Chris289

Hey people, I've been contacted about rebuilding an Olds 400 V8 for a customer. Trying to gather a price guide together, summit don't list much in terms of an engine rebuild kit for the 400 but they list a kit for the 403 which includes all new gaskets, rings and bearings. Just a quick question, will the 403 parts work with the 400? They are both classed as the 6.6 litre engine.

They do list a gasket kit for the 400 which is the same kit I just used on a 455 engine but it's the rings I need that they don't list for the engine directly.

Any help would be appreciated.
Many thanks,
Chris.

oldstata

400 is a big block

403 is small block

Most gaskets are the same for the Bbo / SBO


Not sure on what interchanges with internals. I am sure some one with better knowledge will chime in

Chris289

Ah ok I thought they were both big blocks. How about the piston rings though? Will the 403 fit the 400 engine?

oldsmobiledave

No. The bores are vastly different.

Fun71

FYI, there are two different 400 Olds engines:early (1965-1967) and late (1968-1969).

To answer your question, no, the 403 has a bore diameter of 4.351" whereas the early 400 (65-67) has a bore of 4.000" and the late 400 (68-69) has a bore of 3.875".

In order to determine which engine block you have, check the casting number on the shelf above the water pump, post it here, and someone will tell you which one it is.

Chris289

The car is a 69 442. I can only assume the engine is a 69 engine without seeing it in person.

2blu442

If you need the customer to identify it for you here's an old thread with photos of where to look. The early 400 would have a large letter E at the end of the casting numbers between the water pump and intake. The late one would be a G which would be correct if it has the original engine. John

https://classicoldsmobile.com/forums...s-engines.html

Fun71

There is also a B code for the 65 400 engine.

2blu442

Oops! I keep forgetting about the B block. 1965 442 only but they are out there.

oldstata

Lol didn't any one click on your link john the first pic shows a b block lol

2blu442

Ah... but that's the 3B on a 1977 350 engine. Yes, sometimes life isn't always as simple as we think.

oldstata

Oops ... Know look who needs to read and stop half fast glancing at pics lol

2blu442

OK, maybe I need to add this to the old thread. But here's the letter B and casting number for the 1965 400

DSCN2822.jpg

Octania

Before ordering parts you would do well to find out exactly what casting the block is.

400G the same as 400E the same as 400B the same as 403?

Well, except the pistons, rings, block, crank, rods, head gasket, intake, heads, timing set, lifters, and exhaust manifolds, yeah, pretty much the same.

If you are replacing or buying any of those parts then you need to be precisely specific on the casting numbers involved, therefore which engine it is.

'69 442 should be the small bore long stroke G-400 big block with C heads, J intake, and W-Z exhaust manifolds. Lifters may be the larger .921" - I can't remember.

Fun71

No, the lifters wold be the typical .842" diameter. I think the '67 engines were the last ones to use the .921s.

Chris289

Cool, thanks for all the info guys, good to learn new things. What I'll do is give him a "rough" price on the parts and then tell him that when the time comes we will have to identify the engine correctly to order the parts.

Thanks for all the help,
Chris.

64Rocket

If it is a "G" block, you are going to have some trouble finding pistons. Cast piston may be your only choice. Also if it is a "B" or "E" block, pistons will also be cast.

Gene

Fun71

Finding off-the-shelf pistons may be an issue, but getting them custom made will be simple. Almost all of the main piston manufacturers will make them to your specifications. Cutlassefi just mentioned a set of custom pistons for around $650 shipped.