I would avoid the original cast iron intake, except for last resort or for an exact restoration.
The aluminum versions (any aluminum version) would/should outperform any factory iron manifold. Most aftermarket aluminum manifolds have dual bolt patterns – but not all manifolds have the larger holes in rear (for spreadbore carburetors).
You mentioned you have a Holley 3310 which should be a squarebore carburetor.
This picture is one on sale on eBay.
and an Edelbrock Performer RPM intake (7186) which is also squarebore.
Most of the 4-bbl appearing Sniper EFI units are also squarebore – so I’m wondering why an adaptor is needed.
The location you used for measuring air cleaner height (stick on top of valve covers) might not be the best location. Factory big block valve cover height has changed over the years (three times, that I know of) – unless you are using the same valve covers for your measurements. I would recommend using the intake/valley pan gasket retaining strips (front and/or rear - black arrows, below) for determining height. Also, keep in mind the (automotive) intakes are tilted (front is lower than rear).
The stock (factory) intake carburetor flange height (base gasket to crankshaft centerline) is the same between 340 and 383/400. The 413/440 carburetor flange is about ¾” (19 mm) to 1” (25.4 mm) higher/taller. I ran across this problem with B-bodies with this style air cleaner system:
With aftermarket intakes, the sky might be the limit as to carburetor flange heights. The same also applies to any spacers between intake and carburetor – which you may or might not have.
I found this online about measuring intake heights – but this would apply to Chrysler small blocks, but not to Chrysler big blocks. Therefore, I still Recommend going by the front and rear rails.
Sorta unrelated, your carburetor height would be 3¼” (82.6 mm)
Carburetor Height .
According to Holley’s web site, the EFI height is 3.28” (83.3 mm) – so not much difference.
According to Edelbrock’s website, the Performer 2186 intake has a manifold height of “A-3.65”, B-4.35, measured to engine block” which would not include the intake gasket or gasket rails, that I mentioned. The Performer 2186 is what I plan on using and is very close to the 4-bbl factory intake in shape/size.
They also say the Performer RPM 7186 manifold height is “A-4.90”, B-5.80, measured to engine block”. This would place the carburetor 1.35” (34.3 mm) higher – which might be a problem.
I would ask those members here who has a 383/400 installed into their FMJ body what intake manifold they are using – to avoid hood modifications. Those with RB engines (413-440’s) won’t help much sense the intake is different.
I chose the Performer 2186 sense I don’t plan on high RPM’s and didn’t want any hood clearance issues. That doesn’t mean the Performer RPM 7186 will not fit (hadn’t tried, myself).
Performer 2186
Performer RPM 7186. You can see the height difference between the two.
BudW
and in the end, don't care. I've got the kind of car I've wanted to build since I was 12 years old (way back in '76) but had to wait another 30+ years to be able to do it, money wise. No regrets, no remorse even though other non-car related things had to wait.
