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ClintonH
Dodge Dakota
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3/02/2003
13:36:39
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 Subject: 88 3.9 V6 Head modifications
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I just picked up a pair of spare heads for my 3.9 (premagnum), I was planning on overhauling the engine within the next few months but now that I have some spares to play with I was thinking about trying something a little more drastic.
The biggest problem I've been having is lack of detailed info (it's probably out there but I haven't been able to find it) about this engine. Is it worth my time to port and polish these heads. I have access to the tools and equipment but I'll have to do most of the work myself. I really hate the intake manifold on this engine. Does anyone make a better one?
Everything behind the exhaust manifolds has been completely reworked (all the emissions gone, it was so old none of it was working anyways). And I have a drop-in K&N air filter in a modified air cleaner assembly (bigger smoother intake pipe). So the engine has plenty of air to breath and no problem exhaling.
The main objective of this is to get back compression (the engine has 190k miles) while building extra power on top without putting a large hole in my wallet. If I wanted to spend a lot of money I'd get a truck with a better engine and work from there.
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steve
Dodge Dakota
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3/02/2003
14:42:42
| RE: 88 3.9 V6 Head modifications
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Message:
put 1.88 in,1.60 ex,valve[340-360]manley makes a swirl design valve.open up the ports[be careful here not to over do it,mp makes cams for this motor]bottom end may loss TQ put mid and top should gain 25-50hp+.milling the heads will up your comp.[4.8 thous=1cc on the combustion chamber-don,t take over 60 thousands off heads]good luck.
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ClintonH
Dodge Dakota
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3/03/2003
10:02:50
| RE: 88 3.9 V6 Head modifications
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Wouldn't mind losing a little TQ off the bottom. That engine pulls like crazy down low but falls flat on it's face once you get up into mid-rpm.
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88 SC DAK
Dodge Dakota
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3/04/2003
19:49:21
| RE: 88 3.9 V6 Head modifications
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Have you taken a leak down test to check the rings? The best port and polish job in the world won't help if the rings are shot. With 190K I'd think seriously about doing a whole motor or saving the money and buying something better or maybe doing the V8 route.
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ClintonH
Dodge Dakota
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3/05/2003
22:52:46
| RE: 88 3.9 V6 Head modifications
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When I tear it apart I'm re-ringing it and changing all the bearings so that's not going to be an issue.
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ClintonH
Dodge Dakota
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3/06/2003
09:26:11
| RE: 88 3.9 V6 Head modifications
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I was thinking of putting Crane Cams ductile iron 1.6 ratio shaft mount rocker arms and pushrods in as well.
Would it be possible to use the hydraulic roller lifters? Would I need a special cam?
I'm not having luck finding those valves. Can someone double-check those specs. The 1.60 exhaust valve is fine but I haven't found any listings for a 1.88 intake.
Is the intake valve specific to the 3.9? Any ideas why they wouldn't use the bigger ones that they use the same valves as the 5.2. Nearly everything seems to swap.
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90daknthe12s
Dodge Dakota
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3/06/2003
19:06:27
| RE: 88 3.9 V6 Head modifications
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Message:
it all seams to swap beacause the 3.9 is a 5.2 just missing 2 cylinders
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