400SBC for the street

[70styleVega]

Exactly. Even if a flat tappet cam and roller cam are the same lift and duration @.050, the roller cam will keep the valve open longer and allow additional air and fuel to enter and leave the combustion chamber.
So 400 SBCs should really benefit from the addition of a correct roller cam, as most factory heads and many aftermarket heads can't keep up on their own.

[mldeolde]

IF YOU ARE ONLY GOING TO REV TO SIX GRAND OR THERE ABOUTS THERE ARE PLENTY OF REGULAR HYDROLIC LIFTER CAM SHAFTS THAT WILL GET THE JOB DONE FOR YOU AND CAN BE AQUIRED QUITE REASONABLY DO TO TODAYS GOTA HAVE A ROLLER CAM TO BE COOL PARTS ENVIRONMENT. A GOOD EXAMPLE OF AN OLD SCHOOL CAM THAT REALLY GETS THE JOB DON IS COMP CAMS 480/280 HYDROLIC THAT REALLY SEEMS TO GIVE YOU THE BEST OF BOTH WORLDS BOTH GOOD BOTTOM END AND 6500 RPM PERFORMENCE TOO. HAVE THAT CAM IN MY 355 SBC IN MY 74 NOVA WITH 3.08 GEARS AND IT HAS NO PROBLEMS WITH LOW END POWER, OTHER THAN SMOKEING THE RATHER MODEST T/A RADIALS.

[gt350fme]

never mind

[spyder_xlch]

I thought the lifters were the same bore size but the rollers were taller.

[gt350fme]

never mind

[70styleVega]

The factory hydraulic flat tappets and roller tappets do fit the same bore. The GM Vortec blocks came with either: trucks with flat tappets and cars with rollers.

I just purchased a 55 page info pack off of ebay with instructions and photos showing the the clearancing mods for non-roller blocks.
As I mentioned earlier in this thread, there are a couple of threads on corvetteforum.com that show the conversion in progress.
Hydraulic flat tappet and roller lifters are also compared.

I had planned to install a solid lifter cam in my 406. The factory roller conversion looks good because I can buy the core items for around $400, less than half the cost of a aftermarket retrofit roller setup. This is a great way to build a budget sleeper.

[70styleVega]

I've also been meaning to comment on what mldeolde said about old school flat tappet hydraulic cams. I think the cam he mentioned is the Comp Cams 280H Magnum cam (280/280 adv, 230/230@.05, .480/.480, 110*LCA) which was very popular in 383s when they were all the rage. It would probably work nice in a 400 as well.

I think Aleck's (Stinkibutt) 406 Monza ran 11.80s with a later design Comp Cam hydraulic XE274H (274/286 adv, 230/236@.05, .490/.490, 110* LCA). This is a very streetable camshaft also.
The XE274H and the slightly larger XE284H(284/296, 240/246@.05, .507/.510, 110*LCA) are used today in a lot of 383 and 400 based crate motors.

400 street motors don't seem to need a lot cam if the heads are decent and if the whole combo (cam, carbs, heads, headers, torque converter, gears, tires) work together.
I agree that flat tappet cams can work.... Aleck's 406 Monza proves that.

[T-FATTY]

I'm going to build a 377 and was given a new 292 comp cam. I was thinking of using Rhoads lifters with it, what do ya think? It's going in a '72 Vega with turbo 350 w/3000-3400 stall and narrowed 12 bplt w/4:56s. Also whatsize heads do you think i should use? Car is street weekend warrior. -Todd.

[70styleVega]

I've never built a 377, but if it were me I would get the best heads that I could afford. That means for factory heads, no less than than Vortecs with a valve spring upgrade. As for aftermarket, I would look at 377 crate motors with a similar rpm band.

I've never ran Rhoads Lifters before lifters either, but I see nothing wrong with your combo.

Maybe others who have built 377 or similar 400 based engines can help you more.

[spyder_xlch]

I never understood 383's and 377's. Go for the cubes and build a 400. But I guess if you have a good 400 block and no crank, or a good crank and no block....
I've been thinking of going with vortec heads on my 400. I don't need to squeeze every bit of power out of it. I'd like to make 400HP and 400 ft/lbs. If I can do it with a set of camel humps that's the way I'll go. The thing I don't like about the vortecs is needing a new intake. But that might not be a bad thing.

[70styleVega]

377s are supposed to be able to rev higher than similarly built 400's and 383s due to the 377's lighter 350 crank and 400 bore, but I've never wrenched on one.
A 377 ought to have a hell of a top end charge in an H-body!

383s have a lot of the 400s torque without the 400's siamesed bores and steam holes. Also late model 350 blocks are set up for factory roller lifters, so it is easy to make a streetable roller cammed 383 on a budget.

Nevertheless, I'm still partial to 400s too. They usually get the job done, regardless of what chassis you put them in

[Sirshredalot]

Anything regardless of stroke will rev as high as you want it to so long as you spend the money for the lightweight crank, rods, pistons, titanium keepers and lightweight valvetrain....etc.
As well as a +/- .5 gram balance job....high dollar balance and flexplate/flywheel.

I have never built a 377....but the benefit of them is to build a low reciprocating mass engine for a lesser price and reduced windage...over a 383....therefore reving is higher.

I have seen 377's make as much torque as a 383 at the same or close rpms...stroke doesnt have much to do with overall torque or power...cubic inches do...mainly affects the onset of peaks....but the guys at speedtalk would probably prove me wrong.

What rpm are you looking for? what kinda power? ET? lots of things to know before we/I can make a recomendation.

God bless
-Shred

[mldeolde]

MY OPINION- A 377 CU IN SBC IS MENT TO WORK AT MUCH HIGHER RPMS THAN A 383/406 BORE /STROKE ENGINES. HYDROLIC LIFTERS ,EVEN RHOADS LIFTERS WON'T ALLOW YOU THE RPM THAT IS NEEDED TO MAKE THAT ENGINE PREFORM UP TP IT'S POTENTIAL. 383/406'S CAN BE MADE TO GIVE GREAT PERFORMENCE ON THE STREET WITHOUT REVING THEM ANY HIGHER THAN 6500-7000 MAX WITHOUT ANY PROBLEMS OR GREAT EXPENSE BUT A 377 REALLY NEEDS TO BE RUNG OUT TO 8000-8500 RPM TO REALLY REALIZE ANY SUBSTANCIAL BENIFITS OVER THE AFORE MENTIONED 3.75 IN STROKE MOTORS AND THAT GETS MUCH MORE EXPENSIVE AND MUCH LESS STREETABLE. UNLESS YOU SPEND THE BIG BUCKS ON YOUR ROTATING ASSEMBLY AND CAN LIVE WITH THE MUCH MORE FREQUENT TEARDOWNS NECCESITATED BY HI REV MOTORS YOU WILL BE MUCH BETTER OFF WITH A "RUN OF THE MILL" BUT VERY MUCH PROVEN 383/406 COMBO. BELIEVE ME I HAVE HAD MUCH EXPIERIENCE WITH HIGH REV MOTORS,I HAD A PRETTY NASTY 69 z-28 302 CU IN SBC AND HAVE HAD ALL KIND OF FUN THINGS FAIL AT 8500 RPM LIKE ROCKER STUDS AND PUSH RODS GOING THRU ROCKER ARMS BEFORE WE DETERMINED THAT A STUD GIRDLE WAS GOING TO BE MANDITORY IF WE WERE GOING TO MAINTAIN ANY KIND OF VALVE TRAIN STABILITY. THAT'S PARTS YOU DON'T NEED ON A 6500 RPM MOTOR AND THATS JUST ONE SMALL EXAMPLE OF THE POTENTIAL PROBLEMS YOU WILL ENCOUNTER IF YOU DECIDE TO TAKE THE RPM VS CU IN ROUT IN ACCIEVING YOUR POWER. PS: the 302 had absolutely nothing under 3500 rpm and couldn't get out of its own way under that but between 6000-8500 rpm it was a holy terror and a sleeper at that.

[T-FATTY]

Anything regardless of stroke will rev as high as you want it to so long as you spend the money for the lightweight crank, rods, pistons, titanium keepers and lightweight valvetrain....etc.
As well as a +/- .5 gram balance job....high dollar balance and flexplate/flywheel.

I have never built a 377....but the benefit of them is to build a low reciprocating mass engine for a lesser price and reduced windage...over a 383....therefore reving is higher.

I have seen 377's make as much torque as a 383 at the same or close rpms...stroke doesnt have much to do with overall torque or power...cubic inches do...mainly affects the onset of peaks....but the guys at speedtalk would probably prove me wrong.

What rpm are you looking for? what kinda power? ET? lots of things to know before we/I can make a recomendation.

God bless
-Shred

My main goal is rpm. My car has 4:56s/24" tires and i would like have enough rpm to do a 1/4 mile pass.

[mldeolde]

could only figure for a tire size of 185/60/13 which is a pretty small tire and with 4:11 gears you would only be turning 6350rpm at 100mph so with 4:56 you would still probably be well under 7000 rpm at the end of you quartermile. a 383/406 would handle that pretty easy and would be operating at max potential where as the 377 would be only into the bottom of its power curve and only at about 80% of it's potential. possably some more food for thought. or maybe not!!!!!!!