Small block to Big Block

[ck22]

I spun a crank bearing in my 400 SB. The 400 was the orginal engine, only mods are Edlebrock carb and points replaced with Petronix. A good friend is selling his 1968 bored out 30 over 427 BB. It puts out around 500hp 550 ftlbs of torqe . I know the engine mounts will fit the BB and that it will bolt right up to the 400 tranny. He's giving it to me at a great price if I want it. I'm lookoing for input and ideas on the swap and any upgrades if needed.

 

[Chevy305]

I know all the accessory brackets won't swap over. So you will need those...

 

[ck22]

I should be able to find those at the junkyard, right?

 

[pauly383]

I should be able to find those at the junkyard, right?

probably , or here on ck5 if you post up in the wanted section . You should have had a good 3 or 4 core radiator with the 400 , so you can use that .

Get a big block fan shroud too .

 

[ck22]

The rad. is a 4 core. The shrouds are diff. in sizes? Good to know!

 

[pauly383]

I am not sure on the trucks , but on big block cars it is different , I assume this carries over to trucks .

 

[diesel4me]

Maybe in Florida.....but not here!

I should be able to find those at the junkyard, right?

Maybe....

You might find them in your area,but here big blocks are scarce in junkyards,and they usually wont let you strip backets off even a blown up one here--they sell them online for big $$$$$$!...you'd be better off buying an aftermarket setup from Jegs or Summit,then you'll have all the right pulleys,and wont be ripping your hair out trying to find that one of a kind pullley you need,etc..you could even go serpentine if desired..


Oh yeah--one other thing you'll need with a BBC --plenty of money, for TIRES..especially REAR tires!..

 

[ck22]

What about the front springs? I read in resto. mags that only 2WD trucks came with big blocks, at in 1972. I probably replace them anyway but I should know this.

 

[rjfguitar]

What about the front springs? I read in resto. mags that only 2WD trucks came with big blocks, at in 1972. I probably replace them anyway but I should know this.

If you still have stock springs than it's going to want to squish them down a little bit. You are adding a few hundred pounds. As long as you don't get any tire rubbing, at least it will ride nice.

If you go lift springs I wouldn't worry about it then, infact it will also make them ride a bit better.

 

[SkysTheLimit]

I'm in Tampa and going through this very same issue. If you find a junkyard that A) has what you need and B) will sell them cheap, let me know!!

I'm trying to work a deal with a member here for some but if that falls through, i'll try local.

Good to find some local boys!

 

[ck22]

I have the orginal inverted front leaf springs, not coil springs that come on 2WDs. Would it do the same thing?

 

[pauly383]

I doubt they are inverted . Stock Blazer fronts sat kinda flat . 10 bucks says they are sagging .

 

[obijuan]

you shoudl replace your motor mounts with the competition style from ord.

 

[rjfguitar]

I have the orginal inverted front leaf springs, not coil springs that come on 2WDs. Would it do the same thing?

I know...

Regardless of the type of spring, it's going to sag with more weight on top of it. It's what springs do, this is a factor that will always be in play. The variable is how much sag or squishyness is acceptable and still safe.

 

[ck22]

So change the springs, got it!

As for the mounts, I have engery suspunsion polys, motor and trans, still unwraped. I also added new body mounts, what a pain in the --- that was.

 

[PsRumors]

I had no negative effects on the springs with the added weight of the 454 in my Suburban. Unless you just want to do it now I don't think it is neccessary.

Most people don't go changing springs when they hang a heavy bumper and winch off the front and with the leverage out front you are probably about equal.

Also, springs can be changed after the fact if you don't like it, not like it has to be done now.

My 2 cents.

 

[Chevy305]

Most people don't go changing springs when they hang a heavy bumper and winch off the front and with the leverage out front you are probably about equal.

Well the majority of people that have winches and huge bumpers already have lift springs. So stock springs are not usually in question because lift springs are usually stiffer than stock.

 

[PsRumors]

Most people don't go changing springs when they hang a heavy bumper and winch off the front and with the leverage out front you are probably about equal.

Well the majority of people that have winches and huge bumpers already have lift springs. So stock springs are not usually in question because lift springs are usually stiffer than stock.

I thought lift springs were softer to get more flex. I know when I go to a 2" lift I expect a smoother ride. This would come from softer springs, no?

 

[Chevy305]

I thought lift springs were softer to get more flex. I know when I go to a 2" lift I expect a smoother ride. This would come from softer springs, no?

Well yes and no... Most standard lift springs are stifffer than stock. If you want a softer ride than stock I don't think you will ever get that out of lift springs. But you can come darn close with certain types of springs.

I think someone else can elaborate better than I can...