Yeah they're pretty popular with folks upgrading from stock exhaust manifolds. Your best bet is checking all the junk yards in your area, finding a efi manifold, and cleaning it up a bit.

 

Will the EFI exhaust manifolds bolt up to a 240? I was thinking of using the headman headers but maybe there is a better recipe out here to use!

 

The 240 and the 300/4.9L engine share the same block, so the answer is, "yes".

 

They'll absolutely bolt up. The differences are in the internal rotating assembly. Everything else is identical except for the combustion chambers.

 

Maybe I should just build up my block.
The extra compression with the EFI exhaust and valves, 390carb. Would give me the mild build I'm looking for.

 

Oh the humanity!

Check it out so I got the new headers in and oh how shiny they are.




The issue now is the starter



I even bought a mini starter and there's just not enough clearance for it to mount flush. I've been wrestling with it for about 3 hours this morning and no luck. I had to unmount the starter to get the headers into the bay, then wiggle it into place while adjusting the headers. The problem is now I need about 1/8" more space to get the starter to mount flush. Any tips would be appreciated but I don't see how its physically possible to mount it. So either my mini-starter isn't mini enough or I'm doing something wrong.

 

I think the word you're looking for is: inhumanity.

Sorry, what a bummer! I used normal size starter, $50, and the same Headman header, and did not have an issue. If you can't r&r the starter with the header in place, it defeats the purpose of using a mini. Something is wrong. I would call Summit--if that's where you bought it--and check the application. I noticed on the link you posted that the starter also fit several v8's? That worries me, but maybe it fits several engines?

If you go with a standard starter, install it first, then header/intake. Use Mr.Gasket #260 gasket. Apply high temp atv on both sides around the exh. ports. Torque in two stages, first round half what book says. Iirc, it's 22 lbs. Start in center and work in a c.clockwise spiral. Second bolt/nut from the front, on the bottom, is impossible to get with a socket. You'll have to use a box end wrench from underneath. Don't over tighten. The install is easier with studs and crimp nuts.

Torque them all. Run it. Let it cool to touch, and retorque as stated. Repeat once more and forget about it. Good luck. I've had my starter in for ... is it 2 1/2 years?

 

Might have to heat and tweak the header for the starter clearance...if there is room enough for that.

 

Yeah thanks for the rundown for after getting it in. I took a break this afternoon for a few hours and let my head cool. Went back and it popped right in. Actually not sure if my set is just a little off (quality control) but I had to grind about 1/16" off the frame so the headers would sit flat. So i took it back out, removed the starter (again) and put it all back in. Forgot to pick up gasket sealant when I was getting spark plugs earlier so i'll hop over there tomorrow. Actually I went looking for proper studs to replace the old bolts today but of course none of the auto stores had them. Tomorrow I'll check local hardware stores and see what I can find. I've been looking for the fat concave washers that were on there but no luck so far on those either (might just reused them). They sell a set of exhaust studs at the local autoparts stores but the long ones (with both ends threaded) are waaaay too long so I'd have to cut them just to be useful. Anyway I'll be back at it tomorrow, with any luck I'll get the intake and carb in.

By the way, got the heat plate today thanks.

 

There's nothing wrong with using the old washers. I did. But you have to grind one side down 1/16" with a bench grinder. The header and intake flanges are different thicknesses, so, for the washer to sit flat, and for the but to apply equal pressure, it has to sit flat.

Make sure you get grade 8 studs, 3/8--24 on the int/header side, and 3/8--18 on the head side. Minimum 2'' long. Coat with a copper anti-sieze b/f screwing into head.

BTW: I too had to grind a bit on my frame. Harte3 mentioned something useful. You might have to use a touch and heat one of the tubes to bend it slightly. Good luck.

I sell the stud kits too. $50.

Oh, and when you took the int/exh. off, did you hear that noise? It was the head singing: Port me, please port me!

 

Hah! I just imagined my exhaust ports singing at me, needed a good laugh after today. I might hit you up for that stud kit if tomorrow doesn't go well. Unfortunately after this weekend I've got to leave the truck alone for a few weeks

 

you sure the thread pitch on the head side is 18? it seems I can find 16 no prblem but 18 nowhere

 

Which one performs better? I'll have to buy either one. I like the idea and look of the headers. Keeping the L6 in my car will have plenty of people asking why I didn't upgrade to a V8. So I think the headers will add to the overall appearance and mystyque. I haven't thought thru the exhaust system including mufflers and pipe routing/exiting.

Has anybody found a source for NEW exhaust manifold washers. I understand about grinding down half the washer to make it/them fit. Extras would allow me to make mistakes while grinding (like shooting them across the shop by accident)!

The starter interference that evilci is having doesn't leave the me looking forward to the install!

 

Getting them in with the starter there was just a huge pain in the rear, but they fit. Like the guys said above worst case you need a torch and a little love. I've been looking around for new bolts for the headers but so far no luck locally. I can find 3/8 x 24, 3/8 x 16 but no 18's around on the internet. What kind of car is your big 6 in? As for power and torque, if you look around here the engine actually gets great boosts from headers and intake manifolds. Although if your just looking for performance, you might want to find an old set of efi manifolds, still good performance but almost none of the fitment and heat issues of full on headers.

As for the exhaust I'm pretty sure at this point i'm just going to take it to and exhaust shop and have them to it; usually not all that expensive.

 

I will have to ck my paper work and confirm the threads. I'd just take one of the old bolts to a hardware store and try nuts on it. That will tell you what the threads are.

To my knowledge, no one sells washers for this application. With my kits I use two washers so one can be placed on the thinner flange, then the larger washer on top of that grabs the thicker of the two flanges. Clifford Performance uses the same system.

I was able to install my header with the oem starter in place, no problem. If you use an oem starter, a heat shield might prolong its life. k