377 sbc build questions

[joespanova]

At one time I was hell bent on doing a 377 project , and I had no doubt it would run well BUT , that was using my BRC 4340 crank (3.48 ) and a stock 400 case. After seeing with my own eyes what can happen to the OEM 400 cases I changed my mind and stuck with my 355. If I were going to do a 400 it would require at least an SRP block and good crank...............money I just cant justify for a few weekends of fun.

Sooo , I decided to go the more PRACTICAL route and lighten the car............faster car AND easier on parts............and that means ALOT when you run a manual deal like I do

[af2]

I will say I have been happy with my 377. I have a video the wife shot 5 years ago while I was in the box and you could hear the guy next to her saying blow that MFer up. It likes the rpms just like any good running 350. If you want a 7000 rpm engine go for CI.

[jeepracer]

OK good. Now what's your budget? How much power do you think you need to win consistently??

As of now i dont know what my budget will be. im probably going to take off next year to save up to pay for college but i would like to do it for the following year. i figured id get a jump start on it and maybe here and there buy some parts and hold on to them until im ready. the cars in that class are running about 4.8-5.0 in 300 ft. the class faster, has cars doing 4.1's. the one guy we race with has a 377 and i just talked to him tonight and he said it made 618 hp with an oem 400 block with an aftermarket crank and 23 degree heads. this motor in the car ran a 4.1,, i plan on running a custom jeep, that i can run the dirt obsticle (kinda like road coarse in the mud) and drags(dont really care about winning these). itll have chevy blazer full size rears with 31 inch tires weighing about 3200. this is what im planning on building ""i dont have it right now""

http://www.youtube.com/watch?v=Hh77Wg4iP_A the white car is the one with the 377. mines gonna be set up for obsticle though

[jeepracer]

its good to see people who dont hate this motor. thanks for sharin!

[levisnteeshirt]

i saw a 400 4 bolt block ,, which is suppose to be junk ,, last a good while with a fogger and a plate system ,, before the block split ,,, but it stood it a good while ,,,

my buddy builds stock block 400- 421's with close to 700 hp ,, for dirt racers that require a stock block ,,, he does a low pour , splayed caps , 14-1, 18-15 degree heads ,,, they get the snot beat out of 'em in a 3500 lb car , 20 weekends a year , ususally last for 2 seasons ,,, never had a block split ,, but they will have some cracks in the deck when they come back in , steam hole to bolt hole , he plugs the steam holes ,,,, he has sent them out with a crack steam hole to bolt hole ,,, they run fine ,,, never a problem ,,, never use a head stud with a 400 block is his moto ,, helps keep the deck intact

[BrazilianZ28Camaro]

,,, never use a head stud with a 400 block is his moto ,, helps keep the deck intact

Are you saying that head studs stress the deck bolt areas more than the bolts with the same torque? I've heard that studs are highly recommended for 400 blocks

[levisnteeshirt]

if you bottom the stud ,, then the shoulder of the stud comes in contact with the deck ,, then it might be placing pressure on the deck instead of the threads ,,, maybe if you didn't use a stud near the steam holes , just on the top and bottom of the head away from the steam holes

he just went through a 421 , not poured , its ran for 5 years , 620 hp ,, not ported 18 degree heads ,,, not sure of what brand , mild combo for what it is ,,, dropped a valve , busted a piston , didn't hurt the block ,,, went back together and is running and was raced the last 5 weeks last year ,, factory 4 bolt block ,, maybe some people are just plain lucky

[BrazilianZ28Camaro]

if you bottom the stud ,, then the shoulder of the stud comes in contact with the deck ,, then it might be placing pressure on the deck instead of the threads ,,, maybe if you didn't use a stud near the steam holes , just on the top and bottom of the head away from the steam holes

he just went through a 421 , not poured , its ran for 5 years , 620 hp ,, not ported 18 degree heads ,,, not sure of what brand , mild combo for what it is ,,, dropped a valve , busted a piston , didn't hurt the block ,,, went back together and is running and was raced the last 5 weeks last year ,, factory 4 bolt block ,, maybe some people are just plain lucky

Thats make sense. About the "luck" with 400 blocks, I've been told that there are thin and beefier block castings even with the same casting number. Something like the early ones being the thinnest and the later ones being the beefier.

Maybe this can explain some discrepancies between 400" block durability.

Just for curiosity what max rpm that 421" was turning when the valve let go?

[kirkwoodken]

Studs shouldn't be bottoming out.

[levisnteeshirt]

if you bottom the stud ,, then the shoulder of the stud comes in contact with the deck ,, then it might be placing pressure on the deck instead of the threads ,,, maybe if you didn't use a stud near the steam holes , just on the top and bottom of the head away from the steam holes

he just went through a 421 , not poured , its ran for 5 years , 620 hp ,, not ported 18 degree heads ,,, not sure of what brand , mild combo for what it is ,,, dropped a valve , busted a piston , didn't hurt the block ,,, went back together and is running and was raced the last 5 weeks last year ,, factory 4 bolt block ,, maybe some people are just plain lucky

Thats make sense. About the "luck" with 400 blocks, I've been told that there are thin and beefier block castings even with the same casting number. Something like the early ones being the thinnest and the later ones being the beefier.

Maybe this can explain some discrepancies between 400" block durability.

Just for curiosity what max rpm that 421" was turning when the valve let go?

i don't know ,,, valve head broke off of #7 and ingested in #8 ,,, wouldn't have believed it unless i saw it myself ,, i guess it blew it back up through the intake and sucked it into # 8

[Dick Gazan]

The last 377 I built was for a circle track late model. The rule had rear gear rules for each specific track and a 390 carb and no more than a 22 degree head. There was no cubic inch rule. He ran a 400 for a couple of years and with your normal cams it would just nose dive at the end of the straight away. He had to re ring it several times a season due to running it over the torque range for so long. I talked him into just pulling the crank back to 3.5 and changing the small cylinder heads to Brodix WP10SPXAP and a better cam and it pulled hard on the dyno even with the 390 carb. It made well over 600HP at a relative altitude of 9300ft at Albuquerque. We changed the intake away from the "flat floor" small carb Edelbrock and an 850 and with some tuning made 735HP at 8200RPM. Smooth on the bottom, which is what he needed and would just be a rocket ship at the end of the straight.
When 400 blocks were reasonably available I changed over some customers 400's to the 377 with good success.

Dick Gazan

[6sally6]

using the 400 block and 350 crank......how would the 350 block with the longer 400-style crankshaft compare? Long stroke small-er bore!?
Would it be a complete dawg?
It amazing how even with the same cubic inches.....same brand/manufacturer of engine... there could be that biga difference in the performance.
Comments?!
Great discussion!
6sally6

[BrazilianZ28Camaro]

using the 400 block and 350 crank......how would the 350 block with the longer 400-style crankshaft compare? Long stroke small-er bore!?
Would it be a complete dawg?
It amazing how even with the same cubic inches.....same brand/manufacturer of engine... there could be that biga difference in the performance.
Comments?!
Great discussion!
6sally6

Power is airflow related. With bigger bores the valves will have more room to breathe.

The shorter crank stroke create less piston velocity (ring drag) @ same RPM and less side wall loads (mechanical efficiency), therefore more net power is produced.

Converselly, the big bore engine have a greater area of piston crown to dissipate heat to the oil being less thermal efficient. It will have a greater ring drag too, due the added diameter.

I still believe each single detail in a engine is a compromise between the several forces involved and transformations of the fuel energy. The better the compromise for the application the better the engine will be.

[levisnteeshirt]

pouring the block changes the 400 block deal a good bit ,,,

i still wonder about flipping the block over , and filling the top of the deck , might have to do it with studs in place or a bolt threaded in the head bold holes , pule some plastic tubes in the water passages , that you wanted open ,, it should stiffen the deck

[BrazilianZ28Camaro]

pouring the block changes the 400 block deal a good bit ,,,

i still wonder about flipping the block over , and filling the top of the deck , might have to do it with studs in place or a bolt threaded in the head bold holes , pule some plastic tubes in the water passages , that you wanted open ,, it should stiffen the deck

Fill the upper part of the block certainly will overheat the piston top and ring land, rings and the block itself on applications other than drag race, but in this case a full fill would be much easier and effective.

The majority of relates about 400 blocks failures are related to the main web area, wich IMO came from the roundy round races, 7000+ rpm during several laps with external balance cranks.

I believe a few factory blocks in the world could survive that kind of abuse with a 3.75" stroke, but its just me