69 427 Total timing
Tech Contributor
Joined: Aug 1999
Posts: 14,380
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From: At my Bar drinking and wrenching in Lafayette Colorado
Note all the other problems that can cause the issue you describe as outlined above. I can build you a good carb, but any one of those other issues will cause the problem to persist...
Lars
Lars
Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
I'll send you all the specs of the engine with the carb.
Mike
Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
Yup.
The following is a partial list of issues that can cause that problem:
Lars
The following is a partial list of issues that can cause that problem:
- Plugged or restricted fuel tank strainer (aka, "sock") in the tank
- Kinked or collapsed rubber line section between the tank and the frame line
- Kinked or collapsed rubber line section betwen the frame line and the fuel pump
- In-line fuel filter installed between tank and pump
- Inadequate fuel pump capacity or faulty pump (low fuel pressure at WOT)
- Incorrect fuel pump installed without vapor return
- Plugged fuel filter
- 2 filters installed between pump and carb (in-line filter with in-carb filter)
- Low-flow inlet seat installed in carb
- Low float level
- Incorrect secondary rods
- Incorrect secondary airvalve spring tension
- Incorrect choke pulloff bleed rate
Lars
The carb filter has a check ball in it.
Last edited by Z06CE; Feb 24, 2020 at 05:53 PM.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
No. You run one or the other, but not both. If you have the in-line filter, remove the in-carb unit. It could be causing enough restriction and pressure drop to cause the problem you describe,
Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
Oh well, out it comes
Ill temove it when I disassemble the carb to prep for shipping
Last edited by Z06CE; Feb 24, 2020 at 07:15 PM.
Safety Car
Joined: Apr 2006
Posts: 4,057
Likes: 421
From: BC
In stock factory configuration did GM remove the carb filter on the L36 because of the factory inline filter or did it come from the factory with both? I remember a few years back having a problem with those Napa anti-drain back check ball filters on my 69 427 L36. Under full throttle it would start to run out of fuel at the top of second gear until I changed to a carb filter without the check ball. I always thought it came from the factory with both filters....
I also think the design and materials on that Napa filter were changed awhile back to be less restrictive as the older ones and new ones differ in appearance.
I also think the design and materials on that Napa filter were changed awhile back to be less restrictive as the older ones and new ones differ in appearance.
Last edited by CanadaGrant; Feb 24, 2020 at 11:16 PM.
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Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
In stock factory configuration did GM remove the carb filter on the L36 because of the factory inline filter or did it come from the factory with both? I remember a few years back having a problem with those Napa anti-drain back check ball filters on my 69 427 L36. Under full throttle it would start to run out of fuel at the top of second gear until I changed to a carb filter without the check ball. I always thought it came from the factory with both filters....
recently removed that filter and installed the napa brand check ball filter. Didn't notice a problem until recently becauce I was breaking in a new rear gear and wasn't getting on the engine. I started noticing the issue recently when i was in 2nd gear and at wot full load. The engine fell flat on its face....no power
Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
Well you were right about the check ball napa filter in the QJ inlet housing. It was restricting flow at wot.
Thank you for your help
Heres the culprit.
I'll be sending the qj out to you this week.
Mike
Last edited by Z06CE; Feb 25, 2020 at 12:16 PM.