Clifford 6=8 products? Anyone using?

[CST10]

I seen on the Clifford website they have combo packages for the lil 250 engine that they claim adds 70% more HP and TQ. I talked to them directly and they said they can make that on a stock engine with just these bolt ons.

The package is carb, intake, headers, and misc items for the coversion.

Anyone have experience with this package?

Seems kind of high numbers for bolt ons.

Was going to post this in the engine/drivetrain section but figured it might get more responses on the big board where most people look the most.

Thanks in advance.

[chopnchaneled]

I'm with you on the seeming high numbers,
gonna tag along and see what everyone thinks.

[Tony]

Those number come at a cost... less power on low end and more on top end...250 cubic inches pulling a nearly two ton truck isn't a whole bunch. You can get some noticeable usable power increase with a mild cam and two carbs or a single two barrel or 4 barrel....Maybe 25 HP and an increase in torque at mid-range....
For a big power improvement for a 250 in a truck think like the Ford Ecoboost...Turbo or supercharger and the cost to build the engine to take the boost...
Or drop in a 292 or the best bang for the buck, SBC...

[Shaky]

I had a 250 with the Clifford intake and headers, Holley 390, better cam, and HEI. It made good power.

For me, the conclusion I came to with the GM straight sixes of this era is:

1. If the carb is in the middle, I'm always gonna be running the end cylinders lean and the center cylinders rich.

2. After reading a lot, I learned that the bolt running through the intake ports needs to be removed and "the hump" put into the intake port floors to make real power.

Over coming these two things requires some money.

I love sixes, but I leave them mostly stock now.

Read this book if you want to know more. There's a thread, I believe in the '60-'66 forum with hot-rodded sixes in it.

[trac209]

I like inline sixes and they can be made to make more power,but the cost of the bolt ons is somewhat not worth it. IMHO 6 can only equal 8 when 8 is a stock or tired out.

['68OrangeSunshine]

I have a '68 C/10 Stepside with a 292 L6. Original engine, sidelined for 25 years and rebuilt once. I have 'Clifford Research' long tube headers, an Offenhauser intake and a 4 barrel Edelbrock 1404 500 CFM carb. I ran the Clifford headers and Offy intake with a Holley 4160, 390 CFM 4 barrel for about 25 years on a '67 block that was bored out .030 over. I got about 250,000 miles out of it. When it was time for a rebuild, I took the OEM 292 out of mothballs and over to the machinist's. He also bead-blasted the Offy intake, and the headers were hot tanked and sandblasted and painted with VHT hi-temp paint, and went on the next 292 engine.
Good headers from Clifford. I did have to have a shop re-section a crushed down tube, #5 before the collector, where I had some rock damage from extreme off-roading, about the Mid-'80s. They also beefed up the header mating flange to 3/8'' at that time. When the shop contacted the company, Clifford offered to replace my headers under warranty at the time, but I didn't want to lose the down time, the '68 Stepside was my daily driver and only vehicle, then.
They are no longer Clifford Research now, they're Clifford Performance, and Jack Clifford passed away some years ago, but they're still there and still make good products.
I also have a '71 GMC Jimmy 4x4 [K/5] with V8 350 crate motor, Headman Hedders, Weiand Intake, Carter AFB 600 CFM, and the little 292 in the '68 eats its lunch.

[CST10]

So do you think it's worth the kit for the HP gains?

[Sixteen Tons]

First off, IMO you have a pretty boss truck just as it is. Stock, surviving trucks like yours will always be cool as an artifact from another (better?!) era of the American auto industry. You can never go wrong with keeping it simple.
That said, I have the same engine set up as you, in a LWB fleet at that, and though I have a Weber 32/36 waiting to go on, by having simply swapped the stock points diz out with a mid 70s GM HEI I rebuilt, made a helluva difference, immediately noticeable. In fact, I'm not sure the 2 barrel carb could even provide much more really, unless it makes the damn thing fly!
I would suggest trying an HEI first and then decide how much more you want or need.
As far as dropping etc, I am constantly go over that in my head as well....... good luck.

[leddzepp]

I've used Clifford intake, headers, cam, Holley 390, and HEI on the inline 6 Jeep CJ's I've owned. Night and day difference IMO.

[dirtyjim]

you can make those 6's run and Clifford has been doing it for a very long time. I still remember a truck from when I was a teenager that suckered a lot of hot smallblocks and a few big blocks, it was around a 65 model c10 that looked like youtypical pro street truck till he popped the hood and you saw the straight six with two holley four barrels hanging on the side of it.
I've also always liked trucks with non typical inline sixes, here was a blazer with a jag straight 6 running around about 20 years go, and about 6 month back there as 70 swb with a toyota supra straight 6 and a spd for $1800 that still kick myself for not buying.

I think if I was to do a six today it would be a Pontiac ohc, jag or bmw

[CST10]

So kinda hearing yes they do produce power but no real known amount?

['68OrangeSunshine]

Originally Posted by dirtyjim

you can make those 6's run and Clifford has been doing it for a very long time. ...
I've also always liked trucks with non typical inline sixes, here was a blazer with a jag straight 6 running around about 20 years go,

Wow, that's a switch. Usually Jaguars get the SBC treatment. I hear there's a website called 'Jags That Run' that's all about putting a Chevy engine in a Jag.
The Jaguar 3.8 XK dual overhead cam w/dual Solex[?] carburettors was a great mill.

['68OrangeSunshine]

Originally Posted by CST10

So kinda hearing yes they do produce power but no real known amount?

Have you been on www.inliners.org The Inliners International's website? I think they have some data published from dyno runs with various Chevy L6 configurations.

[CST10]

Originally Posted by '68OrangeSunshine

Have you been on www.inliners.org The Inliners International's website? I think they have some data published from dyno runs with various Chevy L6 configurations.

Thanks for that info. I'm check them out.

[dirtyjim]

Originally Posted by '68OrangeSunshine

Wow, that's a switch. Usually Jaguars get the SBC treatment. I hear there's a website called 'Jags That Run' that's all about putting a Chevy engine in a Jag.
The Jaguar 3.8 XK dual overhead cam w/dual Solex[?] carburettors was a great mill.

yeah, at one time that was very common, parts for jags and land rovers were hard to get and expensive, still are to a point. in the70's and early 80's a sb chevy swap into a jag was less than the cost of the dealer to tune up a v12. the auto jags also used th400 transmissions. I knew several people n the 80's with sb jags and one with a bb jag.

['68OrangeSunshine]

Originally Posted by dirtyjim

yeah, at one time that was very common, parts for jags and land rovers were hard to get and expensive, still are to a point. in the70's and early 80's a sb chevy swap into a jag was less than the cost of the dealer to tune up a v12. the auto jags also used th400 transmissions. I knew several people n the 80's with sb jags and one with a bb jag.

My Dad's old '59 Jag Mk IX Saloon [it did have a bar in the back] had a 3.2 L DOHC 6. It was bolted up to a Leyland lisence-built Power Glide. He used to have a Mk 8 1958, and that engine came out of that. The '58 -- same sedan body style -- came with a 4 Speed synchromesh with an electric overdrive. Unfortunately it had no brakes. The '59 was a dog on the road with that tranny. The 4 speed was cooler.

[Tony]

Originally Posted by CST10

So do you think it's worth the kit for the HP gains?

I used to mess with inline 6's , went to Inliner meets and talked with Leo Santucci who wrote the book above several times...Nice guy..
Once you get through all the claims of this and that a 250 with a stock head ,a hotter cam and the cam, intake ,carb exhaust improvements you have an engine with about 160-180 net HP...Oh you can get more power but it's going be higher rpm with a loss of low speed torque more suitable for a light vehicle.
Typical modifications to a 292 will get about 200- 220 hp with a nice fat torque range.

[CST10]

Originally Posted by Tony

I used to mess with inline 6's , went to Inliner meets and talked with Leo Santucci who wrote the book above several times...Nice guy..
Once you get through all the claims of this and that a 250 with a stock head ,a hotter cam and the cam, intake ,carb exhaust improvements you have an engine with about 160-180 net HP...Oh you can get more power but it's going be higher rpm with a loss of low speed torque more suitable for a light vehicle.
Typical modifications to a 292 will get about 200- 220 hp with a nice fat torque range.

Now that's good info to know. I figured all the claims were not true. This sounds more realistic. With the stock cam I would imagine it might get 140-145 net hp. Which is about 20% of the stock engine net hp rating.

Not wanting to crack open the engine, just bolt on intake, carb, headers. I already installed an HEI, which made really impressive drivability improvements.

[Tony]

The 250 net HP is 120 and the torque 210 ft lbs, this was the realistic power with a stock engine in the truck.
The biggest problem is the intake manifold design with it's very poor fuel distribution. A two carb intake is really best because of much better fuel/air distribution. But it requires adjusting two carbs and making linkage. The available cast iron headers can make more torque than long tube headers that throw off a ton of heat. A slightly hotter cam can boost mid range power without bleeding odd low speed compression...These mild changes have been proven on the dyno and street driving.
Huge HP is often quoted for modified inline 6's.. These are engines built by knowledgeable tuners often at high cost. You can read up on stuff like "lump ports" for the heads and decide if you want to go that far.
I've ridden in various modified GM inline 6's and built a few myself. They have far more power than the stock engines. But just drive a 4.0 Jeep Cherokee with the 190 HP inline 6...That's what a moderately modified 250 will feel like...

[Grumpy old man]

i've seen some videos on you tube of these engines pulling 350 hp on a dyno with crazy exhaust sound .

http://

[CST10]

Originally Posted by Tony

The 250 net HP is 120 and the torque 210 ft lbs, this was the realistic power with a stock engine in the truck.
The biggest problem is the intake manifold design with it's very poor fuel distribution. A two carb intake is really best because of much better fuel/air distribution. But it requires adjusting two carbs and making linkage. The available cast iron headers can make more torque than long tube headers that throw off a ton of heat. A slightly hotter cam can boost mid range power without bleeding odd low speed compression...These mild changes have been proven on the dyno and street driving.
Huge HP is often quoted for modified inline 6's.. These are engines built by knowledgeable tuners often at high cost. You can read up on stuff like "lump ports" for the heads and decide if you want to go that far.
I've ridden in various modified GM inline 6's and built a few myself. They have far more power than the stock engines. But just drive a 4.0 Jeep Cherokee with the 190 HP inline 6...That's what a moderately modified 250 will feel like...

Good info. Thanks for the advice

[CST10]

Originally Posted by Grumpy old man

i've seen some videos on you tube of these engines pulling 350 hp on a dyno with crazy exhaust sound .

http://

Yea. I watched a few of them. Impressive to say the least.

[Tony]

This is a good video of reasonable modifications done to a 250. This is not a hyper expensive engine but probably slightly more expensive than building a SBC...I know the guy doing the testing and build and he's very meticulous and experienced with Chevy inlines. After each test when the printout is shown you can stop the video to clearly see the Torque and HP at various RPM's. Keep in mind this is dyno gross power and may not reflect the actual power seen with the engine in the vehicle.
https://www.youtube.com/watch?v=5uVNQFkIZXc

[dirtyjim]

there have also been a few people that were splicing sb heads together.




ls head on an inline ford

[slomotion]

Just to add another thought.; when I built My 292 it wasn't for extreme performance, just a good all-round street driver. To this end I installed Langdon cast iron headers because they were durable, and fit well around the clutch linkage, but best of all they are quiet. Sometimes with the tube headers you can get a knocking sound that is not there with the cast iron.