The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 400 sbc build need head and ignition advice

tmoble · 10-13-2015, 05:27 PM

generally need 6" rods for internal balance. longer rod allows bigger counterweight without interference with the bottom of the piston at BDC. there are some cranks advertised as internal balance with 5.7 rods but several I have seen needed additional heavy metal installed to balance.

Need to ask the machine shop to very carefully magnaflux the decks of the block before going any further. Many have small cracks between the head bolt holes and the steam holes. Some of these can be used anyway. The 400 block in my car has a couple of these.

10-13-2015, 05:27 PM	#10
tmoble Registered User Join Date: Feb 2009 Location: Glendale, Az Posts: 1,062	Re: 400 sbc build need head and ignition advice generally need 6" rods for internal balance. longer rod allows bigger counterweight without interference with the bottom of the piston at BDC. there are some cranks advertised as internal balance with 5.7 rods but several I have seen needed additional heavy metal installed to balance. Need to ask the machine shop to very carefully magnaflux the decks of the block before going any further. Many have small cracks between the head bolt holes and the steam holes. Some of these can be used anyway. The 400 block in my car has a couple of these.