistons/rings/bearings/camshaft and kit/timing chain and gear set,,,oil pump
we ran out of money a long time ago......
yea thanks for the input but the money amount wasnt the concern as the question to the people that have built a 396 of what has worked or will work to build a decent motor. as the question of has allways came up in previous questionson past post as how much you would like to spend. yes im aware that i can spend thousands of dollars on both machine work and parts but every project has to start and end at some point. my project started as a pill of **** and wont end that way. im not a engine builder so im looking for advice from somone whos main concern isnt my wallet size. so im looking for advice on building a 396 nothing else. does anyone have any good advice on what works well? thanks
Everyone on this forum probably has some good advice for you. You asked about bringing a 396 back to life and I for one suggested that you need to budget about $1000 for machine work. That's real. That's what it takes to do a motor the right way. If you've never done it properly before, then you will just have to learn to bite the bullet the way most of the rest of us have. Can you rebuild the motor on a tree stump for $500 total? Yep, you sure can. Bottle brush hone, cheapo gasket set, re-use the pistons, cheapo rings, cheapo oil pump, no valve job unless you want to lap the valves with toothpaste and forget the guides, no verification of mains or cutting the block deck height to establish the proper squish for pump gas, no balancing, yadda, yadda, yadda. Many have done it before and many will do it after this. It just depends on what you want for a final product, but trust me, you won't produce a quality 400/425 hp 396 for $2000.
great i appreciate your responce and know by your previous responces that you have a great deal of knowledge . i understand the coast of how much machine work will coast me. what do you recomend for rods, pistions,cam, intake? are the heads that i have good enough to make a 400 hp motor or should i thow them to the side.
Hard to build a budget 396. To make the 400 plus figures you will need good heads and they are not cheap. The 108 cc chambers with reasonable compression height/dome pistons. If you use GM stuff. Lots of work needed to make any of the small bore oval heads flow. The ports are not great for flow and the chambers are bad in stock form.
GM used rec port heads but none are cheap anymore. Aftermkt is mostly based on the larger bore with 119+ chambers. To get compression the piston dome has to be huge and that causes flame control problems. I built one back when TRW offered them .Open chamber for big head.. Engine was ok but tempermental and ate spark plugs
If you get past those problems.. BBC like lots of cam lift and split durations. 10.25 or so compression for street. Many good intakes out there. I like the Holley Strip Dominator or its clones for semi serious street stuff. Large tube headders/exhaust. STOCK oil pump. Relieve the front cam bearing to feed the timing gear/T set oil, if flat tappet cam is used. GM "thumb" or "dot" rods with aftermkt bolts will work great.
Yer gunna have to buzz it to get big numbers. Build accordingly.
Yeah you'll probably just have to bite the bullet. You can take the crank to the machine shop but their going to ask for all of it, see if the block needs align honed etc.. You could save a few dollars by assembling the shortblock yourself if you have the knowhow and reuse some parts. Being lucky, and you just turn the crank, clean the block, re-use the heads and get a valve job, you may spend as little as $800 best case.. and then have to assemble everything.
If you want the shop to assemble it, that gets expensive because it's time consuming.. checking clearances, filing rings etc. etc. a lot of times buying a complete new shortblock is just as affordable if not more.. and even then you should disassemble and check it.
If your like me, i really don't mind having the engine on the stand for a while and saving for the parts, it's fun to tinker with that stuff and then you have a warm fuzzy feeling when it's all done, and some more experience etc..
Obviously you want to build the 396 because it's original to the car and you have all the major pieces. Sometimes people don't really want to listen to what people are asking and give suggestions based on what they would build as opposed to what you want to build.
Short block wise a lot depends on the condition of the block, crank, and rods. For what you want to do use the stock rods. Have them checked out by a competent machine shop and if good have them resized with good rod bolts. Same with the crank, depending on it's condition it might need to be cut undersize but you already knew that. For those heads a nice hypereutectic flat top piston will put you at a roughly 9.5:1 compression ratio which is about the limit for your application with iron heads. Get the whole rotating assembly balanced as it's money well spent. If the block needs to be bored you can easily go +.06 as there's plenty of cylinder wall.
Those heads are ok for what you want to do but have limits. If they were going on a bigger bore engine (454) I would put in bigger valves but because it's a 396 they just won't physically fit without notching the tops of the bores. Have the heads stripped down and checked out for cracks and flatness. Get some decent stock size one piece stainless valves. Something like a "street flow" or something from Competition Products with a necked down stem. Have the intakes backcut, and get a good multi-angle valve job. Along with that get the correct valve springs for the type of cam you're going to run.
For a cam something in the 210-215 @.05 range with a lift of around .500 will work nicely. Much more lift than that is a waste as those heads don't flow great above roughly .45 without porting.
On a motor like this roller rockers really aren't a requirement. They're nice to have but not something that will hold it back.
For an intake if you have a stock 4 barrel intake you could use that as they were actually pretty good. If all you have is a 2 barrel intake go with one of tried and true dual plane intakes like an Edelbrock Performer.
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