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cam vs howell fuel injection
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Posimoto View Drop Down
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Points: 71 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Posimoto Quote  Post ReplyReply Direct Link To This Post Posted: Dec/21/2014 at 7:23pm

Originally posted by tufcj tufcj wrote:

It should idle at 11" of vacuum with no problem. Is the IAC (idle air control) working? The computer should adjust the IAC to maintain a 750 RPM idle. If it's stuck in an open state, you'd get a lean condition.

Bob
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I'll look into this tomorrow after work and report back.

Originally posted by tsanchez tsanchez wrote:


The pressure should be 9-13 and when you pinch return should go to about 20.

If my finding of 17.5 tells me I may have a restriction in the TB or return line. What if anything does pinching the return line and finding 8.5 tell me?



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Did you look at the IAC? The pintle on them does get carboned up and degrade its ability to control the idle which it does by bleeding vacuum as required. An engine that was not well maintained could certainly have an IAC issue. Often times, you can just clean it and the passages to it up and it will return to normal function.
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Posimoto View Drop Down
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Points: 71 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Posimoto Quote  Post ReplyReply Direct Link To This Post Posted: Dec/22/2014 at 8:19am
I agree, no telling how long the PO ran rich with the intake leak as it was. I'll clean and inspect later today and post my findings.
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Points: 71 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Posimoto Quote  Post ReplyReply Direct Link To This Post Posted: Dec/22/2014 at 9:11am
Originally posted by Posimoto Posimoto wrote:

If my finding of 17.5 tells me I may have a restriction in the TB or return line. What if anything does pinching the return line and finding 8.5 tell me?


If there were a restriction in the return line and I pinched the line the fuel pressure would stay at 17.5. I would say the restriction is in the TB.

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Points: 188 		Post Options Post Options   Thanks (0) Thanks(0)   Quote RADAMX Quote  Post ReplyReply Direct Link To This Post Posted: Dec/22/2014 at 9:19am
It may sound stupid but if you pinched your return line and the pressure dropped I would check if the lines are backwards. it should never drop if you restrict the line after the gauge
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Points: 4092 		Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj Quote  Post ReplyReply Direct Link To This Post Posted: Dec/22/2014 at 10:13am
Howell does recommend a 3/8" feed and 5/16" return. The feed will be the larger line. I think the fittings on the back of the TB are different sized also, with the feed being larger.

Bob
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Posimoto View Drop Down
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Points: 71 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Posimoto Quote  Post ReplyReply Direct Link To This Post Posted: Dec/22/2014 at 2:15pm

Originally posted by RADAMX RADAMX wrote:

It may sound stupid but if you pinched your return line and the pressure dropped I would check if the lines are backwards. it should never drop if you restrict the line after the gauge


Funny you should say this, early Saturday morning I woke up around 3am thinking about the possibility the PO had the lines switched. I had to check to be sure. I inspected the lines from the TB to the tank and they looked correct but thought it best to swap the line just the same. Turns out the lines were correct and I can tell you first had the engine will not run with the lines hooked up incorrectly.


Originally posted by tufcj tufcj wrote:

Howell does recommend a 3/8" feed and 5/16" return. The feed will be the larger line. I think the fittings on the back of the TB are different sized also, with the feed being larger.

Bob
tufcj

This is correct. I still believe it's a restriction in the TB

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Points: 4303 		Post Options Post Options   Thanks (0) Thanks(0)   Quote tsanchez Quote  Post ReplyReply Direct Link To This Post Posted: Dec/22/2014 at 4:29pm
Driver side fitting should be pressure in, and it should be at 12 lbs or so, if not regulator is bad or you have a pump that is supplying too much pressure/volume for regulator. The gage should be hooked to driver side port and if you pinch pass side it should go up. If not then determine which actually is pressure side and return and physically make sure the lines are clear.
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Points: 71 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Posimoto Quote  Post ReplyReply Direct Link To This Post Posted: Dec/22/2014 at 5:07pm
Driver side = fuel inlet
Passenger side = fuel return
Gauge setup = driver side
First test 17.5 on driver side
Pinched return line 8.5
Swapped lines, gauge on driver side = 0 psi
The lines were originally hooked up correctly
Correct howell fuel pump

Talked to howell tech, gave him the above info and he said something is going on with the meter system. Told me to removed the meter cover ( top half of TB) and send it in and he would send out another. The exchange certainly can't hurt, and will rule out the meter circuit if symptoms continue. As soon as it arrives I'll post results, should arrive sometime next week. I'll wait until I install the meter cover before I check and clean the IAC so as not to mix up which one may have fixed the issue.




Edited by Posimoto - Dec/22/2014 at 5:11pm
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Points: 71 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Posimoto Quote  Post ReplyReply Direct Link To This Post Posted: Dec/29/2014 at 4:45pm

Originally posted by Sonic Silver Sonic Silver wrote:

With the specs that you have mentioned, your cam sounds like Crane #H-260-2. At .050 it had 204/216 duration, .456-.484 lift. It calls for 8 to 9.5 comp ratio. That cam is similar to the Edelbrock Performer with 3 degrees less overlap. I think that about 15 inches vacuum at 700 rpm is what I had with the Edelbrock cam in a 360, and about 165-170 cranking compression with 9.2:1 cr.

I did some more research and the cam is a Crane H-260-2. Crane tech said I should have between 15”-17” vacuum so that rules out the cam.

Originally posted by tufcj tufcj wrote:

Howell does recommend a 3/8" feed and 5/16" return. The feed will be the larger line. I think the fittings on the back of the TB are different sized also, with the feed being larger.

Bob
tufcj

I agreed, so I checked the lines and found the feed line was 5/16” from the fuel pump to the TB. I also found a short 1/4” return line from the filter to the tank. I was ready to change out the lines until I found howell FI installation directions online. Howell calls for 5/16” feed line and supplies it with their kit, also recommends 1/4” to 5/16” return line. The barb on the TB feed side is 3/8” so I called tech and they confirmed the use of 5/16” feed, 1/4" - 5/16" return. Tech said he uses 5/16" feed on his FI.

I sent in the metering cover (injectors/regulator) to howell last week and just received a call letting me know the injectors seem to be spraying fine and the regulator holding at 12psi. Basically telling me all is working as it should on that end.

The first thing I'm going to do when I get my fuel meter cover back from howell is retest the fuel pressure with another gauge to rule out a faulty gauge. I'll also do a voltage drop test at the fuel pump, then move onto the tank pickup.
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