Technical Intake manifold that matches the double hump heads intake??

Hi.

I need a intake manifold that fits the ports on mu double hump 3782461 heads.

The intake ports are 50.30mm x 28.77mm something like 1.98" x 1.13".

Is there a intake manifold that match the ports?

If not I have read it’s important that the intake manifold has smaller ports then the heads, something about turbulence with sharp corners and edges.

The engine (327 with full roller) has dyno results 360hp @ 5700rpm with Edelbrock C3B intake with intake ports 49.45mm x 32.0mm (not a good match)

I have three intake manifolds on the shelf:

Edelbrock C3B intake with intake ports 49.45mm x 32.0mm (1.95" x 1.26")
Holley 300-38 Street Dominator with intake ports 43.2mm x 27.0mm (1.69" x 1.08")
Edelbrock performer 2101 47.75mm x 28.96mm (1.88" x 1.14")

I don’t have the time or tools to port the heads, but I can port a intake manifold.

Any suggestions on intake manifold, or a manifold that I can port to match the heads?

Or is it overrated to match the manifold to the heads with only 360hp?

 

Well the edges can be radiused with a dremmel and a sand paper roll.

The intake that is going to be a good fit is going to be something GM from the era, like the intake from a 350 horse 327. But there are any number of intakes that will fly, maybe look for a '60s era Weiand or Edelbrock or Offy?

 

While slightly overrated, the ports should be close. And yes, as the mismatch goes, the manifold should be smaller than the head to allow for manifold positioning.
NONE will be a perfect match outta the box.

I'd run the Performer.
Try to make sure that the roof is close between the heads and manifold. That's the most important to have match. Understand that it takes a bit of work to get it right.

Mike

 

How about the 2X4 intake from the day?

 

What intake was on it - on the dyno ? Think I'd go with that and lets go for a post # 2 .

 

“Only 360hp”
Lol.

 

This is the HAMB, the C3B is the intake you want.

the other two are late model junk. Even if they work better.

 

Yeah, what about the 2x4, like this C26 I have



Or this Offy I run

 

Z/28 LT-1 intake from '67-'72 would be perfect!... Even if it is late model junk.... Chevy also sold those over the counter for a few years, so there's plenty of those out there.. ...

 

I definitely have an OG one from a '68 327 around the shop. I ran a stock car class that had to use a stock intake, although some guys bent the hell out of the rules with that.

 

In one of your photos you can see what appears to be a slotted screw head for mounting an oil baffle in the lifter galley. You then should have a filler tube at the front of the block. I would use an intake with provisions for that tube. Otherwise, you will need to put breathers on the valve covers . Do the 461 heads have 1.94 or 2.02 intake valves? The factory 275 and 300HP motors used the smaller valves, all motors above that used the larger valves and aluminum intakes.

 

As was said earlier, the C3B with the 461 heads is the ticket. Has it all-performance, looks, fit.

 

This one https://www.ebay.com/itm/174798449539?hash=item28b2ccab83:g:FX0AAOSw7b5gwkKo

 

Uhmmm I'd just do it like I do all performance builds I do, I match the ports on the heads AND intake to the intake gasket.... Problem solved and usually less than 2 hrs work.....

 

Gasket match which ever you choose...

 

More is better..

 

I ran a C3BX on my 327 with 462 heads. I didn't check for port match, but I know it ran good. No problem spinning it to 6500 RPM.

Gary

 

No, cost to mush to get intake and two new carbs and new aircleaners.

Its the C3B from the era thats on the dyno, it have good hight but is to wide for the ports in the heads.

The heads are on the engine, so i will not port them this time, but of corse that's the right way to go.

I will machine a hole for the filler tube or make it a custom design if its not on the intake.

Head specs:
Double hump 3782461, date I184 September 18 1964 or 1974.
Milled valve seats.
Cut spring pocket to fit COMP Cams 986 springs.
New full roller rocker arms.
Valves 2.02” and 1.60”.
New retainers and locks.
New COMP Cams 986 springs .540 lift.
Valve lash clearance 0.008”.

I live in Sweden so little harder to find, but i will look out for these. We have a Camaro junkyard, maybe there.

 

How much are you expecting with the engine you have?
Where does the dyno curve for things fall short.
If it’s the intake you are sure is the issue, can you sacrifice low end to gain on top?

i/e do you have a low enough (higher numerically set of rear gears to give up some bottom end for top end?

Lastly, seems your running a solid lifter cam, since you mentioned valve lash. Share the cam specs and those much smarter than I could probably tell you what it should do. You should also offer up your compression ratio, quench, all-in timing, etc.

Yes, we’ve all know a 327 can rev to 7000rpms, etc, but as I recall the 461 heads have about a 165-170 cc intake runner, so maxing HP at 5700, might not be out of line

Just my thoughts.

 

I don't claim to be an expert on these, but i thought 461 heads were always the 1.94 intakes, yet you say they are 2.02-which indicates 462 heads. Have the heads been changed to 2.02 specs with the rest of the work done on them?

 

The #461s had both intake and exhaust valve sizes.....
2.020"-1.600"
1.940"-1.500"

 

My experience is none, just bought it, still not in the car. The engine has only done 3-4 hour in dyno since rebuild with intake C3B and Holley 650 DP before i bought it.

I have only removed the intake to take a look att the lifters and realized that the port on the intake was bigger then the port on the heads, so i thought i could fix this.


Block specs:
GM 3782870. Date May 27 1965 (E275).
Flint June 14 1965 (VIN F0614EA).
Line honed.
Crankshaft milled 10/20 and balanced.
New standard pistons and piston rings.
New main bearings, rod bearings and cam bearings.
New high-performance oil pump.
New timing set.
New thrust button & wear plate (retro-fit).
New solid roller lifters (retro-fit).
New push rods.
New hydraulic roller cam, Comp Cams Xtreme Energy 218/224 (XR270HR-10, 12-422-8).
New high performance oil pump.

Head specs:
Double hump 3782461, date I184 September 18 1964 or 1974.
Milled valve seats.
Cut spring pocket to fit COMP Cams 986 springs.
New full roller rocker arms.
Valves 2.02” and 1.60”.
New retainers and locks.
New COMP Cams 986 springs .540 lift.
Valve lash clearance 0.008”. (I think i will make this 0.004")


Other specs:
Intake Edelbrock C3B. (On dyno)
Mallory breakerless ignition distributor.
Accel Ignition Coil – SuperCoil – Street – Strip – 140001.
Accel Super stock 8mm spark plug wire.
New Holley 650 dp street hp.
Rear tires 255/60 R15.
Car weight 1790kg = 3946lb.
Exhaust: long tube Flowtech headers, 1-5/8" tubes , 3.0" collector, a 3” reducer to 2.5” X-pipe, two small simons sport mufflers.
3000 stall converter.
Rebuild and prepped TH350.
8.2" BOP rear with 3.73 with a limited slip unit. (Not build yet)
Will run on 93 octane (US) / 98 octane (EU).

Engine only ran in dyno 3-4 hours. 360hp@5700rpm outside car before i bought it.

 

Nice air cleaners. Who sells these.

 

What is so special about double-hump heads? Maybe the best available in their day. If this is a numbers-matching engine, then you would want a numbers-matching intake.

 

Heads probably should have been gasket matched but already done so I'd just live with it. Looks like the difference is about .060" top and bottom and more modern intakes might be worse. If peak power with an early look is important I'd get a Z/28 style intake like mentioned and pull the heads to do some porting or at least port matching.

 

I'm from Sweden, so not a big market here when it comes to parts or good engines. Found this engin rebuild only used on dyno, fair price for it so i bought it. Found a 454 engines not rebuild and only 320hp for the same price so it was not a hard choice.

 

Some of us are living "in their day".

 

Knight prowlers kustom car parts used to sell them, but it looks like they went out of business. I see 11 inch ones listed by a couple sllers on the internet but not the smaller 8 inch for a 2x4 setup.
They're called Stellings mushroom style air cleaner

 

I'm stumped.....

 

Thank you for all the info.

I have looked up some dyno test with and without portmatching the intake manifold, its not mush to gain in those cases 1-3% hp.
The dyno test seems to gain more with a good intake. So i will run with what i have.