Engine bogs at higher RPM - Page 5 - Chevelle Tech
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post #61 of 71 (permalink) Old Jun 18th, 20, 12:26 PM
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Kerry
 
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Re: Engine bogs at higher RPM

You should put a timing tape on the balancer, so that you can see what the timing advances to at higher rpm. If the timing is not advanced enough at higher rpm, the engine will act like it hits a rev limiter. It does require it to be quite a few degrees off though.
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post #62 of 71 (permalink) Old Jun 18th, 20, 1:23 PM
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Rick
 
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Re: Engine bogs at higher RPM

Forget about setting idle timing. Put a tape on the balance and set timing to 34-36* at about 3000 rpm. Let it idle down and put your light on it just to see where it is. If it starts good and turns off good give it a test drive.
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post #63 of 71 (permalink) Old Jun 18th, 20, 1:39 PM
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Henry
 
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Re: Engine bogs at higher RPM

IMO. Why not just take the vehicle and get it on a good chassis dyno for analysis.
Problem(s) likely can be pinpointed fairly quickly without a bunch of fruitless test drives back and forth down the street.
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post #64 of 71 (permalink) Old Jun 19th, 20, 2:14 AM
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Re: Engine bogs at higher RPM

Quote:
Originally Posted by 72 SS 555 FI View Post
IMO. Why not just take the vehicle and get it on a good chassis dyno for analysis.
Problem(s) likely can be pinpointed fairly quickly without a bunch of fruitless test drives back and forth down the street.
Fruitless test drives are free.
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post #65 of 71 (permalink) Old Jun 19th, 20, 2:18 AM
 
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Re: Engine bogs at higher RPM

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Originally Posted by B52bombardier1 View Post
Is the spark advance working?

Rick

Sent from my SM-G965U using Tapatalk
I agree
My first thought was the spark is not advancing,
easy to check with a timing light
you rev the engine you will see the timing advance IF NOT ...That is the problem.
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post #66 of 71 (permalink) Old Jun 19th, 20, 7:27 AM
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Henry
 
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Re: Engine bogs at higher RPM

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Originally Posted by 65cayne View Post
Fruitless test drives are free.
Touche'
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post #67 of 71 (permalink) Old Jun 19th, 20, 9:42 AM
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Re: Engine bogs at higher RPM

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Originally Posted by 65cayne View Post
Fruitless test drives are free.
True....but your time is valuable....and we only have a limited amount of it during our lifetime.

'69 Malibu 383/TCI TH350/8.2 3.36 Eaton Posi. Street Edge 10" 2800, E-Tec 170s, Custom Mike Jones HR Cam, RPM Air-Gap, StreetAvenger 770, Pertronix HEI, Hedman 1 5/8" Headers, Moser Axles, PMT 1320R Kit. [email protected] 111 MPH, 1.6865 60 ft, Nitto 555
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post #68 of 71 (permalink) Old Jun 19th, 20, 11:44 AM Thread Starter
Rick
 
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Re: Engine bogs at higher RPM

@pockets and @mrpaticular I love this suggestion, easy enough to do and I had no idea the timing should advance that far, so I'm all over this test!!!

@72 SS 555 FI Thank you for the suggestion, it's a good one, but quite honestly the test drives are hardly fruitless, you have no idea how much fun I'm having driving the car around, even with the bog. A neighbor who I didn't know flagged me down to say hello and admire my car, it turns out he's a total car guy and now we're in contact. I may end up having to dyno test in the end, but I'm learning a ton, having fun, and meeting new people, so not fruitless at all. To your point though, time is money.

@VonDutch It is advancing, I did check that, but as others pointed out, maybe not nearly enough, so the tape on the balancer is the next test for sure.

Side note to all, I picked up the flare fitting that is needed to connect a tube to the metal fuel line to safely test fuel flow to a container. That test will happen over the weekend.
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post #69 of 71 (permalink) Old Jun 19th, 20, 12:07 PM
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Re: Engine bogs at higher RPM

Dyno test is about $300. for 2 hours in LA. That includes set up and discharge time. After the first 2 hours it is over $100 for each hour. Or you can get the entire day for $600-800. Average cost about $500 for a tune.


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post #70 of 71 (permalink) Old Jun 20th, 20, 10:46 PM Thread Starter
Rick
 
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Re: Engine bogs at higher RPM

I put the timing tape on the balancer and did a preliminary test without the analyzer hooked up, so I was guessing at the RPM. With the engine revved up to what felt like around 3k, the timing advanced to about 26 degrees, which seems to low, so tomorrow I'm going to hook up the analyzer at the same time so I can be sure I'm at 3k RPM and then advance the timing to 34 degrees.

I also looked carefully at the carburetor and realized that the choke is opening all the way but I'm not sure if all the other mechanical pieces are operating as they should. In fact, I thought for a minute that one piece (cog) was preventing the secondaries from opening, but I warmed up the motor, wired the choke wide open and went for a drive and no luck, it still stalls.

I have the fittings to do the fuel pump test but I need to look up how long to keep the motor turning over and how much fuel to expect to be delivered in that time.
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post #71 of 71 (permalink) Old Jun 20th, 20, 11:27 PM
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Kerry
 
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Don’t just rev the engine to 3000 rpm.
You need to rev it up until the timing stops advancing.

Also, remove the cap and ensure the advance mechanism moves freely.
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