I visit the Jim's from time to time and always come away with awe and amazment. The dedication you show to the 409 engine is legendary. When i saw the headwork on my last visit I was amazed. The word Perfection just does not cut it. Cheers Brian
Yeah, we're sort of replicating the ultra rare Z11 head that Chevy made for the 409's back in 1963
Apparently this style head was suposed to be the standard high performance head for 1963 but in the end they only used them in a limited number of lightweight Impalas.
The Z11 heads were a really good design, here's a picture of one beside a regular high performance head...
As opposed to a cast block / heads , what is the weight difference with an all aluminum engine ? 7500 rpm man that has to sound different coming from a W block.
I'm not sure how much difference there will be on the total engine but we'll weigh both the old and the new engines when we switch them over.
The aluminum block is 65 lbs lighter than a factory iron block 131 lbs vs 196 lbs. The aluminum block is built quite a bit thicker and it has heavy steel four bolt main caps so the difference is about what we expected.
I'm not sure why it is but 348/409 do sound a little different. I have a DVD taken at a 349/409 shootout and you can definitely hear the difference when a regular big block or small block goes up the track.
It may have something to do with the shape of the combustion chamber but for whatever reason they sound different.
Here's an in car video of the 409 in my 55 Chevy. It shifts at about 6,800 and crosses the line at about 7,200 rpm. The sound quality isn't great, in real life the sound is much deeper and louder but does sound like it's reving.
I'm guessing the Pontiac is going to sound pretty good with it's higher revs and more powerful engine.
Loved the ride in the '55, sound effects n'all..cheering you on, "reel him in !" What a project you're into, that was already a honey and with the new big guy....
.........Oh I gotta ask one more question if you don't mind. What the heck will that 13.5 have for compression on the starter ? I stuck 12.5's .030 in my 396 and I only had a compression testor that I held in place, one foot on the wall behind me and someone cranking it and it would blow me out @ 232 lbs. Was it accurate I never compared to anything else but just curiuos what this 409 will hit ? Thanks.
-- Edited by Nailhead on Monday 14th of January 2013 09:46:44 PM
I've got a computer program that says we should have about 210 lbs of cranking compression. I would be quite a bit higher with a smaller cam but with the long duration cam in this engine the intake valve is open well after bottom dead center, therefore bleeding off a lot of compression at cranking speed and low rpm. The Cam is 282/292 @.050
The car has separate switches for cranking and ignition so we can get it cranking over first, then hit the ignition. That reduces the chances of the engine kicking back and breaking the starter.
Many or maybe most racers tend to lock up the advance mechanism in their distributors so that the engine starts with full advance. I prefer to have the initial advance set lower, then have the advance mechanism set to advance quickly. The lower initial advance reduces the chance that the engine will kick back.
Funny, I posted a couple of hours ago how much I enjoyed the ride in the '55, and look forward to follow up on the big inch '61. It's in my posted list but not here ?
Anyway very interesting project, those are some big RPM's, my 496 gets into the next gear at 6 thou.
Anyway very interesting project, those are some big RPM's, my 496 gets into the next gear at 6 thou.
Yeah well the original plan for this engine was to have it peak at about 6,000 rpm but the plan was to build it at 540 ci.
Since we couldn't bore it out as big and had to settle for 511 ci we'll have to rev it higher to get the same power. Also by the time I ordered the cam I was starting to think about hitting 800 hp so I went even bigger than I had at first planned, which of course raises the rpm range.
The engine that's in the Pontiac now shifts at about 6,000 rpm like your engine and it's been running great for years. I think that's the smart way to go.
I know there will be more maintenance on this engine, especially things like valve springs will need to be checked out from time to time.
Jim, thanks for the reminder ! VALVE SPRINGS ! Last race of the year I had a backfire/pop at 6 in the burnout box.. that's a sure sign on my setup, but it had sort of slid to the back of mind..
