Weber/Holbay manifold modification using standard Zenith downdraft manifold

[alpine_64]

Jerry of you want such a short manifold you would be better off making one by using mounting faces off any alloy Weber manifokd.. Then cutting alloy pipe abd welding that to a rootes mounting flange .. Then port. They would have to be slightly angled as i think dcoes sre to wide to fit on sttsight runners for the rootes intake port spacing on the head

 

[jdoclogan]

Jerry of you want such a short manifold you would be better off making one by using mounting faces off any alloy Weber manifokd.. Then cutting alloy pipe abd welding that to a rootes mounting flange .. Then port. They would have to be slightly angled as i think dcoes sre to wide to fit on sttsight runners for the rootes intake port spacing on the head

Michael, the runners did not line up straight. I am porting at angles necessary to match the head aligned openings. When I get done with the porting process I will post completed photos. They will show the design better.

 

[alpine_64]

I understand how it works with what you are doing.. Just suggesting there is an easier option it you have someone to weld that will produce a better and neater manifold. ;-)

Ill msg you later... Have to step out for a bit.. Maybe can zoom over the weeknd

 

[Limey]

Jerry the guy that used to own peirce setup a company called " the weber man" TWM .. He took some of the patterns and peice got the rest.

You can see the old link via the part number 0077.. The peirce curved one uses the same but with addtional code.. Assume 0077 is reference to upright rootes alloy head in their codes.

Hi,

I'd like to buy one of these for my SII IS it the same as the one in your pic/ Also I cannot see if it is swan neck or straight. Can you advise?

Thanks

Oliver

 

[alpine_64]

Hi oliver,

Thats the gooseneck manifold peirce offer similar to the one redline offers and both a copy of the original warnerford manifold.

The TWM one is the striaght in short runner pattern... I think i emailed you photos of the TWM one

 

[Limey]

Hi oliver,
Thats the gooseneck manifold Peirce offer similar to the one redline offers and both a copy of the original warnerford manifold.
The TWM one is the straight in short runner pattern... I think i emailed you photos of the TWM one

Sorry if you've said all this before but I take it that the gooseneck gets around the firewall brace issue whilst the straight does not?
Oliver

 

[alpine_64]

Sorry if you've said all this before but I take it that the gooseneck gets around the firewall brace issue whilst the straight does not?
Oliver

Actaully its the other way around... The straight manifolds have a better chance of clearing the brace... But very few do, they must be quite short.

The goosneck lifts them higher and allows for longer runners for more torque and also longer velocity stacks

 

[Limey]

Actaully its the other way around... The straight manifolds have a better chance of clearing the brace... But very few do, they must be quite short.
The goosneck lifts them higher and allows for longer runners for more torque and also longer velocity stacks

So, my best bet is to get the TWM straight manifold and cut it down further? If so where do I get one?? Unobtainium?

Mine's a right hooker.

 

[RootesRacer]

The TWM may be better for horsepower (perhaps not torque) but it fowls the scuttle tubes on LHD configurations and will require some creativity to put a functional scuttle tube in place (which you want becuase without the scuttle tube, my hood periodically pops after hitting a bump). I always felt the redline/gooseneck intake held a better chance than the TWM/Pierce intake but I have never had a gooseneck in hand to check.

 

[alpine_64]

The TWM may be better for horsepower (perhaps not torque) but it fowls the scuttle tubes on LHD configurations and will require some creativity to put a functional scuttle tube in place (which you want becuase without the scuttle tube, my hood periodically pops after hitting a bump). I always felt the redline/gooseneck intake held a better chance than the TWM/Pierce intake but I have never had a gooseneck in hand to check.

Jarrid, i have had the redline on for 17 years now.. It wont fit with the scuttle brace in stock location the issue being the body of the rear carb bring lifted up at a point where its close to the line between the scuttle mount and arch mount.

Obviously rhd doesnt have issues with steering bimox and m/c clearance of LHD


Twm:

Redline:

 

[RootesRacer]

Michael, At the very least, you will have less to zero problems with the steering box with the gooseneck. All the other clearance issues are probab;ly shared with all manifolds (MC, Scuttle and Stack clearance)

 

[alpine_64]

Michael, At the very least, you will have less to zero problems with the steering box with the gooseneck. All the other clearance issues are probab;ly shared with all manifolds (MC, Scuttle and Stack clearance)

Yes RHD makes life a lot easier for the carbs clearance.

A very short manifold with short stacks will fit.. But have seen few examples. The straight manifold with short stacks would make it easier to do a slightly bowed brace.

That said several people have just made arced braces to clear... But oliver would be wanting untouched or close to stock appearance.

Jarrid, do you run the TWM manifold in the picture above?

 

[RootesRacer]

Yes RHD

Jarrid, do you run the TWM manifold in the picture above?

I do.

Jay Laifman and I bought the first ones (we helped get the prototypes into production and did the initial fit checks).

 

[alpine_64]

I do.

Jay Laifman and I bought the first ones (we helped get the prototypes into production and did the initial fit checks).

Ah.. So we can niw officially blame you and jay for any clearance issues... You two should have sorted the steering box/MC issues for your fellow LHD crew.. Or made the manifold shorter.

I do note the TWM appears to be very similar to the period Brabham design ( bar the Brabham ribbing).

The TWM in the photos is one i bought about 12 years ago off ebay in Sweeden iirc... From a guy building a race alpine but never got round to completing it and had the manifold still in the box

 

[RootesRacer]

Ah.. So we can niw officially blame you and jay for any clearance issues... You two should have sorted the steering box/MC issues for your fellow LHD crew.. Or made the manifold shorter.

I do note the TWM appears to be very similar to the period Brabham design ( bar the Brabham ribbing).

The TWM in the photos is one i bought about 12 years ago off ebay in Sweeden iirc... From a guy building a race alpine but never got round to completing it and had the manifold still in the box

Its been probably 20 years now but IIRC, Jay knew someone that had a Hartwell or similar intake and it got "cloned" by Gary at TWM. He was not easy to work with and iterating for fit was not on his agenda. Early intakes (like my 2 I purchased) has an offset in the machining for the mounting holes to the head and I needed to elongate the holes just to get the ports to line up.

 

[jdoclogan]

Actaully its the other way around... The straight manifolds have a better chance of clearing the brace... But very few do, they must be quite short.

The goosneck lifts them higher and allows for longer runners for more torque and also longer velocity stacks

Michael, you don't get more torque with longer runners (which includes the length of velocity stacks) you move the peak torque to a lower rpm. I was trying to accomplish my peak torque at a higher rpm (4000). Thus, by shortening the intake runner that can be accomplished. I satisfactorily was able to fabricate the intake manifold to the goal of peak torque at 4050 rpm. Then I found the unforeseen problem with exhaust header clearance. This led me to investigate the Alpine's exhaust system. As others have pointed out the Rootes 1592 and 1725 exhaust pathway is not the best engineering. Albeit it was probably the most prudent economically. Right from the get go the head pattern has a virtual 90 degree exhaust exit (reducing flow by 15%). Then the 1 1/2 inch header pipes are two large and are not of equal length for maximum molecular scavenging (which would help the head design problem). The step header system does accommodate for the second (#2) and third (#3) cylinders to work together along with the first (#1) and fourth (#4) cylinders. I have done the math and it is best to have 1 1/4 inch header tubes with 1 inch IDs. All lengths should be 20 inches and come together with a 4 into 1 collector. I went ahead and came up with a method to mock-up the header (Note: you saw it here first so don't go and try to get a patent). I will still be able to shorten the intake runner lengths just not as much as my first iteration. I will combine your suggestion Michael with my original process and we shall see where it ends up. I will probably get peak torque at 3900 rpm as opposed to the stock 3400 rpm with Webers. As for the adaptation of a Weber manifold (2020 MR) my Harrington Le Mans setup was configured by modifying the fender brace position on the fender (higher than original). It still has the original look and no hood interference. Also the installer needs to slightly grind the interior forward bolt on the steering box. Shorter stacks would help clearance issue, but, I like peak torque at 3400 rpm for the street use. I fabricated my own throttle linkage and it has performed without fail.








Note: that is a straight Holbay/Weber intake on the right after modifying out the 10 degree angle that compensates for the angle install of the Holbay engine.

 

[alpine_64]

Jerry,

Great progress on the induction system. Ill contact you for a chat about the headers.

I note your HLM has 1 extended velocity stack and the others shorter to clear the guards.

Can you remind me if your car ran dcoe in period or that was your addtion during its recommision?
I know your car had some lightening work etc in period.. I forget about the induction.

 

[jdoclogan]

The length of velocity tubes are the same. My promotional Harrington Le Mans (HLM) came with and was raced with downdraft Zeniths (150s). The Weber setup was available as an option. I chose to incorporate the current setup. I still have the original carburetor setup and 1592 (numbers matching) engine. As you can see from the photo the original owner and race driver Greg Vederoff removed components to lighten the heavy HLM. It didn't do well on the short tracks throughout the West Coast in 1962 and retired at the end of the season.

 

[DanR]

I really like the headers you have fab'd....

 

[DanR]

All lengths should be 20 inches and come together with a 4 into 1 collector.

Doc, What size collector ?