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Bmptree
Samba Member
Joined: November 24, 2006
Posts: 39
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 Posted: Sat Jun 30, 2018 7:38 pm Post subject: Wont Rev Past 3 Grand |
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I have a 78 Bay with a 2 litre fuel injected motor.
recent complete build. approx 5000 kms
Its lifted 2 1/2 inches with 215/15 bfg's
I thought it felt sluggish because of the tires, but recent realized it wasnt rev ing over 3000 rpm
Sitting, in neutral, I can accelerate up to 3500 rpm, at 1/2 throttle/pedal, and then if craps out and drops and stays around 3000
Ive ......
swapped out three different dizzies, with different variations of new points, old points, condensors and electronic
swapped out coils
swapped out air flow sensor
pulled and cleaned throttle body
swapped out dual relays
checked compression
removed muffler
checked for full throttle cable
check fuel pressure
changed fuel filter
still same issue ..... ugh
you guys got anything? |
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aeromech
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Joined: January 24, 2006
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Location: San Diego, California
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| Posted: Sat Jun 30, 2018 8:12 pm Post subject: Re: Wont Rev Past 3 Grand |
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What’s the fuel pressure at high throttle under load?
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airschooled
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| Posted: Sat Jun 30, 2018 9:25 pm Post subject: Re: Wont Rev Past 3 Grand |
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Check to make sure your spark plug wires are 1-4-3-2 in CLOCKWISE orientation.
Robbie
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Tcash
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Joined: July 20, 2011
Posts: 12844
Location: San Jose, California, USA
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busdaddy
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Joined: February 12, 2004
Posts: 51128
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sun Jul 01, 2018 9:36 am Post subject: Re: Wont Rev Past 3 Grand |
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Hydro lifters?, or solids?
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Bmptree
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Joined: November 24, 2006
Posts: 39
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| Posted: Tue Jul 03, 2018 10:14 pm Post subject: Re: Wont Rev Past 3 Grand |
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So, the fuel pressure was 2 psi over Bentley specs, both at idle and accel, and checked fuel pressure regulator. They are hydraulic lifters.
It runs great, but poops out at 3400 rpm. It flutters slightly at top rev, then drops and stays at 3000-3200 in neutral and driving |
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cmonSTART
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Location: NH
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| Posted: Wed Jul 04, 2018 4:04 am Post subject: Re: Wont Rev Past 3 Grand |
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I would hate to suggest it, but broken valve spring? Were the springs re-used?
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busdaddy
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Joined: February 12, 2004
Posts: 51128
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Jul 04, 2018 6:33 am Post subject: Re: Wont Rev Past 3 Grand |
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How many turns preload on the lifters?
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Bmptree
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Joined: November 24, 2006
Posts: 39
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| Posted: Wed Jul 04, 2018 7:01 am Post subject: Re: Wont Rev Past 3 Grand |
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The motor was built by a shop. I'm guessing the usual 1.5 or 2 turns.
I'm rechecking all valves today. Hope not to find any broken springs. |
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Jul 04, 2018 7:05 am Post subject: Re: Wont Rev Past 3 Grand |
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Try temporarily resetting them all to 1/2 turn for a test and see if it helps, if the problem goes away we'll have to figure out which one is acting up.
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SGKent 
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Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Wed Jul 04, 2018 9:00 am Post subject: Re: Wont Rev Past 3 Grand |
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Do make sure the tach is accurate. There is a rev limiter in the ECU at 5400 RPM. Also if it has a catalytic converter that is plugged it will limit the RPM because of back pressure.
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Bmptree
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Joined: November 24, 2006
Posts: 39
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| Posted: Wed Jul 04, 2018 10:09 am Post subject: Re: Wont Rev Past 3 Grand |
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| Tach is fine. Matched dwell meter. No cat |
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Bmptree
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Joined: November 24, 2006
Posts: 39
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| Posted: Wed Jul 04, 2018 10:13 am Post subject: Re: Wont Rev Past 3 Grand |
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| busdaddy wrote: |
| Try temporarily resetting them all to 1/2 turn for a test and see if it helps, if the problem goes away we'll have to figure out which one is acting up. |
Are you saying with less adjust it should run fine but one lifter will act up?
Pulled #4 and exhaust has weird wear. Not oval pattern? |
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Jul 04, 2018 10:25 am Post subject: Re: Wont Rev Past 3 Grand |
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Weird wear on the lifter face?, that may be another issue.
If a lifter is pumping up it can temporarily stay open and drop a cylinder at higher revs, it feels like it has a governer on the engine, usually a little rough or shaky when it happens as well. Reducing the preload temporarily often solves the problem by allowing it to flush itself, but if it still does it after resetting to 1.5 turns you need to determine which cylinder is dropping to locate the faulty lifter.
Don't mix up any lifters, they have to remain in the same bore for the life of the cam.
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Tcash
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Joined: July 20, 2011
Posts: 12844
Location: San Jose, California, USA
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| Posted: Wed Jul 04, 2018 1:34 pm Post subject: Re: Wont Rev Past 3 Grand |
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Lube your distributor lately?
Lubing the Distributor
Does your rotor look like this?
Rev speed limiting distributor rotor 1 234 332 208
Happy 4th
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Bmptree
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Joined: November 24, 2006
Posts: 39
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| Posted: Wed Jul 04, 2018 7:04 pm Post subject: Re: Wont Rev Past 3 Grand |
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So, I was at a reputable shop who checked lifters/valves and determined pull L possible cam failure. Waiting on an ecu/afm to arrive to cross those of list of exterior failures
ps: yes it's lubed and no, mines normal |
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Spike0180
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Location: Detroit, Michigan
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| Posted: Wed Jul 04, 2018 9:38 pm Post subject: Re: Wont Rev Past 3 Grand |
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Youve checked for vacuum leaks, correct? I would think a vacuum leak after the afm, could cause a super lean condition causing a pop at 3400 and losing power at 3200. Does the power seem low? No... you said it ran fine up till 3000rpm... hmm... if check vacuum leaks still.
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Tcash
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Tram
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| Posted: Thu Jul 05, 2018 9:09 am Post subject: Re: Wont Rev Past 3 Grand |
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Don't know about that T., not in my experience. If it was almost completely flat, then yes. Just starting to wear? That's more like having carb jets or venturi that's too small for the engine- OK to a point, then it chokes and acts just like the OP is describing.
The other clue is the "funny wear" on the one follower the OP mentioned. Cams and followers just don't wear independently of each other for no reason.
I'll be really surprised if this doesn't wind up being a cam and lifter replace.
For the record, every worn Type 4 cam I've ever seen was in a solid lifter engine. This was a lot of the reason VW went hydraulic. It's been 20 years since I was elbow deep in these engines, though, aside from a few stragglers. The older things get, stuff starts wearing that never wore before. Look at our bodies.
OP, didn't you say this engine was just overhauled? Did they replace the cam and followers with fine aftermarket units or "rebuilt" ones, by chance?
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Bmptree
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Joined: November 24, 2006
Posts: 39
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| Posted: Thu Jul 05, 2018 11:09 am Post subject: Re: Wont Rev Past 3 Grand |
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Thank you so for all your input.
Muchly appreciated
All new parts I believe, except crank |
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