Ported stock intake, SD Performance
 

I realize Dave has dealt with a tragedy from a natural disaster late last year, due to landslides. Just curious if any of you had Dave port your iron Quadrajet intake, and how well it seemed to perform, before and after. If it is worth it or not? this is a mild '73 455 in my '66 Tempest Custom wagon, 9 to 1 compression, 068 cam, '71 cast iron GM1 intake. Quadrajet with functioning divorced choke. $X heads with 2.11 intake, 1.77 exhaust valves installed. TH400 with GV overdrive and 3.42 gears. Considering getting him to port my intake, or maybe port another identical intake when he is back up and running.

Porting that intake while running stock heads, or even mild bowl ported heads is not a good power return for the money invested in doing such!

With your 068 Cam you would get more bang for your buck by adding 1.65 rocker arms and the needed push rods to get the geometry back in the ball park.

More landslides ? He had a big one, but that was a long time ago.

With your current combo being so mild, IE: 455, 9:1 compression, 068 cam, stockish heads, I don't feel you'll see much return porting the stock intake.

These intakes, both iron and aluminum factory pieces support over 500hp in stock form on a properly built combo. If it were mine I'd be looking in other areas first if more power is what you're after.

This is what I was thinking. Wanted some honest opinions like this. My present setup is very strong up to about 4500. Flattening out a bit above that. May leave well enough alone. This is a street car, after all. Very torquey and idles smooth, runs cool, in the summer even with the AC on. Was just curious if I could have got anything out of doing this, but it makes sense I would need better heads to go with it. This is the best intake for what I am using it for, IMO.

I understand he had another one just a couple of months ago.

Good idea. I actually have a set of 1.65 rockers in a box in spare parts I have.

I would try them out only on the intake side first seeing as you have 1.77” exh valves in the heads already.

SD offers the intake porting in a couple versions. I have the full port version it made 582 at 6200 back in 2012.

Have your heads been clearanced for the pushrods so you can run the 1.65 Rockers?

"This is what I was thinking. Wanted some honest opinions like this. My present setup is very strong up to about 4500. Flattening out a bit above that."

The 068 is a very good cam choice for a 400 build with moderate compression, but smallish on a 455 build. I've built a LOT of 455's here, one time I put a 744 cam in one with high ratio rockers and it was a "turd" for the most part. Don't get me wrong it did OK, but nothing going on much past 4500rpm's.

So I wouldn't expect it to pull much further in the RPM range with an 068 cam. Even with the much larger 041 camshaft we saw peak HP at 5100rpm's on a 455 build with Edelbrock aluminum round port heads. With that said a larger intake isn't going to bring much to the table either, but for sure you'll see a little more upper mid-range power with higher ratio rocker arms.......IMHO......

Since then the 455/744 build (did that one in the late 1980's) the smallest cam I'd even considered for a 455 build would be 230 @ .050 and at least 280 degrees @ .006". Attached is a dyno chart from a Super Duty 455 around 8.8 to 1 compression and the cam used in it. Dead smooth idle making 16" vacuum with only 12 degrees initial timing. I put these things up here for folks contemplating camshaft choices so it may help beyond what the OP is looking for. I've had so many troubled 455's brought here to custom tune, and complaints from folks who've put them in service and not happy, that I feel it's important to realize that a HUGE engine does well with cams this big especially if you've spend money on the heads for improved air flow.

I'll also add here since the topic is intake manifolds that the brief testing I did with the Edelbrock Performer intake very quickly told me that the big 455 sees it as a restriction on higher HP builds (past about 425-430hp). I was unable to even test it effectively on my last 455 at the 500hp mark because the engine simply hated it. Installing it with no other changes induced a stumble/hesitation/big that would NOT tune out. I also had pronounced "surging" in the mid-range when it did get past the stumble. Putting the iron intake back in place instantly cured the issues so when we carried a pile of intakes to the track for back to back testing the Performer wasn't in it.........Cliff

https://forums.maxperformanceinc.com...1&d=1646142052

https://forums.maxperformanceinc.com...1&d=1646142142

Here is a picture of the original iron intake that was supplied to Dave at SD for the CNC scan to modify them. Mine has added material and both bolt patterns so it can used a square flange Holley or AFB style carb without an adapter plate.......

https://forums.maxperformanceinc.com...1&d=1646142611


https://forums.maxperformanceinc.com...1&d=1646142611

Yes

Anyone that's considering building a 455 (or 400) in the near or distant future, needs to print off this thread, AND SAVE IT. When they get down to build time, READ THIS THREAD, PLEASE!!!

The Performer intake isn't even a consideration. Pretty happy with the way the car drives now, just was curious if tweaking what I already have (stock intake) would make any difference in the upper end. Nice to check out people's experience with actually doing these things vs not bothering with them at all. I think if I ever had the intake ported, from what I see on here, I would pull the heads and replace them with a set of ported heads, and a roller cam. The shortblock is all forged rotating assembly, so it is "overbuilt" in case I ever decide to go that route. Thanks so much for the input, guys. For now, "if it isn't broke, I am not going to fix it". Had this car for 40 years, and every once in a while I have an idea to change things up a little bit.

You`re good to go with that stock intake. Especially with the gear vendors.

I don`t know if it`s just heads but, I don`t believe Dave is porting cast iron stuff anymore.

He is doing intakes, but not heads...

Dave's house got his by mudslides & flood back in November, and more floods in December. His shop was o.k. this time, but I think they got 4-5 feet of mud/water hit their house and flooded the basement.

They had to bring in some heavy equipment to work the land, dump trucks, loaders, etc., run multiple pumps, deal with the local government,... then he and his wife recently caught the flu.

Somebody started a GoFundMe for them: https://www.gofundme.com/f/helping-l...qVKfdlrAZ6NGTE

Cliff,
Do you have an explanation for the crazy Air Fuel Ratios on that dyno sheet? This graph show it verses the Air Fuel Ratios from the 2 dyno pulls on the combo sheet that you general post.

Stan