'70 Nova LSX swap LY6/TH400

[TheBandit]

Okay so here is my number crunching on some of the options. Prices vary vendor to vendor, but most of the parts I priced out through texas speed & performance.



The shortcut refresh would be cleaning the best I can and reassembling everything as is out of my garage. I have a couple gallons of "Evapo Rust" I could try out on the crank rods and block. The stuff actually works pretty well at disolving rust, but of course won't help if there's pitting and doesn't do a thing for the bearings. I could replace just the questionable bearings to make this a more desireable option. Some deal killers here would be if the rust in that one bore doesn't come off or leaves damage and if the journals don't clean up.

Next option is to replace all the bearings and rings, polish the crank, and do some machine work as well to refresh the block. To put it in perspective, I paid about $1,600 for the long block and chances are I could find another used (potentially lower mileage) shortblock for less than this, so I don't see this is a very good option.

Next option is to rebuild as above but with forged pistons and rods. Now we're getting into a more robust package, but damn that's a lot of money. I could go cheaper with Eagle rods and Mahl pistons, but haven't heard a lot of good on the Eagles the savings would only be about $100. Mahls may still be on the table to save on the pistons. This gives me a bump in compression probably worth a few hp and the peace of mind of a stout rotating assembly. But with my current cam I am probably not going to be putting out more than 500hp at the flywheel nor spinning over 6,000rpm, so I question whether or not the upgrades are worth it.

Then there's the stroker option using forged stuff. That option has it's advantages - certainly power output and a robust assembly, but at a high cost both for the engine and the potential damage that power will do to my drivetrain (not to mention the cost of shredded tires, speeding tickets, and divorce attorney fees)

These all assume I use the block I have and the heads I have. Now I need to look into the prebuilt shortblock and used shortblock options.

Pretty sure my wife is going to keep me on a shoestring budget. When I explained to hear that this would cost at least 600-700 to repair, I could see her blood boiling and she did not want to talk to me about it any more. If I suddently disappear from OFN, someone send a search party because my wife may have me buried in the backyard.

[Captainfab]

I don't know if they are available for the LS engines (I would think so), but Cloyes offers timing chains that are .005 and .010 shorter for line honed SBC's

Originally Posted by JaysinSpaceman

As for the main tunnel hone, if you are just going to ARP bolts and not swapping to main studs there really isn't a reason to hone the main tunnel. As a side note, unless a block really needs line honing the main tunnel it is the last thing you really want to do and here's why... Since they don't make main bearings with a larger OD you have to grind the main caps and then remove material from both the cap and block to make the hole round and the right size again. And in doing this you effectively move the crank up in the block, not by much but I can always tell when a block has been line honed because a brand new timing chain will go on feeling loose with slack like a used one. This will give you greater slack in the timing chain and therefore less control over cam timing.

Jaysin

[TheBandit]

Originally Posted by entropy

Somebody on another forum has not paid any attention to where the rings were clocked to going in, and where they were when they came back out. Unless the rings are pinned they will, and do, rotate around the piston at random and the top ring may be rotating the opposite direction of the second ring...

Funniest thing happened. That somebody had to pull their engine recently and sent me a PM to tell me he was mistaken - his rings had reclocked into random positions. One of the nicest and most helpful guys on the other forum I know, just happened to be wrong in this case. That's why I ask questions and try to get multiple opinions.

[TheBandit]

Originally Posted by Captainfab

I don't know if they are available for the LS engines (I would think so), but Cloyes offers timing chains that are .005 and .010 shorter for line honed SBC's

Thinking about this today since I have both VVT and a tensioner, I wonder if chain slack is as big of a concern?

[JaysinSpaceman]

If you are going to go with the Main studs it may mean you nee to line hone the block but not always. Install the studs and torque the caps in place and use a dial bore gauge to measure roundness (or out-of-round as the case may be). As long as the main bores are still round within tolerance then no main hone needed. Personally I say use ARP main bolts and don't worry about it, spend the money on forged rods and pistons.

Jaysin

[Graham08]

Originally Posted by TheBandit

If I suddently disappear from OFN, someone send a search party because my wife may have me buried in the backyard.

I don't have any wisdom to add beyond what's already been shared here, but I got a laugh out of that. Sometimes I wonder if the same fate could befall me...as I toe the line on an already over budget shop build...

[TheBandit]

Originally Posted by JaysinSpaceman

Personally I say use ARP main bolts and don't worry about it, spend the money on forged rods and pistons.

I'll have to call and ask. I haven't found ARP bolts anywhere - just studs, not that they don't exist.

Easter update:

I spent most of the weekend with family, but got a little done on Friday. At first I was going to get the engine on the hoist so I could pull the rear cover (not enough room for a wrench on my engine stand), but just prior to getting it in the air I decided I may as well do a test fit to see if my frame notches were going to work out. So in she went.







Things seem to be working out pretty well, but not perfect. One thing I noticed while under the car was that the transmission is shifted at the rear toward the driver's side by about 1.5-2 inches from the center of the crossmember. I tried lifting and shifting it back toward center, but it wont stay there - I am fighting the engine mounting to move it. I'm not sure if this is a problem with the crossmember, engine mounts or what. This is the same TH400 crossmember that I used before with the smallblock. I did verify the tranny is completely mated with the engine and nothing is interfering on the passenger side to keep it from shifting toward center. I'm not sure what's going on - any clues? It may have been this way on previous test fits - I never checked the tranny mount.

The frame notches and accessory clearance turned out pretty good. Here is the alternator. I still don't have an alternator bracket and I used my old locating spacers to make the flywheel holder, so had to employ it to get the front spacing right for this mockup. It has just the right amount of clearance radially. I could have gotten away with less clearance in the back though.







Here is the AC mounting bracket trimmed and mounted. I took a little bit off the bottom and there's about 3/8" clearance underneath.





The problem I did run into is the lower rear mounting bolt. It is in line with the lower control arm perch. In the current position, unless I cut into that perch, I can't use the lower rear mounting tab on the compressor. If I was using neutral instead of 1/2" setback adapters, this would probably clear.



So in the pictures above and below, the compressor isn't completely mounted; it's tilted nose up a bit because I haven't cut off the rear mounting tab yet.







I think the clearance to the left and rear of the compressor is perfect, but without the bottom mounting tab I could have gotten away with less notching toward the bottom and kept more material at the inside corner of my notch. Maybe if I had three or four frames and a whole bunch of time, I could get it perfect, but for a one-shot thing, I think I did okay.

Overall I am satisfied. I do wonder if I couldn't notch out the LCA perch to get enough room for that mounting tab though. I'm not sure if it's worth it to get full four point mounting of the compressor. The front two and rear upper is probably enough.

[entropy]

Originally Posted by TheBandit

Things seem to be working out pretty well, but not perfect. One thing I noticed while under the car was that the transmission is shifted at the rear toward the driver's side by about 1.5-2 inches from the center of the crossmember.

Best guess is your motor mounts are not in the correct location.
Take the bolts out of the K-member on both sides and then relocate the engine to the correct location let the mounts slide where they will. Betting that the mounts will be off.

[TheBandit]

Thanks e. I took some quick measurements from the front of the main crossmember to the engine mounts and the two sides matched. I'll try loosening the frame stands and tranny crossmember mounting bolts and see how much wiggle room there is to straighten it out. Maybe the crossmember is just shifted. I need to get the car a little higher in the air so I can take measurements - I can barely squeeze under it as it sits.

[TheBandit]

What looked like 1.5-2" to my sad eyecrometer turned out to be closer to 3/4" after I got the car into the air and measured from the frame rails. I loosened the bolts holding the engine stands to the frame and shifted the tail end of the tranny back to center by hand without a hitch. Let that be a lesson to start with everything loose - there's some wiggle room in there. I'll try to remember this three or four years from now when I actually put the engine in for good.

[TheBandit]

Work continues on the Nova. After finding satisfaction in the accessory notching and transmission positioning, I pulled the engine back out and removed the rear cover. Look at the nasties I found in the rear crossover oil galley! I think pulling this engine apart was about the best decision I've made so far.



With the engine back on the stand, I rotated it over and pulled the main caps



You can see below the second and fourth main bearings have some black discoloration on them. I think this is oxidation, though I'm not sure. All the bearings WILL be replaced.



Next out came the crankshaft itself. Only a few of the journals show a rusty streak around between where the bearings were. I think this will clean up easily with a light polish.

[TheBandit]

Next I decided to start prepping parts for getting the car back on all four eventually. I think I mentioned a long while back in this thread that I plan to use AFCO adjustable spring spacers and springs on the front of my car.



The AFCO spacers are flat ended, but both the control arm and subframe have tapered spring pockets to accept the pigtailed coil springs. To determine the taper, I took a 4-1/2" cuttoff wheel, which happens to be the same diameter as the AFCO spacers, marked it every 45 degrees, and measured the depth of the taper using some wood skewers. I found the taper to be approximately linear, going from 0 to 1/2" depth around the 360 degrees. You can see here I measured from the lower control arm; the subframe pocket appears to be the same and should be based on the symmetry of the spring.



Next I laid out a template on a piece of paper. The circumference of a 4.5" circle is about 14-1/8", so I had to tape two pieces of paper together to get enough length.



I cut my template out, wrapped it around the spacer, and marked it as shown below. If you do this be very careful to verify the taper goes in the right direction.



I decided to lay this out so that when the adjuster was mid travel, I would have a 2" lowered height, trying to replicate Hotchkiss 2" drop height coil springs. The Hotchkiss springs are the same rate (600lb/in) and have a 12.5" free length. To get this, my taper removes from 1-1/8" to 1-5/8" from the AFCO spacers. I can adjust these a full inch in either direction, which translates to about 1-3/4 inches of ride height in either direction (lower control arm ratio of 9/16). So I should theoretically have any where from 1/4" drop to 3-3/4" drop depending on where I adjust them.

Before cutting, I verified the total free length of 12.5" with the adjusters mid-travel



Then I clamped the spacer onto a folding workbench and made the cut with a cutoff wheel.



Wala! It fits the pocket with even contact all the way around:





From what I've seen, people usually put these into the upper spring pocket, citing interference when placed on the lower control arm. I decided to try mocking it up in the LCA and it appears it would clear just fine in either position.



That's all for now. Next step - get the engine to a machine shop and paint the exposed sections of the frame.

[TheBandit]

I did a bit of research, called around, and came up with a couple of machine shops recommended for building LS engines. One of the challenges with finding a shop was finding one with a torque plate for the LSx, which many do not have. I am not entirely sure if the torque plate is needed for an iron block, especially since the head bolts on the LSx are separated from the cylinder area by the water jackets, but since the jury is out on that issue, I'd prefer to play it safe. A local shop JCG Restorations which has built some really nice stuff recommended QMP Racing in Chatsworth, which is about an hour away. I called them up and spoke to Brad, who was very friendly and seemed knowledgeable. He quoted prices for various services and explained what I may or may not need, depending on what things looked like. Prices fell right in line with what I had listed above.

My at the moment plan is to get the block and crank to him, have the crank polished and clean/hone the block for a set of forged 2618 flat top pistons & moly rings. I am thinking unless something is bad, I will not deck or line hone the block, but I will have new cam bearings put in. I'll replace the rods with forged H beams w/ ARP2000s. Their brand of choice is Manley for the pistons and rods, but sell others as well. I'm not sure if that's the right option (sniper care to chime in?). I don't think the Manleys come with coated skirts and that's something I'd like to have. I could save a few hundred bucks using Scat or Eagle rods, but I think I should stick with a mid-grade rod like a K1 or Manley. Callies makes nice stuff too for another $50 or so, maybe I should consider theirs.

At any rate I'll probably be in this thing a little over $2k, but instead of a 60k mile bottom end, I'll have a fresh bottom end with reliable components and a healthier compression ratio. That's what I'm thinking for now at least. Any thoughts?

[entropy]

Originally Posted by TheBandit

I did a bit of research, called around, and came up with a couple of machine shops recommended for building LS engines. One of the challenges with finding a shop was finding one with a torque plate for the LSx, which many do not have. I am not entirely sure if the torque plate is needed for an iron block, especially since the head bolts on the LSx are separated from the cylinder area by the water jackets, but since the jury is out on that issue, I'd prefer to play it safe. A local shop JCG Restorations which has built some really nice stuff recommended QMP Racing in Chatsworth, which is about an hour away. I called them up and spoke to Brad, who was very friendly and seemed knowledgeable. He quoted prices for various services and explained what I may or may not need, depending on what things looked like. Prices fell right in line with what I had listed above.

My at the moment plan is to get the block and crank to him, have the crank polished and clean/hone the block for a set of forged 2618 flat top pistons & moly rings. I am thinking unless something is bad, I will not deck or line hone the block, but I will have new cam bearings put in. I'll replace the rods with forged H beams w/ ARP2000s. Their brand of choice is Manley for the pistons and rods, but sell others as well. I'm not sure if that's the right option (sniper care to chime in?). I don't think the Manleys come with coated skirts and that's something I'd like to have. I could save a few hundred bucks using Scat or Eagle rods, but I think I should stick with a mid-grade rod like a K1 or Manley. Callies makes nice stuff too for another $50 or so, maybe I should consider theirs.

At any rate I'll probably be in this thing a little over $2k, but instead of a 60k mile bottom end, I'll have a fresh bottom end with reliable components and a healthier compression ratio. That's what I'm thinking for now at least. Any thoughts?

Interesting
I would go Eagle and SRP before Manely and ??slugs.

[TheBandit]

What do you mean by "interesting"? Can you elaborate?

[CarterKraft]

Clint, I might be showing some ignorance here or maybe just bad judgement, but if you aren't gonna boost/ spray etc. why go through all the trouble? I was under the impression that was one of the grerat things about this engine, easy power and reliabilty.

Hell there are plenty of diesel engines with PM rods and while they aren't the best they do just fine with sensible tuning. I think the same applies to coated pistons etc. I am sure we've all had plenty of engines without coated pistons and never put enough miles on them to even matter.

Although to be honest I've watched and commented on this thread because I wanted to see how it whent as I thought I would do the same to my G body thus I didn't really pay attention to your intent.
So if you are gonna boost or spray and drive the hell out of it then you are probably gonna need the work done you propose.

[TheBandit]

You bring up a good point. I have been thinking a lot about what I typed this morning and it's making less and less sense. The idea to go with forged rods and pistons was born from a compromise between building a stroker engine and doing a simple refresh on what I have. The resulting compromise doesn't yield a lot of bang for the buck.

Here's the current picture


I could throw the old pistons & rods back in there with new rings and bearings for a total cost of about $1,000 (including honing and all the replacement parts to put the engine back together), saving the cost of balancing etc. If I go the forged route (middle option), what do I really gain? $1,300 in reliability insurance? Maybe a few hp from the bump in compression ratio? Hmm... I think I need to rethink my rethought.

[CarterKraft]

I think you nailed it, $1300 of insurance.
You really have to focus when doing these types of jobs, what is the ultimate goal?

I am all for making something bullet proof, but at what cost, you bought the long block for $1100, granted it needed freshening what would the extra $1300 get you if you had a catastrophic failure with the bling parts installed, some expensive door stops probably.

Ultimately if your are gonna beat on this engine then get the beef but if you are gonna drive it as hard as the soccer mom's Tahoe that it came from did, what for?

I like the conversion process and the attention to detail on the cornering mods. I kick my self regularly for building a 2 seat pro-street car and imagine I will be following your lead on a similar build in the distant future.

[entropy]

Originally Posted by TheBandit

What do you mean by "interesting"? Can you elaborate?

Long ago after i quit building star ship quantum drives
Things are so much easier in zero-G

Manely I have seen made it into recyclable material. Maybe they have improved!
The Eagle stuff while I expected the same; consistently delivered way beyond its supposed capability.
That is all.

If your builder has confidence and you get a good vibe forget I said anything

[TheBandit]

Originally Posted by CarterKraft

I think you nailed it, $1300 of insurance.
You really have to focus when doing these types of jobs, what is the ultimate goal?

Be at least as powerful as the old 350 before it gave up the ghost. Start and run predictably strong. Have crisp throttle response. Not leak. Sound just a little choppy. Low 12s in the quarter. Drive to cruise nights and be proud to open the hood. Tear up an autocross course and perform admirably on track day.

I don't plan to boost it or juice it. I do want to build a unique normally aspirated induction system down the road, not so much to make more power, but to give it something unique when I open the hood. Dual plenum throttle bodies like an exotic come to mind or maybe ITBs - I don't know, just something cool that I can talk about.

Originally Posted by CarterKraft

I am all for making something bullet proof, but at what cost, you bought the long block for $1100, granted it needed freshening what would the extra $1300 get you if you had a catastrophic failure with the bling parts installed, some expensive door stops probably.

Well the idea of buying the forged stuff is to prevent catastrophic failure. To be fair I paid about $1600 for the longblock, but that also included the intake/injectors/throttle body, the ECM and the wiring harness. I still think that was a steal even with 60 thousand miles on it. It probably wouldn't have needed to be freshened if I hadn't put water in it.

Originally Posted by CarterKraft

Ultimately if your are gonna beat on this engine then get the beef but if you are gonna drive it as hard as the soccer mom's Tahoe that it came from did, what for?

It will get semi-beat on. I can limit the RPM which will go a long way toward keeping things together, but it will see WOT pulls on a regular basis.

Originally Posted by CarterKraft

I like the conversion process and the attention to detail on the cornering mods. I kick my self regularly for building a 2 seat pro-street car and imagine I will be following your lead on a similar build in the distant future.

Thanks. I've taken a long time with this; most finish the process in a month or two, but I'm a bit slower than most. Maybe that pro-street car of yours is ripe for a conversion to more of a pro-touring theme.