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I had another thought……. If the OP has a friend with something like a “known good” 850dp carb he could borrow and bolt on, that might be worth a try. It’s basically just a tool/process to rule out any possible issues with the OP’s current carb. I feel like there has to be some component that’s...

I can only theorize……. The builder had it in his head how he was going to build it…….and basically disregarded the owners requests. Now, keep in mind I’ve got one side of the story, but both the auto shop and engine owner seemed to be on the same page about the goal being 500hp. I never spoke...

Essentially none of the old school platforms are immune from being dogs when built with a poor combo of parts.

I think the Pontiac enthusiasts missed the point of that story……..and that the motor in question was not a SD that was getting a rebuild. It was a bread and butter 455 that the owner wanted built to the 500hp mark. Shop A failed the test with a 315hp effort. My question to the installation...

There was a SB stroker here a few moths ago that was built with some old EQ magnum heads and a Comp XE285HL cam. It was just here for the dyno work. The owners 850DP carb had huge jets in it and was super rich(10’s). After a couple of rounds of jet changes it was into the normal a/f...

My initial thoughts about that series of tests is……there needs to be 2 more tests. Baseline another untouched port, then do nothing but sand the SSR.

Grind the seat on the LA to accommodate the valve out of the poly head and see what happens. Which LA head are you working with?

While we’re all waiting for “episode 3” of Nicks old weaky escapade to air………here’s more underachiever “filla”. Maybe not so much of an”underachiever” as much as the builder really under-delivering the goods on what the customer asked for. This one’s a 455 Pontiac. A shop in town has a...

Like I said, the dist locked out isn’t problem to me. If it runs good like that, just leave it. That’s not you’re missing 1.5 seconds of ET. If your flash stall is only 2800, that’s way shy of what would be optimum with a 505/292 mega cam(you’re sure it’s the 505?). That’s a pretty good sized...

One more thought……… If trying to determine if/how much the surface finish may impact flow numbers on the bench……. I feel that the “test piece” has to be one without inherent flaws to its shape. One that doesn’t have a compromised form, but does have a well developed valve seat & chamber area. No...

The ones that make me scratch my head are when there are two very similar builds, but not exactly the same……….and one just ends up being noticeably better than the other. I guess what I’m saying is, it can be surprising how different the results can be between parts that directly compete with...

Imo, the “correct” way to evaluate changes to the intake port surface finish is on the dyno, not the flow bench. And I don’t work on anything where doing that kind of R&D is cost effective. I’ve seen what I felt were pretty impressive results from smooth, and rough, and cnc finished ports. I...

Another one from a similar time period……. SBC 400. Was in some sort of off road/trail rig. I don’t know much about it, other than he was friends with the dyno owner. I kind of got the impression he was thinking he was going show off his engine building prowess with how awesome the power of the...

Over 20 years ago I tested a coupe of Chevies that were supposed to be “hot street” type builds. Both were already installed and running in vehicles, where the owners weren’t satisfied with the “driving experience”. One was a BB 396, and the parts combination was specified by a local 396...

Headers used on the dyno? Any idea what size? Let’s see a sheet. I realize for your combo, the cam requirement is going to call for something pretty small. But I feel cams like that generally don’t produce power curves that look impressive on a dyno sheet.

I know I’m not saying anything here you’re not already thinking……..but, wow…….that thing was weak!!

No doubt in my mind. Take my old bracket combo and port the heads…….done. I’m sure at that point, a swap to a port matched/plenum tweaked Victor and you’d get a bit more out of it.

Is the sheet you posted a run with manifolds or headers? How much difference did they make? Are those corrected numbers with or without inertia correction?

Here’s my side of the argument…….. I wasn’t looking for a “stock” engine……. So I hotrodded one a bit. This is the same short block I bracket raced for 3 years that made over 480hp. I replaced the unported 906’s with some bowl blended later model castings(1-346, 1-452…… I used up some...

There was a thread about this over on Moparts a year or two ago. Basically, the OP had a BB that was chewing up bronze gears in short order. He ended up going to the melonized gear, and he pulled it out a few times for inspection. It looked perfect each time. As always……ymmv Here ya go……...

318?? That’s soooo last week. The hot ticket is a stroked poly 318.

You guys are pretty harsh…… But I still like my 383.

And yet, I’d be willing to bet the factory gear and cam looked fine after 100k.

Since I hadn’t ever gone about it in the order you did, I wasn’t really qualified to say you were going about it the “wrong” way. As for the 50* testing……. That SM head probably still has a few untouched chambers to experiment on……. Without going “all in” to .090” deep in one shot.

I would say that these days the chances aren’t as good as 50/50 that you’d get a long service life out of a bronze drive gear. For a bracket car, if it only lasted a season or two it’s not the end of the world. On a street car, they can get pretty ugly in 1-2000 miles. The key word being “can”...

I feel that when it comes to porting, it’s good to let people go down their own path. That way there’s a good possibility of them discovering something you(me) may not have even thought about. As an example, in the earlier stages of your exploits with the SM testing, you blew that chamber wall...

I just wonder how much help the steep top angle would be if it was that much shorter…….by not sinking the valve. The transition area from the seating angle to the chamber wall wouldn’t be as “optimal”.

Glad you’re getting something out of it. Frankly, you done some fairly elaborate testing yourself…….that I’ve gotten some nice info from. Like mapping the flow around the perimeter of the valve on the chamber side.

Is that with the seat at the “std” height, or after you’ve lowered the valve in the chamber .090”?

In my limited testing of changing only the valve job from a 45 to a 50, the results were less lower/mid-lift flow, and no gains, or even a slight loss at the higher lifts. Keep in mind these were tests done at the customers request, on a head that had to be usable after the testing was done...