Aluminum 409 Build

jim_ss409

Well Known Member
Supporting Member 5
#1
As many of the members here know we got one of Bob Walla's aluminum 409 blocks earlier this summer. Here's Bob delivering it.



We are just now getting started on the actual build. I dropped the block off at the machine shop earlier this week. (A P Racing Engines, Windsor Ontario Canada) They have experience with race engines and 409's so I'm leaving it up to them to order the parts they think are best for the short block assembly.
We're shooting for about 520 ci. with a 4.25" stroke. The bore will depend on the best availability of ring sizes but it will be around 4.42 Since this will be a "race only" engine we're hoping for about 13.5 to 1 compression.
Bob Walla is supplying the cam. The specs I've asked for are 276 @.050 intake and 286 @ .050 exhaust with a lobe separation angle of 112 degrees. The lobe lift will be about .450 intake and .420 exhaust which translates to .765 - .714 lift with 1.7 rockers or .787 - .735 with 1.75 rockers. The cam company he deals with may not have those exact specs so they may change a little.
The heads we'll be using are the ones we got from Bob a few years ago. As everybody knows cylinder heads are usually the limiting factor when it comes to making horsepower so we've got some modifications planned to help feed the bigger engine.
The regular 690 style heads work great up to a point but when the air flow gets really high like at high rpm or with a big cubic inch engine the air has a tough time making it's way around sharp corners like the short side turn of the 690's



The raised port on the Z11 style heads are much better. Here's a picture of a Z11 head beside a 690
(I think I got this from one of Wrench's posts)



We've been talking about grafting a slab of aluminum onto the heads to raise the ports and today we finally bit the bullet and started milling down the heads. We're doing this on the mill at our shop.



We milled the valve cover rail down and made it parallel with the deck surface just to keep things simple. You can see the difference if you compare the untouched head in the background to the one we milled.



The piece we'll be adding will look a little like a valve cover spacer except that it will be much heavier and it will have two rails that will span across the head directly over the intake ports. It will be clamped down with four head bolts and be bolted to the head with several other bolts. It will also be epoxied into place.
We're hoping to raise the ports by about 1 1/4 inches but valve train clearance will be the limiting factor so we may not get that much.
We'll be using a T&D shaft rocker system like the one on the Sherman engine in the 55 Chevy.



The rocker pedestals will have to be milled down to the proper height to accept the T&D setup but before we can do that we'll have to get the new longer valves so that we can determine the proper height and angle.

Anyway, this engine build will probably be a winter long process but I thought I'd get a thread started.
 

jim_ss409

Well Known Member
Supporting Member 5
#10
Oh man that's going to be one hell of a motor! What are using for an intake? Sheet metal?
Yes, we'll build one out of aluminum. We've got a really good intake design program (Pipemax) that will allow us to get the length and cross section areas right.

Jim, I'd get a hold of Dave Mills. He's started a mod like that and maybe he can give you some pointers.
Yep, I've been talking to Dave quite a bit. Our plan is to send these heads to Dave to complete once we get a port roughed in. As you know he's experimented with raising the intake port on a scrap head and has reached over 400 cfm. :beer
I'm not sure if we'll be able to raise the port high enough to reach those kind of numbers but I'm optimistic that we'll see a fairly good gain.
 

tripower

Well Known Member
Supporting Member 2
#11
Once again we get to tag along on a new adventure brought to us by none other then Jim & Jim...:clap Can't wait to see this new series unfold...:pop

In the first post when Bob was delivering the block it looks like he is getting ready to throw in the trunk of the Pontiac to make its new trek home. Then this spring will we get to see it up front in the Pontiac powering it down the track...:dance
 

Ronnie Russell

Well Known Member
Supporting Member 2
#12
I'm really excited about this project. The updates will help the long cold winter go by. I hope Jim and Jim whip up a few extra sets of the adapter plates, and yes I realize they require a special made intake but well worth the efforts. Thanks to Jim and Jim for sharing their project.
 

k9hotrodder409

Well Known Member
Supporting Member 15
#13
Hey Guys !! Wil we see the new motor at Thompson ? Is it going in the Pontiac or the 55 ?:love
Best of luck with the build. I saw that block at Thompson in June and was (and still am ) amazed !!

:crazy:cheers
 

jim_ss409

Well Known Member
Supporting Member 5
#15
Hey Guys !! Wil we see the new motor at Thompson ? Is it going in the Pontiac or the 55 ?:love
It'll take a while to build it but It'll be ready for Thompson for sure. We'll dyno this engine when it's done. I'm pretty sure we'll hit 800 hp but it will all depend on how well the heads flow. The engine will be going into the Pontiac.
 

jim_ss409

Well Known Member
Supporting Member 5
#20
Why not just start with the Walden Z-11 heads? Starting costs?
We thought about that but they're pretty expensive,,, $6,000 and they're also limited production items so it might take some time to get a set.
But most of all, we just wanted to try and see if we could make something like this work. Just for the fun of it.:beer
 
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