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Jack
Dodge Dakota
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4/05/2007
19:07:32
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 Subject: Diffrence between HO Heads and non-HO
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I bought a 2000 dodge durango (96k miles), with blown head gakets. I replaced the head gaskets and also put in other heads (HO High Output).
It starts, but idles erratically (inconsistent) kinda has a little vibration. It also backfires sometimes. Also when you press the gas pedal, it does not give enough gas and also gives it late. I checked all my spark plugs and coils work. I also pluged in a OBD II Tool and it said No faults detected.
The engine is a 4.7 V8. I just checked the timing and its perfect.
And when i changed my heads The other ones that i put it said HO (High Output). My originals did not say that, but are the same. I put in my original cams too (non-HO). The HO heads had a little diffrent springs, that i used and the haudraulic lifter that used too.
What is the diffrence between HO and the orignal heads? Could i use everything non-Ho, but the heads only HO, like i currently have, or would i need original heads. Could this be my problem?
Thanks
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01Motorsport
Dodge Dakota
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4/06/2007
12:45:58
| RE: Diffrence between HO Heads and non-HO
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The non-HO engine has 9.3:1 compression, the HO 9.7:1. I'm not sure if D-C achieved the HO increase via the heads or the pistons. Maybe one of the Mopar mechanics on here or the allpar site can fill us in.
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kj
Dodge Dakota
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4/06/2007
19:24:48
| RE: Diffrence between HO Heads and non-HO
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I doubt the compression would make that much difference. They probably gave it a more advanced spark and fuel supply.
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Kowalski
GenIII
4/07/2007
08:24:29
| RE: Diffrence between HO Heads and non-HO
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Definitely more spark advance with the HO. I'm not sure if the compression difference is in the heads or pistons either. I'm pretty sure there are some differences in the heads, even if you don't see them - but I think others have posted they used those heads with no problem. Definitely stronger springs. I don't think that's where you're problem is though. I'd start by checking for a vacuum leak; but I think its most likely the timing chains controling the cams may be installed a bit off. That or something got knocked loose in the valve train when the covers were put back on. You didn't stress the pins locating the cam gears during the R&R, did you ?
Lead, follow, or get out of the way
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Jack
Dodge Dakota
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4/07/2007
14:54:01
| RE: Diffrence between HO Heads and non-HO
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So these HO heads DO NOT require any other HO parts like Cam shafts?
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Jack
Dodge Dakota
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4/07/2007
14:55:30
| RE: Diffrence between HO Heads and non-HO
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Oh and what did you mean by stress the pins locating the cam gears during the R&R?
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Manny
Dodge Dakota
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4/07/2007
20:20:35
| RE: Diffrence between HO Heads and non-HO
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For 4.7L engine info, go to
http://www.wjjeeps.com/engine.htm
and
http://www.wjjeeps.com/ho_engine.htm
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Kowalski
GenIII
4/08/2007
07:50:03
| RE: Diffrence between HO Heads and non-HO
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The cams should work in either - for example, many of us have put the HO cams in our regular heads for a performance gain. If you weren't aware that you need to be careful not to stress the locating pins for the cam gears, then that is most likely your problem. Some did this by putting a wrench on the crank bolt while tightening the bolt for the gear. My plow frame prevented that, so I just held the cams steady with a big set of water pump pliers while I torqued the bolt for the gears while the timing chain wedges controled slack in the timing chain. We've heard of symptoms as you desribe from those who ignored this important step; and damaged the locting pin on the cams.
If you find that youv'e damaged that, your cams are junk. You could step up to the HO cams (or go more radical); or if you aren't ready for that, many of us still have our stock cams and might sell them for reasonably cheap if you need them. Let us know what you find. If you have to change the cams, let us know if you aren't aware of how to use some wedges to keep the chain tensioners from moving too far during the swap too.
Lead, follow, or get out of the way
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Jack
Dodge Dakota
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4/08/2007
13:03:14
| RE: Diffrence between HO Heads and non-HO
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Can you tell me wher this locating pins are located. and maybe find a pic on the web somewhere.
thanks
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Kowalski
GenIII
4/09/2007
17:24:52
| RE: Diffrence between HO Heads and non-HO
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Message:
It's at the very front of the cam, about a 1/4" pin that engages the gear that bolts to the cam.
Lead, follow, or get out of the way
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GraphiteDak
GenIII
4/10/2007
02:07:59
| RE: Diffrence between HO Heads and non-HO
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Wasn't the trigger wheel on the cam different on the HO vs. non HO from what I once read???
I know it wouldn't make any sense that DC would have made a difference there but i thought I read that.
Did you use your original trigger wheel on the cam or the one that came with the HO head/cam?
That JEEP webiste link someone posted above has good info.
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Kowalski
GenIII
4/10/2007
07:12:50
| RE: Diffrence between HO Heads and non-HO
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Message:
Isn't that a crank sensor that uses the different trigger for HO ? If it was simply a difference between HO cam or regular, those of us who've installed HO cams would have seen that problem ? After a certain year , I believe they changed the way a crank or cam signal is read by the PCM - we've seen problems from that when people have swapped the wrong year 4.7 for their truck. GD - I wonder if that is what you are thinking of ?
Jack - take your valve covers back off for a better look yet ?
Lead, follow, or get out of the way
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