car not fastest with foot down : MGB & GT Forum : The MG Experience

car not fastest with foot down #1
Spitfire mgb Christopher Seely Seattle, WA, USA Sign in to contact 1963 Triumph Spitfire 4 (MkI) 1967 MG MGB 1971 BMW 2002 1991 Saab 900	Topic Creator (OP) Mar 31, 2015 08:56 PM Joined 10 years ago 825 Posts

Alright, so here it is. My 67 mgb is running g great after its ring job, idles well, nice torque, starts right up no problem, no odd noises, so far very happy with it. However, when I put my foot all the way to the floor, the car produces a louder noise, but doesn't go a whole lot faster. It seems that I get the best acceleration is when my foot is about halfway down. What could this be? Timing is good, maybe a bad vacuum advance, or carbs slightly rich? (Although there is no other indication leading to this)
Thanks,
Chris

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Re: car not fastest with foot down #2
spikemichael Michael Caputo Canton, IL, USA Sign in to contact 1973 MG MGB "Freebie" 1973 MG MGB 1974 MG MGB "Spike" 1976 MG MGB "Cecil" & more	Mar 31, 2015 10:41 PM Top Contributor Joined 14 years ago 19,079 Posts

Are you SURE about that timing?

Are your carbs balanced?

Michael J. Caputo
'79, '77, '76, '74.5 (rubber dual SU), and '73 owner. Extensive experience in 12v Audio System design and installation. Vendor of Regalia and Promotional Products since 1993. Supplier of Accessories to MOSS. Forum Member since 2009; with a warped sense of humor since birth. Publisher of the annual MGB & GT Calendar, mailed worldwide.

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Re: car not fastest with foot down #3
riley1489 Bruce H Great White North, QC, Canada Sign in to contact 1953 Jaguar XK120 1959 Riley 1.5 "King George" 1973 MG MGB	Apr 1, 2015 06:54 AM Top Contributor Joined 12 years ago 26,297 Posts

I would investigate the state of the ignition components and general tuning, carburetor balance etc.

B

Life's most persistent and urgent question is, "What are you doing for others?"

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Re: car not fastest with foot down #4
B-racer Jeff Schlemmer Shakopee, MN, USA Sign in to contact 1950 Willys Jeep Pickup "Ratrod" 1964 Land Rover Series IIA 1971 MG MGB	Apr 1, 2015 07:30 AM Top Contributor Joined 17 years ago 20,006 Posts

Cam timing changed? Valve lash correct? Engine timing and carb balancing are critical.

jeff@advanceddistributors.com

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Re: car not fastest with foot down #5
ex-tyke Graham Creswick Chatham, ON, Canada Sign in to contact 1976 MG MGB	Apr 1, 2015 07:53 AM Top Contributor Joined 15 years ago 2,748 Posts

Clutch slipping?

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Re: car not fastest with foot down #6
Spitfire mgb Christopher Seely Seattle, WA, USA Sign in to contact 1963 Triumph Spitfire 4 (MkI) 1967 MG MGB 1971 BMW 2002 1991 Saab 900	Topic Creator (OP) Apr 1, 2015 08:09 AM Joined 10 years ago 825 Posts

Clutch is definitely fine, carbs were balanced recently, and all new distributor components at last summer. I think the next step is to find an open stretch of road and time the car to what feels fastest. This is usually the most effective method.

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Re: car not fastest with foot down #7
ingoldsb Terry Ingoldsby Calgary, AB, Canada Sign in to contact 1971 MG MGB	Apr 1, 2015 12:06 PM Top Contributor Joined 20 years ago 20,141 Posts

I would be concerned about cam timing. However, another possibility is that your fuel pump can't keep up with the higher air flow and the mixture is leaning out when you open the butterflies all the way. Test your pump by doing a flow test into a container.

Terry Ingoldsby
terry.ingoldsby@DCExperts.com

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Re: car not fastest with foot down #8
Spitfire mgb Christopher Seely Seattle, WA, USA Sign in to contact 1963 Triumph Spitfire 4 (MkI) 1967 MG MGB 1971 BMW 2002 1991 Saab 900	Topic Creator (OP) Apr 1, 2015 12:37 PM Joined 10 years ago 825 Posts

Can timing would make sense, although the can is stock and I have never played with the cam timing.

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Re: car not fastest with foot down #9
Dell-WA Delbert Golightly spanaway, WA, USA Sign in to contact	Apr 1, 2015 01:05 PM Joined 10 years ago 369 Posts

Chris..........you shure you replaced the carbie filters? No filters would allow you to hear the carbies suck air. .......hearing challenged Dell

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Re: car not fastest with foot down #10
Spitfire mgb Christopher Seely Seattle, WA, USA Sign in to contact 1963 Triumph Spitfire 4 (MkI) 1967 MG MGB 1971 BMW 2002 1991 Saab 900	Topic Creator (OP) Apr 1, 2015 01:10 PM Joined 10 years ago 825 Posts

I have used k&n's on the carbs that should be OK, although I have never cleaned or oiled them.

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Re: car not fastest with foot down #11
ingoldsb Terry Ingoldsby Calgary, AB, Canada Sign in to contact 1971 MG MGB	Apr 1, 2015 02:51 PM Top Contributor Joined 20 years ago 20,141 Posts

Quote: Can timing would make sense, although the can is stock and I have never played with the cam timing.

I think what we are concerned about is if the camshaft were inadvertently timed one (or more) tooth off. It comes down to how careful you were when you assembled the timing chain and gears.

Definitely check your fuel flow rate before you go delving into the engine!

Terry Ingoldsby
terry.ingoldsby@DCExperts.com

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Re: car not fastest with foot down #12
Spitfire mgb Christopher Seely Seattle, WA, USA Sign in to contact 1963 Triumph Spitfire 4 (MkI) 1967 MG MGB 1971 BMW 2002 1991 Saab 900	Topic Creator (OP) Apr 1, 2015 02:59 PM Joined 10 years ago 825 Posts

That's the thing though, my fuel pump is new last year. I might have to check the timing again. Shouldn't it be like 13 at idle with no vacuum advance?

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Re: car not fastest with foot down #13
supernatural jean gagne St Andrews, NB, Canada Sign in to contact 1971 MG MGB V6 Conversion "Supernatural"	Apr 1, 2015 03:03 PM Joined 14 years ago 535 Posts

Fuel filter clean and flowing in the correct direction?

Eschew the dominating paradigm -me

because

When you buy the ticket, you take the ride -Hunter S. Thompson

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Re: car not fastest with foot down #14
CederholmC Carl E. Cederholm BROOKLYN, NY, USA Sign in to contact 1953 Chevrolet Bel Air "The Sled" 1969 MG MGB GT "Supercharged" 1972 MG MGB "Brooklyn B" 1981 Toyota Land Cruiser	Apr 1, 2015 03:53 PM Joined 19 years ago 3,473 Posts

Doubt it's directly related to you issue, but without oil, K&N filters are useless. The filters need the oil to trap dirt.

~ Carl

In reply to # 2954014 by Spitfire mgb I have used k&n's on the carbs that should be OK, although I have never cleaned or oiled them.

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Re: car not fastest with foot down #15
Spitfire mgb Christopher Seely Seattle, WA, USA Sign in to contact 1963 Triumph Spitfire 4 (MkI) 1967 MG MGB 1971 BMW 2002 1991 Saab 900	Topic Creator (OP) Apr 1, 2015 04:26 PM Joined 10 years ago 825 Posts

I bought the carbs used from somebody on the site. When I say not oiled, I just mean I myself have never oiled them although they have been oiled before.

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