Hey everyone,
I am going to get myself an early Christmas gift, a new intake manifold and 4bbl carb to go with it.

As you probably know I have an FE 390 with a new 2bbl Holley 500cfm carb that leaks gas.

So any suggestions on makes, models and suppliers for both a carb and intake? I heard there is a good Australian intake maker, anyone know the name? I am guessing a 60-750 cfm carb, what do you think?

Who do you suggest I get it from? I want to stick with the FTE sponsors if possible.

Thanks for your answers.

 

Hey Karl...just avfew guidelines...

Definitely stick with a dual plane intake, there's a lot of choices out there, personally I'
ve always like the Edelbrock Perfromer in the past, but I'd also like to try out the RPM Perfromer and the AirGap perfromer, I've hear good things about the Stealth intake for SBC's, Wieand made them, could be Holley took over the line.

I don't know of an Australian maker for an intake, I do know there was a company in Au making Aluminum heads for some time and they performed pretty well.

As far as a carb, I'd probably look at something like the Q-Jet design, small primaries, larger secondariies...before you spend your hard earned money on a carb , let's just put a kit in this Edelbrock 750 I have and see if you like it...cheap way to use it as a test mule.

 

I really like the idea of the cheap test mule.

 

Karl, I've got the Edlebrock Dual Plane Manifold (performer I think) and an Edlebrock 750 CFM carb. I like them just fine. Good prices at Summit Auto Racing.
T
http://store.summitracing.com/partde...1&autoview=sku

ON EDIT: Actually, the link I posted above is (i think) for a Jeep, but you can call the 800 number on that page and talk to one of the Summit CS guys. They are pretty knowledgeable and can steer you the right way if you give them the info for your application and how you intend to use it. They can also quote you prices and help you with your carb choice.

 

karl,

you heard my truck at mikes bbq. im running an edelbrock performer 390 with edelbrock 750 carb. runs good. but i still have my holley 500 if you want to stay with a 2bbl, and i still have the 4bbl-2bbl plate if you want them too.

i will be up in antioch and rio vista area tomorrow, it that is anywhere near you. call me on wk cell 209-595-1740

 

What type of engine do you have it on? 460? Is a 750 too much for a 390 with a mild rv cam?

Thanks for the info Tim

EDIT- OOPS f250 we posted at the same time. Thanks for the info on you truck. I will probably go for the 750... sounds like it would be fun.

 

I have a 750 on mine and it seems to be good for my 460. I did an edit on my post, which also suggests that you call Summit Racing to talk with one of the techs. They are knowledgeable and can help steer you in the right direction. I believe that the telephone number is listed on the top of the page on the link I posted on my last post.

 

I disagree with most people in that I think almost everyone over carbs their engine. Too much carb is as bad as too small of one, for anything except a full race set up.

How To Calculate CFM:
Engine size (CID) x maximum RPM / 3456 = CFM
CFM @ 100% volumetric efficiency
(Example: 390 CID x 5000 RPM = 1,950/,000 / 3456 = 565 CFM)
Approximately 565 CFM would be required for this engine. However, most Street engines are capable of achieving only about 80% VE; a modified street engine with ported heads, headers, intake and carburetor can achieve about 85% VE; a fully modified race engine can achieve 95% or greater VE. The CFM number arrived at with this formula must be factored by this percentage.

I don't think your engine would do better than .85 VE, so 565*.85 = around 480 CFM.

I sure would not go more than 600 CFM. Too big a carb hurts you on the lower end of your power curve.

Also, I would pay a lot of attention to the length of the runners on your manifold. The longer the better as a long runner works best at the lower RPMs. In a dual plane all the runners are the same length, in single plane ones the inside 4 are much shorter than the outside 4.

Note: You can not directly compare CFM ratings on 2bbls to 4bbls - the 1 and 2 bbls are rated with a 3 pound vacuum, the 4bbls use a 1.5 pound vacuum source. Your 500 CFM rated 2bbl delivers about 353 CFM. The official rating needs to be multiplyed by .707 when compared to a 4bbl.

 

Great data .... I can use this too ... I'm thinking Edelbrock 600cfm on the 390 I plan to build. I'd like to get 6000rpm out of her by the time I'm done. That's another story ...
Looks like I have to wait just a little longer until a job comes my way.

Thanks for the information !!!!

 

6K RPM is a lot to ask for out of a FE - there were some blocks produced with extra webbing around the mains, and even some very special blocks with cross bolted mains that would do this and more, but they are very expensive!

You are likely safe enough with short excursions to 5500 RPM.

Also, I suggest you find a 428 crank and rods - makes your 390 into a 410 without any extra machining. Is the cheapest 20 cubic inches you can get.

Just don't spend a lot of money on the crank without first having it checked - those cranks are famous for microcracks.

 

I'm thinking Forged crank(edit-looks like a New Steel Cast Eagle Crank rated at 700HP will be just fine).... ah ... when I can afford the build. I actually have the money and approval to build ONCE I get a job.

Your reading my mind. What I really want is a torquey 390 built to 428. So maybe I really don't need to bother with trying to get her over the 5000rpm mark. But, I do want a smooth quick reving motor like the 454 I have. Head work / Alum heads, Crank, Rods, Pistions, nice cam, headers, Electronic Ignition with pills etc..

FYI - Here is the 454 ... Something along these lines. I know it'd hard to tell in this picture ... But, this should let you know this will not be your normal build.



I'd like to sit down with you and talk about it when I get there. Mike/Dan has some great ideas too. I just have to decide.... plan my budget... see what I can do etc.

So really cool things for my truck soon. Gear vendor, Lock-right, Motor/Tranny Build, driveline disconnect and new paint I think.... ;-)

 

I found this from when I was looking to rebuild the engine in what is now Thumper - I got one of the FE experts to run this combination of parts on his engine simulator software. I was not looking for race, but for a good pulling truck engine.


1. Port the 390 heads. (have 'em done by a compotent machine shop for best results)
2. 428 crank, 390/428 rods (standard short rods, 6.488" length)
3. Standard 1.680" compression height 390 truck piston, dished w/ 10.5cc dish and valve pockets - results in about 10.2 compression.
4 Crane 343941 cam
5. Edelbrock performer intake
6. Holley 600cfm vacuum secondary

This should be relatively affordable and result in 387hp @ 5000rpm, and 459ft-lbs @ 3500rpm. The torque "curve" is as flat as a pancake from somewhere less than 2000rpm up 'till 4500rpm. If the block is bored .030" over (usual to clean up the cylinder bores) it'll result in 416.9 cubic inches.

I figured up the compression for a 410 with a set of 1.66" compression height pistons with a 10cc dish, with 70cc combustion chambers, and .041" thick head gaskets. I got 9.82:1.

I'm sure he'd have no problems running 9.8:1 compression with the 941 cam on pump gas. FE's aren't prone to detonation even with the stock 10.5:1 compression ratio. Not only that, the torque curve peaked at 2500rpm, and was as flat as a pancake before and after.

 

OOO ---- That what I'm looking for. That's right where I want to be. Sounds like I'd have money left over for other projects that I'd like to do. Your spot on with what I was thinking. I might add a couple of NICE components to that so that she'll spin up faster but, maybe I'd just be wasting my money.

I want the power .... But, I also like to rev the motor and hear it rev up fast too like that 454. It unbelievable that you can make a big block spin like that.

 

Would be great to get my truck to be as wild and sound as cool as the truck in this video. I posted this video before. We can use it for inspiration for getting Thumper racing. I love how the Chevy locks his brakes at the top of the hill and the Ford keeps dragging it around the corner.

As for carb size, the guy who rebuilt the engine... twice.. and still screwed it up.. said that a 600 cfm would be about right. I wonder what 4bbl Dan has on his '68?


http://youtube.com/watch?v=5RjxPzFAq30

 

I have an Edelbrock 600 cfm sitting on top of a Performer 390. agree with Clint...anything over 600 is too much for a stock or mild engine of this displacement.

The Performer is a good manifold, but doesn't offer much (if any) perfomance improvement over a stock 4-barrel FE manifold as the runners and ports are actually about the same size, if not slighty smaller than stock. The main advantages to using the Performer are the availabilty, ease of swapping to a 4-barrel from a two-barrel, and weight savings (as well as esthetics!)