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B21F Intake Modification

A

aprophet13

New member
Joined
Aug 6, 2013
Hi guys I've got an '82 242 with a B21FT. I want to switch over to megasquirt, and also want to switch to a B21F intake ( I have read this is one of the best flowing stock intakes). I have some questions about modifying a B21F intake to accept efi injectors.

Before you tell me to go search I have spent the past few hours doing just that!

Some people sandwich efi injectors into the k-jet ports, or weld on bungs and run them where they would traditionally go. Lets say I welded on some injector bungs, could I in theory run any stock fuel rail since the injectors would have to equally spaced regardless of the intake manifold? I.e. going to the pick n pull and grabbing an LH fuel rail off a b230 and modifying that to mount on the b21f intake or is it more complicated than that?

I know sometimes people get annoyed when no context is given so if this irrelevant sorry. I basically want a reliable DD with some good power- other mods will include turbo (.60/.63 a/r T3 probably from ebay, ebay I/C, already have a 90+ manifold, already have 740T fuel pump, already have MBC, want to convert from k-jet to megasquirt and will be using a B21F intake. I'd be happy in the neighborhood of 225-250whp at around 15-20pis. Hope that clears up any confusion.

**TLDR; could I use any stock fuel rail (modified to mount) on a B21F intake?**

any and all help is appreciated,
-Adrian
 
Yes you can. I have mounted 8v and 16v fuel rails to B21 intakes.



You can also mod for a 960 t/b



Or make you own -6 fuel rail and mount.

 
Just started learning how to TIG 2 weeks ago so I think I'll try using an existing fuel rail and only weld the bungs on to minimize fab work. Thank you for the detailed/helpful responses guys!

-Adrian
 
VB242 said:
I have this setup on my car. I have a lh 2.2 fuel rail mounted in the kjet holes. I had to drill out the K jet retainers to have enough clearance for the fpr.
Click to expand...

Pics? I'm putting together a 405 K-jet head and B21F intake manifold and I'm trying to figure out how to mount my EFI injectors too.
 
aprophet13 said:
Do you have a build thread? It would be really helpful to see how you end up doing that!
Click to expand...

Yeah, its the '87 linked in my sig. I have to build a bottom end first and I'm not sure if I'm going to do the intake before or after I put the engine back in the car.

I think I'm going to try to go through the K-jet injector holes if I can get the efi injectors at the right depth and angle. My second option would be getting Nathan to add some bungs to the B21F manifold. I'm tempted to talk to him about getting a 960 TB on there anyway.
 
To mount injectors in the head, as VB242 said, you slightly modify the K-jet retainers to fit EFI injectors, and weld/braze a mounting tab on a stock fuel rail and the rail will bolt to the head via 2 k-jet retainer tapped holes.
Doesn't get much simpler than that.
 
Canuckvolvo said:
To mount injectors in the head, as VB242 said, you slightly modify the K-jet retainers to fit EFI injectors, and weld/braze a mounting tab on a stock fuel rail and the rail will bolt to the head via 2 k-jet retainer tapped holes.
Doesn't get much simpler than that.
Click to expand...


Do you have any photos or more details on this conversion? Sounds pretty simple, but are there any pitfalls to watch for?
 
I'm working on pics, I had my whole build hosted on CarDomain, but they changed their website and I can't access them anymore. It seems like old links work but I can't pull them up on their site. I'm transferring everything to Flckr but it's taking some time. I used two pieces of 1"x1/8" angle for the mounting tabs for the head and the fuel rail and a short piece of 1/2" round stock in between. I had to shape it with a grinder to fit at the head. I had the head and manifold off the car when I fabbed mine up. Just make sure the injectors are seated tight and straight when you tack it in place.
 
Canuckvolvo said:
To mount injectors in the head, as VB242 said, you slightly modify the K-jet retainers to fit EFI injectors, and weld/braze a mounting tab on a stock fuel rail and the rail will bolt to the head via 2 k-jet retainer tapped holes.
Doesn't get much simpler than that.
Click to expand...

VB242 said:
I'm working on pics, I had my whole build hosted on CarDomain, but they changed their website and I can't access them anymore. It seems like old links work but I can't pull them up on their site. I'm transferring everything to Flckr but it's taking some time. I used two pieces of 1"x1/8" angle for the mounting tabs for the head and the fuel rail and a short piece of 1/2" round stock in between. I had to shape it with a grinder to fit at the head. I had the head and manifold off the car when I fabbed mine up. Just make sure the injectors are seated tight and straight when you tack it in place.
Click to expand...

Thanks for the info! I'm going to try to ditch the kjet for a standalone so I'll be fitting the F intake at the same time.

-Adrian
 
Only pic i could find
DCP00800.JPG
 
pics

manifold2_zpsfcd4bf9d.jpg

manifold1_zpsa8833396.jpg
IMG_1821_zps0a643a44.jpg

IMG_1818_zps7b1721b0.jpg

Couldn't get it to idle below 3k so removed icv. idles fine when hot, bit sensitive when cold. Thats installed on my RHD 945. The 960 throttle body needs spacing, had to fit the 960 tps upside down, the 940 one is far too big. I pulled the the throttle plate bar out and put it in reversed so the flat bit was in the right orientation for the tps. I also fitted 3" pipe work from the intercooler to throttle body too. Reduced the lag and feels quicker now.
 
Last edited:
Wow- guys thank you for all the detailed responses! I'm just glad other people had similar questions. When ever I come up with my own solution I'll post it back here.

-Adrian
 
Sorry guys, that's an old project, long gone. Don't think I have any more! It's really just a stock fuel rail that one of the Calgary guys brazed a second mounting tab on- I think the back one maybe fit the head already by chance.
 
Canuckvolvo said:
Sorry guys, that's an old project, long gone. Don't think I have any more! It's really just a stock fuel rail that one of the Calgary guys brazed a second mounting tab on- I think the back one maybe fit the head already by chance.
Click to expand...

notice a lot of old treads on this but I'm just trying to figure some of this stuff out. Does the B21 manifold flow that much better that a b230 manifold to justify the effort? Looking a the long runners makes me think it make more torque.
 
value

It's definitely worth doing . Whether the bigger throttle body is more of an improvement than the manifold I don't know but as a cheapish upgrade it's been enough to knacker the dmf.
The increase in torque has sort of tipped it over the edge of what the dmf was happy with so I'm putting in the dogdish flywheel/dtic clutch next.
I think it's worth an extra 10-15 bhp?
 
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