I didn't want to hijack an existing thread about the 400G vs a 455, so I am starting a new one. Can one of you experts school me on the main differenced between the 400E and 400G engines?
Thanks,
Randy

 

E is closer to a square block meaning bore & stroke are about the same. A G uses a 455 crank but has a much smaller bore so it is actually less than the stroke. E's will rev better and are considered more desirable & better to build. G's can run good in close to stock form (I like mine at least) but aren't considered good engines to build because they won't rev.

 

The main reason "they don't rev" is because they don't breath as well with the smaller bore.

 

Thank you professors!!
I just bought a completely stock 66 L69, and am wondering about engine potential. Is/was there anything special done to the L69 engine to enhance the performance?
Thanks again.

 

.060 over bore on the early 400 block, using std 350 Olds piston, becomes a 410 cid.

Gene

 

Here's a real good thread on the differences between them:

http://www.realoldspower.com/phpBB2/...ighlight=truck

This part is my favorite:

 

For those who haven't heard this story before...

The 400 motors were relatively low production rate items, since they were primarily used only in the 442s. To save money, Olds designed the 400 to use the same crank (and thus the same stroke) as the 425. This resulted in the short-stroke 400 used from 1965-1967. When the 425 was stroked to the 455 in 1968, Olds again wanted to use the same crank to save money. Unfortunately, the GM mandate of a 400 cu in max displacement in the A-body line was still in force, so Olds had to reduce the bore to keep displacement at 400 cu in with the longer stroke. The advertising BS at the time claimed that the smaller bore was intended to reduce combustion chamber surface area to reduce NOx emissions or some such crap, but this was purely a decision driven by the bean counters.

 

There may have been some truth to Oldsmobile's claim. The smaller surface to volume ratio of an undersquare engine does contribute to less emissions.

I do agree that keeping parts interchangability at a maximum was an important, if not greater part of the decision.

 

Yeah, but if you REALLY cared about emissions, you would have done this on the 350 and 455 that were produced in much higher numbers than the G-block motor. Just sayin...

 

How bout the heads on the L69 400E?

 

And???? How 'bout em...

 

This is the most logical explanation IMO.

 

Positives, negatives, potential??

 

Guys all I can tell you is I had a 69 442 bench seat 4-speed (in 70) and that poor car could not get out of its own way. I was embarrassed, kept the car for a year traded it for 69 Grand Prix SJ.

 

I have a 68 442 with the g block 400 rebuilt the top end new cam,lifters,timming chain,big valve c heads,edelbrock 750 carb and intake. Had decent power but ran it past 5000 rpm 1 to many times and spun a connecting rod bearing,in the process of building a 455. I did have to keep my foot in it to get it to move......

 

Did any of the '68 400/455 engines use a "smog" pump for cars sold new in CA, or was '67 the last year for CA "smog" pumps?