need help in Tx

[ThatOneGuy]

A little back story: picked up a '78 Scout II w/392 about a year ago. The previous owner had dumped an ungodly amount of money on this truck and his wife finally said it had to go. I got it running and it ran great until the carb finally gave out. After reading that the carters were 800cfm I figured an edelbrock 750 was a good choice.

I have had nothing but problems since. Once warmed up it will idle perfectly. It will free rev perfectly. Once it was put under load it had no power and occasionally would backfire out the carb. By occasionally I mean it has shredded the filter I installed and the underside of my hood is black. However it was sporadic and vacuum was good. So I don't believe a stuck valve is to blame.

Thinking it was possibly the ignition system I replaced almost everything. Still backfired. Set timing according to the manual a total of 4 times. Didn't change.

It has been sitting in my parents driveway for about 5 months. As of the last couple days I have installed a new holly 600cfm carb and stocked up on gaskets and fluids to patch the many leaks it has.

This of course provoked a father son chat, as secretly my father and a friend of his from work have been drooling over it. After the long heart to heart I've agreed to let them take it on as a long term "family" project.

Short version: I need someone from the dfw area that is willing to come out and check this thing over.

Give us some direction as to what parts/areas to look at. What tends to be problem spots on internationals. What parts should be used, and a few general pointers.

If ya work for beer that's a plus. If not, we can work something out.

 

[Rusty Scout]

Was the original carb a 4 barrel carter thermoquad? I must be one of the few but the tq on my 345 has always done me right. If I were you I would get in touch with ihonlynorth and get a carb that is already dialed in for a 392. Or contact them and see if they can get what you got dialed in. Or if you want to get her done today search it out in the forums here for some answers. Do some browsing here: http://www.forums.IHPartsAmerica.com/carb-tech/ And id what you got first.


Take some pictures so we can get you started.

 

[Michael Mayben]

a little back story: picked up a '78 Scout II w/392 about a year ago. The previous owner had dumped an ungodly amount of money on this truck and his wife finally said it had to go. I got it running and it ran great until the carb finally gave out. After reading that the carters were 800cfm I figured an edelbrock 750 was a good choice.

I have had nothing but problems since. Once warmed up it will idle perfectly. It will free rev perfectly. Once it was put under load it had no power and occasionally would backfire out the carb. By occasionally I mean it has shredded the filter I installed and the underside of my hood is black. However it was sporadic and vacuum was good. So I don't believe a stuck valve is to blame.

Thinking it was possibly the ignition system I replaced almost everything. Still backfired. Set timing according to the manual a total of 4 times. Didn't change.

It has been sitting in my parents driveway for about 5 months. As of the last couple days I have installed a new holly 600cfm carb and stocked up on gaskets and fluids to patch the many leaks it has.

This of course provoked a father son chat, as secretly my father and a friend of his from work have been drooling over it. After the long heart to heart I've agreed to let them take it on as a long term "family" project.

Short version: I need someone from the dfw area that is willing to come out and check this thing over.

Give us some direction as to what parts/areas to look at. What tends to be problem spots on internationals. What parts should be used, and a few general pointers.

If ya work for beer that's a plus. If not, we can work something out.

A few comments...

The oem carb was a carter thermoquad, a completely different animal as compared to the edelbrock you installed which is way too fat a carb for that engine. This whole "cfm" deal really scruus with folks who don't understand this stuff. The edelbrock simply could not be made to work successfully on that engine and depending upon the intake manifold it's not even a correct match. The tq was a total emissions carb and calibrated as such. The edelbrock is simply a clone of a carter afb and is a total performance calibration and is way too much carb overall (not just in the cfm department). The edlebrock carb is not a spreadbore item and it's not a squarebore carb either, it's a bastard.

If the edelbrock you installed is a clone of the rochester quadrajet, then it is a proper spreadbore design and is a match for the IH spreadbore manifold. But it's a total performance calibration and again, without extensive work is not suitable for that engine. The edelbrock quadra-clone has not been produced in the last six years or so.

As for the Holley application, that would be totally dependent upon which Holley list number is installed. We have extensive experience with the Holley setups but without knowing the list I can't tell you what the hot ticket is.

edit: in reviewing your other thread regarding the carburetor, I now understand that the intake is a spreadbore and you installed a square-to-spread adapter. The Holley carb can't be connected to the oem choke stove (divorced choke) so I assume it's an electric choke carb and the choke switched b+ feed is connected to a proper circuit and not connected to the positive terminal on the coil??? Since it appears that carb is "shiney", that means the list is a 80457s, if so, then that carb is a perfect match for that engine. I use those extensively in my work.

Please positively identify the carb for me and we can move forward.

If the intake manifold is original to the 392 engine, then the motor would be a '74 or '75 out of a pickup or Travelall 200. The 100/150 series trucks of that period received an amc 401 engine for the most part. Those are the only 392 motors that ever had a spreadbore intake oem.

No doubt this whole rig is a "previous owner" deal. We have addressed probably every known issue regarding this stuff in the sub-forums here, just start at the earliest thread in each carb tech and ignition tech sub-forum and work forward!

With the non-stock changes made in this engine, the tuning info in the service manual is no longer valid! That was all for oem setups and emissions tuning. You are far away from that!

You can post good, sharp pics (not from a dam cellphone cam!) right here of the engine bay and I can do a real good job of picking this apart and advise.

The most knowledgeable commercial dude in the dfw area regarding IH stuff was Jeff over at "jefftech" in arlington, but he retired and closed his shop last fall. I've worked with him several times by phone. Last I talked to him he was working a few days a week with his brother's shop involved in vehicle restorations, iirc, they are located in mansfield, Jeff doesn't "do" computers though!

I'll be spending probably a month or more in the dfw area at xmastime this coming December, my people are in hurst and up in texarkana, dfw is my "home" though the weather there suks year-round so I left many years ago. If the rig is still viable at that point, I'd be happy to hook up with ya and check it out.

Bottom line is...we need an extensive itemization of all the changes/mods made to this engine along with pics! Then we can do something!

 

[ThatOneGuy]

Holley 4160 600cfm Holley #510-0-1850s
jegs manual choke cable
jegs spread to square bore adapter
Holley electric fuel pump
mr.gasket cheapo fuel reg
lokar throttle/kickdown cable
msd coil and new resistor
new distributor points
accell cut-to-fit spark plug wires
ngk-r xr5 v-power (direct cross for suggested champions)
reman alternator
ran a compression test and did anywhere from 115-125psi. I was using a crappy gauge I borrowed so who knows if it was right

I May be forgetting something but that's a general idea. After reading the edelbrock was that far oversized this thing May run once I finish resealing the coolant system. I'm having to work at night due to the wonderful 104 degree weather.

Sadly my iphone takes better pics than my ancient digicam does. Also added a couple pics of the fuel tank that no-one can identify as maybe you have seen one before.

 

[Michael Mayben]

Additional comments:

1) that particular Holley 1850 is the "no trouble" version with the non-external adjustable fuel levels. In order to verify/set the fuel levels the bowls must be removed and inverted, not the best choice for this application, the "no trouble" series of carbs are a fairly recent development (last 6 years or so) intended for "cost reduction".

2) the out-of-the-box setup on that carb is somewhat fat for that engine application, the main jets are #66 and the secondary metering plate is #9 with a #65 power valve. I would suggest that it be jetted with #64 mains and a #39 secondary metering plate. The #65 power valve is fine. All those numbers are based upon the use of e10 fuel.

3) the Holley electric fuel pump easily produces above it's "rated" pressure range of 7psi if it's the Holley "red". If it's a Holley "blue", it's range is way out of spec for any IH application with a carb.

The "red" pump must be used with the fuel pressure regulator. The tick marks on the regulator you describe are in no way accurate enough for setting the pressure, you must have a pressure gauge in series with the carb and set the pressure accordingly at idle. All Holley carbs except the 4500/dominator series are rated for a standard inlet pressure of 5.5psi.

4) your pic shows an ac sparkplug cleanable pcv valve installed in the passenger side valve cover, it's not connected to anything in that pic. Is there another pcv valve installed in the rear of the valley cover and plumbed into a vacuum source on the intake manifold or carb? It looks like the entire pcv scenario needs to be put back in original condition, the "cleanable" pcv valve was not used on any IH engine application after 1971.

5) if the wiring on the '78 sii is oem, then it had no "resistor wire" for running to the coil positive terminal for use with a breaker point distributor. The original distributor in that vehicle (not that engine) was most likely a prestolite electronic and the wiring for that unit is somewhat different as compared to breaker points. I need to know what the part number on that coil is and what the value is of the ballast resistor that was packed with it. I know what it's "supposed" to be...but I want to know what it actually measures before going forward. Without proper wiring and proper "value" for all components, then the ignition system will never function properly.

6) it appears that the vacuum brake booster is properly connected to the #8 runner on the intake manifold. Verify that the vacuum check valve and it's sealing grommet on the face of the booster is serviceable and will seal preventing any vacuum leakage.