I am looking at buying a 454 shortblock with 2-bolt mains.

The seller has offered to convert it to 4-bolt mains if I desire. I haven't heard back yet, but I'll assume he is going to use stock GM 4-bolt caps and just drill and tap the 10 new holes...

Is this a problem? I heard the small block webs are thin, but are BB okay?

How much to convert to 4-bolt stock caps?

How much to convert to 4-bolt splayed main caps?

How much more is a stock 4-bolt block worth?

Also, I am thinking of building a 496 stroker out of this motor, but a mild, high torque motor street motor (good vacuum, pump gas-92 octane), probably not seeing over 6000 RPM (maybe I'll set the rev limiter at 6000).

Is this a good idea? Or not really necessary?

Sorry, I really have no idea what HP it will have...

Or is it better to just get an original 4-bolt block?

I don't think his price is bad (for either the short block or the conversion)... He is a TC member, and I trust him to do good by me... I just don't know if its in my best interest...

Just looking for advice to help me decide if I should do the conversion...

thanks...

Tony

i doubt youll need 4 bolts... gene run his 2 bolt 427 past mid 7000rpm mark! :eek:

My Dad and I just converted his 427 to a 4bolt main using stock GM caps the only problem we had was on the back cap the machine shop nicked the passage from the oil filter return line it leaked oil out of the back of the block we were able to have it fixed and had no other problems get a good line bore and have the machine shop size the main bearings and you should be good to go,

Tony,

I don't see why you should be too concerned with the block/main caps. I've been racing/building BBlock's for 30 years, both 2 and 4 bolt mains, and I've never had the main caps fail. Even on a 7500rpm 427 2-bolt block....it ran for 12 years until it bent a couple of pushrods.

My opinion, use the 2-bolt main block, keep it under 6-6500rpm and you will be fine. Spend your money else where and/or have the seller throw in something else.

One alternative to the main bolts....use studs. I've used both studs and bolts on 2-bolt mains and never had a problem.

graemlins/thumbsup.gif

Yes, please consider the studs!!

I installed them in my motor by first cleaning the holes really good with BrakeKlean and such and then using some Tightener to lock them in place after putting them in a schosh over finger tight, then installing the caps and torquing them down a bit so that they would be straight when set up!!

Next, just install your crank and tighten it down in steps spinning it all the while. When about at 20/30 pounds t, grab a big Ford Tool anda blocka hard wood a whack it good a couplea times from the back, then the front to set the thrust bearing and continue spinning the crank while tightening it down until you get it totally tight!!

This allows you to make sure that it works so that if it doesn't spin, then you will know that you have to line-hone the mains.

Mine spun fine and that was that!!

Cheap insurance to say the least sorta thing!!!!!

Oh, I did pein my main saddles sides or top corners with a dull chisel to cinch them down a wee bit, too, just for good measure..... Feeling with my finger at the parting line too...

pdq67

at least use arp bolts

Tony, for sure, use ARP studs, have the saddles checked with the new studs in place , and align hone if necessary.

Unless you really push the envelope, nitrous, 6500+ rpms with a stroker, etc, IMHO, you'll be absolutely fine with 2 bolt mains. Not worth the added expense. I'd spend the money elsewhere in machine work, deck heights, precision balance,etc.

It cost me right at 800 bucks to convert a 2 bolt SBC 400 to a splayed 4 bolt...splayed caps..studs..align bore..align hone..register the caps..set thrust

Thanks everyone...

I do intend to use ARP studs anyway, i figured that was cheap insurance...

And I will definitely be getting the crank bore checked and line-honed if necessary, as well as a good balance job...

My thinking on the 4-bolts was purely "psychological", as I really want to overbuild the bottom end (within reason and budget) just for piece-of-mind.

I have really beat on my 396 2-bolt (seeing well over 7000 many times, and its a relatively cheap rebuild... I used NEW main bolts, but they were Pioneer (rebuilder quality) and not ARP... Still, no problems...

With my latest heads and cam, my DCR is way low, so I am looking to increase torque through displacement and DCR, while still maintaining a reliable engine...

Thanks...


BigJimz,

I originally built this engine when I lived in Redding... Most of the machine work was handled at Franklin Engine, and balanced by precision...

I even bought the block from a guy named Donny (?) (he used to have it in his 1957 pro-street Suburban) after he threw a rod and took out a cylinder...

I am debating bringing my new motor back up to Franklin (Doug helped me quite a bit), but I now live south of Sac, so its a long trip to the shop...

I know Doug well..Randy Liddel is doing my machine work..they farm out the clylinder borring to Franklins...email me if you come back to town.. jimscott2309@charter.net maybe we can swap stories...I might be going out of town for awhile starting next week

My 427 went 634 hp at 7100 rpm with ARP studs and a two bolt. I don't know what you would have to do to hurt it. You can get metal transfer if it is detonating, though, so whatever you throw at it, nitrous, whatever, make sure the tune-up is where it needs to be.

Your fine with 2 bolt mains in a big block. Have lots of experience with the Mark IV 454's we have built in my other hobby - boating. Had a Scarab with two - 2 bolt 454's which dyno'd at 500 HP each, normally aspirated. Next season add two 6-71 Blowers and was pushing over 600hp for two seasons (and these motors were romped on). We pulled them apart to freshen the up and everything was perfect. Given we were running a top of 5400, but it was 5400 for relatively long periods of time. Just my 2 cents....