[lapersinger]

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.

[bigbadbowtie]

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.

[jerrydbur1]

i have a 64 nova building twin turbo engine do i need 377 or 400 or 383 need help

[TiMeWaRp]

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.

[TiMeWaRp]

anyone home?

[chrismac]

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.

[65smallblock]

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.

[chevelle13]

Originally Posted by killerformula

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

[ap72]

Originally Posted by chevelle13

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.

[JayRod78]

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?

[lapersinger]

7500rpm wouldbe my guess.

[JayRod78]

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

[Double_v23]

I don't pretend to know alot about Cams, but I think that cam is going to only be good from 4500-8000 rpm. If you plan on doing anything but full throttle driving then you will want to go another way.

[Double_v23]

Originally Posted by JayRod78

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.

[JoshF]

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

Originally Posted by lapersinger

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.