Scored Offy dual quad intake for my 392 WEDGE project!

-
Ottmundr

Ottmundr

68 Fastback
Joined
Oct 5, 2012
Messages
13,447
Reaction score
23,779
Location
Sonoma
New, never used. Single plane for 273 and 318 engines.

I am a little annoyed as it was advertized as a 5615, not a 5488. From the research I've done this evening, it looks like I will need to re-bore the manifold bolt holes and mill the flange so the intake manifold bolts will sit flat on the maifold. No biggie, just annoying. Gasket matching down the road for either the upcoming trick flows for LA blocks or a set of the iron INDY/IMM heads. Trying to decide on whether I want to eat the approx 50 lbs over the front end. Compression will be another deciding factor for the heads. I'm leaning towards the IMM heads now.

Next up, a pair of Edelbrock 1404 or 1804 500cfm carbs.

IMG_20180117_165131.jpg
IMG_20180117_165211.jpg
IMG_20180117_165222.jpg
IMG_20180117_165305.jpg
 
Coooool! That should be nice for some high rpm’s.
 
A 392 stroked 318 I guess? You'll also have to open the intake ports up as those are 273/318 sized ports, hardly enough to support 392 cubes. Also, I do not think there's enough material on those flanges to open the ports up enough. If there is, the port frame will be VERY thin. Those intakes were not designed for the 340/360 port window.
 
Nice score. If your interested I still have a set of matched freshened, carter comp 9503S's with new strip kits and linkage that came off my Offy dual. pm me. there's pics here, I had held them for a member that kinda led me on and the ad got locked out.
 
I agree Rob, I bought one six months ago for a 360 I'm building and the ports are tiny compared to the 360's. I ended up selling the intake to someone building a 273.
 
RustyRatRod said:
A 392 stroked 318 I guess? You'll also have to open the intake ports up as those are 273/318 sized ports, hardly enough to support 392 cubes. Also, I do not think there's enough material on those flanges to open the ports up enough. If there is, the port frame will be VERY thin. Those intakes were not designed for the 340/360 port window.
Click to expand...

Yes, it is a 318 stroked 4". I wanted to do something different than a 360 with 4" stroke and rpm air gap.

If by opening it up some, but not opening it up all the way to 340-360 port size, will it cause the fuel to drop out of suspension either due to the narrower ports causing higher flow speeds, or the non-match at the step to the larger port of the head?

Would I be shooting myself in the foot here by trying to split the difference in keeping enough material, but opening it up some?
 
Does a magnum style head have a slightly narrower intake port opening. If so would that be an option?
 
Ottmundr said:
If by opening it up some, but not opening it up all the way to 340-360 port size, will it cause the fuel to drop out of suspension either due to the narrower ports causing higher flow speeds, or the non-match at the step to the larger port of the head?

Would I be shooting myself in the foot here by trying to split the difference in keeping enough material, but opening it up some?
Click to expand...
I don’t think that harm will happen but just the reverse. By opening up the port you will help it all out. As YR was saying about port window sizes (head and intake) a match as close as possible is good. As the port window size increases, you would want to maintain that size as far up the port as possible but never smaller as you go up. It is better to have it larger as you go up so it can be feed well by the plenum.

Home porting tips are to raise the roof and widen the port. Leave the floor alone. This is outlined in the MP books.

I have not held that intake in my hands so I don’t know how far the roof can be raised. More the merry but not higher (or wider) than the head port.
 
I've had issues with this manifold used with large port(360) heads..
There's simply not enough meat on the ports (floor side) for adequate gasket sealing.
I've seen these manifolds welded and machined to build up more surface area for gasket sealing on the floor side...
If the OP is gonna have a machine shop mill the bolt hole angles, you might look into welding the ports. Then have the intake face milled flat and perform a gasket matched port.
Laying an intake gasket in the head and then on the manifold will help see any issues.
 
I've been thinking of doing the dual quad thing to my 70 340 with 202 U heads . I cant seem to find any intakes that match up, only the ones for 273 and 318 poly. I looked at all the main players including Offy and found nothing. Just looking for the "cool" factor and not really any performance gains.
Thanks, Jerry
 
Nice score! That will look cool and run great! Love it!!
 
If you want two carburetors, why not just bite the bullet, cut a hole in the hood, scoop it and run a tunnel ram? At least that way, you will have the right port size.
 
Looking at the #s it's for 65 and earlier 273, You never know there's a guy out there that might be looking for it so before you hack it up try selling it for big $$ you might get it sense it's new in the box.
 
brian6pac said:
Looking at the #s it's for 65 and earlier 273, You never know there's a guy out there that might be looking for it so before you hack it up try selling it for big $$ you might get it sense it's new in the box.
Click to expand...

I was sorta thinkin that too. Offenhauser is effectively OUT of business. They haven't casted anything since the late 80s or very early 90s.
 
I was considering that Brian and Rusty. I don't like the idea of cutting the 273 bolt holes and flanges for that very reason.

Lesson learned, get the ******* pictures of the part number. Yes, I can make it work with machining, but crapola.
 
I had an Edelbrock Str12 dual quad for a Smallblock. 20 years ago I traded it for a set of nice rallye wheels. It wasn’t useful for anything I was building but it was cool. Neat find.
 
Last edited:
Butcher and milled like crap, ready to go again, worked well, sealed fine.
Problem with the butchering, PM me for my feelings.
D-64 001.jpg
D-64 002.jpg
D-64 003.jpg
D-64 004.jpg

 
Ott can you lay a 340 gasket on the intake and take a picture of it? I can't remember how far off they actually are.

Thanks
 
yellow rose said:
Ott can you lay a 340 gasket on the intake and take a picture of it? I can't remember how far off they actually are.

Thanks
Click to expand...

I'll call oreilly and see if they have any in stock, if they don't I can order up a set from Summit. I'm going to need them some time anyways.
 
Ottmundr said:
Lesson learned, get the ******* pictures of the part number. Yes, I can make it work with machining, but crapola.
Click to expand...

Don't feel bad, I did the same thing. A guy had all of this listed on CL supposedly for a 340 for $400 and I let my excitement cloud my judgement. I snapped it all up before doing my homework and realizing that it would take a lot of work to make it fit on my 360. Good news is, I parted it all out and doubled my money which will help find the correct manifold.

upload_2018-1-19_5-25-20.png
 
The problem with the mod man is the runners are only about 2" long, very short!
 
You must log in or register to reply here.
-

Back
Top