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377 stroker

92K views 50 replies 30 participants last post by  bigmac73 
#1 ·
can any tell me the advantages of a 377 cid ? 400 SBC With a 350 Crank ? what CC heads ? this rap high enough that it needs forged interds ? sounds interesting, a 377 would be similar to 327 with 283 crank witch = a 302
huh ? does a 377 have a short stroke that raps faster ? or a longer stroke from 350 crank ? 377 has longer rods or shorter rods than a 350 ?

is there more machine work on the 400 block than there is on building a 350 10.25:1 CR ? what RPMs does a 377 turn ?

so a 350 crank in 400 block, different rods than the stock 5.7" 350 rods ? is there more machine work ? so there is a spacer / thicker main bearings in 400 block to run a 350 crank ? what CR we talking ? what for heads them 76cc ?

I Guess I'm Real Curious about the 377


can parts be bought for as cheap or close to same money as the 350 with the 10.25:1 CR from like northern auto parts ?

and a 10.25:1 CR 350 with 76cc Heads was not lookin bad money wise,

Thanks


Mustangsaly
 
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#27 ·
Well a strip ride is really a different animal completely. Assuming this is a naturally aspirated motor and you're dealing with a high stall, you basically just want to build a motor that will stay in the greatest amount of power for the longest time. Since gearing is probably a factor, a high spinner may be an advantage. One thing to think about is that if you have a given set of heads that have a finite airflow potential at 28 inches, you would get there sooner with a few more cubes, and perhaps have to spend less money on "RPM" parts (stud girdles, main brace etc etc). The nice thing about an engine that's more forgiving on its RPM limit at the track, however, is that you can miss a shift or two and over rev so that your shift will dump you back into your power band at a more desirable RPM. You're a bracket racer, you know all this.

More cubes will basically just shift your power band lower. On the track it really doesn't matter as much, given that you can use a stall and slicks. With a little research you'll be able to see which motor is better for the money.

K
 
#28 ·
Killer, thanks for the reply. My big concern is consistancy. Since bracket racing is all about hitting your dial, is it really worth the extra money to build the 380? It'll make more power and over a broader range and I'm only assuming that the higher end parts will only aid in the consistancy of the motor. I haven't heard of or talked to anyone running 'built' 377s before so I'm not sure how they hold up to competitive racing. I have a lot of experience running stock stroke and mildly stroked motors so I know what to expect out of them but I'm curious and looking to try something new. Another concern is how a stock 509 cast block will hold up to 650HP and 8k at the track once a week. If I have to go aftermarket block, this motor won't see the light of day until at least the start of next season.
 
#29 ·
Assuming this is a naturally aspirated motor and you're dealing with a high stall,
A 377 is rarely used in an auto car, due to it's nature. As you know, smaller cubes intensify the stall speeds, and basically makes the stall rquirement go up. If the cam spec says 3500 stall (based on a 400), the 377 may require 4200+. As was said, combination is the key, and in the right trim, a 377 is dynamite.

I totally agree with Royce, this RPM limit on "stock" parts is somewhat ambiguous. With a little work, stock cranks/rods can withstand some fairly decent RPM/HP #'s. I personally had a 283 @.060, 350 crank and stock rods, that, with some deburring, peining, ect, turned 7500+ RPM regularly. Ran like that for me for two years in an 85 Z28, and the current owner also flogs the snot out of it in a shortbed p/u. 5 years, still thumping...... This engine walked all over 2 400's, a 383, and a 355. Displacement increases potential, but with some know how, a few bucks and hard work, smaller can beat it.
 
#30 ·
Well, let's settle this debate.

I have a 377SBC right now. For a street car, I prefer it over a 383 and would definitely build one again over a Std 400.

The 377 lacks in the low end grunt torque department. Which is actually fine for vehicles that lack in the traction department, like the S-10 I have it in.

That said, once your past 2000 RPMS you forget about the lack of low end torque as the RPMS fly by so fast you have trouble focusing on shifting gears. It runs the RPMS out so fast you swear Boost kicked in.

Mines set up @ 9.5:1 compression, runs factory heads ported and polished, nice overlapped cam with decent idle "numbers I will keep to myself" a Stealth intake manifold, 650 Holley and headers, runs on pump gas and makes over 400 HP.

This engine prefers to be closer to the rev limiter than near idle and makes me smile every time I start it up.

Engines are a matter of preference for the driver more than anything else.

If I had a 3300# Chevelle that would accommodate an L60-15 Race master, I would prefer the grunt of the 408 or 383. However, keeping an S-10 stuck to the ground is an issue, a major issue, so I prefer the 377.

If one wants to build a ridiculous engine there are many Race Fuel 377's running around well over 600HP.....

If I changed cams and installed a set of fast burn heads and changed intake and carb I could pick up and easy 50-75HP and run the RPMS out even better than now....

All it takes is money.

:thumbup:
 
#31 ·
I Love My 377!!!

I Heard So Many Bad Things About A 377, So I Went And Built One.and Wow It Is Now My Favorite Engine.i Have It In My 67 Camaro 373 Gear 4 Speed.the Engine Has Kb Flat Tops, Comp Roller Cam, Afr 180 Heads, Rpm Gap Intake ,holley 750, Msd 6al,comp Mag Rockers.it Flat Out Flys.let Me Remind You This Is A Street Car, Runs Awsome On Pump Gas.from 2500rpms All The Way To The 6500 Chip This Engine Pulls Like There Is No Tomorrow.so My Advise Is Build It And Get Ready To Smile. :)
 
#32 ·
I will also agree..... well prepped/balanced GM production cranks and rods will live in high rpm condition. I run a 355 with a GM crank and rods and turn it 7200 every shift. I have run so many bottles of nitrous in this engine that I cant even count. 4 years so far with only minor freshening.
 
#34 ·
377 vega street car

I've got a '72 vega with a basicly stock 350 that i used for mock up. It also has a full man. turbo 350 with a tci 241000 converter [advertised stall 3000-3400, not sure what it is in a light car aprox. 2800lbs.] and a narrowed 12 bolt with 4:56s. I'd like to use my edelbrock str-10 crossram on it, but not a must i just like the retro and wow factor. Any way i was originally thinking of doing a 383 or 406 but i'm afraid that the low end torque and steep gear the car will = no traction. Also with this set up [383 or 406] i don't think the 5500-6000 rpm range would work well with the 456s and i really don't want to change gears again. I would like to take the car to the track once in a while and i dont think it would run through the 1/4 under the 6000 rpm limit. I thought the 377s lower bottom end grunt would get the car moving before getting in it's power range and would have plenty of rpm to run down the track. What do you think/suggest? Thanks, Todd.
 
#36 ·
I would personally build a 406 with 6 inch rods, more bearing clearance and forged internals with the pistons having mm style rings total sealed to turn up the heat all the way around. most tq at the bottom and most hp at the top end with the right cam and heads like pro topline 235s or big afr heads around 650 lift and 262 @.050 with a 1.6 rocker.
 
#37 ·
Interesting thread.

I think that building an effective high RPM package is more technical and complicated than a high torque machine, but make no mistake, it works!

Gobs of torque is kind of a one size fits all proposition, effective in most all applications. One thing that is rarley mentioned in these threads is the fact that gear reduction = torque!!

In a high reving package everything needs to be done right and made to work together. ALL of the engine parts and its composition as well as the rest of the car.. The whole idea is based on the principle that the HP "rate of gain" grows as the RPM's escalate and so they need to operate in a higher band. Pro stock cars are an excellent example of this principle, the amount of technology that goes into one of those motors alone is staggering, to say nothing of the rest of the car. They are able to run at speeds that are almost unnatural for carbureted engines because of their unprecedented utilization of RPM's.

Weight to HP ratio is also another very important factor with a high RPM street rod.
 
#38 ·
377

killerformula said:
I can understand your point, but we're taking these non-scientific terms like "RPM engine" and "loves to spin" and trying to tack on a quantitative attribute to them. The problem with both motors is that unless you spend the money on internals, you're not going to run more than 5500RPM. A 350 CID chevy motor with stock internals is about a 5500 RPM redline motor. Why then, would a 377 with the same stroke be able to rev any better? A 377 with some high buck internals will probably be nicely efficient at a higher RPM, because of the large over-square. The issue is that stock rods are going to stretch above 5500 or 6000 on a regular basis, not to mention the fact that those big 400 CID slugs on the end of them weigh more than a normal 350 slug does. So now you're talking high dollar rods, a big cam and some upper-end heads to make your 110% VE at 6700RPM. Furthermore, to do that you've lost a bunch of power between 0 and 3000 RPM and your motor is basically a race-only setup.

So I guess what I'm getting at is not only is a 400 a better overall choice, but dollar for dollar if you want to start spending money on internals and give the 400 a bullet-proof bottom end like the 377 will need, you'll see the difference even more.

K
i have a 377 and i spray it i have made a 427 406 and a 434 the 434 makes the most power but when sprayed the 377 out preforms the others i ran 250 shot to all made 6.90 pass in the 8th with the 406 a 6.72 pass with the 427 a 6.28 pass with the 434 and a 6.19 pass with the 377 . i shift it at 7800 rpm and have a 3255 lb 1970 chevelle so i like the 377 over all combos but for just motor i would build a 434 or 427 with the 400 block but if spraying go with the 377
 
#39 ·
chevelle13 said:
i have a 377 and i spray it i have made a 427 406 and a 434 the 434 makes the most power but when sprayed the 377 out preforms the others i ran 250 shot to all made 6.90 pass in the 8th with the 406 a 6.72 pass with the 427 a 6.28 pass with the 434 and a 6.19 pass with the 377 . i shift it at 7800 rpm and have a 3255 lb 1970 chevelle so i like the 377 over all combos but for just motor i would build a 434 or 427 with the 400 block but if spraying go with the 377

that's probably a result of excessive tire spin... getting better times with less power usually means there's a problem somewhere in the suspension or tires.
 
#40 ·
First post on engine forum.

Hey guys, since we are talking about 400's. I am building a 406 sbc with a Scat lightweight 3.75" stroke crank which requires a 6" rod to clear the pistons. Using World 235 series alum. roller heads with oversized valves, a 0.700+ lift cam, and JE high domes. Don't plan on running NOS right away. With these little bits of engine info, what RPM range do you think this mill can be pushed to?
 
#42 ·
406 cam info

Hi Lapersinger,

Thanks for the reply, we are still gathering parts for the 406 and picked up a roller cam from a friend. You mentioned the 7500 range. Here are some specs from the cam card. Comp Cam 12-000-9, 106 LS, 306 IN/310 EX @ .020, 273 IN/277 EX @ .050. What do you think this would do for the RPM range?
JayRod78
 
#44 ·
JayRod78 said:
Hey guys, since we are talking about 400's. I am building a 406 sbc with a Scat lightweight 3.75" stroke crank which requires a 6" rod to clear the pistons. Using World 235 series alum. roller heads with oversized valves, a 0.700+ lift cam, and JE high domes. Don't plan on running NOS right away. With these little bits of engine info, what RPM range do you think this mill can be pushed to?

What kind of a block are you using, you are spending alot of money on internals, I would hope you would get an aftermarket block to hold it all together.
 
#45 ·
Has anyone else actually run this motor? I have been thinking about it and would like to hear from more people with more experience with it. The car is a 68 firebird that is getting an M-21, and a 9-inch in the next month or so after I finish gathering parts.

My goal for the car is for it to run a solid 12 second quarter mile and more importantly all around fun to drive. I also want to use (with the exception of safety items) parts that were available in the seventies where possible, my Dad has a set of camel humps he is giving me, how would these be on this motor? This is not a DD and is only driven when I want to, and I am used the quirks of a modified vehicle. I am thinking a nice fast spinning small block would be well suited to this goal. So please let me know if I am in line here.

Josh

lapersinger said:
I Heard So Many Bad Things About A 377, So I Went And Built One.and Wow It Is Now My Favorite Engine.i Have It In My 67 Camaro 373 Gear 4 Speed.the Engine Has Kb Flat Tops, Comp Roller Cam, Afr 180 Heads, Rpm Gap Intake ,holley 750, Msd 6al,comp Mag Rockers.it Flat Out Flys.let Me Remind You This Is A Street Car, Runs Awsome On Pump Gas.from 2500rpms All The Way To The 6500 Chip This Engine Pulls Like There Is No Tomorrow.so My Advise Is Build It And Get Ready To Smile. :)
 
#46 ·
406 Setup

Double_v23 said:
What kind of a block are you using, you are spending alot of money on internals, I would hope you would get an aftermarket block to hold it all together.
The motor is a fresh stock cast #511 4-bolt 30 over. By fresh I mean just been bored and now being clearance for first time. This engine is being built for 78 Monza drag car currently being built. Will probably run the 1/8 mile mostly but will make 1/4 mile passes eventually.
 
#47 ·
I would expect you to split that block in half about halfway down the track the second time you launch it. The stock 400's were not very strong and the 4 bolts were the weaker of the castings. Ask CNC Block N/E what he thinks of the 4 bolt 400's and he will show you some pics where guys tore the mains right out of them. And they weren't doing the RPM's that you are planning to pull.
 
#48 ·
If you really want a nice little RPM loving package try a 4.125 bore with a 3.25 stroke. It yields 348 cu. in
From waaay back, but I dig that deal. I have a 3.26 stroke billet piece with intentions for a 400 based mill, +.040 for 355 CI. You know, grab a gear and wring it through some RPM on the way to church.
Buddy shop owner down the road runs a 377 in his camaro. No joke. It flat out rips with 1/4 mi times high 9's all motor. RPM KILLS, so keep that in mind. I personally like the 3.875 combo, always made plenty of TQ/HP for me, no matter. You can get a 3.48 stroke crank with the 400 main size and LJ or SJ rod, whatever you want. You need to come up with a specific goal for this motor, figure out how much track time and how much street time and go from there. Gears tire size trans weight heads cam intake etc etc etc. I'm looking at 10 400 mained 4340 cranks with strokes from 3.3, 3.35, 3.4, 3.48, 3.5, 3.562, 3.625 and 3.875 available for 5.7 or 6.0 rods. You can build your 400 beast into a variety of c.i. with more head options than you'll care to look at too. It's all in the COMBO, and it all works together... when you get it right. JMO One more thing you might consider, that being how much HP you make in the stock block. I've seen them over 700HP on motor but that's a crap shoot not to grenade. I've run them with 500+ and hit 'em with a 150-200 shot without trouble. All I'm going to add is to run it with a solid flat cam so it makes some noise.
 
#49 ·
Such a good argument...!

:spank:OK GURUS, HERE WE GO...
I WANT TO BUILD A QUICK "WINDING" MOTOR, MAXING OUT @ 62-6500 RPM I DONT WANT TO SPEND HUGE MONEY... AND I DONT WANT TO GO 140 MPH!

IM THINKING 377 (BIG BORE/SHORT STROKE)

AM BUILDING A 31 MODEL A ROD FOR STREET USE... TREMEC 5 SP, JAGUAR REAR W 3:70-ISH RATIO, 32INCH TALL CHEATER SLICKS.

THE WHOLE RIG SHOULD WEIGH LESS THAN 2000 #

NOW HERES THE KICKER, THE CAR CAME W A 671 ROOTS BLOWER AND 2 FOURS. SO IM PRESUMING THAT WILL MAKE UP FOR ANY LOW END TORQUE PROBLEMS.

I HAVENT BOUGHT HEADS YET BUT HAVE A NICE COMP ROLLER CAM THAT LIVES @ 2000-6500 RPM...

AM THINKING SOME SEMI MILD ALUM HEADS THAT WILL FLOW @ THESE RPM RANGES.

DO YA SEE ANY HOLES IN MY PLAN SO FAR??
 

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#50 ·
make a new thread just for yourself. ask why a big bore makes better/more power,ask about light weight rotating parts and short stroke Vs long stroke and slow throttle response,state N/A or boosted and get a bunch of answers that apply to your application. a 7 year old thread is not a good place to start
 
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