I need to replace the manifold on my T-Code 1970 440. I want to go as close to stock as possible. I am running an Edelbrock carb. Does anyone have any helpful hints?
Joined: Thu May 01 2008, 11:15AM
Location: Chicago,IL
Posts: 2868
70 intakes have the 2 slots vs 4 holes (and not the later oblong slots for spreadbore). Almost any mopar swap meet should have some for cheap. if you want an alum one, the Eddy CH4B was the direct replacement.
Joined: Wed Dec 21 2005, 07:34AM
Location: indiana
Posts: 791
My thoughts, as I’ve now looked at this old thread with fresh eyes:
Why do you need to replace the manifold?
You won’t see much performance improvement by swapping an Eddy Perf intake on a stock-cammed T-code 440, and zero for drivability IMHO. The OEM intake is on par with the CH4B, and the intake is the same between T and U-code engines. The intake swap isn’t exactly a bolt-on, and you should really have a heat isolator under the carb as the alum will transfer more heat into the carb, and I believe today’s fuel is more volatile than back in the day (a double-whammy). I currently have an Eddy Perf and an 800EPS with an isolator and on warm days I can sometimes smell a little fuel when it heatsoaks, and that would stink (literally) in your ‘vert.
The 750 Eddy has a bad rep for being a crappy carb. I had many struggles with mine, and as I ‘netsearched I found I wasn’t alone. 2 theories I found – bad casting quality on the 750, and/or when it was scaled up from the 600 some of the geometry became not-ideal. Take either of them as internet rumor. But I will say that 750 was the worst carb I ever had (by far) despite *much* tweaking, documentation of changes and results, and monitoring with a WB O2 gauge. I saved it for test-running engines in my testrack; I’d feel guilty selling it to someone.
If your 750 is working well then ignore that. But if you have drivability issues (you didn’t specifically say that) consider that the carb may be a contributor, especially on a T-code 440. In my experience (with 2 different T-codes, both stock except for dual exh and MSD ign) the 600 carb is the best match for that engine (IMHO). I can’t remember if I noticed much difference between the 600 and the 800EPS either (it still has the stock 256° T-code cam).
So if you’re running smooth, I wouldn’t change a thing except for adding an isolator, as there’s not much to be gained and there’s risk of something degrading. A ¾” divided isolator could maybe make a torque increase due to increasing runner length???
Thank you for your thoughts. I want to replace the manifold because - long story coming - my factory carb was giving me issues, had it 'professionally' rebuilt to no avail. Decided to go with a new carb with electric choke. The 1411 750 Eledbrock has given me nothing but smooth sailing since I bolted it on, so I am good there. The issue comes from the hole in the manifold for the manual choke. Initially I left the pot for the choke in place to block the hole, but that failed and now the hole is obviously causing drivability issues. I'd rather not change the manifold, but the extra hole renders it virtually undriveable. I know it is the hole, because she was running like a champ with the Edelbrock before the hole opened up.
Joined: Wed Dec 21 2005, 07:34AM
Location: indiana
Posts: 791
Ah, I see a little better now.
There is a metal cup that fits in that hole, is it still in place? Or is that now leaking? I've always thought that a poor design although I've never had one leak on me.
I believe most of the earlier 4-hole manifolds have a cast-sealed choke well, so that would solve your problem. But I suspect the 750 throttle blades might rub on those plenum holes, as some of the AFB manifolds are smaller, I'm not sure what all of the configurations are in the 4-hole-oval plenum/AVS/AFB combinations are. Might require a specific casting#.
You could swap to a manifold from the thermoquad era (72-up) as those also have a closed choke well. You'd need that thin square-plate adapter that the Eddy carbs usually come with to seal the carb to the intake, possibly a spreadbore adapter too.
I have a handful of intakes and choke parts at home (and that dang 750 carb), maybe I can find some time to get some pics, and if I have something that'll help you we'll work out a good price.
Post a pic of your problem also if you can, or maybe answering my above musings will be sufficient.
Ironically, on a 3rd 440 I had (my 70 300 U-code) it had terrible drivability with several carbs (among other things) *until* I had the original carb rebuilt, then it was a champ.