I was told that they planned to replace the rotors and rear bearings plus rebuild the nose drive on principle - even though the nose drive was fine, it sounded like they were replacing the front bearings and the coupler. I asked about the case since there was a lot of bore scoring. It did not seem like they wanted to replace the case. I expressed some concern and was told the blower would be bench tested before it was released as repaired ok. You can bet I'll be looking at the serial number on the case when it's returned and will pay close attention to generated intake pressure when it's installed. Maybe the rotor tip to case bore clearance isn't as critical to performance as the clearance between rotor tips and the root of the rotor. We'll see how it performs after the repair.

Frank

Frank, you would have been an excellent politician. I've noticed in your posts how careful you've been to point out how forthright Magna Charger has been in your dealings to date, highlighting their integrity, good reputation, quality product, and your expectation that they will eventually resolve this situation to their credit--"deserving of their reputation."

But as with any politician with a loyal following, I sense that there is a flip side to that generosity. Should they make a horrible blunder and fail to meet your very reasonable and modest request for reimbursement of out-of-pocket expenses to correct the damage caused by their faulty product, I'd be surprised if you weren't equally enthusiastic in presenting the alternative viewpoint--and in rallying your constituents who would share it. I hope I don't have to witness the firestorm that would result from THAT shortsightedness.

Some progress made - the blower has been rebuilt with a new rotor pack and bearings, courtesy of MagnaCharger.... the housing is original and they claim it's been bench tested, so perhaps the case bore-to-rotor tip clearance isn't as critical to performance as rotor tip-to-rotor tip clearance..... we'll see when it comes on line:


The block and crankshaft are at the machine shop for crank journal polishing and cylinder re-honing. I don't know if a re-hone will take out a couple of deep scratches I found in #1 cylinder.... or if it'll have to be re-bored to .035" over and new pistons bought. If it requires new pistons, I might be better off prepping another block - probably 6 of one, 1/2 dozen of the other. I'll know tomorrow if the re-hone will work.

Meanwhile, I've been frying my brain with some cam-think and need to call a grinder for advice on how to get the cylinder pressure up without penalizing exhaust gas evacuation.... need to figure out whether to play with the Diamante cams, reinstall the truck cams, regrind a Diamante set with a blower lobe profile and install them 7* advanced... or cringe and buy a custom grind.

Frank

Aye-yie-yi...... my head hurts........ <img src="/forums/images/graemlins/shiner.gif" alt="" />

Delta Cams tech says the truck cams would be best for building cylinder pressure - particularly with a blower, and that even if I increased cylinder pressure by advancing the Diamante cams, the extra 4* overlap would bleed off cylinder pressure at low-moderate rpms. I asked if there was a penalty on the exhaust side to using the Montero cams.... he didn't think so.... but then it took him a while to understand that his suggestion of simultaneously advancing the intake and retarding the exhaust couldn't be done on a SOHC engine - even with eccentric cam bushings.... unless he could figure out a way to twist my camshafts in several places. <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

The Dodge Racing tech cam designer at Custom Cams on Motorsports Drive in Martinsville, VA was next on my list...... he listened to my findings and concerns about intake closing point.... then proceded to take me to school. <img src="/forums/images/graemlins/wink.gif" alt="" /> Smart fella, that'un and well worth listening to. After running some numbers through his calculator brain, he asked for piston stroke, valve opening/closing points, LSA, C/L, duration, lift, lobe design, rocker ratio, etc.... and declared that the Montero cam was good on power to 6000rpms and the Diamante cam was good to 6300rpms.... but that the 115*ATDC centerline of the Diamante cams installed straight up is way too retarded give best power (Montero is 110*ATDC). He explained that while the intake closing point is important to cylinder pressure, what is most important is piston speed at the moment the valve is near maximum lift..... that's what really packs the cylinder. So, since he liked the longer duration for top end, his suggestion was to use the Diamante cams, but advance them to 110-108*ATDC, which rolls the Diamante cams forward 5-7* and coincidentally closes the intake valve exactly where the Montero cam does. <img src="/forums/images/graemlins/wink.gif" alt="" /> He also thought that rolling the Diamante cams forward would increase power from bottom-to-top AND move the torque ramp down a few hundred rpms.

So, he and I have arrived at the same conclusion for different reasons to resolve the same issue from different perspectives with the same remedy <img src="/forums/images/graemlins/scared.gif" alt="" />...... the most power from the cylinder - produced by the largest charge under the most pressure. The truth is, it's all important - the trick is to get as much of all variables resolved toward a best compromise... and to do it via guesswork.

I tell ya..... some days are better than others. In the end, you sometimes flip a coin, turn the wrench and see what happens.

Frank

Holy cow, this thread has surpassed the Turbo Bible for views- by a long shot now.. <img src="/forums/images/graemlins/zombie.gif" alt="" /> <img src="/forums/images/graemlins/patriot.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" />.

Way to keep marching on Frank.

I have faith in your project, and I believe gas prices will suddenly drop when the SC G-Raider rides again. <img src="/forums/images/graemlins/cheers.gif" alt="" />

High test seemed expensive when regular was $2/gal and the difference was ~10%. Now that regular is almost $4/gal, the difference is still $0.20, but it only represents a 5% premium...... with funny money gas prices, I don't feel so bad buying premium. <img src="/forums/images/graemlins/lol.gif" alt="" />

I just spent 1 hour getting 1 piston ALMOST clean and my hands feel like I've been soaking them in acid..... Yikes - it'll take a while to get these ready to go back in:


Frank

Frank,

Do you plan to do anything different or special to the bottom end while you have it apart? Just curious for my own notes when I do my 89 rebuild. I figure if yours can handle a blower I want to use it as a model for a Bullet proof N/A 3.0.

Justice -

Not really, the bottom ends of these engines are pretty stout and the Diamante SOHC block appears to be the best of the SOHC blocks strengthwise.

I'm waiting to hear from the machine shop on whether the bores will clean up enough to reuse the same pistons. If not, it'll probably be cheaper for me to prep another Diamante block than buy another set of $650 forged pistons.

BUT -

I'd like to find out if there's an ARP main stud that will fit the SOHC main girdle.... there's nothing listed for the engine, but perhaps I can find someone at ARP that knows more than the last ignoramus who told me they had nothing to fit the SOHC heads..... even when I gave him the size and thread pitch. Funny how it was the same size as the DOHC..... I guess nobody ever told them.

If you don't want to use (or if I can't find) main studs, you can do what I did in this engine - use the bolts from the Diamante DOHC block.... they have more bearing surface under the head than the SOHC bolts..... just make sure the girdle area where the bolts will seat isn't burred from the SOHC bolt.

When you rebuild yours, the best thing for the bottom end is to get a later DOHC crankshaft and rods so you'll have the forged (and supposedly nitrided) crankshaft. From what I've read, the rods are also stronger. I don't know if only a turbo block had those, or if all of the later DOHC engines used the better parts (I think so). I used the crankshaft and rods from a later DOHC Diamante engine and there is a definite difference in particularly the crankshaft..... it's a brighter color than the SOHC crankshaft and has a real nice long ring to it when you strike it with a hammer..... so it at least appears to be forged steel.

I'd also recommend spending ~$200 for balancing the rotating assembly. I had my crankshaft static balanced, then dynamic balanced. The rods were balanced via beam weight. Pistons were custom and no balance was needed.... you might want to check yours if you use cast pistons. The flex plate and harmonic balancer were also checked. It made quite a difference in smoothness. At idle the engine doesn't even wiggle and as it revs, there's no noticeable torquing..... and it revs quickly. There's nothing wrong with an OE oil pump, but I tried a stock Beck-Arnley from NAPA and it works fine (I need to clean it), seals were all OE from a rebuild gasket set.

I did install seal surface repair sleeves on both ends of the crankshaft - they're available from NAPA as are the (expensive) installation tools. The seal surface sleeves require extreme care when installing the seals because the extra thickness tends to cause the seal lip spring to jump out of its retainer groove, so be very careful if you use those. You can install the seals at new depths to avoid the old grooves, but I wanted to try these.... I do like them, but would be remiss if I didn't warn you about the possible consequences.

Oh, I had the machine shop install ARP rod bolts, which requires resizing the big end bore - a tricky operation for a shop that's not well-equipped. It's easy to get back rods that aren't the same length from big-to-little end. If you install those, you'll want it done by a good machine shop before you have the rods balanced.

I'm assuming you'll deck the block - so you'll want to move rods and pistons around to get the same deck clearance on all cylinders. If you want to avoid some hair pulling, I'd suggest using pistons that can be installed with full floating wrist pins so you can swap rods from side-to-side to allow for differences in crankshaft throw dimensions by using a shorter or longer rod. Ideally, you would have a perfect crankshaft and identical rods, but it ain't gonna happen without spending a lot of money, so the next best thing is to identify the differences and have the ability to adjust for fit. If you use full-floating pins, you'll have to rebush the rod small ends, so that decision also needs to be made before the rods are balanced.

I really like the ARP head studs. They completely eliminate the issues with 3.0L head bolts. You still need to clean the block threads with care, but there's no longer a depth issue. There's plenty of threaded length on the studs for worry-free installation and they'll take a lot of torque.

The FelPro pan gasket seemed to work very well - they make two styles. I used the more expensive of the two.... it has ribs that run the length of the entire pan flange. It may not be necessary, but it is probably slightly more reliable than an RTV seal if there's any flange warpage.

Some of the blocks were milled poorly around the water pump flange area. Check the water pump fit before you install anything into the block so if necessary you can improve the fit for the pump flange surface. I've seen it necessary to use a grinder to lightly knock down high spots under the pump outlet flange area on the passenger side of the block face.

Back to rods again - Last year, Eagle had some ESP "H"-beam rods for the 6G72 for a reasonable price of around $300/set - maybe they were closeout prices because they're no longer available at any price anywhere that I've looked. I thought about them then but considered them overkill for a 6000rpm engine. They might have been a bit stronger than the OE forged DOHC rods, but I figured if the late DOHC rods were the same as what's in the 3000GT TT engines, they should be plenty strong. I am looking longingly at a set of "H"-beams from 3sx, but they're real pricey for what they are and really an unnecessary expense - particularly for a N/A engine. They do eliminate the cost of conversion to floating pins, balancing and ARP rod bolts and if I had to do it all over again, I'd probably buy these:

3sx Rods

I guess that pretty much covers the bottom end. It's not a difficult engine to rebuild - just has a few quirks that are uncovered over time.

Frank

The block bores cleaned up ok with about 4 strokes of the hone - only removed .0005", so hopefully it'll be ok. The score lines still show on #1, but it should be good enough.

It looks like some of the bearing cage went down #6 and was beaten around on the piston top for a few revolutions:



The burrs are gone, but this is the best I could do with a file, sandpaper and a Scotchbrite pad:



It's not perfect, but I don't want to remove any more from the piston.... hopefully it won't cause detonation.... don't think so.

Frank