427 engine..

[nuch_ss396]

Hey Tom !

I'm still waiting for you to build that oval port 396 with
the L/78 camshaft. And after what we learned last
week about using the rectangular port intake with the oval
port heads ( power up to 6500 RPM's ), I can't wait to see
someone try it. Odd thing is I have all the necessary
components ready ( L/34 - 402 long block, L/78 camshaft,
and the now infamous rectangular port intake ). I just
have no time to do it or a car to implant this into.

Steve

[WILMASBOYL78]

I agree...it is on the list of things to do. Got 2 396 blocks in the garage and 4 sets of oval port heads..that should get it done. I have 6223 crank and a decent set of rods and lots of misc. stuff. I am out of 163's at the moment..used the last one on the project car. But they are avaialble.....it would be a cool motor to drop in Karen's 69 Camaro and put that little small block in the corner still need to build a 4spd street Nova that I can beat on..this would be the engine for that effort!

[SuperNovaSS]

I was told all 427s used the 7115 crank.


Jason

[KevinCav]

Hi Guys,
I have had two original 69 L89 Corvettes(one for almost 30 years)and both of them had the 6223 crankshafts. One is a January car that is a 4spd and a late Feb. car that was an automatic.Both cars are very original and unmolested. I also have a spare original L89 engine that is serialized for a car built 2 or 3 days before my Jan. 4spd. car and it also has a 6223 crank. To the best of my knowledge, the 7115 cranks were only used in the L88's and ZL1's.

[Hotrodpaul]

My guess is that the 7115 cranks were probably used with the heavier open chamber 12.5:1 domed pistons for the L88 and ZL1 since the counterweights are slightly wider for balancing purposes. The 396 and 427 11:1 closed chamber pistons were lighter and worked with the narrower counterweighted 6223 crank.

Paul

[Musclecarkid]

I checked with someone i know who has taken alot of virgin motors apart and here is what i was told,it kind of falls in to what i had stated.Hope it helps ! 1967 435hps taken apart for the first time have had 7115 cranks with very few exceptions, 2 bolt main 427 motors usually had 6223 cranks,only corvette w 2 bolt mains ever used a 7115 . 427 COPO 427s mostly had 7115. Impala and passenger 427 hi perf used 6223 exclusively,this is from a pool of around 150 motors that were taken apart seemingly for the first time. As far as L88 and ZL1 ,only 3 L88 and 1 Zl1 were taken apart like this and all had 7115, Still have yet to see a 6223 crank even in a new crate motor from the late 70s as has been claimed,although certainly a possibility 8 nos assemblys from the 70s have had exclusively #7115 cranks " There you go !

[nuch_ss396]

Hi Kevin,

I don't want to bang heads with you here but I have not
heard of one COPO 427 with a factory '7115 crankshaft.
Several members here own them, perhaps they would care
to elaborate.

Additionally, I addressed this very issue last year on
the NCRS forum and walked away with the understanding that
the '6223 crankshaft was the common crankshaft in use at the
time. It existed in various forms: standard, cross-drilled
and cross-drilled/tufftrided in both 396 & 427 applications.

The comment about the '7115 being used in conjunction with
the 12.5:1 pistons seems quite plausible to me.

[Michael4yah]

Has anyone heard of using a tall block spacer to match up or transition an oval port manifold with rectangular heads? Hey Nuch, what was that about using a rectangular manifold with oval heads?

[nuch_ss396]

Michael,

Not sure about using an oval port intake with rectangular
port heads. Doesn't make much sense. The oval ports are
good up to about 6,500 and that is about where the rectangular
port heads are getting started. I would think that the intake
would reach the choke-off point just about when the heads
were ready to go-for-it.

From the number of posts here and on the NCRS forum, it's
evidently quite common to mount a rectangular port intake
up against oval port heads and get good HP up to about
6,500 RPM's. The bolt pattern is exactly the same so there
is no problem there. Just use the rectangular port intake
gaskets if you do this. I will try this myself one day.
It's got my curiousity peaked.

Steve