400 Stroker Build Documentary
 

I'm building a new 400 stroker engine to replace the 455 (41.5 X4.25 474) that was destroyed at Norwalk this year. I plan to use the same cam, heads, intake, carb and headers that was used on the 455.

Previous build was .060 over 455 converted to program engineering 4 bolt main caps, J&E pistons, Eagle 6.8 H beam rods, and 4.25 Ohio cast crank. Ultradyne solid roller 264/268 @ .050, 176/187 @ .200, .3944/.3944 Lobe Lift .592@1.5 Harland Sharp rocker arms, LSA 108, 1-7/8 Indian Adventures headers with Flowmaster merge collectors, Victor intake with 1050 dominator.

I am doing a documentary of my new build step by step to share on the board. I am by no means an expert engine builder just going to share my build with others. who may want to follow along. I'm starting with a 71 400 block purchased at Norwalk, it was supposed to be a STD bore but it looks to be bored .005 to a 4.125.

So far I have had the block hot tanked and used a wire wheel to clean off remaining paint and rust. Next step to de-burr sharp edges on the casting flash around the lifter bores, install a SD Performance lifter bore brace and hard block up to the water pump holes.

Replaced NEW SFI Balancer sounds like a good idea. Will try to keep up wit the Thread.

How much weight does hard block add?

Cool, I'll be watching/reading

Cylinders with hard block distort differently than cylinders without it.
So, you need to have a head or tq plate with the same head gasket you will use in the build torqued down while the hard block cures.
At least that was the way Whitmore did mine. He had his reasons.

Are you going to billet cap the block ?


Thin rings planned ? Power to be had there.

Glad you're posting the build, will be fun to follow along.

The block has been pre-cleaned, I drilled and tapped the lifter galleys 3/8 NPT, deburred the casting flash around the lifter bores and am currently fitting the SD Mega Brace.

Christmas came early this year, look what the UPS man brought me today from Butler Performance.

Definitely watching this!

It's standard bore. Pontiac literature showed 4.12 but
that isn't right. 4.125 *ISN'T oversized. Pete McCarthy
touched on this weirdness. The 428 is actually a 427,
the 350P is a 354, etc. HTH.

I cleaned every threaded hole in the block using a thread cleaning set, WD-40 and compressed air. I don't use a machine tap as it can remove metal and actually weaken the threads.

This block is a bit of a mystery I wish I knew the history of it. There is absolutely no ridge at the top of the bore. You can still see some hash marks in the bore and this block came out of a GTO. The block was very dirty with grease and grime and a lot of rust on the exterior of the block. There is evidence that the engine had been apart and/or rebuilt at some point by high temp silicone on the pan rail and in the rear main seal area. There are a couple bores that had enough rust that it would need to be bored to remove. If this is a standard bore it is a low mileage mystery.

We've built many Pontiac 400's using a 4.125 finished bore. If the bores are in good shape things work out perfect. Bolt on a torque plate and hone the cylinders to 4.125. Excellent selection of rings and leaves a lot of meat in the cylinder walls.

Recommended....

RACE ENGINEERING: "ULTIMATE" BLOCK FILLER
https://raceeng.com/race-engineering...25-each-bf-25/

Fast setup time
No need to vibrate block
Easy material to work with
Block machinable in 24 hours
Will not crack or separate with age

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The counterweight will hit the block in the front more than likely. Easy fix. I have built allot of these and love them. It's my go to for a quick easy to duplicate build. 400 blocks are not easy to find but the easiest of what's left.

I am going to put in a plug for Butler Performance just because I think their rotating assembly package is a pretty good deal. The package includes the crank, rods, pistons, rings, wrist pins, and bearings. You select from the available cranks, rods, the piston overbore, type custom dish, dome, or flat top, choose your rings and bearings. After you select all your options the assembly is then balanced, and they provide the balance card in your shipment. They had EVERYTHING in stock and from the time I ordered it till it was on my front porch was about a week. In todays world that is saying something and the price is hard to beat.

Mega Brace installation complete, torqued to the full 40' lb with no lifter bore distortion. Dave provides excellent instructions with his Mega Brace if you follow the instructions, you can't go wrong. My cam is not a super aggressive cam and it's not necessarily in the category that needs a lifter bore brace but I feel better having it than not and the cost is very reasonable.

Whenever you are running solid lifters, flat tappet or roller it is recommended that some of the oil going to the top end be restricted and send it down to the rod and main bearings. This can be accomplished by installing restrictor plugs in the lifter bore or by using restrictor pushrods. I tapped the oil hole in the lifter bores 1/4-20 and installed 1/4-20 plugs drilled .060. No need to drill the holes, it is already sized to accept a 1/4-20 tap. Carefull you don't tap too deep go slow and check it doesn't take much. Make sure you test each bore with a lifter to make sure there is no interference after your done and put red loctite on the plugs.

Always use brass freeze plugs you don't want to pull your engine to replace a rusted leaking freeze plug. I clean each hole with a wire wheel on an air motor to make sure the surface is 100% clear of rust and clean metal. I then wipe it with lacquer thinner or brake cleaner to remove any contaminants. I then rough up the edge of the freeze plug with scotch brite. Then put a very thin layer of silicone on the I.D. of the hole in the block and the same on the mating surface of the freeze plug. I start the plug in the hole with a good size hammer then drive it the rest of the way with an aluminum rod working around evenly until it it's flush with the block. I know you may be thinking this is over kill but this is how I do it. The correct size freeze plugs for a Pontiac is 1-61/64".

I'm not sure hitting the brass plug on the sealing area flange to finish your install is such a good idea.

I understand that my method may differ than others and may not be the "best" method, but I have never had a freeze plug leak and the sealing surface is not damaged or deformed using my method.

I used to restrict the lifter bores and noticed premature lifter scuffing and bore wear. Just my experience. Been using restricted pushrods and even restricted the rocker arm holes, jfyi. Your build good luck.

sorry if i didn't catch it, but are you going with a 4.25 crank or 4.5? if not 4.5 any reason?

I am going with a 4.181 bore and 4.25 stroke. There are a few reasons why I would prefer not to go to a 4.5 stroke. With my heads having a 71cc combustion chamber it would bring my static compression way too high, of course I could of ordered dished pistons to get my compression down. A longs stroke like 4.5 puts additional stress on the crank and the block, I don't want to push my luck with an OEM block. Longer the stroke the faster the piston speed thus shorter ring and bore life, I already have increased piston speed using 6.8 rods that's a tradeoff for less side loading on the cylinder wall and better cylinder filling since it dwells longer at TDC. If I were building a monster engine with an aftermarket block I'm not sure even then I would go with that large of a stroke. Many have done it with good results in my opinion it's not the best choice for me. I'm not going for max power I'm trying to stay in the low 10 second range for a reliable long lasting bracket engine and I don't want to put in a cage and window net.

I like the 4-inch stroke there assome, kind of the best of both worlds
Just thinking out load. Good Luck.

GT

The reason to fill your block with a block filler is to prevent flexing of the block which may compromise your ring seal and cause additional friction between the piston skirt and the cylinder wall. I started filling the block this week, the material I am using is from Race Engineering and it came recommended by some members here on the forum. It comes in a 25 Lb. bucket, you need to divide it in half and use half for each side, there is more than enough material to do both sides. I leveled the block by shimming my engine stand and got the block level in both directions. This is only the second time I have done this process, so I am far from an expert here. The other time I did this I used "Hard Block" and that was quite a few years ago. If you ever do this do NOT do it when it's hot as it may harden up VERY fast. When I did the first side it was very hot and it turned out to be a disaster, after mixing it started hardening almost immediately. I didn't even get half of the material in the block and it was hardening in the funnel and what I did get in didn't reach very far in the block. Mind you I was prepared and had everything ready in advance all I had to do is add water mix and pour.

I believe I made two mistakes; it was too hot (around 95 degrees) and I think I didn't make the mixture thin enough. I have a game room inside of my shop and it has AC, so I moved the operation into my game room and turned the thermostat down to 65 degrees and left it in there for 24 hours and got everything good and cold. This time I added more water and got it thinner and had my wife hold the funnel for me. Now I am re-pouring the same side to get a complete fill. With my assistant holding the funnel and me working fast with my thinner mixture in a 65 degree environment it was a success.

I believe that most people that do this only fill to the bottom of the water pump holes but based on the recommendation of my machinist I filled it to about one third of the way above the water pump holes. I am waiting for the negative comments on this as I am sure they will be coming. Since I used the other half of the material to finish the first side I had to order another bucket of material it should be here Tuesday. Once the block fill is complete it will be going to the machinist for the line bore/hone (to mate the new 4 bolt caps), boring/honing the cylinders and decking for a zero deck.

One more thing I did while filling the block I used an air hammer with the pressure turned down to vibrate the block to eliminate any voids and help level the material out. If you do this don't hammer on the side where the cylinders are you could damage the block. I hammered it at the bottom where the motor mount pads are because the block is plenty thick there. I also used a firm wire and poked it into all the holes in the top of the deck to agitate the mixture. Maybe over kill but I wanted to make sure there are no voids.

I will be re-using the same E-Heads I had on the 455 that was destroyed at Norwalk. These are 330 CFM heads done by Dave at SD Performance back in 2007. I have them stripped down and I removed all the carbon and scale from the ports (lots of work) and I will have them milled about .020 to get the compression to around 12.3. I checked the springs, they are still good so will re-use them. I removed all the carbon from the valves using a wire wheel they cleaned up pretty fast. There were a few bent valves that I have replacements for but the valve job looks really good so I will install new valve seals, lap in the valves and re-shim the springs and that should be it for the heads.

Tom,
While increasing the rod length does change the piston velocity curve, where in the velocity curve are you looking at when you say velocity has increased? Peak velocity is actually reduced as you length the rod. You also move the point of peak velocity and where the rod and crank journal are at 90 degrees to each other farther ATDC.

Stan

Since you're running race gas, mill the heads and get compression up to 13.5-14. Might as well make running race worthwhile.

Yeah I get your point but I am trying to duplicate my 455 engine because I don't really want to make any more power than I did before for a few reasons. I was already low 10's with the 455 engine. I know with more compression and a bigger cam would put me well into the 9's.

1. Don't want to put in a cage and window net
2. Currently running the largest tire that fits in the stock wheel well (28X10.5X15) MT drag slick and I don't want to tub it and if I go much faster I will need a bigger tire.
3. The more power you make the more parts you break so I will sacrifice speed for a longer lasting engine.
4. Bigger cam and more compression more RPM now I need to higher stall converter.
5. Bigger tire oh now I need to tub it, oh now I need more gear, now I am overpowering my suspension, and on and on...

If I had a much larger budget for my toy I'd love to go faster and faster but it's not in the cards

That's my plan and I'm sticking with it.

It is my understanding that with a longer rod the piston dwells longer at TDC and gives more time for cylinder filling and this also increases piston speed at some point in the stroke over a shorter rod. I don't understand your statement that peak velocity is actually reduced with a longer rod or maybe my understanding is flawed.

Stan is pretty smart. Your build is one that has been done by probably everyone in the race section 20 plus years ago. The higher block fill will probably net you higher oil temps and lower cooling system capacity. I hope it runs well and lasts many years.

I've got two motors that are hard blocked to the water pump holes
Both of these motors run cooler then any of my other engines.
On the street and at the track, I'm useaully running the motor in
the staging lane's to keep the temp up where it needs to be.

GT

Do you monitor oil temp also?

These were done a number of years ago using the same bore and stroke with varying rod length.

Stan

The hard block process is complete, the block is now ready for the machine work.
1. line bore/hone for the 4 bolt main caps
2. Bore/hone cylinders using a torque plate with main caps torqued in place
3. Mock up with pistons/rods installed on four corners to verify how much to remove from the deck to get pistons even with deck
4. Machine deck surface of block
5. Mill heads .022 to increase compression. Mill an equal amount on head and intake surface
6. Engine assembly

With Pro-Gram Engineering steel caps we used oversized dowels to ensure a tight fit.

https://butlerperformance.com/c-1459...owel-pins.html

I read that dowel pins are like fingerprints-no two are exactly alike.



.

No I haven't done that yet

GT

Around 20 lbs

When the block was tanked, was it also magged/sonic checked?



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Howdy former neighbor!

What did you put in the water pump holes to keep the fill material from running out while you filled it about 1/3 of the way up the holes?

I just put duct tape on the outside of the opening. Then while it was setting up still not completely hard, in the back I scaped off the excess material to make room for the freeze plugs, and in the front, I removed some material so as not to restrict water flow to and from the water pump, made kind of a gradual transition.

I had it sonic tested before I had it hot tanked but I did not have it magged

This engine should have been to the machine shop two weeks ago, but I was not comfortable with the amount of dowel pin engagement. I had to locate some correct size pins, I didn't want to go oversize pins as that would require reaming the block and the caps. I finally found the correct size dowels and got them installed today. There is only one company I could find that provides the longer factory size dowel pins for a Pontiac (Precision Automotive Specialists). While installing the caps I was going over the surface with a small stone to remove any burrs that may be present and found cracks around the dowel pin hole in the rear main cap. Not too happy about it but sure glad I found it. Now I need to get a new rear main cap.

Dang that sux. Sorry bud.



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I probably have a rear main cap for 3in

you got lucky on reusing your cam, when my rod broke piece went up into it and bent the camshaft.

I might be confusing some people who are following my posts as I have two projects going on. The 455 engine that had a catastrophic failure at Norwalk, I am building a new engine to replace it, a 400 stroker (4.25 stroke) for my 65 LeMans drag car. My street car (67 LeMans) that is also a 400 stroker but with a 4.00" stroke is a fresh engine and this is the one that has the number 3 misfire. I will be pulling the head today to get that car back on the road.

I got a new rear cap thanks to Paul K. All new dowel pins installed, and I took it to the machine shop today to get line bored, cylinders bored and decked. After that heads will be milled to bring compression up a bit.