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Search found 610 matches

by PRH
Wed Sep 18, 2019 2:54 pm
Forum: Engine Tech
Topic: Are valve springs w/ dampers less senstive to clearance from coil bind at max lift?
Replies: 5
Views: 317

Re: Are valve springs w/ dampers less senstive to clearance from coil bind at max lift?

Brad....... just pull out the stops and go for the dual conicals.
by PRH
Mon Sep 16, 2019 10:03 am
Forum: Engine Tech
Topic: Port velocity vs cfm
Replies: 18
Views: 821

Re: Port velocity vs cfm

It may or not fit in well with the rest of the overall package, but a solid cam would likely liven things up....... especially in the upper rpm.
by PRH
Sun Sep 15, 2019 5:45 pm
Forum: Engine Tech
Topic: Port velocity vs cfm
Replies: 18
Views: 821

Re: Port velocity vs cfm

I’m pretty sure if you flowed the manifold by itself it would flow more than 230. For example, on that head the M1 single plane flowed 263......... but on a better head I’ve seen it flow over 280. Yet, if you bolted it to a stock 230cfm head, it would still flow less with that manifold attached. I h...
by PRH
Sun Sep 15, 2019 11:57 am
Forum: Engine Tech
Topic: Port velocity vs cfm
Replies: 18
Views: 821

Re: Port velocity vs cfm

I don’t flow the heads with the manifold installed very often, but I have done it for some F.A.S.T. R&D on a BB Mopar. 8 cylinder average of the head with a radius plate and the valve @.700 lift vs the head with an untouched 383 4bbl manifold(and a few others) and a 1000hp Holley carb on a 1/2” spac...
by PRH
Sun Sep 15, 2019 11:20 am
Forum: Engine Tech
Topic: Port velocity vs cfm
Replies: 18
Views: 821

Re: Port velocity vs cfm

It seems obvious to me that if you have low flow numbers for a given port area, the velocity will also be low. Imo, for 1hp/ci............ you’re way over thinking it. Put some bigger valves in it, get all the easy flow you can....... cam it accordingly for the intended use/desired power level.........
by PRH
Tue Sep 10, 2019 7:17 pm
Forum: Engine Tech
Topic: Finally figured out how to move some air on these heads...
Replies: 14
Views: 1102

Re: Finally figured out how to move some air on these heads...

4 hours per head, or per pair of heads?

If it’s per head, is the rest of the engine package going to be able to take advantage of that work?
by PRH
Tue Sep 10, 2019 12:13 pm
Forum: Engine Tech
Topic: Finally figured out how to move some air on these heads...
Replies: 14
Views: 1102

Re: Finally figured out how to move some air on these heads...

I’d do the 1.84 intakes with some minor blending....... and take the added area under the curve you get from the larger curtain area.
by PRH
Tue Sep 03, 2019 6:59 pm
Forum: Engine Tech
Topic: Air flow vs valve size
Replies: 2
Views: 418

Re: Air flow vs valve size

What I usually see by installing a bigger valve into a stock head with minimal porting is better low lift flow, and often the peak flow is nearly the same as with the small valve...... but occurs at a lower lift. Often the c/d is lower than it was with the smaller valve. Of course, only one way to r...
by PRH
Tue Sep 03, 2019 6:39 pm
Forum: Engine Tech
Topic: Comp QXI Lobes
Replies: 50
Views: 3330

Re: Comp QXI Lobes

And then sometimes you get this: https://m.youtube.com/watch?v=ol7XPJVqvz8 I stumbled across that video while reading a thread on another forum about noisy lifters. The scary part for me was the owner saying in the thread the motor had been dynoed like that!! From what I recall, it eventually got a ...
by PRH
Tue Sep 03, 2019 4:34 pm
Forum: Engine Tech
Topic: Comp QXI Lobes
Replies: 50
Views: 3330

Re: Comp QXI Lobes

I’ve sold a few cams for BB mopars with the QXI lobes. No complaints of noise....... in fact on a couple it was noted from the users how quiet they were. I’ve only had one on the dyno here, and I didn’t think it was bad at all. Def quieter than a solid....... but not silent like an OE cam. Related s...
by PRH
Tue Aug 27, 2019 5:49 pm
Forum: Engine Tech
Topic: Custom vs Catalog Cams
Replies: 204
Views: 8662

Re: Custom vs Catalog Cams

Most of the “old school” based builds work just fine with old school cams.

I’m not too thrilled with fast rate hyd stuff in many applications.
Which usually ends up being that the lifters can’t keep up with the cam.
by PRH
Tue Aug 27, 2019 4:10 pm
Forum: Engine Tech
Topic: Custom vs Catalog Cams
Replies: 204
Views: 8662

Re: Custom vs Catalog Cams

One other thing I find is that many times someone is calling about a cam when many aspects of the overall combo are still in limbo. I feel that while the engine builder should have a “picture” of what the finished project will be like....... the final cam selection doesn’t need to be made until a lo...
by PRH
Tue Aug 27, 2019 1:19 pm
Forum: Engine Tech
Topic: Custom vs Catalog Cams
Replies: 204
Views: 8662

Re: Custom vs Catalog Cams

The last customs I was involved with where I didn’t specify the lobes myself were those Stocker grinds........ and none of those worked out very well. When some lobe data became available, and I was able to get what I wanted, the car ran much better. So, my experience of having some cam experts pick...
by PRH
Tue Aug 27, 2019 1:12 pm
Forum: Engine Tech
Topic: Opinions on this valve job.
Replies: 16
Views: 1137

Re: Opinions on this valve job.

In the second pic of the ex valve, you can see it was leaking by the carbon track.
by PRH
Wed Aug 21, 2019 12:35 pm
Forum: Engine Tech
Topic: Custom vs Catalog Cams
Replies: 204
Views: 8662

Re: Custom vs Catalog Cams

Last year one of my customers put together a mild 455 Pontiac street motor. Bought a house brand “white box special” from a big retailer. About 50 miles after the cam break in the motor developed a rod bearing issue. They pulled the motor apart and noticed one lobe looked “iffy”, so he brought it ov...