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Re-read all of post 11

The build details should be based on the application. As in, what’s it going in, gears, converter, type of exhaust, intended use, and performance goals. Of course, I usually tell people to figure out their budget first……..as that’s often the biggest determining factor when it comes to what big...

When you check “P/V” clearance at full lift……..what you’re really checking is retainer to seal clearance. The piston is inches away when the valve is at full lift.

How do you explain the .035” lobe lift difference between #1 and #3 exhaust lobe(.297 vs .332)? Also, duration @.050 for #3 is 238/241.

On the SB heads I have here to look at, the cavity by cyls 3/6 looks to be the largest. Just work the lifter rearward to that hole and it should fit thru. Nonetheless, it seems as though you’ll be doing a cam swap.

Looks like the #1 ex lobe is .035” shy on lift compared to #3. As I recall, a lifter can be retrieved out of the valley thru one of the open areas of the head. Id pull the one out of #1 exhaust for a peek at the bottom of it. .332 x 1.5 = .498 That’s a big ask out of the springs that go with...

That’s what I was thinking. I mean, if you were only checking the C/L of the lobe, then I can see it. But if you’re checking the open/close points…….. it would be obvious if you were on the wrong lobe. I’ll slip in an anecdotal story here…… A few years ago a customer brought in an Olds 350...

The timing events are clearly depicted on the paper here. The open/close points for both lobes are occurring in the correct part of the cycle. However, the installed position and lsa seem to differ a bit between the .050 open/close points vs the “centerline” method. Based on the .050 intake...

Fwiw, I took it all at face value that the test was done correctly, and that EA had a handle on what he was doing. I wasn’t confused by it at all.

What’s the cut off point where a 318 is considered “high hp”, vs just being another run of the mill semi high hp build?

Continuing on with the CR theme……. Are the heads off the engine yet? How far down the hole are the pistons? I’d determine that as a first step, and make the decision on whether or not that should be/will be addressed.

Depending on how “mild”, mild has to be…….you either will or won’t be able to reach 1hp/ci. A really mild, nearly stock idle type build, utilizing unported factory heads won’t get it done. The other consideration is the budget. Plenty of mild pump gas 440 builds dyno tested at Nicks garage on...

Somebody must have thought so. I believe the IH difference with the correct 2 groove valve and rotator is about .200” less than the non-rotator combo. Plus the rotators are heavy. Like I said…….for any type of performance app, I remove them.

“Generally”, the rotator and spring on the exhaust will not accommodate much more lift than the factory cam. If I’m going thru factory SBM heads, and there is any hint of a performance slant on the build, and the heads have rotators on them………the factory 2 groove valves and rotators get...

The photo of the engine was used for illustration purposes. The numbers on the paper are from EA.

I’m not sure how the picture not being from his measuring makes any difference in the measurements themselves. There could be no pictures and the numbers would still be the same.

My first thought is……assuming the measurements are correct……it would be no surprise to me that a cam with 292* of advertised duration being installed 5* retarded from straight up(or 9* retarded from where I would have put it) is lacking some grunt. My second thought is that’s a pretty big...

All of the exhaust mounting holes on passenger car BBM heads go into the water jacket of the heads. I’d be surprised if the instructions for installing the headers didn’t call for draining the cooling system as one of the first steps.

I agree. I was thinking it was gonna be 6-10hp. It was an eye opener for sure. Those heads came off a 9:1 358” 18* nascar engine. Up here, that series had to run 390cfm carbs. They would pull about 8” vacuum @8000. During a dyno session on one of those I swapped on a hp950. It picked up...

The MT 408 build isn’t exactly what I’d consider super budget friendly with a solid roller and TF heads. Somewhat comparable build…… 410”, 10:1, bowl blended RPM heads, easy on parts .600 lift roller, Victor 340, street Q 850 carb. 524tq@4700/538hp@5900. Start of pull: 3900 = 496tq End of...

Unless you can find where someone has already built the combo you want, and has it documented well enough that you can follow the recipe…….then you’re going to have to build it how you think will work…….and see what happens.

Well, the description of the 408 implies low buck…….which doesn’t coincide with tons of head r&d. (After reading the article the engine appears to have TF heads) I’m sure plenty of time was spent on the 371 heads for the contest. RPM heads that flow 270 will easily make 550hp+, using any easy...

On both of those, the 2” funnel was used. It’s like running Q16. On some combos it’s “wow”! On others it’s “meh”.

if I’m not mistaken that 371 was at least somewhat built with the EM testing parameters in mind. Part of the big TQ is from the smallish cam. In those contests, it needs to strong right from the start.

I’d say the first thing you want are really good heads for the application. In your case, something like a ported EQ head would seem about right. Then, I look at it as, the worse the induction/heads are, the higher the CR you’ll need, the hotter the cam, etc. Fundamentally though, I would just...

I had forgotten about one that beat the 1.40 mark here recently. 358” SBC for a road race car. Dry sump(iirc), cnc ported 18* heads, solid roller about .700 lift, ported intake. Made 509tq@5600/619hp@6700(still 603hp@7700). That’s 1.42/1.73

Nothing special bracket race SBC 383. 12:1, ported World sportsman 2’s(flow 280), roller cam, cleaned up SV, 1-7/8 x 2 x 3.5 headers. Cam A made 490tq/599hp(1.28/1.56) Cam B made 478tq/588hp(1.25/1.53) Cam C made 509tq/608hp(1.32/1.58) Only the cam was changed between tests. These cams were...

Here’s how I see it, in practical terms……. However much fuel that 408 was using to produce its peak TQ, you’ll need to use at least that much with the smaller cubes. But without a dramatically different head/combustion chamber, you’re going to need to turn the smaller engine to a significantly...

1.3 TQ/CI isn’t really that hard to do. 1.4+ is very rare here.

Off the top of my head, I’m thinking the highest TQ/CI combo I’ve ever built came up a bit shy of 1.44/ci…….it was 1.417. A 14:1 572 with cnc ported Indy heads, a TR and a .800” lift roller cam. It seems like those numbers are much easier to achieve in theory……..than in actuality. I’m talking...