Holly manifold

[tvrgeek]

A bit confused. I keep seeing talk of a Holly manifold, but nothing about a source. I have seen 7 degree spacers and comments about a adapter plate, but no designed for manifold. Are they all modified stock ones? Off course. does whatever all fit under the bonnet? Don't want some stupid hack like the DGV on a B where you have half an inch from air horn to air cleaner cover.

Has anyone modified a stock manifold for port injection and fitted a single large throttle body? Making enough progress I am thinking about the engine now. Before I rebuild the 175's, I want to know what options there are. Maybe just porting the manifold and putting on decent tube headers is all it needs.

[tvrgeek]

Holly 390? Is there some thread on correct jetting?

[Stagdad]

Monarch used to offer an opened up manifold that had the 4 barrel mouting plate welded on the top also a few people have done this themselves. Or this guy has done efi to the std manifold with no plenum though so not sure how that would perform.

https://youtu.be/3OegcHzMpfI

[mjheathcote]

There is no such thing as a 100% Holley manifold, either they use a bolt on adapter, or the original manifold is cut up and welded with the adapter.
I have the bolt on adapter, however I made it fit better with a bit of grinding and polishing, port matching if you like.
I then found I needed an angled wedge plate to level up the Holley.
I also carried out a few other modifications to the Holley, replacing the secondary jet plate with one like the primary using screw in jets for easier tuning, and replaced the electric choke for a manual choke instead.
It has been fine in my case for the last 25 years.
A drop side K&N pancake filter clears the bonnet just fine.
If you search there are plenty of info on jet sizes.
Yes i could replace the Holley with an EFI throttle body instead, straight swop.
There are loads of options really these days, even fitting stromberg pattern EFI throttle bodies for an OEM look to complete one off custom setups.

[Goldstar]

or this https://www.holley.com/products/fuel...parts/550-511K

[tvrgeek]

Much thanks. That is what I was looking for. I wonder if I can use this as an excuse to buy a TIG welder
I was thinking about a FAST or Holly TBI. I gather the manifold issues are really just at the carb and if opened up, woudl be fine. Not perfect like a long tube port injection, but fine.

[KOY 23]

or this https://www.holley.com/products/fuel...parts/550-511K

That’s an impressive proven kit and includes fuel pump, LCD screen and O2 sensor, great value for around £1k.

[mjheathcote]

That’s an impressive proven kit and includes fuel pump, LCD screen and O2 sensor, great value for around £1k.

It does however they recommend the power range from 200 to 600 BHP so could be a bit oversized for the duty!
I looked into their efi kit a decade ago, was less advanced back then but the same applied and I determined it was too big for the Stag.

[flying farmer]

There isn't much point in going for the Holley these days, and if you feel the need to modify a standard manifold you might as well start from scratch and build a new one for injection.

I have built 4 efi manifolds so far, the first three being in mild steel plate and tube, and the last one in alloy using a spool gun on a MIG welder.

180bhp is about right for a standard engine on injection, the one in my triumph estate does 185 but with a bit less torque than Steve's but it does have ported heads (and only 8.5:1 CR)

My K reg Stag is putting out 246bhp with fast road cams and lots of development work on heads and manifold, and the Stag engine in my TR is giving 253bhp at the moment, and I am sure there is a bit more to come when I have sorted a few niggles.
All my cars use the original Triumph transmission without any problems so far.

If you want to entertain yourself for hours try looking at the Flying Farmers new project thread which has got a fair bit about the engine work as well as the restoration stuff, or alternatively the Pushing the limits thread which is just about the engines.

Neil

[Carboy0]

I too looked at the Holley Sniper kit, the potential power range is dependant on the potential fuel flow volume from the injectors. It would be possible to fir slightly smaller injectors, or perhaps go for a similar option from Webcon - designed to fit UK car’s that used the Weber 38 DGAS twin downdraft carb, V6 Fords etc. For which there is already an adaptor available for the Stag inlet manifold.

http://www.webcon.co.uk/shopexd.asp?id=15299&bc=no

and then their high pressure pump and integral swirlpot would mean the existing Lucas pump pushes low pressure fuel up to the swirl pot and then the high pressure pump pushes on to the throttle body

http://www.webcon.co.uk/shopexd.asp?id=15149&bc=no

I’m not sure what the overall height would be though. Also you still get a ‘wet’ inlet manifold, rather than a dry one using one injector per cylinder.

[tvrgeek]

Yes, port injection, a hacked GM ECU ( popular with the Rover V8 mod folks, more advanced and cheaper than MegaSquirt) , crank trigger COP ignition is the best option, but a really big project.

I contacted Holly and FAST about smaller injectors and neither responded. Pretty much, if you are not running a small block Chevy they don't care as that is 99% of their market.

Thanks for the links, I'll keep looking and thinking as I work my way forward fixing stuff. One more front outrigger to weld in, then rebuild the rack and front suspension while waiting to solve my T35 tailshaft problem. I really had hoped I was bot buying a major project, but seems that is how it goes.

[mjheathcote]

There isn't much point in going for the Holley these days, and if you feel the need to modify a standard manifold you might as well start from scratch and build a new one for injection.

I have built 4 efi manifolds so far, the first three being in mild steel plate and tube, and the last one in alloy using a spool gun on a MIG welder.

180bhp is about right for a standard engine on injection, the one in my triumph estate does 185 but with a bit less torque than Steve's but it does have ported heads (and only 8.5:1 CR)

My K reg Stag is putting out 246bhp with fast road cams and lots of development work on heads and manifold, and the Stag engine in my TR is giving 253bhp at the moment, and I am sure there is a bit more to come when I have sorted a few niggles.
All my cars use the original Triumph transmission without any problems so far.

If you want to entertain yourself for hours try looking at the Flying Farmers new project thread which has got a fair bit about the engine work as well as the restoration stuff, or alternatively the Pushing the limits thread which is just about the engines.

Neil

I'm still so suprised at the 246bhp and 253bhp figures you have achieved.
I compare to the engine in my Maserati 4200.
That produces approximately 390bhp from 4.2lt, which I had confirmed on a rolling road a few years ago. Naturally aspirated.
If you pro-rota 4.2 lt down to 3.0 lt, that would be 278bhp.
However the engine in the Maserati is a derivative of that fitted in the Ferrari 430, 32 valve, all the fancy variable cam timing, tubular exhaust manifolds etc and red lines at 7500 RPM.
I can not see how it would be possible to get any more out of the Stag engine, lacking the above 32 valve heads etc and higher red line, and dare I say, suspect the rolling road you have used may be giving figures a bit on the high side!
Even the modern 3lt n/a BMW/Jag/Ford engines are producing no more than 240bhp, again with 4 valve heads and VVC etc.

[tvrgeek]

We should all know, dynos absolute numbers are always suspect, but their real value is the before and after difference and any help for the shape of the curve. 253 does sound high, but a full race high RP peak HP driven design, sounds within the realm of possible. Not sure I would want to drive it on the street. I like big fat truck type torque curves for my street car. Consider all the fancy variable cam stuff is to broaden the power range allowing a race top end but still drive on the street. Modern engines all have to have low emissions, so not able to run 12.5:1 AFR, open exhausts, etc. For a race car, you can fine tune the AFR with a carb just as well as EFI.

I would be quite interested in the head work. I have not been able to find much for Stag, TR-7 , or Saab other than comments they are not bad to start with. ( from the perspective of a Westlake head in my B) Is it still mostly intake pocket and back side of intake valve?

[flying farmer]

We should all know, dynos absolute numbers are always suspect, but their real value is the before and after difference and any help for the shape of the curve. 253 does sound high, but a full race high RP peak HP driven design, sounds within the realm of possible. Not sure I would want to drive it on the street. I like big fat truck type torque curves for my street car. Consider all the fancy variable cam stuff is to broaden the power range allowing a race top end but still drive on the street. Modern engines all have to have low emissions, so not able to run 12.5:1 AFR, open exhausts, etc. For a race car, you can fine tune the AFR with a carb just as well as EFI.

I would be quite interested in the head work. I have not been able to find much for Stag, TR-7 , or Saab other than comments they are not bad to start with. ( from the perspective of a Westlake head in my B) Is it still mostly intake pocket and back side of intake valve?

Dyno plot for both the 246bhp and the 253bhp shown below, not a peaky race motor. 285 degree cams so nothing radical. I am hitting a valve bounce limit at 6500rpm on the 253bhp engine, yet the one in my Stag hits peak power at 6650rpm and revs to 7000. I suspect I need to look at the installed lengths of the valve springs as the seats were re-cut due to corrosion when I rebuilt the engine. I am also going to revise the exhaust manifolds as I tried slightly longer and slightly shorter pipes on the 253 compared to the 246 engine and both seem marginally worse in some areas so I think I may have got lucky the first time! The 253 figure is achieved with slightly shorter pipes than the 246.

As a TVR geek perhaps you know the rolling road I use, Joolz at Kits and Classics in Chesterfield, he is a TVR specialist and TVR owners come from all around the country for his ECU conversions (Emerald not Megasquirt like mine, but he is getting better at Megasquirt!
246 and 253 compared.pdf

[flying farmer]

One more comparison, this time the 243 and 253 bhp are the same engine in my TR with different cam timing, the 246 is the one in my mk1 Stag 253 246 243 comparison.jpg