Have a question . The owner before me put a big block 454 in my 76 this winter it started to smoke so i pulled the engine to do a rebuild. After tearing the engine down was disappointed that it doesnt have 4 bolt mains. Guess the question i have is if i rebuild it with mild cam new intake and carb what kind of horsepower can i expect with what looks like stock heads. Or am i just better off getting a 350 crate engine thats ready to drop back in .

 

build the big block......two bolt mains are all right for 500-600 horsepower............you could also convert to 4 bolt for not too much money but i think it a waste.....

 

Post the head casting numbers. It's downright amazing what kind of power you can get out of a big block using factory parts. ^ midyearvette is exactly right, a 2-bolt 454 is tough, will make a good bit more power than the rest of your drivetrain can handle

 

should i change out the rods and pistons or will the stock parts be fine in producing horsepower

 

post some specs, automatic car or clutch?.....recommend 10-10.5 compression....edelbrock or gm oval port heads....rods should be ok if they are 390 horse but an up grade would not break the budget....cam kit pick is critical here......great power to 6000 rpm and loads of torque at around 3000 on up.....don't believe all the crap that a big block is best used for a boat anchor....

 

I dont know what the horse power was of the 454 all i know by the casting numbers on the block was that it was a truck engine . I have a budget of 3 grand to rebuild the engine for machine work and parts is that valid and still produce at least 350 horse

 

You can make 350 horse with a big block by accident.
Since you are rebuilding replace the pistons, but the rods and crank are more than up to the kind of power you are talking about.

 

LOL....

i would suggest the first 20 bucks you spend....buy ed staffel's book " how to build chevy rat motors" for max performance...he has all the factory part numbers and is a great guide on what to do

 

I agree get some good books on the Big Block Chevy. Now keep in mind some stuff is a bit dated lol. But it all works.

As said a 2 bolt main Big Block can make 600HP or more with ease on factory parts. So you do not need to spend a great deal of money on one.

And this means a stock cast crank is fine as well. Also the stock 3/8's bolt rods are fine as well. Just use good aftermarket bolts for them. If it makes you feel better you can use studs on the mains instead of the bolts but depending on what power you are after I do not feel they are needed. Even a good set of factory Oval port heads with 2.19in 1.88ex with some bowl work will do great. Then just pick the cam that will work with the intake manifold you are going to use and rear gear and trans and you are set. But to be on the safe side I would say to get forged pistons.

As said you can make 350HP easy. And up to 500HP pretty darn easy as well. Above that things get a bit lumpy lol. Well a lumpy idle due to the cam needed lol.

I wanted to add again that the factory Big Block Oval Port heads with a little work work great. You do not need to use square port heads. And as far as spending a bunch of money on Aluminum heads for performance on the street they are really not needed. Now do not get me wrong they will make the weight lighter over the front end and help with how the car handles and will add about 35HP or so but again are not really needed. The best street head I feel you can get would be the Brodix Race Rite heads as the runners are in the factory location.

 

So are you saying to use the same connecting rods but to get new forged pistons

 

Yep.
I would invest in new rod bolts but the rods are fine for what you want to do.

 

Nothing against SB's, but after Big Blocking my '78 years ago I'll never go back, so I can't see setting aside your BB in favor of a SB crate engine being the best course.

Head casting numbers?? Knowing what heads you have is so critical to what will be the best combo for your budget, you'd be making a mistake to start spending money on key components without determining and giving due consideration to this info first. And, even more important, what are your priorities and purposes?

I agree the 2-bolt BB bottom end is fairly stout, but I suggest going ahead and installing the high-quality rod bolts and main cap studs, if there's ever the chance you might decide to add some power goodies (better heads, roller valvetrain, juice...) in the future. Also, 10 lbs per 1000 RPM being all the oil pressure any BB requires, don't waste your money on a HP/HV oil pump; just don't screw up the bearing clearances and an OEM pump in good working order is all you should need. And, if that engine doesn't already have one, plan on buying an appropriate aluminum intake. If you get forged pistons, stay with high silicone 4032 alloy, which permit tighter piston/cylinder clearances.

You may not have the answers, but the good news is that you're asking questions; a sign you're willing to do your homework so you won't have to get lucky to end up with a sound build capable of making some real power. Post up with more info, and there are enough knowledgeable members here (tho figuring out which ones they are isn't always easy) to help you do this right.


TSW

 

What Skunk said......50 lbs oil pressure is plenty, and that's what the stock pump will give you...

 

Two words:
Stroker Kit
496 cu in

 

My two are [{cam and compression}=HP] and let the rest of the parts fall where they belong....

 

I would spend the money on heads....for the price to port the existing heads...I assume the heads are truck, same as the block...one can buy a set that will flow some good numbers...pistons, or stroker per Joe's post, then a good flat tappet cam...intake can be purchased at a later date if budget has been spent on above.

 

i have a 74 454 (2 bolt main) and with a hydraulic roller cam i was able to make 428 hp and 521 ft/lbs of torque simply with relatively low compression - runs pump gas....

of course that's on a dyno - but i'd like to think that's power enough?!?

RR

 

Ya need to get the block to the machine shop before you buy pistons/bearings to check and see how much boring/grinding will be required. I dont know a lot about it but I think your better off only going 10thousants over if possible, but if its been gone though before you may have to go 20-30. My machine shop guy always suggest just 10 if possible cause you dont get closer to the coolant passages and also it can be rebuilt again the next time. I did a good complete rebuild on my z-28's 350 for about a grand, decent brands, sealed power, national, felpro, cloyes, precission.. I have not got my 454 back in the car I purchased in pieces yet, but I got it running on a stand in my shop and I cant wait!!! its my first BB and my first vette..good luck!