Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Add a turbo and intercooler, fuel injection, and back it with a T56. However, a rebuild with some forged pistons, mild porting/clean up of the head, and a larger than stock but still turbo friendly cam would be a good idea. The best of both worlds. :burnout:

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

If you're interested in going the TBI route, I'm a machinist and I can make you an adapter plate to put the throttle body on your intake.

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

I've heard the Offy intakes are better for the street, with more low-mid range power gains, while the Clifford is better for the 292s and power gains up high in the powerband.

Do the Stovebolt cast headers clear the clutch linkage alright? I'm planning on putting a set on my truck.

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Yes, with absolutely no problems. I had a set on my truck for awhile but liked the looks of the Clifford headers so much better.

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Okay how I do subscribe to this thread?

Great topic and is a wealth of information.

You guys rock!

:metal:

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

When I get an L6 eventually I want to bring it to Procharger and have them make a kit for it. It'll be pretty sweet.

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

I have sat and thought long and hard about my 6. Do to the fact that its not the original 6...its a 75 to 79 integral head...which I dont like anyways... I am going to do a transplant in the spring of the 396 into mine. When its all said and done...I will have two big block trucks. Pass everything but a gas station. I was asked if I could afford it...I said no. Then asked why i was doing it...I said cause that is what I want.

if you want the 6...then keep it.

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Thanks for the info, Brad. I'm planning on putting them on my '64 so the vintage look of the cast headers will look just right for my truck. :metal:

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Anyone use those long tube headers from Clifford? Any fittment issues, or sealing issues?

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Yes, I have them on my 292 in the '68 Stepside. I bought the ["Clifford Research"] headers in 1978, ran them on my last engine for 25 years /250,000 miles. In 2002 -2005 I had the headers hot tanked and bead blasted and then painted them with VHT hi temp cast iron gray. They are now running on my '68 daily driver with the rebuilt orig engine.
In the mid '80s, when I had a shop install an exhaust system with turbo mufflers and balance tube, they also resurfaced the header flange, beefing it up. Some off-road rock damage had crushed the #5 downtube and this was also resectioned at that time.
So for a 31-year-old part, they are doing OK.
As far as sealing issures, you have to use the Clifford header gasket. I spray both sides with Copper spray Form-A-Gasket. Manifold leaks can be prevented by keeping the fasteners tight and checking them on a regular basis, especially when freshly installed.
The headers clear the clutch Z-bar and linkage OK.

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Thats great! I bet they sound badass!

I've heard that long tube headers are the only headers to actually give you hp gains, whereas short tube headers are only for sound. True?

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Definitely not on a 250 L6. Any split header will be better than the stock manifold.

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Ah, and long tubes are better than split headers?

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

anyone running any of these?
http://store.summitracing.com/egnsea...=KeywordSearch

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Pretty much any set of headers for the six are going to be split by design. Clifford claims 18%-22% power gains over stock with both thier shorty and long tube headers. I'm not sure of the difference in power versus the two. If you really want a strong 250, head work is where to spend your money, the stock design just doesn't flow well at all. With head work and headers alone, you'll notice a night and day difference.

Here's a pic of my motor and some video just because I like posting it.

Specs are:
250 L6 .040 over
Cam and Z28 valve springs (forgot the cam size, but it's somewhere in the middle, turbo friendly!)
Ported heads with head bolt bosses removed
Clifford shorty headers 2" exhaust
Offenhauser intake with holley 390 cfm carb
HEI ignition
4 speed

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

What did the intake, carb, hei, and headers set you back?

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Intake and carb I practically stole at $400 for both. I picked up the headers in crusty condition for real cheap(dont remember the price) and then blasted and painted them. You can get any year HEI for about $40.

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

I've been looking at the hei kits on ebay, seem super complete for 140ish, a rip?

Man, most carbs alone are 400+, the intakes are a few hundred, you scored!

I wonder if it is worth the extra money to get clifford headers versus some of the cheaper summit ones?

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

I just got a used one of ebay then added a new cap and rotor and plug wires. I think a new one with wires for $140 doesn't sound too bad though.
Yeah I really got lucky on my setup, just found a person swapping to a big block and offered him cash for the intake, carb and air cleaner.
I would keep an eye out on ebay, there's normally alot of good parts for cheap.

Heres what you really need.
http://cgi.ebay.com/ebaymotors/Parts...1%7C240%3A1318

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Ha, not for a driver! I think I'll stick with the carb, hei, intake, and headers for now. Reliability is key and based on your truck that should do the power department some good.

When changing the intake to an Offenhouser, do you need any special studs, gaskets, hardware? What about carb linkage to the 390? Anything special?

Some day maybe do the TBI conversion

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

The Offy intake is an aluminum clone of the GM cast iron intake, so it fits in the same configuration. It does not have any fittings for carb linkage, however. When I ran the Holley 390 [on the old engine] I fabbed a boomerang-like bellcrank on a special pivot off the right rear carb stud connecting with the '68 accelerator rod coming out of the firewall. It was a Rube Goldberg-type operation and at times I couldn't get WOT. Other times it jammed or tiny cotter pins broke off and caused control failure. It even "carb-iced" up once. Before I swapped engines, I changed over to a '72-style gas pedal and pull-type throttle cable. Much more reliable. Also, after a hard life of 25 years, the Holley gave up the ghost -- I couldn't get it to set up right on the new engine, so I bought an Edelbrock 500 CFM [Edl-1404] copy of the old Carter AFB. Good carb after some teething troubles with the metering rod springs. Maybe a little rich, but it's got juice!
As far as mounting the carb on the Offy intake... It's just like any other 4 Bbl on a V8. Good base gasket [I wet it down with spray PAM or WD40] new carb studs and nuts. Don't tighten them on too hard and use a 'kittycorner' alternating pattern. I like to mount the carb "sidesaddle" on an L6 with the primaries outboard. That way cylinders 1-2-3 get the same air/fuel mix as 4-5-6 throughout the acceleration cycle. Some people [Brad?] will argue that it doesn't matter. With the AFB carb, it makes tuning easy with the mixture screws accessible from the drivers side fender. With the Holley, maybe not so much.
If you're converting from the stock configuration, you need to lose the mounting guide pins on the head at positions #1 and # 8. They will unscrew counterclockwise with vice grips and PB Blaster. Replace them with 3/8-16 UNC header bolts or studs 3/8-16--3/8-24 and stainless or Grade 8 3/8-24 nuts. I like to use studs at positions #1, #3,#4, +#8. That way it's easier to hang the headers when you're mounting the 2 header pieces and intake. You'll still wish you had 3 hands. ;)

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

If you look at the picture I posted, you can see that I just used 3/16" rod and bent it to connect to the factory pedal rod. Works great.

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Forget the carb and do it now if possible! I love mine! Turned the key and it was minus 5 this morning, walked away from it and it was idling the same when I walked away as when I returned!

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Yea, but 2 grand? Holy crap that's expensive. I'm already looking at that much to rebuild my suspension. Is it really worth it? I'm going to be using a poly tank relocated to under the bed, and problems with that?


Thanks for the info guys, this thread is great!

Re: 250 Inline 6 Performance Build Q's---Hello Brad---
 

Doesn't have to cost that much does it?