Any experience with Edelbrock 38783 Throttle body?

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Philip Lochner
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Any experience with Edelbrock 38783 Throttle body?

Post by Philip Lochner »

I'm using this TB on my Jensen Interceptor Mk3 (Mopar 440) but I'm not having joy with the Hitachi PWM idle valve that comes with this unit. MS-2 is controlling the EFI.

I specifically ordered the 38783 BECAUSE it comes with the PWM idle valve and not a stepper IAC as the 3878 does.

I'm not sure the unit I have (brand new) is working right. I removed it from the TB and in its unpowered state the valve is half open as per pic below. Is this right? Should it not be fully closed in the unpowered state?

Also, when I apply 12V directly over the two terminals (briefly), I can see/hear/feel the valve being pulled towards the solenoid but not very hard. The solenoid does not feel "strong" enough to pull the valve open against the vacuum from the engine at idle. Is this how its meant to be?

Image
Best regards
Philip
'74 Jensen Interceptor Mk3 (MS-2 EFI, GPIO + GM 4L60e)
'80 Jaguar XJS 5.3L V12* (MS-2 EFI + dual EDIS-6)
and about 10 others.
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Matt Cramer
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Re: Any experience with Edelbrock 38783 Throttle body?

Post by Matt Cramer »

Some valves only operate correctly when they have vacuum applied. This one may fall into this category.
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Philip Lochner
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Posts: 96
Joined: Thu Feb 16, 2006 5:18 am
Location: South Africa
Contact:
Contact Philip Lochner

Re: Any experience with Edelbrock 38783 Throttle body?

Post by Philip Lochner »

Thanks Matt

It looks like you are right. It does look like the engine is getting too much idle air via the PCV circuit, and thus too little air is having to pass via the idle valve. I do seem to be getting more "reaction" from it now, still not what I want but enough to give me hope.

The main throttle plates are cracked open still, so I think I must gradually close them off and try to open the IAC more. Pursueing this course.
Best regards
Philip
'74 Jensen Interceptor Mk3 (MS-2 EFI, GPIO + GM 4L60e)
'80 Jaguar XJS 5.3L V12* (MS-2 EFI + dual EDIS-6)
and about 10 others.
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