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View Full Version : need to rebuild 98 dohc Looking to upgrade too


Paradisd
04-10-2005, 07:14 PM
I need to rebuild the motor in my 98 Cobra. It's a long story how it came about, but regardless it has to be done. I also have the opportunity to acquire a blower assembly off a 03 cobra that was removed to install a whipple unit. What mods would be necessary to install this blower or is it even feasible? This is my first modular engine and I unfourtionately don't know all too much about them. I'm very quickly missing my simple pushrod motors. This is a stupid question, but aside of the tool to hold the cams in place when removing and installing the timing chains, are really necessary to buy? I've never purchased special brackets to pull a motor before. But then again, I've always had cast motors. I've rebuilt many pushrod motors, but this is going to be my first modular. I must admit, it's a little intimidating. Although, not as intimidating as the prices I've been given to have the rebuild done for me. Any help for a modular newbie here will be greatly appreciated. I realize I put up a lot of questions at once.

NO 5 OH
04-11-2005, 01:08 AM
It can be very intimidating that's for sure. I've never rebuilt a modular motor yet, but I will share with you what I do know (and you might find that somewhat limited).

If you rebuild the ENITRE motor yourself, then you'll know some of what you'd need from previous experience. You'd need the tool to install the pistons, a ring filer and gapper... so on and so forth. For the modular motor you need the tool to hold the cams in position, and you also need one for the chain tensioners I'm thinking, I'm not absolutely sure on that one. You basically take the spark plugs out when the motor is out of the car, and bring number 1 piston up on TDC. This will line up all the timing marks, etc. on the sprockets and chains. Then I'd say you would place the tools for the cams and chain tensioners in place, then take the tension off the chains... disassemble the motor. Do not place the heads on open valves... basically try laying the heads down on the head surface all together.

To swap everything over to an 03 setup would require a good list of parts... it's not cheap either. I'll give you most of what I believe you'll need but this isn't a full list. You'll need for the swap:

Eaton supercharger
Garrett A/W intercooler (sits below blower)
03 Cobra lower intake
42 lb injectors (39 psi Delta)
03 Cobra TB and plenum (or Accufab TB/Plenum)
03 Cobra inlet tube
03 Cobra idler bracket assembly (for supercharger drive)
03 Cobra front cover
03 Cobra "dummy" idler (sits in place of alternator on pre-03 cars)
03 Cobra alternator
03 Cobra lower "caged" crank pulley (or Metco lower/idler bracket)
Intercooler pump
Intercooler resevoir
All 03 Cobra intercooler hard lines, etc. for heat exchanger
03 Cobra heat exchanger (or aftermarket equivalent)
EGR tube/valve
Associated connectors/vaccum hoses for EGR functions (if you keep it)

I think that's most of the "major hard parts" you'd need... but not everything. As you can see it's a lot of parts and takes a good deal of work to complete the 03 set-up. It would probably be cheaper in the long run to just forge the bottom end of your motor and add a centrifical blower. Kenne Bell also makes a twin screw for the 96-98 cars if that interests you as well.

HTH,



Shannon

Big Daddy
04-11-2005, 10:23 AM
There are two more major parts you will need. A new wiring harness and a new gage cluster. I've seen this done to another '98 and it is a real PROJECT! :D ;)

smashedheadcat
04-11-2005, 10:45 AM
Also, you won't get very far with "B" heads with the 03 cobra lower intake either. You'll either have to get pretty agressive port matching the heads to the '03 cobra lower intake, or you'll need a set of 99-01 cobra heads, '03 cobra heads, navigator heads. Some light port matching may need to be done to the heads other than the '03s. For the money to do this swap, it is definately not cost efficient.

As for the rebuild, you'll need to find a better than average machine shop. Some of the tolerances of these engines need to be dead on accurate. Line boring/honing also needs to be done. As far as cam chain tensioners, you can compress them and it has a little hole that you can put a paper clip in to hold them compressed. Then, just bolt them on. There is a tool that holds the cams in position. I really don't know if there are any other required tools that you are going to need to do this rebuild other than things you probably already have from building pushrod motors. Also, replace the oil cooler when you rebuild. These things hold all kinds of junk in them and its dang near impossible to get out. Randy Haywood showed me all the crap that came out of mine (he cut it apart). I recommend a centrifical supercharger as it will cost less, and will make plenty of power. Head units are easily upgraded if you want to start small and grow. Also, a big supercharger with low boost is easy to do as well. With the stock 9.85 compression, low rpm power isn't too bad with a set of 4.10 gears. I would recommend just buying a shortblock from VTengines and assemble it the rest of the way. It's really a pretty good deal as most companies will stand behind their shortblocks in the event of failure. Plus, by the time you pay to have all the machine work done, buy a whole pison/rod kit, plus bearings, oil pump, billet oil gears (Get these, i learned the hard way), arp main and head studs, you're not saving much money.

Josh

smashedheadcat
04-11-2005, 10:47 AM
This book may be helpful. Book (http://www.seanhylandmotorsport.com/online/product_info.php?cPath=57&products_id=952&osCsid=4e84663e02c1af583159d0b63d41baf3)

This lists all the part numbers you'll need, plus gives tips on timing cams, the tools you need to install them etc.

Paradisd
04-12-2005, 06:12 AM
Thanks to everyone that replied. I do appreciate the help. I was sure there were lots of little things that I may over look with this motor. :thumbsup:

As far as the 03 blower goes, it was wishful thinking. Again, thanks for talking me out of it. Much easier and more efficient to just buy a vortech. I'm sure I will be looking to you guys again for more guidance as soon as I get the time to extricate this motor that seems to be shoehorned into this car.