I'm seriously looking at buying the intake manifold, dual outlet headers and cam kit from Clifford Performance. Just as soon as as the block gets to the machine shop this week and checked out, I'm going to order from Clifford. Has anyone used any of this stuff? They claim with the 264 cam, Holley 390 4-barrell on their intake manifold, headers and .060 milled from the head, you'll get 240 horse and 360 ft pds of torque. I'm thinking that'd be pretty wicked out of that six.
I'm just curious if anyone has used this setup, or recommends any other enhancements. And no, I'm not gonna run a stroker. I'm sick of hearing about stroker this and stroker that.
Glad to hear the intake is a good one. I was stink-eyeing the Offy intake, but think I'll go with Clifford and keep everything a match. Thier headers matching up to their intake makes more sense to me that "hoping" the Heddman Hedders match up to the Offy intake. Could be just my simple way of thinking, I dunno.
Thanks for the imput.
My spare motor is 0.030 over with the 4.0 head, Crane torquer cam, with the Clifford intake for the 4.0 head. The exhaust is the somewhat stock 4.0 exhaust.
I ran their 4.0 head, intake and dual outlet header with the 264 cam. Its ran pretty good but the carb i had on it was too big. I had a 525 CFM and never got it tuned right. I have since switched to a 4.0 intake with fuel injection and EDIS spark controlled by megasquirt. I havent had it out to get it tuned quite right yet but it runs way better than it ever has. Im sure you could get it running pretty good with the carb too but mine just runs so much smoother with the fuel injection. I still have the 4.0 head, dual outlet header and 264 cam in it.
I dont know about HP numbers but id say its got to be close to that. It definately feels alot more powerful than any stock 4.0 so i would think it would at least be up over 210 HP or so.
Yeah, I think I'm going to stick with the Holley 390 cfm carb at the moment. I would've thought that anything over 450 cfm would be overkill.
I've had so many people tell me that I should inject the thing and be done with it. I've heard it's a pretty sweet deal, but I'm just not sure yet about doing that this time around. Hot rodding is all about playing around with combintations and experimenting.
Thank you so much for your input. Sounds like you've got a sweet setup.
I like the Clifford stuff, but I think they are misleading you at 360 lbs of torque. You have to remember the stock 258 was rated for something like 180 hp and at say 4500 max RPM, that would only get you 210 lbs of torque. I think you will probably end up closer to 220 HP and 260 lbs torque with the items you listed. The 258 head is the biggest obstacle to producing good power and it looks like you are leaving it on. I have the 264 cam, the Holley 390, the Clifford manifold and while it runs pretty good, it's not over 300# of torque. Also read up on exhaust and headers. The dual outlet headers can hurt your low end performance due to lack of scavenging and the 258 is a great low end motor. Clifford makes some good stuff and the people that work there are proud of their products, but I think they over sell the end result. The biggest improvement you can make is a 4.0 head. If you want to ad FI, great, more power, more economy, etc. Like carbs? Fine. Not as good as FI but way better than the 258 head. Either way, you miles ahead.
I like the Clifford stuff, but I think they are misleading you at 360 lbs of torque. You have to remember the stock 258 was rated for something like 180 hp and at say 4500 max RPM, that would only get you 210 lbs of torque. I think you will probably end up closer to 220 HP and 260 lbs torque with the items you listed. The 258 head is the biggest obstacle to producing good power and it looks like you are leaving it on. I have the 264 cam, the Holley 390, the Clifford manifold and while it runs pretty good, it's not over 300# of torque. Also read up on exhaust and headers. The dual outlet headers can hurt your low end performance due to lack of scavenging and the 258 is a great low end motor. Clifford makes some good stuff and the people that work there are proud of their products, but I think they over sell the end result. The biggest improvement you can make is a 4.0 head. If you want to ad FI, great, more power, more economy, etc. Like carbs? Fine. Not as good as FI but way better than the 258 head. Either way, you miles ahead.
Yeah, I was thinking that 360 ft pds sounded like quite a lot compared to the horsepower. I'm thinking that anything over the stock 115 horse is better than what I started with.
I've heard so much about the 4.0 head being better than the stock 258 head. When I bought the Jeep, I had larger valves installed and a little millwork. I think at this time, I'll keep the stock head and mess around with it a bit more before giving in to the 4.0 head. Just a little hot rodding in progress, and it's only money, right?
I've not heard anything about the dual outlet headers, so I'm a bit concerned that you say it can take away from the low end torque. I was planning to run a H-pipe just south of the headers. I'll need to do more research on my header choice now.
Thank you very much for the information.
My Jeep came with the Clifford stuff on it. Don't know about the cam but I have the header, intake and valve cover. I took off as soon as I got it.
Intake is single plane meant for high speeds, I use my jeep for off-roading, not road racing so I considered it useless for me, although I do plan on re-using the header is possible with my 80's style aluminum intake if it will fit right.
The intake is doing a great job collecting dust. I would think about selling it, but I think shipping would be high, its kinda heavy, but if you want it PM me a fair offer, and I will find out how much the shipping would be
Good point. Yeah the Clifford is a single plane, the Offy is the dual plane. As long as you keep the carb size reasonable and run a low RPM cam, the single plane manifold isn't as bad as you would think. I have never had the experience of driving a 258 motor with the Clifford setup, but the Clifford manifold on the 4.0 head is a pretty good combo.
I had this setup, but I wound up taking the holley 390 off and putting a motorcraft 2150 on it and the low end was ten times better and climbing on inclines were were nicer. it didnt sputter like the holley.
I've never had a problem on inclines with my 390, and it doesn't sputter. I'll put that carb up against anything else. As far as the street goes, if you gas it and open up the secondaries it accelerates like a V-8.
I bought jeep with the Clifford and 40 (1980). How did you get the right Motorcraft carb. Our junk yards have dumped those so are hard to find unless thru parts place and not sure what vehicle to order against?
Thanks in advance for the info:
I run the intake and 6>1 header with a webber carb and Jacobs electronics. No engine work at all has been done over stock. The gain in low end grunt was amazing, as well, it starts instantly, runs like a watch, and the fuel mileage took a huge jump. I'm a big fan.
Just rebuilding my 258. Using a Clifford cam 264, intake and header. I took the head in to be redecked and while it was there had it ported for $200. I thought that the porting way to go was easier with almost the same results. I have a hei distributor and centech wiring so when the arp head bolts get here in the mail, I'll be anxious to fire it up.
the header and the intake both had to get grinded to fit up but i was just trying to get the jeep running no max power so a 3-5 hundy $ range header wasn't what i was looking for.
i spoke with someone at clifford recently about their 4.2 kit and he didn't say anything about race gas and he knew i intended on running 93oct, then again i don't know the final compression #'s
there stuff is good but pricy
i had to go with the $30 ebay aluminum vlv cover as well - at a tenth of the price its a no brainer over thiers and still beter then stock.
my brother is pushing the 4.ol head on me cause i have a few and the manifold fits up port wise but if i did it i may by the propper high port from them.
I have the Clifford cam, headers, intake and this afternoon I will fire up the Weber Redline FI kit i just finished the install last night. Their stuff is top shelf and I think to much is made of the single/dual plane intake debate at low RPMs you just are not moving that much air. The same can be said of the exhaust manifold scavenging while technically correct in reality its a inline 6 cylinder and you will have limitations on configuration. and there is alot more to the scavenging debate than just the headers. There is intake and exhuast valve sizing, valve overlap, duration condition of the current exhuast and on and on.
In reality they work better than the stock stuff. Now will you see their numbers? If everything else is perfect timing, fuel with all the other stuff and you are running a 72 degree day with low humidity on a dyno you will. But perfect conditions are hard to come by.
Personally the quality is some of the best i have seen and it will make a nice improvement.
I just installed the Clifford on my 258, it runs great, the weak link is the gasket they give you, I have blown-out two in 700 miles. now I'm in the process of making my own. I found one site that would make the gasket out of 1/8" graphite composite, but the cost is $200.00 for 4 gaskets, that was mainly for the set-up charge. Any ideas out there
I just installed the Clifford on my 258, it runs great, the weak link is the gasket they give you, I have blown-out two in 700 miles. now I'm in the process of making my own. I found one site that would make the gasket out of 1/8" graphite composite, but the cost is $200.00 for 4 gaskets, that was mainly for the set-up charge. Any ideas out there
I blew out my Clifford gasket at 2,000 miles. I replaced it with a Hedman header gasket and it has held up longer than the Clifford and still going strong, plus you get two gaskets when you buy from Hedman. I think the Clifford was just too thick of a gasket to be long-term effective.
If it were me, I'd stay clear of the dual-outlet header. If you merge the two into one, similar to the Doug Thorley Tri-Y headers, then it would probably function pretty well but as a true, dual exhaust I'd be pretty hesitant. Scavenging is important for torque at any rpm and can be optimized with any camshaft/head/intake/underwear color and birthday combo.
Don't buy into the "you need backpressure to build torque" stuff. I just did a Hedman header 6 to 1, 20 inch long 2.5 in collector into 3 in system and it makes way more torque than stock and pulls nicely from 800 rpm in third gear with 34 inch swampers and stock gearing.
Next up for me is recurving the dizzy, Cliffy intake and most likely a Street Demon 2 barrel.
Lawless,
Just curious at why you didn't go with larger Chevy valves like what's listed on Clifford's site - 1.94" intake, 1.50" exhaust?
With the cam size do you still get alot of off idle torque for offroading?
I'm still in the information download on which avenue to venture down, the 4.0L head swap, or play with the stock head. I have a great local machine shop, so I'm undecided.
Later, T.J.
Oddly enough, that's one thing I didn't double check with the machinist when he was working the head. He just said that it already had larger valves in it, and I didn't ask about the size until it was all done. In hindsight, I'd put the Clifford recommended valves in.
The cam is still very responsive and has a lot of torque off idle. If I was just offroading in my Jeep, I'd most adsureadly go with a cam more in a lower rpm range though. Gas mileage isn't that great in the lower ranges of the cam. Since my Jeep is a daily driver, and I wanted it to move down the highway and interstate, I went with a higher rpm cam.
Being a bit old fashioned, I really wanted to make the 258 head work instead of opting for the 4.0 head.
It will be interesting to hear opinions on this. Though I never considered the Howell injection system, I was stink-eyeing the Clifford Weber side draft setup.
I did run that combination and it worked well enough. There are some limitations to the Howell TBI kit mostly it has to do with the fuel pressure at 12 PSI it dosent atomize like the higher pressure systems. And cold mornings the fuel will puddle in the manifold till it warms up. So when its cold it stumbles a bit but after that its ok.
If you can run the Weber Redline look into that it blows the doors off the Howell TBI Big Time.
I have a 250 in a 1963 chevy 2 with the clifford intake 390cfm holley dual exhaust and also one of their cams. I don't remember what the lift and duration is on it but all I know is that before I put my posi in it and 4:11 gears I was beaten in the 1/4 mile by a 5.9L dodge dakota by only 1 car length. Don't think that is bad for a little inline 6. The car has been on the road for 14 years and I have had no problems so far. Clifford makes a good product and I am looking into rebuilding my 258 with their parts this time too. Just remember to put the dual valve springs or they will break over time. I broke 2 over the years until I put the better springs in it.
I'm in the process of installing a Clifford header and intake on my 258 right now actually, can't wait to fire it back up.
After removing the stock exhaust and intake, I installed the new dual outlet header with no problem. It's the intake that I'm having trouble figuring out. Clifford told me to remove my centering pins and replace with 3/8 bolts or I will have a vacuum leak? When I tried to remove the pins with a vice grip, it seemed I would score the metal before turning the threads on the pins (I assume they are threaded)? This Jasper block has under 2k on it, so the pins shouldn't be seized.
Also, the header flange is much thinner than the intake flange. I had considered either building up washers, or welding steel stock onto the header flange. The guys Larry at Clifford advised against this. He told me to slide the 1/2" washer over to cover the header flange, and then put a 3/8" washer over the intake flange, and torque the header bolt, which I don't understand. I think my 3/8" washer has too large of an outside diameter to do this and I might need new hardware. Any others had this problem with the flanges?
I'm in the process of installing a Clifford header and intake on my 258 right now actually, can't wait to fire it back up.
After removing the stock exhaust and intake, I installed the new dual outlet header with no problem. It's the intake that I'm having trouble figuring out. Clifford told me to remove my centering pins and replace with 3/8 bolts or I will have a vacuum leak? When I tried to remove the pins with a vice grip, it seemed I would score the metal before turning the threads on the pins (I assume they are threaded)? This Jasper block has under 2k on it, so the pins shouldn't be seized.
Also, the header flange is much thinner than the intake flange. I had considered either building up washers, or welding steel stock onto the header flanges. The guys Larry at Clifford advised against this. He told me to slide the 1/2" washer over to cover the header flange, and then put a 3/8" washer over the intake flange, and torque the header bolt, which I don't understand. I think my 3/8" washer has too large of an outside diameter to do this and I might need new hardware. Any others had this problem with the flanges?
With some modification, both the header and intake now fit perfectly. I welded 1/4" square steel stock onto the header flanges after measuring the areas where there was a gap between header and intake flanges. Much happier with this than stacking up washers that will, of course, rattle loose.
Also had to shave the aluminum intake, just slightly, to get the header bolts in straight and have the intake fit properly. Happy with it, will post pictures soon.
All I need now is to buy some thicker washers (I'm thinking 1/2" circumference with a 3/8" internal diameter?) so that I can torque them both down properly and not leak vacuum. After that I'll fire it back up for the first time. :cheers2:
I installed only the intake and exhaust manifold and the Holley 360 that Clifford recommended. I fabbed up a exhaust pipe out of stainless, ending with a Borla muffler. Not sure of the power gains, as I have bad rings in one of my cylinders, so I'am losing a lot of power down through the sump, I will be sorting this out over the winter. It certainly was a lot easier to tune and throttle response is very good, it also sounds fantastic.
They are good products, but require a bit of jiggery to install, as the guy above found out. I used washers of various sizes, including split locking washers, to tighten everything up. It was tricky, but no vacuam or exhaust leaks.
Felpro X 2 the Clifford one that you soak in water for an hour is meant for racing and fails quickly.
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