Hot Rods Let's talk Cadillac 331's, 365 and 390's

ages ago (probably 15 years) I missed and aluminum 4bbl of unknown origin (although it was from a boat) on the auction site. still regret not grabbing it.

I've got some good tech on performance from an Allard group on my desktop. I'll try and remember to post it up tomorrow. Short story is 4bbl stock performs better than 2 x4 and 3x2 options.

but more carbs just look cooler

Sent from my SM-G920R4 using The H.A.M.B. mobile app

 

I don't know much about the old Rochesters. Do they seal up decent (throttle shaft wise) ? Can I still get OH kits etc? Any idea on the cfm range? Are we talking 4GC series?

 

Will this intake also bolt on to a 63 390? I know the intake gaskets are the same but the head gasket changed that year.

Sent from my SM-G935V using The H.A.M.B. mobile app

 

I think 63 was the change year. Didn't the distributor move to the front?

 

Nope. 63 is a one year only experiment, block is 4" narrower than earlier 390. 64 whole new deal, (although I think 63/64 may share intake manifold)

 

You're teasing me Mark.

 

A lot of haters for these old carbs, but I'm a fan. Even on ebay you can buy cheap cores, (most have frozen throttle shafts so just make sure you get cores where the shafts aren't seized) kits are all over and cheap. I bought boxes of cores so I could have lots of spare parts. A frozen clapped out core might be $30, but have good floats, which are like $90 for a set, etc.

Modern CFM standards are a bit different, but short answer is 4gc's came in 500, 600 and 700 cfms, based on their bores which varied.

Take minute to read this:

http://wildaboutcarsonline.com/memb...ine_Modification_and_Tuning_Rochester_4GC.pdf

 

At my age, trying to get out from under my inventory, not buy more; but at that price, probably should think about buying that unit. Clean it up a little, do some detailing (there are some minor corrections needed), hold it for a buyer, and TRIPLE my investment!

Surprised it hasn't sold.

Jon.

 

Quote:
"I think you really need the manifold that takes AFB's don"t you? these small WCFB's may not be large enough for you... "
End quote.

The 1957 factory intake will take early, small AFB's, and is the only one of the factory intakes that will.

The throttle center-lines on the larger AFB's was moved apart from the early small AFB's, so larger AFB's on a factory manifold would require either adapters or milling the intake, even though they will bolt on (the throttle plates will hit the manifold).

Jon.

 

Good info. I think moriarity is just taking the piss out of roothawg, he's taunting him with that sick Weiand intake.

 

I think they would be enough.

 

Have you read this thread on Caddy speed gear?

http://www.jalopyjournal.com/forum/threads/odd-ball-cadillac-331-390-speed-equipment.319750/

 

I have a Smoljan 3-2 for my 331. Guy up in Maine still making them


from BangShift.com Nov.26,2012

Last week we showed you an interesting looking intake manifold and challenged you to tell us what engine families it fit. In true fashion several of you nailed it. The intake is a reproduction of a classic Smoljan intake that was made in California during the 1960s. Dave Thibeault of Studebaker Parts and Services in Maynard, Massachusetts now reproduced these intakes and has them available for sale. Call him up at 978-897-3158 if you want one!

These intakes were designed and intended for Studebaker engines but according to Dave they can be adapted without much trouble for use on old Caddy engines in the same family as the 390. Thibeault said that the Studebaker V8 shared many similarities with the Cadillac engine and the Caddy design strongly influenced Studebaker engineers. The Stude engines are legendary for their robust built quality. Dave said he sets these intakes up with Stromberg WW carbs of Rochester 2CG pieces.

 

Wow. I like that a lot. I had no idea that anyone was reproducing those.

 

I ordered a raw casting from Dave Thibeault. I trying to determine what carbs to machine it for. Thought also crossed my mind of making a blower plate to bolt on to it. The design reminds me of the Detroit Speed ones.

 

Here's another Caddy Link for reference.
http://www.jalopyjournal.com/forum/...ngine-what-engine-mounts-in-a-hot-rod.682345/

 

finally remembered to post it up.

http://www.allardregister.org/blog/...ne-tuning-tips.html?rq=cadillac engine tuning

 

Just a heads up. A recent ad still on page one of AACA "buy/sell" forum:

Quote:
Two 1950 caddy 331 ci engines. One completely apart, other is short block. Have NOS headers for one. No intakes. $400 each. Waukesha, Wisc.


If you search there, look for ad title: "Engines for sale"

.

 

I have been reading this thread intently lately. I am looking to improve my 54 331 4v w/hydramatic since it was time to rebuild. Can I simply just machine this thing to the same bore as the 390, give it the same or hotter cam spec, buy a rebuild kit for a 390, then have a 390 when its all done? I mean, what all can I use from the existing 331?

 

Take a look at this thread... http://www.jalopyjournal.com/forum/threads/new-skool-331-caddy-build.803459/

 

you have to use 390 pistons but basically yes

Sent from my SM-G920R4 using The H.A.M.B. mobile app

 

I thought the later heads had bigger intake ports??

 

The heads are bolt on, even though the ports are much larger on the later heads. When 390 heads are used on a 331, the 390 push rods must be used because the height differs. Usually someone boring the 331 out and using hot cams will be using Studs adjustable rockers and custom valve covers, and will already be having a geometry project to work out with the rods anyway.

Here's a pretty quick thread where an engine builder simplifies it for the OP.

http://www.cadillacpower.com/forum/viewtopic.php?t=8853

The stock 331 had 160 HP and 312 lbs of torque, the stock 390 with tri-power had 345 HP and 435 lbs of torque, so there's a significant difference. Neither is a light motor, the 331 is around 700lbs, and the 390 20lbs more.

 

Well, I didn't say they wouldn't bolt on, the point I was attempting to make was that just boring it out and adding the pistons isn't the whole deal,if you want to make your 331 into a "390", you have to swap the heads as well.

 

Oh right, exactly. You were just explaining to post 174 that there's more to transforming a 331 into a 390 than the bore. Got it.