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Discussion Starter · #1 ·
I am getting close to building my rat motor. I have my L88 (L89) Aluminum heads, L88 aluminum intake and the four bolt 396 block, of course. Now, if money were no object (it will be but this is a good place to start) what crank, pistons, connecting rods, bearings, rings etc. would you use to build your dream engine?
 

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I am getting close to building my rat motor. I have my L88 (L89) Aluminum heads, L88 aluminum intake and the four bolt 396 block, of course. Now, if money were no object (it will be but this is a good place to start) what crank, pistons, connecting rods, bearings, rings etc. would you use to build your dream engine?
That top end package (L88) will work well with 100 more cubic inches.You would need to rev a 396 into the stratosphere to justify that combo.Stroke a 454 to 496 or consider oval ports for the baby big block.
 

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Discussion Starter · #3 ·
I know the 454 would be cheap and the 427 would be better. But I really want to use the 396. I want it to be as bad *** as possible but still be what it was - at least on the outside. And I know the blocks are all the same size but the casting numbers date codes, etc would be all wrong.

Don't get me wrong, I'm pissed that after collecting parts for years I now hear that I'm building a big block Z28. I had a Z28 in my teens. I loved the car but it left you wishin for torque. Apparently, the baby rat does the same and especially when you strap on the rect port heads. But it's too late. I'm committed to the 396 375 L89. Now, if I could find a cam that could help or even bore (or stroke) it a little. I'd be open to that.
 

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I'd reconsider. It's your car do what you want,..but you're going to spend 95% of the time below 4000 RPM where this engine will be dog. You may can get away with it if you go mild on the cam and 4.11's out back (or at least 3.73's).

I'd either do some oval-port stuff or jump to a 454 shortblock (or better yet, a stroked 454) if you're dead set on running the L-88 top-end stuff.

Otherwise, I think the misery factor will be high.

My opinion.

PS,..why would you consider a 427 better than a 454?
 

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Discussion Starter · #6 ·
PS,..why would you consider a 427 better than a 454?
There were some COPO'd 427's in 68's Nickey, Dickie Harrell, etc.

I thought about boring the 396 and stroking it. But I've been told that might dog the motor too. Know anyone who has stroked a 396 with success?

By the way, the 3919851 intake I have looks like a 193 without the plenum divider. Suposedly, this was done by GM on the 851 to increase high RPM horsepower.
 

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Discussion Starter · #7 ·
HERE is a piston that you can use with a 4" stroke (454) crank, you can get 434 cubes out of that 396 block.
The cubes sound good. Did you see the foot note.

(HYPER) Chevy 396 block, Chevy 454 crank. Low cost 427 power with 396 economy. .180" hollow dome. Fits open and closed chamber heads.
If open chamber heads are used, pump gas will work with this engine. If quench, timing, plugs, and cam are all just right, you could try regular.
Closed chamber head may work in a Corvette, but never a truck

I've got to use these L89 heads (closed chambers).
 

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To start with, you didn't tell us what your intended use of this engine will be. Is this a street racer, dragstrip car or a mostly correct show/cruise-in car? I'm going to assume that this engine is going into a really nice street/show car. Seeing how I quit wasting money years ago at the dragstrip and now 'invest' my money in restored cars. If that's true, then I'll tell you what I would do. I would have the block cleaned, magnafluxed, decked, line honed, cylinders bored and honed to a finish of 12 microinch with a plateau hone. I would buy a new Scat 4-43856223 steel 5140 crankshaft and a set of Scat 4340 forged I-beam rods. Federal Mogul 'A' series bearings #4400MA mains and #3190A rod bearings are really nice and are also some of the latest in bearing technology. Seeing how I have no desire to buy and store race fuel at my house anymore, I would build this engine around 9.5 compression with TRW forged L2240NF pistons (if your heads are truly the L89 #3919842 closed chambers). Have the entire rotating assembly balanced and finish the pistons with a set of Speed Pro plasma file fit moly rings. Use a Melling M77 STOCK volume oil pump. High volume pumps due nothing but decrease the life of your distributor shaft gear, risk shearing the pin, or breaking the oil pump shaft. Not to mention takes more power to turn it. If you keep your rod and main clearances between .002 and .0025, your oil pressure will be just fine. I have also seen guys spin main bearings in big blocks due to high volume oil pumps sucking the stock oil pan dry. I would then compliment this engine with a complete Comp Cams valve train kit. Magnum roller timing set, Magnum push rods, Magnum roller tip rocker arms, matching valve springs, locks and retainers. As far as the cam, I would put the Comp 282S solid flat tappet in it. This cam sounds great but doesn't have all the nasty downfalls of the bigger 'racing' cams. If you don't like the idea of occasionally setting valve lash, try the Xtreme Energy 274. It sounds great in a 396, runs good and still has 13" of manifold vaccum for your disc brake booster. Just make sure you break the cam in with the inner springs out of the Comp 924's, they have too much open pressure for cam break-in. Cam break-in, hummm, that's a story for another day. Top all this off with a Holley secondary carb, a high energy breakerless ignition system and a nice set of Hooker Comp. headers. If all the machine work is done properly and assembly is done RIGHT, you will have a great sounding, running and reliable street motor. Yeah it might be a little soft of the bottom end due to the large rectangle port heads, but we're not racing here, right? I have learned one thing through out the years, you can't have a race engine in a car you intend on driving a lot. And one last thing, I believe your car will bring more money with this engine than some huge 500+ cubic inch gas guzzlin' creature. That's just my opinion, plus I wanted to freshen up on my typing skills tonight too! Thank you for reading all this mess. :)
 

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Bigfish45 makes 100% complete sense.

68ssrag, when I built the baby rat for my car way back in 1991 I caught alot of flack for not going with a 454 or 427. Hey I bought that 396 for $200 and it was spotless except for a slightly bent rod. This of course was 16 years ago. Times have changed but old school still works today!!

Anyway back then I had the 396 bored .030 over. I went with a regular hydraulic cam & hydraulic lifters. The cam card said .292 duration w/ a .544 lift. It was a Competition Cam. The heads were stock cast iron heads with minor work done. I think they were oval port. I went with an Edelbrock performer dual plane intake. The carb was a bit undersized but worked well. It was a Holley 750 single pumper w/ vac secondaries. The compression was 12.5:1. The ignition was a performance HEI. I tried to get the Hooker Super Comp headers in there but they would not fit so I went with a good set of Blackjacks if I recall. My trans was a THM400 w/ 10" convertor and a 3,000 stall. The rear end was a stock 12 bolt posi w/ 3:73 gears.

That engine was throwing out close to 500 horsepower. I think originally it dynoed at 414 HP before a valve problem was fixed. Nearly 500 HP was insane back then for a 396 and I drove it many times to work 30 miles and back another 30 miles for 6 days per week; 60 miles a day. I revved it to 7 grand before and it was ok but usually I tried to stay around 5,500-6,000 RPM

Bottom Line: I'm no expert but I spoke to alot of experts back then who were master ASE certified. They advised me to offset one area with another. Case in point most guys would have built that engine with a huge single plane & massive carb. Great on the high end but crappy on the low. I tried to balance the combo & it worked well. I miss that car very much and I don't think I'll be lucky enough to build a drive train combo like that again. But I'm gonna try. Live and learn!!

Good Luck!!
 

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I agree with Bigfish and Southside. Chevrolet engineers did their homework when they designed the 375 horse 396, a lot more of it than anyone in this forum! True, that was in the days of leaded 102 octane, but we can make adjustments for today's fuel.
I am probably in the minority, but I am a big fan of big ports and big cams on smaller engines, even on the street. I understand the advantages of low speed torque and vacuum and gas mileage and all that. I just don't think Camaros are about that. I guess what ruined me was when I was at the drags with my dad one day and we watched a 4 speed '68 Camaro SCREAM down the track, banging that shifter at what must have been 8 or 9 grand. That wasn't the fastest car at the track that day, but it was definately the most fun to watch! He had way too much camshaft and way too much port volume for his displacement, and that made it just right.
 

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Discussion Starter · #12 ·
The car will be used mostly for shows and cruisins. But I'd like it to go down the stip without being embarrassed. Let's face it though. These care are too vauluable to just bang. Thanks for the advice especially Bigfish, SOuthside and Speedshift. I agree that some of this stuff GM got right way back then. Another board I'm on talked about the best small block cam ever still being the LT-1, mostly old (like me) Corvette guys.

I have a 350 HP crate motor in the car now with a Comp 291 /501. The sound is perfect but it suffers in the torque department. I was hoping to cure that witht the baby rat. Sounds like it's going to be better but still I'll want more. But it's important to keep the L78 / L89 appearance for me. I understand that I'd be better off maybe even cheaper to leave the 396 on the stand and drop in a 502 /502.
 

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Hello, I think Bigfish45 is right on, the only other caution I would add is that running that open plenum intake will result in no bottom end street performance, I would get the aluminum divided plenum intake for better manners on the bottom end RPM's where these motors really live and breathe when used on the street.
Just my two cents.
 

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I also would get a different manifold and go with a dual plane. I dont see why you cant have both torque and good hp with the 396. You can easily build 500 hp with your current engine.You do want to avoid pieces that will only have high RPM hp and lose all your low end. Not to hard to do though. Just avoid a radical cam and a single plane manifold and have good flow from the heads and presto you have a street terror!:D
 

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For the record,..427's were biggest engines you could get for a first gen. 454's hit the scene in 1970,..(of course there's always the unconfirmed stories of the 454's installed in late 69's). Regardless, run the cubes if given a choice.

All Chevy V-8 BB intakes were dual plane. I've never heard of the intakes you describe, but in 69 (more familiar), yes, the 198 (ZL-1 intake) was a 163 with the plenum divider ground down. This was to make the Holley 850 DP work at high rpm for a ZL-1 427's of which Chevy hoped would never be run on the street for warranty reasons. Heck, these cars (ZL-1's) brand new, had a hard time starting after arriving at the dealers to which they shipped. Yes, Chevy knew what they were doing and only built 71 ZL-1's (69 in Camaros, 2 Vettes).

Now you want to run this combo on a smaller engine and tool around the city where you'll spend 95% of the time between 1500-3500.

Again, I'd reconsider.

My opionion.
 

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The cubes sound good. Did you see the foot note.

(HYPER) Chevy 396 block, Chevy 454 crank. Low cost 427 power with 396 economy. .180" hollow dome. Fits open and closed chamber heads.
If open chamber heads are used, pump gas will work with this engine. If quench, timing, plugs, and cam are all just right, you could try regular.
Closed chamber head may work in a Corvette, but never a truck

I've got to use these L89 heads (closed chambers).
If you have the 842 heads, they are 107cc's in the chamber. Using their calculator, it will give you 9.9-1 compression. You mean to tell me that you can't run 9.9-1 compression on pump gas?!?

That foot note is a "CYA" disclaimer.....If you build it right, i.e. right cam for optimum DCR, quench, timing, etc., you can get away with a little more compression than you think.
 
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