Small block Chevy question

[olbuddyjack]

Will a big block Chevy flywheel work with a 400 small block? I have heard that the bolt pattern is the same but are they balanced the same?<br />A friend gave me one off of his jet boat and I wanted to see if I could use it on my project.<br />Bondo?

 

[Bondo]

Re: Small block Chevy question

That Depends,............<br /><br />The bolt pattern is Either the 3" New style(late model) 1pc. main seal type.. <br />Or, the 3+" pattern used from the beginning till mid-80s........<br /><br />Some of the Big blocks were Externally Balanced, like the 400SBCs,... 454 is 1......<br /><br />But,.....<br />It Still May, or May Not be a Plug & Play issue.....<br /><br />Tell me More about your Project.....<br />Are you having the Engine built from scratch ?????

 

[olbuddyjack]

Re: Small block Chevy question

Hi Bondo, I'm putting a 77 Blazer 400 in place of a 87 5.7 Cobra. I'm just gonna freshen up the 400 and put a Merc cam in it. <br />My buddy wasn't sure but thought the flywheel was from an older(two piece seal) 454 or 406(406?)

 

[Bondo]

Re: Small block Chevy question

454 Is a big block,+ the flywheel Should fit.....<br /><br />The 406 is a 400SBC bored .030 Oversize........Of Course,.. This flywheel will fit,.. It's the Same Motor.......<br /><br />Are you going to have Any Machineshop work done on the 400 ?????<br /><br />The Best Advise I can give you about Rebuilding a motor is,........<br />Spent the Extra few dollars,+ Have the Rotating Assembley Balanced........<br /><br />Balanceing is the Best way to insure a Long Carefree Life for your motor........

 

[olbuddyjack]

Re: Small block Chevy question

I hadn't planed on going the full route(75k motor), but I'll give that some consideration. I have to see what everything looks like when I get it opened up.<br />Whats a good head gasket to use since theres no marine one avaliable? I'm going to use the original heads like you suggested in an earlier post.

 

[Bondo]

Re: Small block Chevy question

Fel-Pro's..... Composite......

 

[olbuddyjack]

Re: Small block Chevy question

Are the composites the same as the Fel-co-prenes or is that a different animal?

 

[Bondo]

Re: Small block Chevy question

Without going,+ Digging through a few websites,.....<br /><br />Use the Best Fel-Pro you can find, with the Steam-holes nessessary for the 400.......<br /><br />There are Several different Composite gaskets....<br /><br />Composite just means it's Not a single layer gasket........"Composite" equals Made with Multiple Materials.....<br />As in, Not a Steel Shim gasket.......

 

[olbuddyjack]

Re: Small block Chevy question

Oh, ok, no steel shims. <br />I'll check the nos. on the flywheel to make sure it is what he says it is and go from there.<br />Thanks Bondo, your advice has been invaluable! I do appriciate it. Thanks again!

 

[Olds Eddie]

Re: Small block Chevy question

I hope you are running a heat exchanger as the steam holes will clog with scale if you don't. Felpro makes marine head gaskets for the 400 SBC however I don't think they are necessary if you have closed cooling.

 

[olbuddyjack]

Re: Small block Chevy question

No heat exchanger. Is there anything I can do, besides changing the cooling system, to prevent this?

 

[Olds Eddie]

Re: Small block Chevy question

No. You could probably find someone willing to trade you for a 350 SBC or use the crank to build a 383. You will have to get the main journals ground down to the 350 specs though. I'm sure you could sell the block for enough to buy an internal balance crank from Scat. My San Juan Engineering closed cooling system only cost $500 and went on real easy. It will pay for it's self after a few years of not having to winterize the block. Probably your best option.

 

[Bondo]

Re: Small block Chevy question

The Steam Holes are a Non-Issue...... Virtually no water passes thru them.....<br />Any Crud that's passing thru the system will Fall to the bottom of the waterjacket,.. Not the Top...<br />There's just a tiny Air Pocket at the top of the block that has to be Vented during the block filling proscess.............<br /><br />Granted, A 400 wouldn't be your 1st Choice for a Saltwater Motor,.......<br />But, I'm Sure that jack will be boating in Freshwater,....Atleast Most of his time........

 

[olbuddyjack]

Re: Small block Chevy question

But, I'm Sure that jack will be boating in Freshwater,....Atleast Most of his time........<br /><br />

Aye, that would be all the time. I gotta go a long way to get to a salt pond...

 

[Olds Eddie]

Re: Small block Chevy question

What about the scale that forms in the head above the steam holes? I would think that this would cause problems. I heard somewhere that this is why Merc never offered this engine. I have a link for the 400 SBC marine head gaskets. Is it OK to post or should I sent it by e-mail?

 

[Bondo]

Re: Small block Chevy question

Well,......I've never heard of Why, or Why Not Merc. never offed the 400...... Chevy only cast them for a Few Short Years..........<br /><br />The water flow is Into the Block, Then Up thru the heads to the T-stat...... Any Crud has fallen out of suspension by the time it gets to the Heads....<br />And, It would have to Really be Packed into the holes Tight, to Stop the little bit of Air from Venting up into the heads.........<br /><br />As for your link,......<br />We Always try to push business To iboats,+ Other Advertisers here......<br />But,...iboats Seems to Not Mind posting leads to required parts If They Don't Offer them.......<br />So,...... Go ahead,+ Post It.....

 

[olbuddyjack]

Re: Small block Chevy question

Thanks Eddie, I'd appriciate the link. <br />I looked into the 383 conversion at first then ran across this Blazer for the cost of the crank kit. The 383 isn't out of the question, but I figured the 400 would be quicker and easier. I still gotta find out whats up with the 350. It ran ok just didn't have enough poop.

 

[Olds Eddie]

Re: Small block Chevy question

Here is the link:<br /> http://www.fastengineparts.com/products_view.php?id=1051 <br />Let me know how it works out as I am building a 400 for my 'fishing boat'. I have a friend that builds racing engines doing the machining and balance work for me. He supplies a Busch team, several CASCAR teams, as well as a lot of local racers and I have to wait for him to work it in. I sure hope my Alpha 1 can handle the extra torque.<br />Good luck with your project.

 

[Bondo]

Re: Small block Chevy question

Eddie,<br />Where you from ??<br /><br />I'm in the Early stages of a 400 Twin Turbo build........ Going to mount it ahead of a Jet Pump......<br /><br />I clicked on the Fel-Pro link at that site,..... Fel-Pro makes gaskets for motors I didn't even Know were Ever Built..............<br />Reverse Rotation. 4.3ls..........

 

[Olds Eddie]

Re: Small block Chevy question

I'm a hillbilly form the mtns of western NC. Sounds like you have the same addition to HP that I do. How are you going to get the compression ratio low enough for a turbo setup. The lowest comp pistons I could find were SRP's at 8.7 to 1. My friend has all his pistons custom made for about $100 each for his race motors.