intake/exhaust manifold

Howdy all:
Ok finished my build a year or so ago, frame up, has 6000mi in everything new. Had to take the exhaust and intake manifold off today due to a cracked header. (headmans) thinking of taking all the fancy crap off and going back to stock. It is a 74 with the 258. Has clifford manifold with weber 2barrel and a clifford valve cover......Valve cover leaks like a Texas wildcat with dysentery. the weber sucks fuel like a new Orleans prostitute. and well you know the story on the dam headers.
Your thought????

 

When you get a chance tell us what you really think about your motor combination............(LOL)
You haven't mentioned what is inside the motor? Horsepower does cost money...........If the aftermarket Items are of no value in how you drive your truck then by all means take them off.............perhaps a stock motorcraft Carb would better suit your fuel needs and the headers sometimes can over scavenge a motor but they normally do help the torque side of the motor..............tell us more about your combination?

 

x2. A weber carb has about the best fuel metering you are gonna find in a non-feedback carb, unless it is grossly mistuned or the wrong size for the motor.

 

Engine is a stock 258 nothing special. I use the jeep for hunting,light wheelin and driving around town. I have another 74 that is all stock. I don't seem to notice much power difference between them. Pardon my rant but I guess my question is, do the headers and fancy aluminum manifolds really add all that much to the performance and is it typical that these headers crap out with only 6k on them.
Thx
Dave

 

Go stock...It's nice!

 

:iagree: the performance gains from the manifold and header will be less on a stock engine

 

Which Weber is it, the 32/36 DGEV or the 38DGES? The progressive 32/36 should give mileage about the same as the original carburetor, as long as you keep your foot out of it. Lots of people report very good results from this carburetor, especially when replacing the original 2V BBD.

Sorry if this rubs salt into the wound, but I would predict that adding the Clifford 2V manifold would provide zero gain over the Jeep aluminum factory 2V intake used with the 2V BBD carburetor. Especially on an engine that still uses the factory cam.

Now, I'm not a fan of headers for daily drivers, especially for Jeeps. They are hot, leaky, noisy, fragile and expensive - more suited to race cars operating on asphalt. Back at the Jeep dealership, they raced V6 Jeepsters, and those engines had iron manifolds. Bumps And Jolts, Anyone? Headers break. But they do provide a boost in HP over iron manifolds. The amount of boost depends on the iron manifold it replaces. The 258 iron manifolds, before 1981, are quite restrictive, so headers should make a noticeable difference.

Regarding the valve cover, I'm sorry to hear that. The original steel valve covers leak, IMO without exception. You can reduce the leakage with proper preparation of the valve cover and proper installation of the gasket. Your (cast aluminum?) Clifford valve cover should not leak any more than the factory cover, as long as it is not defective. I would check the fit and flatness of the gasket surface, and it there's a problem, ask Clifford to make it right. If they have no better product, get a refund or sell it. You can make the factory steel cover work pretty well, with some preparation and proper installation technique.

Regarding your complaint about no noticeable change in performance, a bigger carburetor and header should provide some gain, if they are installed and tuned properly. If you are judging based on seat-of-the-pants feeling, your expectations are likely influencing your judgement. Too bad you didn't record strip times or such before your modifications. At least then you'd have some objective way to compare before and after.

The old school approach to horsepower was the 4 Cs - Cam, Carburetion, Compression, Cubic Inches. Both the changes you made change only one of the Cs - carburetion, aka induction. Other changes, like a hotter cam or boosting the compression would likely have noticible effect in combination with your induction changes.

If you are unhappy with the highway performance of the 258, it's probably cheaper to swap in a 4.0L than to try and hop up the 258. The 4.0L is a more free-revving engine than the 258, and you'll notice significantly more highway power, even though the displacment is smaller by about 16 ci.

 

Thanks guys for the input. This is all great information. Tim I will try and find out which weber it is.
Is there any way to open up the stock exhaust manifold by be burring or die grinding that would be beneficial prior to putting it back on. What about the ERG valve can that be blanked. I can't see that it is better to cool or retard combustion. I think dred is right. Stock is good and simple. I have three more 74 rebuilds planned before I kick the bucket and simple sounds better.
thx
dave

 

You can port match an iron manifold if you want to. The iron manifold from 1981 or later is much smoother than the earlier rectangular iron manifolds. So that's an option. The later manifold won't work with the earlier iron intake, but it may work with your Clifford manifold.

The EGR's purpose is to allow a leaner mixture without raising combustion chamber temperatures. The exhaust gas dilutes the air-fuel mixture with low-oxygen gas (exhaust), lowering the combustion chamber temperature. The lean burn keeps HC emissions down, and the low temperature burn prevents the formation of NOx emissions.

But all this is pointless and counter-productive if you are running a replacement carburetor that has not been jetted lean to make the same mixture as the original carburetor.

 

Howdy all:
Tim thx for the information. I have decided to put this thing back to stock or as near there as practical. save for maybe a carb if there is something out there better than the stock set up. The carb I have on the clifford manifold is a 38dgasm-11g. The old exhaust and intake manifolds are cast iron and had a separation plate between them. I do not think this was correct as it appears the design needs exhaust gas to flow around an exchanger plate in the intake manifold to preheat the air/fuel mixture. What say you on this point? I do not know if there was issues with this because my other 74 does not seem to move very much when manually turning the counter weight at the end of the deflector shaft. It feels like it hits a plate in there as well (don't know). As for the EGR do I not want a hotter burn for more complete combustion? should I blank this off or keep it in the system. and how do I know if it has the california pintal in it or other, (which pintal is best)
THX
Dave

 

Do you have any emissions testing where you are?

I had to get mine tested and it passed with the NOS original Carter carb. The EGR helps to eliminated pinging when these are tuned for lean burn emissions.
Mine pings sometimes when its disconnected.

 

The heat riser built into the early manifolds should have a flap that directs the exhaust against the intake when the engine is cold. IME these don't work very well, and tend to leak.

The separation plate is not right - possibly some modification.

The flap on your other '74 should move freely.

If you are not going to use the factory carburetor, there is no need to go back to the factory iron manifolds. Instead, I suggest the aluminum intake and iron exhaust from a 1981 or newer 258. This is a 2V intake, and your Weber will bolt to it. The aluminum intake uses both cooling water and an electric element to heat the manifold - no more exhaust gas heat riser.

I feel your choices are either the stock Carter 1V carb, or the Weber 2V, or a Motorcraft 2V, or fuel injection. I have a Motorcraft 2V on my truck with manifolds from a 1985 CJ, and it runs great. However, it sits a lot, and the bowl dries out very fast. I usually have to prime the carb with gasoline to start it. If you want to go Motorcraft, this guy http://www.ebay.com/itm/NEW-MotorCr...pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr has a great reputation for selling complete kits.

If you really want to keep the old iron 1V manifolds, IMO your best choices are the factory Carter 1V, or the progressive 32/36DGEV Weber carburetor. The Weber would need an adapter, and I don't think there's any real advantage to the Weber on the iron manifold over the Carter 1V - other than you can buy a new one.

Regarding manifolds, I would suggest that you fix what you've got. Did you do these mods, or did you buy the Jeep with the mods in place? IMO the Jeep aluminum 2V manifold will work as well as the Clifford unless you are building a race engine, but you may as well keep the Clifford if you already have it. The factory aluminum manifold does have the provision for heating with the cooling water, and the electric cold-start heater, but these are more about emissions and cold-start drivability than anything.

Take your headers to your local custom muffler shop and ask them to weld it up. See if they have any advice about adding some extra reinforcements for use on a Jeep, so they won't crack so easily. Unless you bought these new, they could have had a hard and/or long life, and headers are not great for longevity or durability. Or get an iron manifold from a 1981-on 258 and use that.

Regarding the Weber, this is your carb - http://www.redlineweber.com/html/Tech/38_dgas_tunning.htm - This is a synchronous performance carburetor, and you may want to replace it with the 32/36DGES carb since it's more targeted at economical operation. No personal experience with these, but there's a lot of discussion on the 'net about the 38DGAS - a little research is likely in order.

For economy, drivability, performance and reliability, no carburetor beats fuel injection. Lots of ways to do this with junkyard setups, or a kit. But it's either expensive or requires a lot of research and scrounging. The throttle body fuel injection from a 4.3L Chevy V6 will bolt on with an adapter, and run with no changes... though you'd need to tune it to be optimal.

 

Thanks for the suggestions Tim..
Welding the headers is not a problem.. I can do that in my shop. I did some investigation into the carb. It turns out the distributor and rep for Weber is 3 miles from my house. I talked for a while with a fella named Bud there and he is adamant that the 38DGASM is the best carb for this application with the headers and manifold. He said that the combination will provide more low end power and better fuel economy. When I questioned him about the 32/36. He said that that was a replacement for the carters and performed much better than the carters but not as well as the 38. He said that they have been having problems with the new fuel blends here in California so they have a calibration kit to properly calibrate and adjust the carb. I picked one up while I was there. Properly calibrated he said this card will not exhibit any bad symptoms. OH ya he said the bowl level should be 17mm. I will give this 38 another go and weld up the headers and put back the clifford manifold... I think I will put the stock valve cover back on though. Any suggestions on the best gasket to use???? also the headers have two pipes come off the center cylinders yet one large hole for the two in the head. What is the point in the separated gasket and header there ?? seems I could weld the pipes together there on the header... same result. I will get some pics on this
THX
Dave