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AH Spares Fast Flow Manifold....

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HealeyPassion

HealeyPassion

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Gentlemen,
Has anyone installed the AH Spares Fast Flow Manifold, part FUL340 for twin SU's? I'm pretty sure this manifold is sourced from the Healey Factory they list as the DMD Twin SU manifold.

Either way, interested if anyone has actually installed one of these manifolds on their Healey engine (not the DMD Healey engine). If so, what's your reaction... installation, power, etc..

No, it's not for my EFI car. I'm looking at a new project and just wondering if this manifold yields any real value in a street engine.... albeit with tube headers.

Thanks,
Steve
 
Steve,
'I am pretty sure that Steve Gerow on the Healey list-serve has one on his car. I have some photos if you need them. It does require that you use flat float bowls like a Jag rather than the angled bowls used on Healeys.
Lin
 
They're different. I have the DMD manifold:
screenshot.558.jpg

Here's the AH Spares manifold:
screenshot.557.jpg

I installed the manifold with HD6 carbs with Kirk headers at the same time and got a noticeable seat-of-the-pants increase in oompf. Later I switched to HD8s and didn't get any noticeable increase.

I've gone through several air cleaner iterations to deal with the horizontal carb vs the slanted frame rail:
https://www.pbase.com/stevegerow/dmd_air_filter_mods
 
Steve,
Thanks for all that good information! I really appreciate it!

I find it interesting that both the DMD and AH Spares manifolds are so similar.... makes you wonder which came first. The DMD unit does visually look a bit better for flow. You mention seat-of-the-pants improvement, so I'm guessing that you haven't dyno'd it. That would certainly be extremely interesting. If you do that, I'd sure appreciate it you would share the results.

I'm trying to decide how to go on my next Healey project. I will be using Kirk headers, modified (eliminated slip connection and changed collectors to custom Burns) as I did the set on my EFI car. But, I haven't made any decisions on intake/carb selection.

IMG_0678.JPGIMG_0687.JPG

I'm really interested in studying all the images on your site... thanks for sharing!

Cheers,
Steve

MAF-Concours2013 23 DDLs.jpg
 
FWIW I don't believe steel headers make a difference you'd see on a rolling road. Some of you may watch Roadkill on YouTube, they do all sorts engine tests including fancy headers and on one occasion fancy headers beaten nearly flat to clear a steering box. Some constriction gave a 4bhp boost and more lost nothing.

With the exception of Mercedes who are the most advanced in such things, most old engines have inlet tracts that are too short, so that if you use cams with more overlap, you lose torque because fuel is being ejected while the inlet valve is open and until you're revving hard enough to be in the power band. If the AH inlet manifold has longer ones, there will be reduced interference between cylinders and more torque with a hotter cam because the inlet charge isn't being pinched by another cylinder or blown out by the piston rising with the inlet valve open.

However the AH manifold may make no difference with the standard set up, these problems were understood at the time, but there wasn't need then to increase specific power outputs. That came later.
 
EV2239,
Point of clarification please... I think your 2nd and 3 paragraph all has to do with with intake manifolds...right? If so, I think you may be right...and you are saying the DMD manifold with the longer intake runners may be an advantage to the short stock inlet tracts on the stock intake manifold?

My cam will be reground by Dema Elgin (https://elgincams.com), to optimize all around street performance... not radical. He did the cam on my EFI car and used a slightly modified BJ8 profile with pushed LSA to improve the vacuum... injected engines like vacuum. If I don't do EFI on this engine, I'll give Dema a free hand to give me his opinion of the best cam for a street AH engine. He's an amazing guy with vast amounts of theory and real world experience in engine/cam design.

Regarding steel tube headers referenced in the first paragraph. I'm not claiming to be an expert. A friend of mine that has raced 3L Healey's for 30-40 years, and has blown-up and rebuilt probably more Healey engines than I've ever seen... with extensive engine dyno and rolling road.... told me that the the stock exhaust headers were one of the worst pieces on the engine (very restrictive) and to go with a small tube (like Kirk's 1 1/2") header as a basis for any other work. The small tube headers would scavenge better (make more hp) in the mid-range for the Healey better than the larger 1 5/8" or 1 3/4", which may be fine for racing but not for my street application. Based on that, I've considered the small tube headers to be a basic building block for my street engine.

I'm certainly open to other input on the subject, since as I said, I'm not an expert on the topic.

Thanks for your input.

Cheers,
Steve
 
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I believe the DMD was first as I recall that being the only one available when I bought mine in early 2007.

My pix show I've had to make a spacer to allow the rear air filter to clear the slanted frame rail. The AH spares manifold appears to be deeper than the DMD - this may give the rear air cleaner clearance.

However with the DMD the front carb dome barely clears the shroud on removal. This is with Joe Curto's thin Jag insulators in place of the BJ8 instulating blocks. There is a slight interferance problem with the rear HD8 and the steering colum - I solved that with a combo of a slight dent in the steering column tube and a 1/8" shim under the left motor mount.

If the AH Spares' rear air cleaner clears the frame rail, then the front dome will likely be underneath the shroud - that means you'll need to remove the carb to remove the dome. If I were contemplating buying the AH Spares', I'd want to see an installed picture before purchase.

CarbDomeClearance.JPG
 
Hi Steve -

I love the sound of your new build. In addition to the stock exhaust Healey manifold being pure crap, the stock head is the worst following design there is. I'm sure you're planning on a performance upgrade in this department as well. Keep us posted on your build. BTY, Dema's a genuis......
 
Dougie, regarding "stock head is the worst following design there is" ... my Healey racing friend said exactly the same thing about the head! Any suggestions there are appreciated.

Steve G., thanks for the additional info on the DMD intake.

Cheers,
Steve
 
I had my head gas flowed by www.spamspeed.com who rolling roads many of the cars my son rebuilds. He's a renown A Series tuner and has a friend who worked in the competition dept at Abingdon in the sixties. My head was done exactly to mid sixties works spec with a 10 to 1 compression. It revs straight past 5000 with a Piper reprofiled BJ8 cam and Tappets, it's surprisingly fast, but I've now way of knowing how it compares, so I took it to Dan Howell who worked for Johnn Chatham for twenty years, he's built literally hundreds of competition engines, some with alloy heads and others with alloy blocks as well. He ought to know and he was very surprised at how well the thing goes, so now I'm waiting till it has some a few miles before we put it on the rolling road and find out how much power it's making.

In short I think the C Series head is a very good one for the day, but that the inlet tracts need to be longer if higher performance than a standard cam is used. Otherwise I suspect the loss of torque will be noticeably and tick over a tad lumpy. I'm using standard inlet and exhaust manifolds with a BJ7 exhaust. It's much louder than the BJ7 engine was, which surprised me, especially as a BJ8 cam is identical to the one in an 850 Mini, so pretty tame.

18160633610_1aac95030a_z_d.jpg
 
EV2239, sounds like your head has had some nice work. So, do you think the nice head is being somewhat strangled by those stock exhaust manifolds?

I met and chatted with John Chatham at Bonneville ... think that was 2009. He was with Steve Norton of Cape Int'l... much talk about fuel injection.

Cheers,
Steve
 
HealeyPassion said:
EV2239, sounds like your head has had some nice work. So, do you think the nice head is being somewhat strangled by those stock exhaust manifolds?

I met and chatted with John Chatham at Bonneville ... think that was 2009. He was with Steve Norton of Cape Int'l... much talk about fuel injection.

Cheers,
Steve
Click to expand...

I very much doubt that nice headers would make any worthwhile difference in power and I don't like the extra heat that radiates from them.

When we've put later engines in '45-'55 R-R&B we've had headers made and then ceramic coated to try and keep under bonnet temperatures down.

the biggest gain you can get from an old head is by clearing the area around the inlet valve away, so that as soon as it's starts to lift, gas flow isn't impeded because it has some distance to travel before it clears the surface of the combustion chamber. Total lift on a BJ8 cam is only 0.368".

Watch this header test to see what I mean.

https://youtu.be/azPKIjxmmdU
 
My son runs a restoration and trimming business and he builds/rebuilds vintage hotrods

View attachment 42905

This is car has a 350 Chevy that is about to lose its fancy headers for standard corvette ones to to get heat down and also noise.
 
In 2007, I had my Kirk headers matte black ceramic coated inside and out. They are no hotter or noisier than the cast iron ones were.

The coating shop recommended the matte black as the best one for heat suppression.
 
Steve G. .... Yes, that is also my experience. My headers have been ceramic coated inside and out in matte black.... my power coater said that lower external temps in the 140 to 170 degree range. I don't notice any additional heat and they certainly don't seem to be any loader than the stock cast iron exhaust manifolds.

Steve
 
EV2239... thanks for the additional head info.... much appreciated.
 
EV2239 ... just watched the header video that you recommended... that was very interesting. At the end he says that it does make a difference what tube diameter you choose (example he used was 1 5/8" vs 1 7/8") in tube diameter. IMHO, I'm not sure that from the video it's fair to conclude that a stock cast manifold is as good as headers.... didn't see any reference to that.

Cheers,
Steve
 
I have the DMD manifold on my race car. Designed by a David Woodhouse around 12-15 years ago or so.

HD8 carbs, Welch head which has been flowed, Welch header and Welch cam

compression is 9.44 - 1, realatively stock. The combination makes pretty good power
 
RA_Healey,
Thanks for the post. Do you have any dyno results?

Steve
 
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