Fia69

Any one build a 3.76 x 4.50 bbc

Pop Chevy

Don't think you're gonna bore a 427 out a full 1/4 inch (.250) .

Grumpy 427

I would not bore a BBC std bore block more than .070. A buddy here tried to go 0.100 and it got thin and broke through.

Fia69

See Dart M block short deck 4.5 or 4.6 bore

Vortecpro

YES I have.

Fia69

The combo with this block would be 466 cu.in. Using the 3.76 and 4.5 or 477 using 3.76 and 4.6 bore .

427Hotrod

They were screamers in some NMCA class racing a few years back. Need to spin them up.....

JIM

Fia69

Vorecpro , I take you have a blower on yours. I was going natural aspirated. What rod length
did you use .

dmaxx3500

ive got a couple fresh 588'',just dyno time,1/2 of what you could build them for

Vortecpro

I used a 9.800 deck bow tie block. Rod length 6.535. Carb with Nitrous for street racing many years ago.

TheGreek!

When I saw the title of the thread I thought the OP was talking about building a big bore motor that was 427 cubes. To get 427 cubes with a 4.5 bore you'd need a crank with a 3.36 stroke. It would be a high rpm screamer with a stroke that short. It would be a cool build but it would be better to build a lower rpm big cube motor instead because as the old saying goes, there's no replacement for displacement.
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L88Plus

I have one in the works.
Scored a Bowtie block a couple of years ago, cleaned up at 4.635". It has bronze lifter bores for .903's. Scat introduced a line of cranks a couple of years back with center counterweights so I snagged one of those with 3.766 stroke. Haven't picked rods yet but I'm leaning toward 6.7" which would put a piston pin at around 1.200. Choke point is heads, I have some of the "new" L88 heads, casting ends in 3401. I haven't figured out yet who to send them to for porting and I am open to suggestions. It will have a Straub cam with .750" lift...because I always wanted a 3/4 race cam haha. Intake will probably be one of the old Edelbrock C427's. I have two sets of very low run time Crower HIPO lifters, I'll size-match them to the bores and send them out for new needle bearings or might bite the bullet and go with bushings. My machinist and I are just beginning to rebuild the diff, we will upgrade to the 12-bolt pinions and big stub and outer axles.

I blame this engine on Jim (540HotRod) and his incessant raving about how much fun it is to drive a car with a big inch engine that likes to rev as opposed to the hydraulic roller tow truck engines that everybody shifts at 6K. I have no desire to have anything with the power that Jim's is making, I'd be happy at 700hp or so.

69ttop502

Sounds like that would be a great combo. Amazing how Jim seems to get us all in trouble!😀. Wouldn’t have him any other way.

Fia69

I am not aposed to a aftermarket head . AFR recommends there magnum
315 and victor jr intake . It would be cool with a new set of Chevy NHRA
heads and intake but not sure how much power I would lose. Cam is a big key I will try comp cams on that. Plan on running bushing rollers and Jessel shaft rockers, a cannon road race pan.
On another note I could jump the cu. in. to 509 and use a 4.00 stroke which may not be bad either. I did crank a LS-7 to 7500 in the old days .
Wish I could tell just how the car would act. I raced a 425 h.p. Motor and a
LS-7 in the old days and always liked the 427 but the 454 was faster now it is about traction. This ride is to autocross and street drive. Oh I also thing spray is the answer if needed easier to control. What do you think ?

derekderek

dont want that much power. i'd be happy with 700 or so... what you mean new L88 heads? iron GM rectangles? oh, ok. bow tie aluminum heads...

Pop Chevy

Your original post was misleading to me. Now I see what you are trying to ask, good luck. Short stroke+big bore = high rpm power

gkull

I bought a 508 BBC the biggest problem with max bored blocks is not just loosing strength, but you are done unless you want to sleeve the block.

CI adds to the amount of TQ produced, but the hp is about the same with everything being equal

I have a Motown SBC and a 4.155 bore the max bore is something like 4.200 so I still have a couple of borings availaible

69ttop502

Fia, sounds like a good plan. I am using AFR 315’s on mine with a small single plane ( Holley Strip Dominator), along with Jesel Competition’s and Morel bushing solid roller lifters. My cam is 263 and 269 at .050. Peaked in my 502 at 6500 but holds on forever. Only been on the Dyno but can’t wait to drive it in the car. I have seen some nice 532’s making serious power as well. Large bores with the 4 inch stroke. All good stuff! I do agree with Jim and L88 above, that in our relatively light cars, it is more fun to move the powerband up a little and lose a little on the bottom. All these combos are going to have plenty low end in my opinion.

Vortecpro

" It would be cool with a new set of Chevy NHRA"

No it wouldn't if wanted it to make power, I built a L88 with those heads with lots of work.......what a disappointment.........don't do it.

Jebbysan

I have.....I think it came out to 477 cubes.
Dart Big M Block and Brodix race ovals with an ancient Comp Bracket roller....748/714.
It used a ported Brodix intake and a 1000hp 4150 Holley.
Guy wanted it for his Nostalgia drag GTO gasser...in Canada. The idea was to pull some torque out of the combo to make it manageable....well....the Race ovals had so much VE/air speed that it made 808 horsepower@6900 rpm and 650 ft/lbs across 4000 to 6000.....
He was happy and pissed at the same time!

BTW....we bolted his headers with mufflers and a 4" K&N air filter for the next pull and it made 810.....

Nice big bore small stroke combo........but for my money I would probably do a 509 or 540........your call.

Jebby