Cracked Block

Well the machine shop cleaned the block and found a crack using magnaflux. Ugh!!! Well they are wondering if in the new/used block I want a roller cam instead of flat tappet? What is the answer given cost is not out of the question.

They also found a crack in one of the heads. Oh boy how I love buying used things. The boat was in my garage all the time and it doesn't get below 40 in the garage. The boat came from Phoenix but it figures the guy probably never even let the water out of the engine due to how nice it normally is down there.

At least it's winter and not the middle of the summer to figure this out. Just hope the local machine shop costs are near Jaspers $3000 price.

1999 Ski Nautique GT40

Yeah I would roller cam that in a second. If they can find you a roller block and some stock lifters there should be plenty of cam choices out there. If it were me I would be looking for a relatively low mileage roller short block out of the junkyard to slap a top end on and go skiing .

Below is what I recieved back from a PCM rep. This thing is stressing me out! The guy at the machine shop says the cam is nothing more than a lightning cam. I found another article old article where the lightning cam didn't work due to an idle problem. The guy at the machine shop is saying the rockers are a different size than the lightning and if just buying the lightning motor that wouldn't match up correctly. He says he can piece it together with a roller setup that will work. I can't remember all the details and he's still working on a parts list. In simple terms shouldn't be as simple as convert to roller with a cam that matches the specs of the cam in it. Of course I can't find the PCM cam specs anywhere. I have to rely on the machine shop and that they measured it and didn't just read the numbers on it. My fear is that it is the original lightning cam with a custom grind on it for PCM.   I can't find anyone who would be able to reprogram the ECM. I don't know the cost of a custom ECM and not a darn shop in Denver is willing to work on the GT40 motors. I don't think any of them know what EEC-IV is or how it works any better this this backyard mechanic(myself). Anyonw know a good EEC-IV tunner in Denver that would be willing to reprogram the ECM if I have issues. Would really not be good to go roller than find out it doesn't run right and have to tear the motor apart again. I'm on a budget :-(

PCM - "We only built flat tappet 5.8L Ford engines here, so it would be up to you which way you go but if replacing the base engine using all your existing parts from us you must stay with a flat tappet engine base.
If you go with a roller cam engine already set up as a completed engine package then I'm sure that would be fine too, just don’t use our ECM or fuel system on it."

The ECM can't tell whether a cam is a roller or not. It's limitation is the fact that its pre-programmed fuel tables cannot compensate for better flowing induction parts (heads/intake/cam). If you change any of those parts, you need to make sure the changes are mild enough such that the engine is not leaned out under any conditions. A wild head change or huge roller cam may be unadvisable with the stock programming, but sufficiently tame parts should be ok. I believe that is what joe is suggesting. We have seen a few successful head swaps (GT40 to GT40p) which I believe proves there's a little bit of head room in the stock tune.

Measuring the old cam should get you the info you need. I would not advise switching to 1.7 rockers if that is what the lightning used (I know the '93 gt40-headed mustang cobra did). No reason you can't reuse your old stamped 1.6's on any of the factory iron heads you're likely to consider.

Changing the tune (fuel maps) is a whole different project that could get complicated and/or expensive, so I'd be sure to know what you're getting into before venturing down that path. The PCM ECM is locked down so you can't simply "tweak" their baseline, you'd be starting from scratch. There are companies out there that sell marine efi tunes, whether they have the expertise needed to do this on a Ford may be something worth lookin into.

We are in a similar boat... Pun intended.

If you see my earlier post you will notice I considered and researched at length the swap to a roller cam with the stock ECM and couldn't find anyone that had done so. I still think it is completely possible but would come at a cost and probably involve tuning.

I ended up with a broken in/new cam and lifter set from Cam Research. Scott had a few different suggestions on cam grinds. I ended up going with essentially a stock replacement.

When I replaced my GT40 (frozen from PO) I had saw some where or was told, that PCM advised not to bore block more than 30 over(I thinK )due to computer/fuel issues.

I was sold on Michigan Motorz if I was going to order a complete long block. I went the local route as I have several friends that have used them with good results.

jhersey29 wrote: I'm wondering if I should go with a long block motor from Michigan Motorz or Jasper. The machine shop is slow trying to figure this out and I'm worried.

The machine shop is either familiar with marine engines or they aren't; not much gray area in my experience.

I emailed the seller the other day. I'm not sure I want another block that isn't rebuilt. He's swapping to an engine that supports ZO. It seems odd to me that some with a 14 year old boat with an engine that only has 500 hours would even need to upgrade to ZO. If your able to ski enough that it matters in competition I would think the motor would have more hours. Heck I put 200 hours on my boat this year. I guess the used thing scares me at the moment.

I put GT-40P heads and a slightly better cam(cam research) in my '95 and it runs pretty darn good.

I have the orignal flat tappet cam and lifters from the '95 had about 450 hrs on it, if anybody is interested.
And I have a stock roller cam and roller lifters out of a used motor I used for the block if anyone wants them.

It's the GT-40 EFI MPI in my '95. I stayed with the flat tappet in that one.
If I was to do it again I would probably go roller.

Also found the lightning cam on there it is definately not the same as the marine.

http://catalog.elginind.com/app/Engine_tech.asp?part=E%2D881%2DS&category=Camshaft

gun-driver wrote: jhersey29 wrote: I was able to get the CAM part number from PCM. The Ford P/N for the cam is F1JE-6250-BA and the pistons are F1JE-6108-AA. Also ran into this tool for some part look ups. http://catalog.elginind.com/app/Engine.asp?mfg=FORD+MARINE&model=004&cat=Camshaft Not sure those are the right specs for the stock cam. I'll check my numbers when I get home tomorrow.

Yet another mystery about this darn engine. Would be great to confirm. I can't find much else on that cam.