[RAIIIJudge]

Nice, Scott! Interesting the negligible hp/tq differences between headers and R.A.R.E. manifolds. Good stuff.

How far up into ME are you? Is your nearest track NE Speedway?

[scott70]

Last time I was using standard ram air manifolds with 2.5” headpipes and I think it lost about 15 hp over headers . I was really surprised this time it only lost 4hp with the better manifolds and 3” pipes over headers.. It made the same 570 trq as it did last time but got a decent bump in hp. Peak rpms is now 200 rpms higher with the new HR cam.

The closest track to me is new Oxford dragway,about 50 miles.

Looking at the 2019 dyno sheets it looks like it’s a little lower oil pressure this time. Maybe a 8 psi average lower now through out the pull. The mains are .0028 but the rod clearance is .0029,, last time it was like. .0023 rods. That might be causing the lower pressure. Idling today was around 19-20 psi at 800 rpm at temp.

[scott70]

It now has a Cloyes double roller racing Z timing chain. Whats does the Z add over the standard racing double roller?

[grivera]

What oil viscosity?

[scott70]

Originally Posted by grivera

What oil viscosity?

15w 40 cenpeco

[OCMDGTO]

Outstanding results!!! Really impressive for iron heads and intake manifold. Even better with RA manifolds

[PAUL K]

Nice! Good job

[scott70]

Not bad for a junky old quadrajet,,, or so I’m told.

[grivera]

That’s a great build!! Congrats

[scott70]

Looking at the 2 dyno sheets it looks like switching to the manifolds and pipes richend up the air fuel ratio some.

[Jay S]

Originally Posted by scott70

Looking at the 2 dyno sheets it looks like switching to the manifolds and pipes richend up the air fuel ratio some.

That may indicate there was a little more power left on the header test with some tuning. Probably not much though, 510HP with RA manifolds is really getting it done. Makes me want to try a set of those RA manifolds with the 3” outlets.

[scott70]

Yeah they call these 2.5”outlets but actually they’re a little smaller than that. Rare then adapts a 2.5” end to a 3” pipe. I run those into a 3” x pipe system with 2.5” mufflers and tailpipes.

[Skip Fix]

A little shocked the headers were not worth more. On my 455 dyno yesterday the Tri Y headers lost a lot to the 2" and my cam was kind of close, bigger heads and intake runners though.
I had issues with my RARE 2.5 manifolds sealing at the head pipes on the 81 car. It is getting the 455 dynoed yesterday in place of the mild 400.

[scott70]

The headers were 1 3/4 hooker super comp the engine shop has.

[grivera]

Do the 3" headpipes use different manifold flange adapters than a 2.5"?

[scott70]

I believe what he did was use the very beginning of a 2.5” pipe with flare, maybe 2” and then welded that onto a 3” mandrel bent head pipe. So the very beginning is necked down but the rest is all 3” . Not ideal I guess compared to 3” the whole way. I believe it’s the same flange as a standard 2.5”. Like I said they call these oversized but comparing the ID of these compared to my other standard aftermarket manifolds there wasn’t much of a upsize but there is some.

[67Lemons]

I was wondering what the difference was with the R.A.R.E. OS manifolds but the webpage is gone now. I wonder how they compare to the new Ames 2.5” outlet versions?

[TXSTARFIRE]

Maybe can get the old page using the wayback machine?

[scott70]

I asked today for some valve spring specs from the engine builder. Using my previous 995 comp springs they were shimmed to a height of 1.685 which resulted a 130 lb closed and 370 open pressure.
Did a 3/4 turn on the comp evolution which was .063 preload.
Piston to valve clearance was .185
I asked about shimming the springs a little more but he said he really didnt want anymore than the 370 open pressure. Peak HP on the dyno was 5400 with the 236/244 .580 HR cam.

[scott70]

Got the engine home today, they had to replace a rear main seal and pan gasket from a leak on the Dino ,ran it for a a total of a couple of hours on the Dino. Don’t see any leaks so that’s good. Here’s the old bearings that came out of it from the 2019 rebuild. I was hoping they’d look a little better.. The engine doesn’t get babied