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4 bolt 454s are hard to come buy or they want a fortune
Got rid of my 396 yrs ago couldnt see the sense where it would make much more than the current 383 does
427 prices are a joke.
If a 502 fell into my lap wouldnt complain
Do like some rpm (7kish) I dont care about low rpm flat practical stuff want something rowdy no roller cams
Motor I have now can haze them (sbc) fairly easy so sheer size of the BBC will be plenty want more up top though. Addicted to that pull
Something that screams bloody murder from 4xxx-5k on up. Keeping the 4.11 and 6 spd I think

See a few 2 bolts std bore cheap on cl
Plan would be a weekend toy as the 383 is
Min 11.5:1 +- a decent head big solid flat tappet ported single plane, double pumper HEI mech fuel pump (maybe) something simple for once that wont break the bank.

Will a studded 2 hold up or just wait?
Converting to 4 gets too pricy done with $$$ builds.

Not in a rush to do it just little by little trying to locate pieces, stick to a plan for once


Dont know what yrs the 4 bolt block came in. Seen some std bore 70s truck blocks they are all 2 bolt though

What yrs dont have mech fuel pump boss?
 

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I think a 2 bolt with studs will be fine. My studded 2bolt 454 block has lived for ten years with 600 hp and I know people that makes over 700 hp with 2 bolt blocks. All mark IV 454 blocks have mech fuel pump(70-90). All 2 bolt block are mark IV, gen 5(91-95) 454 never had mech fuel pump boss some gen 6(96-) 454 crate engines came with mech fuel pump.
 

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Mine is a two bolt, stock caps and good bolts, spins past 7 , lots of two bolt big blocks at the track :thumbsup:
 

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No problem as said studded 2 bolt block will go 6-700 hp no issue im building another right now will be close to 700 hp. Good machining and parts is key
 

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Although I only have dyno time on my 489, it's a studded 2 bolt block. From everyone I talked with, you'll be good up to 700'ish with a good balance and proper machine work - we cut the caps and did an align hone. Mine made 700 at 6800 RPM and seemed to hold up ok after 10 or so pulls.
 

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I have a 496 sitting on my floor that is mark 4 two bolt main. I ran it for 2 years with no issues to 7k rpm alot. I would stud the mains just for piece of mind. They say that rpm is what kills them, but I don't know I never had one give up.
 

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11.5:1. Is this going to be on E85 or race gas mix?
 

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4 bolt 454s are hard to come buy or they want a fortune
Got rid of my 396 yrs ago couldnt see the sense where it would make much more than the current 383 does
427 prices are a joke.
If a 502 fell into my lap wouldnt complain
Do like some rpm (7kish) I dont care about low rpm flat practical stuff want something rowdy no roller cams
Motor I have now can haze them (sbc) fairly easy so sheer size of the BBC will be plenty want more up top though. Addicted to that pull
Something that screams bloody murder from 4xxx-5k on up. Keeping the 4.11 and 6 spd I think

See a few 2 bolts std bore cheap on cl
Plan would be a weekend toy as the 383 is
Min 11.5:1 +- a decent head big solid flat tappet ported single plane, double pumper HEI mech fuel pump (maybe) something simple for once that wont break the bank.

Will a studded 2 hold up or just wait?
Converting to 4 gets too pricy done with $$$ builds.

Not in a rush to do it just little by little trying to locate pieces, stick to a plan for once


Dont know what yrs the 4 bolt block came in. Seen some std bore 70s truck blocks they are all 2 bolt though

What yrs dont have mech fuel pump boss?
If you want to sleep better ask your machinist about setting up the existing 2 bolt caps for some add'l 7/16" outer edge fasteners. We've been doing this mod for years now. Photo below and in the "linked" post here: http://www.chevelles.com/forums/13-...build-cam-advice.html?highlight=bbc+main+caps (see post #9)

Runs about $200.00 with the ARP fasteners and the labor!

Thanks, Gary in N.Y.

P.S. Needs no line honing/boring with the add'l fasteners finished, the main holes remain constant. Here's another shot of that finished modified cap.

 

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There is a point where it will fail. I read for years that 600 hp and 6000 rpm was about the limit for a 2 bolt block. I was pushing approximately 650 hp to 7500 rpm and lost oil pressure. 2 bolt block, cast crank, 3/8 rods. Still haven't torn it apart to find the weak link.

Devin
 

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MK IV blocks can be 2 or 4 bolt mains. "hi perf" intheca sting is not a guaranty it's a 4 bolt. Gen V & VI are all 4 bolt but the caps are a little taller and need an oil pump to accommodate it. Both have updated timing cover and oil pan mounting and a one piece rear main seal. Gen V has no provisions for a mechanical fuel pump or clutch Z-bar, Gen VI added them back in. MK IV heads will not mate with the coolant ports in the decks on Gen V blocks, some work with the right head gaskets on the Gen VI.

I think if you're gonna get the RPM's up, four bolt mains for sure, splayed is always better.

 

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I'll speak from personal experience. Back in the 80's, I put together a fairly stout 2 bolt main 468 using heavy ass TRW 13:1 pistons, big Crower flat tappet cam, steel crank and dimple rods. It had factory square port heads, Holley strip dominator intake and 850 DP. This motor saw 7K every time I drove it, I showed it no mercy. Of course, wanting more power, I added a 250 HP NOS plate, which destroyed the rings in short order. Upon tear down, I was amazed at how the bottom end looked. I saw no evidence of cap walk and the clevite 77p bearings were in remarkably good condition.
 

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2 bolt is fine with studs.

Just tore mine down to freshen it up, 2 bolt with studs, 496 shifting @ 6300, high side @ 6800, 400+ passes. Mains looked perfect. no cap walk or chatter at all.

Studs, good line hone, no detonation, good balance job, it'll live just fine. Good tune and good machine work is the key, imo.

Had a 454 block with "HI PERF ASS" cast on it once. Saw one a couple weeks ago with "HERF PASS" cast on it..
 

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What are your actual goals?
 

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MK IV heads will not mate with the coolant ports in the decks on Gen V blocks, some work with the right head gaskets on the Gen VI.
I wonder where this comes from time to time.

I have used 3 different mark iv heads with gen v block and all fit well. Two of them were from 60s. You only need to realize that you can not use mark iv head with mark iv head gasket as cooling opennings in gen V block are bigger and made for parallel cooling flow. Gen V head gasget controls the correct cooling flow to head, it does not matter if the head itself is for gen iv or v. Just use gen V gasket with gen V block.

Gen V is a great option for 4 bolt block and many if not all of them have a forged crank from factory. You only need electric fuel pump witch is better option anyway.
 

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I wonder where this comes from time to time.

I have used 3 different mark iv heads with gen v block and all fit well. Two of them were from 60s. You only need to realize that you can not use mark iv head with mark iv head gasket as cooling opennings in gen V block are bigger and made for parallel cooling flow. Gen V head gasget controls the correct cooling flow to head, it does not matter if the head itself is for gen iv or v. Just use gen V gasket with gen V block.
Some good details and tips here: http://www.chevelles.com/forums/13-...-going-mark-iv-block-confirmation-please.html
 

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4 bolt 454s are hard to come buy or they want a fortune
Got rid of my 396 yrs ago couldnt see the sense where it would make much more than the current 383 does
427 prices are a joke.
If a 502 fell into my lap wouldnt complain
Do like some rpm (7kish) I dont care about low rpm flat practical stuff want something rowdy no roller cams
Motor I have now can haze them (sbc) fairly easy so sheer size of the BBC will be plenty want more up top though. Addicted to that pull
Something that screams bloody murder from 4xxx-5k on up. Keeping the 4.11 and 6 spd I think

See a few 2 bolts std bore cheap on cl
Plan would be a weekend toy as the 383 is
Min 11.5:1 +- a decent head big solid flat tappet ported single plane, double pumper HEI mech fuel pump (maybe) something simple for once that wont break the bank.

Will a studded 2 hold up or just wait?
Converting to 4 gets too pricy done with $$$ builds.

Not in a rush to do it just little by little trying to locate pieces, stick to a plan for once


Dont know what yrs the 4 bolt block came in. Seen some std bore 70s truck blocks they are all 2 bolt though

What yrs dont have mech fuel pump boss?
Compression and piston speed are the 2 things that are hard on blocks. If you can keep these both down and make the power you want your better off.
 

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I'm not in the market for a BB or looking for one but saw this today...
Seems reasonable for a 4 bolt block, based on previous posts?




...Hang on, the hyperlink didn't show up
 

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If you NEED a 4-bolt block, chances are that you actually NEED an aftermarket block. There's not actually that much difference in capabilities of 2 versus 4 bolt big blocks but a HUGE difference in capabilities of production versus aftermarket.
 
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