Picked up the shortblock from the machine shop a couple weeks ago. Specs I can remember:

'72 4-bolt 400 block, bored 030 over
eagle cast steel crank (radius journals type)
Federal mogul (speedpro) pistons H616.030
Federal Mogul main bearings 4926M
shop prepped 5.7 rods
ARP bolts
Assembly balanced.

Balancing and assembly were the big ticket labor items. The parts were pretty basic and cheap enough... good enough for the highway. Looks like my calculated Compression ratio is about 9.78:1 with the 75 cc (76cc milled 8 thousanths) chambers.

The block is tapped for screw-in oil squirters behind the cam sprocket (3/1000ths) and also tapped for oil control fittings in the valley pan area. The deck has been tapped for pipe plugs which are installed below deck (no deck milling on this one) The retro-roller lifters' locks interfere with the oil control plugs I bought so I will likely use short brass plugs in their place. These are the things that keep the return oil from the heads from dripping down onto the crank. Think of what happens if you were to pour water on top of a running fan blade.. thats what we're trying to avoid with these pieces.

Presently I am working on squaring away the late model stepped face type roller camshaft installation. The late L98 motors used a cam retaining plate to keep the cam from walking outward. If the plate is not used in the 400, there will be too much room between the cam gear and the block and the cam will sink back about 1/8 inch into the motor and the chain will not be aligned. The problem with using the factory (89 for example) L98 retainer plate is that there is no place to screw the bolts to the block. I don't think its a good thing for the retainer to spin around and Ligenfelter makes a spacer that looks like it spins too so what's the diff? I dunno.. still working on that one.

Discovered upon starting to install the cam and heads that the rotating assembly HITS the camshaft upon rotation. Turns out it hits in 3 spots! I had given roller cam from an 89 Iroc to the machine shop to clearance, and I guess they charged me for it but forgot to do it.

Here is a Picture of the rod modification that had to be made to rod #2.



Here is a comparison of the calculations made for balancing. no rebalancing was done based on the rod modification being slight, and the balance is "over" which is more desirable than 'under' for higher rpms.

The Oil pan needs to be able to clear the K-member, as well as leave room for the exhaust crossover. From what I can see here, the stock 400 oil pan leaves just a hare MORE room for the crossover than the L98 pan. The front seal still uses the overlapping method to join with the timing cover. Note the oil dip-stick releif location on the 400 pan. This is going to be the only easy giveaway under my hood that a block swap has been done... thinking of using a chrome dip stick to draw attention ;-)

Finally today we're changing out the 305 for the 406. 33% cubic inch increase! Had a few snags: the machine shop left a pipe plug in the oil pressure sensor port by the oil filter. Busted a few sockets trying to get it out but then sucessfully got it out using an impact driver. Had to relocate the coolant temp sensor from the drivers side head to the front of the lower intake manifold because the head has a pipe plug in it that I cannot get out. Used a brass adapter to put the coolant switch in the passengers side head where luckily there was no plug.

I was planning on using the factory exhaust manifolds for now, but the drivers side manifold won't allow installation of the dip stick. The 400 SBC has the dip stick in the drivers side insted of the passengers side.

The heads I have are old enough to NOT have the one of the holes drilled for the serpentine system bracket on the passenger's side. Also, the same head does not use the newer heads' location for the rearmost exhaust manifold bolt. I must use the manifold for a few weeks, good enough for 30 miles a week.

Just have to hook up the harness and put together the upper intake, today the engine and trans went into the car as a unit, with a little finesse where the trans hits the firewall and the motor mount brackets are not far enough back to be able to drop in. The motor mounts themselves were a hassle to get changed. the nuts inside the K-member are hard to access. have to use a 'gooseneck' ratchet for the rear top nut on both sides, and a straight extension works for the bottom nut, but the front nut on both sides requires fishing an open end wrench inside the K member. Getting the nuts and washers BACK in there was even harder. Just need to stick the washer to the nut using some grease or silicone, then fish them up there using the appropriate wrench.

Feb 24 '02

Well, Theres been gremlins. I start the car and it runs real funny. Finally get the base timing set right and it seems ok, a test drive did not last long.. the FUEL PUMP DIES!! Now I know why the 305 was acting sluggish under load.... so I replace the fuel pump (take out the rear, take out the exhaust) and 7 hours later.. it STILL does not run right. Turns out.. I got the WRONG FUEL PUMP and it is doing 18 psi!.. pfff... Now I can do a fuel pump swap alone in 3 hours from all the practice. Fuel pressure is ok now, but it seems these 140k mile injectors might need replaced.. theres an awful lot of misfire noise happening and the cat is glowing! raw fuel.. hmmm...

Mar 3 '02

Still ironing out 'wierdness'. I had lashed the #4 intake valve down too far and it was open a hare all the time. A leakdown test showed 100% loss and a compression test showed 15 psi! (compared to 180 in an adjacent cyllinder). All is well with that one now and the car idles well, but developes a lumpyness after it gets warm. Still working at the valve lash, then I'll check all cyllinders for leakdown. I had to leave the dipstick out for now as the factory 305 exhaust manifolds interfere with it. I have headers in the garage but it looks too cool under that hood with NO visible mods. To check the oil I figure I'll drain it, measure it, then put it back in. (kidding) .. I'll have the headers on before the car has 20 miles on the engine.

3-3-02

I wrote this up for someone, and I took a bit of time to do it so I pasted it here. I'll add to it if I get anymore gotchas that I want to admit to.
Q: "What do I look out for when swapping a 400 into a TPI setup in an thirdgen"
A:

In a nutshell.. make sure your upper intake has a rear water passage crossover, make sure the heads are drilled for the 400 steam holes and you use the correct head gasket, Get a cam spacer and fiberous button from ligenfelter if you are going to use the GM stepped face cam like I did (LT4 hot cam), plan on a "small base circle" cam if you don't want to have to grind into the rods and rod bolt edges like I had to, doublecheck to see that your oil pan will accomodate the exhaust crossover well enough, remember that the headers you buy will need to be able to accomodate the oil dipstick that is on the DRIVERS SIDE, remember the retro-roller lifters are $$$, and that the pushrods are different length than either the 400 or the 5.7 L98. If you use very old heads like I did, make sure you drill the heads for the accessory mounts needed for your stuff. Also drill out the starter bolt boss in the block to accomodate your starter if it is not already drilled. If doing a MANUAL tranny like I did, theres only ONE company I think selling a 153 tooth flywheel for the 400 crank.. Centerforce. I have the part number on my site somewhere.

A couple weeks ago I installed the 1 5/8 headers, the oil dip stick tube, larger exhaust pipes, flowmaster muffler, and the 4th generation rear end (Disc rear, Auburn pro, Richmond 3.73) . and finally I have a car that can drive on the road! I replaced the leaky pinion seal ($15 at GM), leaky axle seal ($3 non-GM), and leaky exhaust donut. So far, I'm on the third chip and everything seems dialed in. BLM's at or near 128 and o2 sensor says 90 mV at WOT. The temporary 22# injectors from the 89 Iroc are maxxed out as expected, I have 24 #ers on the way. . I'll estimate about 275 RWHP and 400 FT/LB TQ. We'll see what the dyno says.


4-5-02

Heres a picture of the motor in the engine bay. Obviously some detailing is in order but the look matches the rest of the car.... run down, high miles, not cared for very well, stock. (the "don't steal me" look ;-) If you look hard enough, or zoom in, you'll find the dip stick on the drivers side.

07-24-02: Finally! the above heads PLUS a Ligenfelter Super-ram mounted on top the 406. Dyno next.. it feels like a 406 now :))


Above are Felpro 1628 valve cover gaskets. Great when you want to be finished with aligning those cork things. steel core, super stiff, sleeved bolt holes. 1/4" thick to help the stock valve covers clear the rockers, $42. slide on like they were machined-to-fit.


More Later...

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