Hey guys, so I found a 396 from a guy and bought it for my 65 impala project car. I have some questions that I hope the guys here can answer about building it up to 450-475 HP. The specs. The block just came back from the machine shop when this guy sold it to me, it has been bored .60 over (making 408), forged crank and Keith Black hypereutectic pistons. It is a Mark IV block with an upgraded 2 piece rear main seal. Questions: 1. the block is marked P*** HIGH PERF it has the external oil cooler lines BUT is a 2 bolt main, the books I have say HIGH PERF should have 4 bolts. Whats up with that? 2. I am having trouble tracking down any kind of build specs to get a rough idea on a build for this engine. What Heads, Cam, Intake should i be looking at to get my HP goals out of it? 3. Its HIGH PERF P*** so its hydrolic roller rockers or what? Any links or build ups that you guys have done would be awesome as a ref. p.s. Budget build is always good. and i understand 400-450 is a more reasonable goal.
My two cents (and I'm a Ford guy, so I don't usually chime in on Chevy discussions) are to get rid of the Keith Black hypereutectic pistons. Any detonation and they will disintegrate on you, ask me how I know. Again, just my thoughts. Forged pistons are worth the money and the piece of mind. Mike
The old "HIGH PERF P***" doesn't mean ****. I've seen that cast on bread and ****er oval port heads and two bolt main blocks.
All Mark IV blocks were two piece rear main seals. Most of the blocks had HPP in the casting and to get good power out of a 396 a good set of heads is a must. Factory cast oval port 781,049 retangle port 088,990 are good for starters. To make a long story short I would try to find the 781s and try for about 9:1 compression with around a 280 Comp cam and you should be close. Cams are not the same as they used to be in flat tappet. A good hydro roller cost more but one wiped lobe from a flat tappet will eat the difference up quick!
Why is this? I have read that the KBH pistons are good as long as the rings are set correctly, the engine was ***embled and balanced by an engine builder shop, i hate to make ***umptions but since it was professionally ***embled I would think they set it up correctly.
One thing that needs to be added is that 65/66 396 engines take a cam with a groove cut in the rear journal for oiling or the oil won't go past that journal. The cams aren't hard to get but those blocks need the cam with that groove in it.
The problem with trying to build high horsepower in 396-402 engines is it is very expensive. They used Keith Black pistons for the build because they are the only performance 396 pistons stocked/available anymore. All the "reasonable" high compression performance forged pistons are not available. TRW Fed-Mogul 396 type pistons haven't been produced for years and Fed-Mogul destroyed the mold/forms when they moved production overseas years ago. If you can find a part number listed. It will not be available. Only option is find some Ebay or order custom pistons for $700.00+' The piston dome has to be so tall to build compression that the flame travel is terrible. The 049-781 heads will not work on a 396. They drop compression a full 2 points. 119 cc. or more. Great on big bore blocks but not 396. Aftermkt heads are all designed on the 119 chamber. The 396 needs the early heads at 96-98 cc. Getting as rare as hens teeth and either worn out or $$$$$' I've been thru the problems with several customers. You can build a 496 cheaper and better than a 396.. I've stated this in several other forums and the guys think I'm a 396 hater. I am not. This is real world fact. I raced them in the day. That day is far past. Been building/racing BBC's since the late sixties.
what turboxt said is on point, decent oval heads and a cam, and depending on budget etc, it may be worth getting new heads, some of the cheap ones on ebay are 1000 per pair for new aluminum.....hard to say what to do, they are made overseas I am sure, but I know some people build some sick fast, dependable cars with them...finding a cheap 454 may also be a good idea
Yes only on the first two years production. Takes a rear cam bearing with groove and camshaft with groove. Back in the day all aftermkt BBC cam cores came with rear journal grooved. Causes a minor oil loss in later blocks. Cores started being non grooved in the seventies and now you have to have the rear journal done by a machine shop.
So, I forgot to mention that along with the block i got 2 sets of heads 3933148 - oval open 112cc chambers 2.06 intake 1.72 exhaust 3856206 - oval closed 97.2cc chambers 2.06 intake 1.72 exhaust I used an online calculator and determined that: bore 4.154 stroke 3.76 cylinder head volume 97.2 Effective dome volume -17 deck clearance .023 compressed gasket thickness .050 gives me: 9.67:1 @ 407.66 Cubes sound about right? I will have the heads machined so might knock a few thousands off of them.. want to keep it about where it is thought.
Good info here, ProComp Electronics Aluminum heads are less than a grand a pair... http://www.superchevy.com/sch/02/mean-little-rodent/articles/ http://www.store.procompelectronics.com/index.php?target=products&product_id=37067 PARTS FOR 500 hp •396-cid, two-bolt block, bored 0.060 over •10.25:1 compression ratio •GM-forged crank, 3.76-inch stroke •GM truck connecting rods with 3/8-inch ARP Wav-lok bolts (polished and shot-peened) •Speed Pro engine bearings •Speed Pro forged pistons PN L2287F •Total Seal gapless moly-coated rings •Fel Pro gaskets (PN 1027 head gasket) •Brodix -1 OEFI aluminum heads with 2.25-1.88 valves •Comp Cams valve springs PN 939 •Comp Cams locks, pushrods, and ***anium retainers •Comp Cams 1.7:1 aluminum roller rockers •Comp Cams XR274R Roller camshaft •Comp Cams Endur-X roller lifters •Edelbrock Performer RPM manifold •Speed Demon 750 carb •MSD distributor •****** 1 3/4-inch headers PARTS FOR 540 hp •Same as for 500hp except: •Comp Cams XR280R Roller camshaft •Edelbrock Victor Jr. intake manifold •Wilson 1.5-inch four-into-one tapered hole carb spacer PARTS FOR 575 hp •Same as for 540 hp except: •Comp Cams 1.8:1 stainless rocker arms •Race Demon 950-cfm carb •Wilson 1 3/4-inch open spacer •Headman 2-inch headers •XR-1 3 1/2-inch Borla mufflers •Moroso three-vane vacuum pump &bullComp Cams valve springs PN 954 Read more: http://www.superchevy.com/tech/0106sc_how_to_increase_horsepower/#ixzz2ODnnkXEg
Would need pistons for sure. In the article they used Brodix RR B 0 I think they are 270 CC, but twice the dollars. It's a shame proComp oest have a smaller head. Some head info
And the key word here is BUDGET. Besides I quit believing those magazine builds a long time ago. Those guys don't live in the real world.. I think it comes from all the free drinks and parts they get.
Another experience for perspective, similar budget I usually come up here with input on our 'higher-end" units forgetting sometimes not everyone is looking for this type of setup. We just had kind of a different request for a build as it says above, a 396 BB built around the "budget-only". Not caring about HP or Torque numbers whatsoever. The customer left the choice of parts up to us with only one exception, he wanted the results to include any type of "cast" pistons. We figured it was the perfect choice to test the KB160's, we've never used a "hyper-eutectic" in any testing before this time. The weight of the piston was a factor in the choice. Weight-wise we considered it an "equal-replacement" piece (kind of heavy). Once in a "blue-moon" we'd sell a set of these, but have yet to "test" any. As I stated above, there was NEVER an HP/Torque number mentioned. But we were very curious. What we were handed was an all-original 396/325 HP oval port unit. Block casting #3916323 (2B.M.), Cast crank, 3/8" rods, cast 10.25 pistons, and a pair of factory #3917215 "oval" port heads. We had no intake for this unit, so the customer and I agreed ahead of time to use a "Performer" figuring it would fairly close to original. We said nothing to the customer during the build/test, but what we were really most interested in besides the pistons was the "fuel-consumption" results. The only two parameters we were "locked" into was the C.R. had to be around 9.0:1 (final was 9.2) and absolutely no "tricks", this was the customers wording, not mine. In simpler terms, there was to be no excessive milling, no gasket matching, definitely no porting (including any bowl work), this was a good ol' "down & dirty" rebuild, nothing more. Stock valve sizes, no "light" stems, had to use stock pushrods, rockers, and valve covers. After writing the order, but before we starting the program, we envisioned an "RV"/truck style unit with corresponding HP/Torque numbers that would probably be able to achieve some "decent" gas mileage. We haven't done a unit "down" at this level in a very long time. The best thing is we were getting paid to go through it all, it wasn't us "digging" in our own pockets this time for answers to questions about products we really weren't concerned about! Here's a list of components, the dyno "numbers" follow: Pistons: KB130's Rings: E243K's gapped at .030" top and .022" second. Bearings.: Clevite's mains-.020"s F/M's rods-.010" Oil System: Stock pan/screen, Melling pump #M77 w/M77020 HPspring (Idles @ 25#, runs @ 55#) Cam/Lifters: Blue-Racer "hydraulic" 214* @ .050" x .500 x 114 L/S (In @ 109 C/L) / Johnson #817's Gaskets: Corteco's #32377CS Valves: G.M. Stock 2.060" and 1.720". No back-cuts (seats located at outer edge however). Springs: G.M. Stock "singles". Customer's choice, we recommended dual's. Pressure’s at 110# / 285#. Rockers: G.M. Stock "stamped" with a set "slotted" balls and new lock-nuts (16 new studs also). Fasteners: All stock, the original's were retained. Unit came off the dyno at 362 HP @ 5650 and 420 Ft.Lbs. Torque @ 4100. We tested this with the only headers we had available at the moment, which were 1.750", and a 750 Holley. There was absolutely no "traces" out the exhaust ports. We were surprised somewhat by the numbers considering the C.R. was almost 1.5 points lower than the factory units back in '68! Everything seemed fine and it's been delivered. Thanks, Gary in N.Y.
A very sensible street 396 that will squack the tires and last many reliable miles.. Best of all the guy will tell everybody good things about the shop/engine..
Run whatcha got, including the -206 heads with stock valve sizes. Upgrading to a 2.19/1.88 valve combo woud be worth a bit, but that's money not yet spent. If you don't have a cam, look for something with mid 230's @.050, without excessive advertised duration (probably in the 270-280 range). Lunati's Voodoo line is very good. Devin
Bump the cam up to the .530 lift intake/.220 duration. Dual plane intake (used) proper turning, dual exhaust, smart shopping and yes you can budget build this into a performance engine. Those pistons are fine as long as they are not abused. Low end (low RPM) is where this engine will live along time.
Here's my experience with the KB pistons: I rebuilt a Ford 289 with them, mostly a stock rebuild with an added cam and intake and a Holley, really standard stuff. But I did want the compression up about 10.5:1 or so, and the only (reasonably priced, so I thought) pistons were the KB set. I did all the ring gaps myself, per cylinder, after a bore and hone job by the machinist, and put it all together. It ran just fine, good little motor, until one day when it started to detonate. I can't say that I know how long it did it before I noticed, as the exhaust was a tad rumbly, but I know it wasn't long. From the time I noticed it to the time I got where I was going, I had a significant "bang" and huge power loss. Limped it home and started tearing into it, ***uming it wasn't as bad as it was. turns out one piston had a hole burned the size of my finger right down the side from cross firing on the plug leads (that ****'s a *****, pardon my language) and one other piston was starting to burn through too. Don't get me wrong, I'm not saying it couldn't have been prevented, I'm just saying that a forged piston usually gives you enough time to get home and change the timing before going kaput. Mike
My friend Ed has a small machine shop. He has used many sets of K.B. pistons. If the piston to wall clearance is right and the ring end gap is set right, they will last as long as anything else. If not, they will scratch walls, run hot, and in the end come apart. 408 cu.in needs to make 1.2 hp/cu. to get you in the 480 hp. range. I have seen this done with 10-10.5 comp. bowl ported oval port heads and a .590 lift hyd. cam ( this is not as high as it sounds, b.b.c.'s have 1.7 rockers). With a good intake and carb. The main problem using early heads is that they don't have hardened exhaust seats. A good machine shop can fix that though.
hypereutectic is a four letter word ( cast) not for hi-po use and priced the same as entry level forged pistons---plenty good enough for most applications ,but so are badger pistons and they are 10 bucks a piece...
I put together a 396 one time using standard bore pistons out of a 402. Zero decked the block, cut a set of closed chamber oval port heads for 2.19-1.88 valves ported the **** out of them and angle milled them .100". Had a .550 lift cam and WOW. Never did blow it up. It was in a 59 biscayne and it was very fast. Problem with this plan for you is your block is already bored....
Hey guys, thanks for all the responses. I have been doing some calculations and will probably stick with the stock heads I have and get some work done to them. Yes this is the first bbc I have even seen on an engine stand, sbc i've seen my fair share built. I am in the middle of doing rust repair and body work bought myself a hobart handler 140 off a guy on craigs list. Doing trunk and small spot in floor pan, and the rear window filler panel is rotted out (typical). I should take pictures of all this. I'm out to play some pool. Thanks again for all the options/opinions.
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