re-wiring from small block to big block how-to

[Eat My Dust-er]

I plan on switching from a small block to a big block (318 to 440) on my Challenger..... I know, I know this is an "A" body website but the bulkhead connectors are the same on A and E bodies (they all look exactly the same as on my Duster).:thumrigh:. Anyway, I see that the distributor wire is different, how do I change that so the 440 will run and is there any more wiring changes that will have to be made? The car and wiring are '74 but the 440 that's going into it are a '78. Any help will be greatly appreciated:salut:

 

[abodyjoe]

wiring is the same.. just have to extend the dist and maybe the alt. wires .

what do you see that is different between the small block and big block dist wires?

 

[Eat My Dust-er]

O.K., upon double checking, I found that the Dist. hookup IS the same, I was looking at the wire that comes out the other side of the dist. that has a different plug in but that must be for the lean burn set-up that the 440 originally had. I plan on getting a different dist and heads though. On this lean burn 440, can I just swap dist. and heads and have decent power? Or isn't it that easy? If so how much power can I expect from a stock lean burn 440 with 906 heads?

 

[abodyjoe]

whats the lean burn motor have on it now? 452 heads? you can just change the dist. to a regular electronic dist and it will run fine.. even a stock smog 440 will run nice i an a-body.. from there its all up to what you are looking for out of it.

 

[rumblefish360]

195 HP stock, optimized, better distributor and ignoring stock timing and re-jetting the carb, 220 HP.
The engine lacks compresion, cam and better heads. Headers would add a good amount.

Joe, it's in a E body Challenger.

 

[Eat My Dust-er]

I'm not sure what heads are on it, I can pull off a valve cover tomorrow and see. I will probably have to switch carbs though right? Is the electronic dist. going to hook right up to the old wiring?

 

[rumblefish360]

The distrib will hook up no problem, your heads are 452's, they do very nice when ported. Stock, the exhaust side is layed down and flows poorly.
The T-Q may need a re-jetting, however, it more tham like a lean burn carb is on top so it lacks the port for a distributor vacuum advance hook up. Luck still be OK though, big blocks tend to still run well without it hooked up.

 

[abodyjoe]

Joe, it's in a E body Challenger.

my bad.. i saw that and then read his screen name...

 

[Eat My Dust-er]

I have a set of 906's that have new valves, springs and hardened seats for unleaded gas? I'm thinking of putting them on and switching the intake and carb, how will it run then?

 

[rumblefish360]

The closed chambers will add minor power and flow.

What intake, carb and size?

 

[rumblefish360]

my bad.. i saw that and then read his screen name...

He he he, I do like his screen name. Easy mistake.

OH, hey Joe! Did you or do you get E-mails from E-town? I got one about Pinks and signing up to try out.
You? Or any Jersey boy?

 

[abodyjoe]

no i didn't get one from them.. thought i was on the mailing list...

 

[Eat My Dust-er]

I'm not sure, I'm not that familiar with this area of the car. I was hoping for some suggestions from here on what to do/use. I can do the mechanics but don't know what to choose as far as carb/intake combo or heads. So what your saying is that the 906 heads aren't going to make much difference?

 

[rumblefish360]

You can do the 906 heads over the 452's, but it is not a huge gain. I'd use them because of the fact there re-done and good to go over the whats on there now. Any additional work on them 906 heads?

What is the performance goal of the car?
Just in the street and mello enuff to go anywhere?
A bit of bite for it?
Are you up for a rebuilding of the short block and change of pistons?

In short, an excellent intake and carb combo IMO would simply be a Edel. RPM intake and your choice of 750 cfm carb. Holley or Carter...what ever you OK with.

When it comes to a cam, are you OK with doing it yourself?
When it comes to chooseing a cam, pick one with the duration that matchs your cruise RPM in the intakes operating RPM.
If you need help.....we'll be here.

 

[Eat My Dust-er]

I was looking in the "junk" and found an almost new edelbrock performer 4 bbl. intake for the 440 also. The cam I don't think I would tackle. Will the rocker arms from the old heads fit the 906 heads?

 

[abodyjoe]

yes the rocker shafts and arms will fit the 906 heads

 

[demon seed]

I was looking in the "junk" and found an almost new edelbrock performer 4 bbl. intake for the 440 also. The cam I don't think I would tackle. Will the rocker arms from the old heads fit the 906 heads?

Eat my Dust-er, I like that to. The 906 heads are the best way to go if you're staying stock and the 906 will react quite well to any porting but you'll probably want to farm that out. What year is this 440, cuss if it's a low compression 8.5 to 1 lunger then first thing I would do is bump up the Comp. Ratio to 10 to 1 otherwise all the add on's in the world is not going to wake that puppy up. From that point on I'd look at a nice street cam, go with the performer and minimum 750 cfm Demon or Holley. Take a good look at the old rockers, where they fit over the shaft, and make sure the holes haven't opened up otherwise they are reuseable.

Terry

 

[rumblefish360]

Good point about the hardened seats Terry. Once the heads are ported out, from what I remember hearing, the 452 is a better choice.
Beats me?!

 

[AdamR]

There is very little difference in flow between the 906-346-452 head castings. Its really not worth the effort to swap them unless the 906 heads have work done to them or are at least freshened up with a nice valve job.

 

[demon seed]

Good point about the hardened seats Terry. Once the heads are ported out, from what I remember hearing, the 452 is a better choice.
Beats me?!

\

Ha Ha Rumble, you replied before I edited my response cuss I went back and noticed that he said the 906's had the hardened seats.

Terry:thumrigh:

 

[rumblefish360]

Ahhhh, I missed that. But he did say new stuff on it. I guess we mean rebuilt? Beats old OE w/many miles on them.

 

[Eat My Dust-er]

If the heads are all comparably the same then why does everyone want the 906 heads? How do I tell if the motor is a low compression motor (by the year)? By the way the motor is a '78. Would I even have to change the intake then or maybe just put a different carb on it. How do you lower the compression, shave the heads (not my head, the motor:thumrigh

 

[Small Block]

I'm posting so as to bring this back to the top as this is where i am on my /6 to 440 conversion and i'll need this, Maybe. thanks

 

[rumblefish360]

Small block, this is a good thread so far. It's just a shame I missed Eat-My-Dust-ers next question. It's a good one. He hasn't posted since. Probably still driving the car like nuts enjoying the perma smile.

IIRC, the 906 heads are a closed chamber design and again, IIRC, they have an edge in flow in there as cast form.

Low compresion engines came out in '72 - '73. The '78 model year is likely to have the piston down in the hole about .100 - .130 area. (Can you say ECHO - ECHO - echo - echo )

Even a heavy shaving of the heads wont bring it up that well and if you did go that far as to get it up high, the intake may have to be worked on as well as to get it to fit properly.

The 440 as is, will move the car decently, for whats powering it. You'll have lots of torque and moderate HP. Giving the engine headers, cam, and a decent ignition will make it fun. The OE iron intake can stay for now. You can allways change it later or in a group shot along with the cam.

The OE T-Q ... is this a truck motor? Depending on engine application, or model number of the carb, will tell you if it is OK to use or if another carb is recomended. Smog T-Q's aren't to great to fuss with.
Truck T-Q's are not smoggers because they were exempt from car standards.