Inlet Manafold part 2

Josh · backyard mechanic Joined: 04 Oct 2001 Posts: 602

Well what a waste of time that was... I tryed to weld that pipe on the bottom of where the steel t peice goes and Tryed to fill that hole under the thermostat and it just didnt wanna happen. I pressure tested it and the manafold leaked all over the place guys. My boss said it's because the manafold is cast alloy which makes sence.

Anyway i'm gonna start from scratch! 16mm flange (about 3mm will get machined off it because it'll warp and shit when I TIG weld it. I also am going to get a external thermostat housing made up. i'll probley use a 46mm OD pipe and It has a wall thinkness of 4mm so the ID is 38mm. i'll let ya's know how it goes

Josh · backyard mechanic Joined: 04 Oct 2001 Posts: 602

Also a quick question to any technical minded people... When I make this small plenum that the carby sits on top of... Should I make it fairly wide so that the runners on number 1 and 4 are closer to the same legnth as 2 and 3 or doesnt it really matter?

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

Hey Josh,

I dont want to crush your dreams about having a super duper inlet manifold for your ADM carb, but if you are going to the extent of making a custom job like you describe, then have you considered making an efi maniofld, maybe a quad throttle setup, using cheap holley throttle bodies, or old weber or dellorto carbs, and just taking the guts out.

Wouldn't be much harder at all compared to making it to suit a carb, and a fuel only computer is a sinch to setup.

some injector bosses welded on to suit easy camira cold start injectors, or something similar.

Or an off the shelf efi manifold, and once again, a fuel only computer.

Its just that you are going to so much trouble to mount this carb, and its just my opinion, but the sort of gains that I would hope from that much effort just wont be there.

Its a 2 barrel downdraught, trying to feed 4 inlet runners, so straight away, the flow is a compromise. Although if done well, it should flow as good as a 4ZE1 manifold for example, but not as good as a custom quad runner setup, with a big plenum and TB, or quad throttles.

Anyway, whatever you end up doing, I hope it works out for you.

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

True dat. I would look at what you are doing if you are going to that extent.

The main issue to deal with is the flow, which results in leaning out of cylinder 4 and sometimes 1. I wouldnt go into making a super dooper inlet and thermostat housing etc. unless you were really serious about sorting out a single carb manifold. I would continue with mucking around with the standard one, and making it a bit better.

And why cant it be TIG'ed. TIG welding is the most gentle welding you can perform, with the lowest heats etc. Why cant you use it??

Josh · backyard mechanic Joined: 04 Oct 2001 Posts: 602

Cast alloy is hard to TIG weld because the cast material sacrafices it's self for the extrusion that you are welding to it and therefore it bubbles ect... pain in the ass I'd say... Yer I know whats ya meen about the EFI set up... I'm just worried about how I would go about getting then injector boss's??? Anyone know who sells them and how much and then theres the matter of converting to an XF throttle body and hi pressure fuel pumps and then I gotta get my head around one of them incar engine management controllers.... AND THEN if i do all that i might as well have a turbo hahaha

TXcoupe · petrol head Joined: 05 Oct 2001 Posts: 1675

are heads better quality alloy then the manifolds? i know they are a better finish. Josh keep at it. Maybe use thicker TIG rods? becuase if i can get my 308 manifold repaired you should be able to repair/modify the gemini one.