Rod knock in '99 Cobra - replacement options?

[jmichalicek]

My poor '99 Cobra has developed some nasty sounding rod knock. I love the car and new cars are expensive, so I'm going the new motor route. I've got some questions, possibly stupid ones, since I've never done this and am not so hot with the mechanical stuff.

Will I be safe just buying a shortblock or is there risk of the heads or other parts not included with a shortblock being damaged?

What are your recommendations for replacement? The most obvious replacement seems to be an Aluminator, but that's a lot of money to end up with a basically stock motor. I've got my eye on an MMR 5.0L Stroker shortblock. Good idea? MMR seems to be kind of hit or miss as far as quality and service, but of course there's always more complaining to be found on the internet. People don't get all excited and talk about it when things went as they expected.

Can anyone in the Richmond, Va area recommend a place to do the work?

 

[Brutal Metal]

I'd rebuild your stock block, keep the Forged crank and upgrade the Pistons and rods.
If the Cylinder sleeves are nice and smooth go standard bore, if they need a little cleaning go .020 over! And the price of an Aluminator is crazy!

 

[97V8SHO]

As far as anything else being wrong with the heads...probably not, only way to tell is to pull em off and look and the cam bearings for scoring. Same for the valve guides and seals. Wouldn't hurt to add a new timing chain to the mix as well. I had my old short block lock up due to no oil (previous owner said something hit the oil pan that caused a leak) and it was replaced with a factory block and no head damage occurred (or at least as far as I know). So I'd say you're safe to bet the heads are good.

Keep your aluminum block and have it built by some one...you can buy just the rotating assembly from MMR.

OR buy a full 03-04 engine set up for 4K over in the Termi section...it says it includes wiring harness and computer and just drop that bad boy in :burnout:

 

[jmichalicek]

It certainly is tempting to save a couple grand just buying the rotating assembly. I've got a couple concerns with going that route, though.

1) Am I going to eat most of the saved money back up in labor having the rotating assembly ripped out of the block and the new stuff put in?

2) Is it going to be reliable? Both the Ford mechanic and the guy I talked to at Performance Autosport (Performance Auto Sport in Richmond, Virginia) recommended a new motor. The person at Performance Autosport said that they can rebuild it, but they've found the motors to be less reliable and usually end up with rod knock again far too soon.

 

[CanuckCobra]

I'd rebuild your stock block, keep the Forged crank and upgrade the Pistons and rods.
If the Cylinder sleeves are nice and smooth go standard bore, if they need a little cleaning go .020 over! And the price of an Aluminator is crazy!

this is what I did, just decide now if you want to stay N/A or maybe add a power adder later, so you can figure out what compression you need. I did Flat Tops and that ups CR about a point.

I dealt with John at Modular Performance and I think you'll find they have an excellent reputation.

good luck!

 

[Brutal Metal]

this is what I did, just decide now if you want to stay N/A or maybe add a power adder later, so you can figure out what compression you need. I did Flat Tops and that ups CR about a point.

I dealt with John at Modular Performance and I think you'll find they have an excellent reputation.

good luck!

+100
And NO rebuilding your stock motor isn't gonna turn it into an inferior product if you get a quality machine shop and builder to do it for you!!:rockon:
There's TONS of peeps on here who have gone that route, especially the 99-01 New Edge Guys!

 

[Brutal Metal]

It certainly is tempting to save a couple grand just buying the rotating assembly. I've got a couple concerns with going that route, though.

1) Am I going to eat most of the saved money back up in labor having the rotating assembly ripped out of the block and the new stuff put in?

2) Is it going to be reliable? Both the Ford mechanic and the guy I talked to at Performance Autosport (Performance Auto Sport in Richmond, Virginia) recommended a new motor. The person at Performance Autosport said that they can rebuild it, but they've found the motors to be less reliable and usually end up with rod knock again far too soon.

Most honest Ford Speed shops will pull the motor and tranny at one time.pop off the intake, heads, and accessories for about $300 bucks, then have the block and heads sent out to be hot tanked, valve job, various boring and honing, balance the assembly, etc.. It isn't a HUGE amount of money.
Their gonna have to pull the blown motor out anyway, why not rebuild what you already have which is a Teksid with a Stout crankshaft!:beer:

 

[jmichalicek]

What you guys are saying makes sense to me. It was my original thought, but when told not to by Performance Autosport, I decided to ditch the idea. They do that kind of work every day and I never do it. They should know better than me. They're also trying to get my money, though, so they could just be assholes.

I'm going to try to track down a few more local places to talk to. This is a decent sized city with one of the fastest drag strips on the east coast just a short drive away. There's gotta be more options.

As far as Modular Performance, is that this place these guys at Welcome to* Pro Modular Performance ?

I'm seriously considering going the 5.0L Stroker route since this is really the only time I'd ever be able to justify it, in which case I'd have to replace the crank anyway. Still, saving some money re-using the current block would be great.

 

[gmsux]

That's not the site, for whatever reason modularperformance's site has been down about a week. It does seem like there should be a great shop for you where you live. Livernois and Eagle make nice stroker kits, about $2300 for the rotating assembly. You can sell your stock forged crank if it survived too.

 

[brkntrxn]

Your timeline should be your determining factor. If you want to minimize down time, buy a complete shortblock (or longblock for that matter). If you can wait on it for just a tad longer, have your block rebuilt.

My personal vote -- build your block and reuse what you can.

 

[jmichalicek]

Your timeline should be your determining factor. If you want to minimize down time, buy a complete shortblock (or longblock for that matter). If you can wait on it for just a tad longer, have your block rebuilt.

My personal vote -- build your block and reuse what you can.

Yeah, I've got a second car I can drive, so time is no worry, within reason. It's all about getting the most reliable solution at the best cost. I don't want to pay more than I have to, but I'd rather pay $1000 more and get another 10 years of basically trouble free driving out of it instead of 2 because I went cheap.

I did track down another place to talk to. They're closed today, of course, so I'll give them a call tomorrow. It's starting to sound like the first guy I talked to was either a liar or didn't know what he was talking about, so hopefully these guys can come through for me. I haven't seen any local guys pop in here yet, but I'm sure there are some on this board, so if anyone is familiar with Paradise Road Speed and Custom, please chime in with your thoughts.

 

[brkntrxn]

If you are willing to come 4.5 hours, I can highly recommend Boosted Performance in Mooresville, NC. Donnie and Wayne built my current engine and I have nothing but love for it.

-Kevin

 

[jmichalicek]

That's tempting if I can't find a place here I'm comfortable with. I wouldn't want to drive it that far and I bet that's one hell of a towing fee to get the car hauled down there, so I'm definitely going to look local first.

I'm going to give Performance Autosport another call tomorrow along with that Paradise Road place. I've talked to some friends locally who have heard nothing but good about them, so I'll give them another try now that I've had a few days to clear my head and figure things out.

 

[cobraracer46]

2) Is it going to be reliable?
Both the Ford mechanic and the guy I talked to at Performance Autosport Performance Auto Sport in Richmond, Virginia[/url]) recommended a new motor.
The person at Performance Autosport said that they can rebuild it, but they've found the motors to be less reliable and usually end up with rod knock again far too soon.

It is easier for a shop to drop in a new replacement motor than to overhaul the original engine, plus a shop will make more money on a new motor VS servicing a rebuild so that is why the Ford mechanic and Performance are recommending a new motor.

With that said, provided that you can find a good machine shop along with a qualified engine builder and use premum parts during the rebuild, the talk about a rebuilt engine being less reliable than a new long block is a bunch of bull. If it were me,I would rebuild the original motor with some nice connecting rods and pistons. For reliability, I would not go with a stroker set up.

 

[omj]

Holy shit. Racer just made a 100% spot on post. I'm totally in agreement with him too. I need to look outside and make sure world is still here.

 

[jmichalicek]

It is easier for a shop to drop in a new replacement motor than to overhaul the original engine, plus a shop will make more money on a new motor VS servicing a rebuild so that is why the Ford mechanic and Performance are recommending a new motor.

And that's exactly what worries me about Performance Autosport. That's the sort of behavior I expect out of dealership service, but from a proper engine builder, I'd like a place that's going to do what's best for me in hopes of me coming back if/when I have car issues in the future rather than trying to take me for all I've got right now.

With that said, provided that you can find a good machine shop along with a qualified engine builder and use premum parts during the rebuild, the talk about a rebuilt engine being less reliable than a new long block is a bunch of bull. If it were me,I would rebuild the original motor with some nice connecting rods and pistons. For reliability, I would not go with a stroker set up.

Does going the stroker route really hurt reliability that much? 281ci -> 302ci seems fairly tame compared to what the 302 and 351 guys do, but then it's a very different engine. I'm also looking at kits that are good for 800-900 or more rwhp to go in a car that's not likely to ever break 400 rwhp and gets driven 30-40 miles 2-3 days/week (although that could change if my work situation changes). I'm not questioning you, just trying to get as much info as possible. This is the sort of thing I've always wanted to do, but could never justify the cost, and probably won't be able to again so I want to make sure I'm not missing out on a good opportunity to do something cool here.

 

[wma8706]

Holy shit. Racer just made a 100% spot on post. I'm totally in agreement with him too. I need to look outside and make sure world is still here.

:lol::lol::lol::lol:

 

[Brutal Metal]

It is easier for a shop to drop in a new replacement motor than to overhaul the original engine, plus a shop will make more money on a new motor VS servicing a rebuild so that is why the Ford mechanic and Performance are recommending a new motor.

With that said, provided that you can find a good machine shop along with a qualified engine builder and use premum parts during the rebuild, the talk about a rebuilt engine being less reliable than a new long block is a bunch of bull. If it were me,I would rebuild the original motor with some nice connecting rods and pistons. For reliability, I would not go with a stroker set up.

COOL I'm in total agreement too!! Words of Wisdom, YUP!!

 

[99slowbra]

Been there done that. Rebuilt that sucker with forged internals and bore it out ONLY if cylinder walls are scored, which mine were!

 

[jmichalicek]

With a stroker, does the extra piston travel cause that much extra wear or is the risk in something else with how it's done?

Is just bumping the compression up to the 11:1 range without stroking it going to be a safer plan? This is a motor that will never see a blower, turbo, or nitrous.