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MG MGB GT V8 Factory Originals Technical - V8 edelbrock 500 jetting question

Can anyone advise me what jetting to set up a edelbrock 500 on a edelbrock performer manifold using a stock 3.5 engine please
regards
mark
Mark Mathiesen

Hi
I have the same set up as you as does Simon mentioned below and what RPI recommends.
When I changed the jets over from stock I talked to a fellow here in Western Canada who use to be the trouble shooting 'God' for Holly carbs in Western Canada. When the factory wasn't able to fix a carb problem they sent it to him. He told me that even identical cars could require different settings.
In my case since I changed the 'Rods' I have increased gas mileage and no noticeable lack of power.
Hope it helps

Bruce


Primaries Secondaries Rods
Stock .086 (#1423) .095 (#1425) .065 x .052 (#1460)
Bruce .086 (#1423) .095 (#1425) .067 x .055 (#1463)
Simon .080 (#1421) .086 (#1423) .062 x .052 (#1441)
RPI .080 (#1421) .095 (#1426) .065 x .052 (#1441)
Bruce Mills

Bruce has the correct numbers. As he mentioned, different calibrations for different cars. As well, I have to deal with emissions testing in the Vancouver area whereas he lives up the coast and, fortunately, doesn't. This will help to explain the leaner settings in my car.

RPI doesn't change their secondaries from stock but it did help in my car.

Cheers
Simon
Simon Austin

Hi Mark,
Edelbrock have an excellent users manual on their website for the Performer series carburretors.I spent some time calculating the differential areas between the jet and rod of various combinations, and related them to Edelbrock matrix for the 1404 and other sources such as RPi and Simon who were most informative.What we all seem to find is that the 1404 is overly rich out the box, both on the primary and secondary venturis; this is not altogether suprising as the 1404 is sized for the 289 to 302 ci range of engines.However you will get a first time start out of the factory settings, which will allow a new camshaft to bed in at least; the factory setting is not recommended for prolonged road use owing to excessive richness and bore washing.
Basically, you could follow the leaner line in both cruise and power modes through the matrix; a reasonable calculated progression is as follows:

Matrix#6(leaner)
Prim .086(1423) jets with .067x .055 rods(1463)
Sec .095 jets(1426)
I am using this at present on a heavily modified 3.6l SD1 engine with a Performer manifold, but it's still too rich.( Same as Bruce)(Probably good for a 3.9l motor)

Matrix#11(leaner)
Prim..083 (1422) jets with .065x.052 rods(1460)
Sec .095 jets(1426)or .092(1425)
I think this will be good for a performance(fast road)3.5l motor

RPi setting( for standard engine)(leaner)
Prim .080 (1421) jets with .062x.052 rods(1441)
Sec .095 jets(1426)

Matrix #10( leaner)
Prim .083 jets(1422) with .067x.055 rods(1463)
Sec .095(1426) or .089(1424) jets

Simon's setting ( the leanest)
Prim .080 jets(1421) with .062x.052 rods(1441)
Sec .086 jets(1423)

I hope this will help you and others to get a handle on these wonderful carbs, which betray not a little of their Weber parentage..They really do make the Rover V8 perform.At the end of the day, the setting can only really be optimised on a rolling road or by back to back tests at the track, with a possibility that they would need changing between summer and winter.

Best Regards,
Tony.





TONY FREW

This thread was discussed between 05/08/2006 and 08/08/2006

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