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Old 08-03-2005, 09:57 AM   #29
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In regards to fuel injection

The HT 502 is designed for pre late 70's applications and it is not advised to put fuel injection on that motor as it may lean out and damage the engine. As for the fuel pump, the 502 does not have a mechanical fuel pump and can only be run with electric. Mine already has two electric ones mounted by the previous owner. Now the shop has rebuilt my Quadrajet and is starting from square one. I did order the Hedmann Elite Ceramic headers and am going to put those on as a way to help reduce heat. Any suggestions are appreciated. Thanks again and I will keep you posted. John
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Old 08-03-2005, 12:35 PM   #30
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Question Nonsense!

Wtrdawg,



I am not trying to start anything here but in a word – nonsense .



I bet the same mechanic that is having the problems and delays with your engine change, and can’t seem to keep it running is the one that explained the “fuel injection will go lean on that engine; it’s just not designed for it”.



My 454 is a 1969 just for reference. Perhaps there is a bit of truth in his statement - any fuel injection system that runs lean will ruin an engine – any engine, new or old. But I can’t accept that fuel injection on this HT 502 will not work.



Additionally, look up the Edelbrock Pro-Flo System in Summit or Jeg’s. You will find the big block kit will fit “Big Chevy 1965-up”.



Awaiting flames ,

Henry
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Old 08-03-2005, 05:27 PM   #31
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In reply to Nonsense

Ok, I think you do want to start something, but you need to check your facts, GM says the HT 502 is "not intended to be used with fuel injection, with heavy load or high altitude lean fuel mixture may occur and engine damage may result". I may have had problems with the mech. that installed the motor but, I did do my homework. I suggest you give it a whirl. Oh yeah there's your flame from me. Thanks anyway.

P.S. I don't want to spend $5200.00 on a motor and just go against what GM says, based upon what experience you may have had with a 69 454. You know warranty and all......P.S. sallee-chevrolet.com, they are a performance chevy parts dealer in Oregon.
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Old 08-03-2005, 09:43 PM   #32
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As usual, everyone's partly right. The CARB model 502 isn't supposed to be run with STOCK fuel injection, as it will run lean. However, the FUEL INJECTION 502 with the conversion kit - for example for 91 or 92 - which includes an uprated fuel pump and pressure regulator - will run fine and it's the same motor. I mentioned these items in a previous post, where I guessed the job might cost $9000, based on my experience.

Sorry, I don't know what the current problem is, but a $15 fuel pressure gauge and a new distributor - also mentioned in previous post - will probably reveal the culprit.

Good luck.
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Old 08-03-2005, 10:30 PM   #33
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I have the crate 502 with a Howell port injection system in my MH and can shed some light here. I had trepidations about injecting my engine because I read the same factory info that wtrdawg read: fuel injection isn't recommended for this engine.

I was a test case for Howell with the truck 502. The first program they sent me ran terribly. Finally, the tech guy realized that mine was NOT the 502/500hp model, and then they got it right.

I went with this setup because I believe in electronic engine management as the best and most efficient way to operate a gasoline engine. I also know that modern fuel injection systems are designed to protect the engine under virtually all circumstances.

With closed-loop feedback, a "smart" ECU that learns and remaps fuel distribution, and a knock sensor, I think my engine is very well protected by the GM/Howell system. The one exception occurred on my last long trip when my fuel filter started clogging. That's when one other item, a digital air/fuel mixure gauge, saved the day. It showed that my engine was going very lean on hard pulls; a lean cackle verified the gauge reading. After I replaced the fuel filter all was well again, and the gauge verified the cure.

The Howell system isn't cheap, but it works very well. If I had it to do over, I'd do exactly the same thing again.

Bob
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Old 08-04-2005, 06:28 AM   #34
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Quote:
Originally Posted by mcneon
I have the crate 502 with a Howell port injection system in my MH and can shed some light here......one other item, a digital air/fuel mixure gauge, saved the day. It showed that my engine was going very lean on hard pulls; a lean cackle verified the gauge reading.....The Howell system isn't cheap, but it works very well. If I had it to do over, I'd do exactly the same thing again.
Bob:

Thanks for sharing your experience - I have several questions -

The digital air/fuel gauge - do you have a manufacturer and model number on that? Also, is the air/fuel gauge run through the computor or is it a mechanical add on.

You said "a lean cackle verified the gauge reading" - does this mean you heard a light ping on the hard pulls?

Lastly, "The Howell system isn't cheap, but it works very well"...did you install the FI system, or was it done by a shop after the engine change. What prompted you to change out the carb after the 502 installation? Poor performance or poor gas mileage?- I KNOW that a bunch of us are interested in your previous gas mileage, and some pics of the engine, computor, and your instrument panel after the installation.

You quoted R&R of $2700 in a previous post - do you have an idea of what your labor that went into the project (if any) was worth? - since so many of us are near (or at) engine swap time any info you could give us would be most appreciated.
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Old 08-04-2005, 08:03 AM   #35
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Air/fuel gauge: Mine is a Nordskog, Summit Racing's part number NRD-M7009. They have another one that looks identical and is a little cheaper. These hook directly to the same oxygen sensor that supplies feedback to the ECU.

The "lean cackle" is just as you imagined - not a continuous, heavy knock but a fairly strong intermittent clack. Engines run most efficiently at the point of what's called "incipient knock," which means on the hairy edge of being too lean. Having the knock sensor allows the ECU to maintain that condition. If you start to have audible knock like I did, though, you're into a potentially dangerous region. Of course, when something something goes out of spec - like my fuel pressure drop due to a clogged fuel filter - the ECU can't compensate fully for that.

The Howell PFI system was about $2200 when I bought mine, and I did the installation. It's pretty straightforward; I'd estimate I put maybe 30-40 hours into locating components, routing harnesses, replumbing for fuel return, etc. I also had to raise the doghouse cover on mine to accommodate the new air cleaner. My old carb was okay, but I've just never been a fan of carbs in general. As I said in my previous post, I think electronic injection is the best way to go.

I never really measured my fuel mileage before, but it wasn't very good. I now tow about a 5,000 lb trailer with a 10-11,000 lb motorhome. On my last two fillups, driving 70-75 and running the generator some, I averaged right at 8mpg. If I ever drove without the trailer, I'd expect to break 10mpg.

It's impossible for me to estimate my labor or its value. This motorhome has been far more of an ongoing project than I ever imagined it would be. If I kept track of the time I've spent on it, I'd go crazy! Of course, I find things to work on all the time; that's my nature. For example, this week I'm getting ready to go racing. Instead of working on the racecar, I installed a Fantastic Vent in the MH. Go figure.

I have to add, too, that I've spent lots of time correcting funky things the previous owner did, things I just can't live with, so my labor numbers would be very skewed anyway. If your MH has never been hacked as mine was, you're way ahead of the game.

Bob
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Old 08-04-2005, 10:23 AM   #36
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wtrdawg,

Just wanted to say that this is a VERY informative thread and I really hope you won't be put off by the critical tone of one poster. Please keep us all posted. As has been said, every classic motorhome owner will (or already has) faced your situation. We all benefit for understanding your experience. Many thanks.
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Old 08-08-2005, 08:42 AM   #37
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Thumbs up Really

Quote:
Originally Posted by wtrdawg
Ok, you need to check your facts, I did do my homework. I suggest you give it a whirl.
Wtrdawg,



I went to the location that you suggested to do some homework .



http://www.sallee-chevrolet.com/frame.html



I see that the HT502 GM part number is 88890533 is this the engine that you are using?



Additionally, I see a kit 12360893 that allows this engine (88890533) to work with fuel injection (by GM). “This new emission-legal (50 state) Retro-Kit engine conversion kit is designed for 1991-93 Chevrolet and GMC 10, 20 and 30-series trucks with 2-wheel drive, originally equipped with a 454 TBI engine and 4L80E automatic overdrive transmission.”



Am I missing something here? I did see the warning about fuel injection that you spoke of but then I saw this – what gives.



I really am not trying to flame anyone – I just support fuel injection. I was simply trying to offer some advice that may remove several of the frustrations that you are facing.

I have been doing homework and hands on work with fuel injection on Chevrolets for several years. I am one of three guys at a local track, Osceola Dragway, that run fuel injection (on cars that did not come EFI equipped from the factory) on a street/strip car. I see that mcneon (previous post) has used the Howell system with success – I was simply suggesting the Edelbrock.



I like to learn and offered my two cents – please don’t take offense. Your points were well received and I did some homework – honestly I simply hope that your conversion provides years of trouble free operation and exceeds your expectations .



Regards,

Henry
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Old 08-08-2005, 09:33 AM   #38
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Axleman-no Flames Intended!

Henry:

No flames here, but if you will refer to post #5 of this thread (my post-wascobob) and go to the link in it and look up engine part #88890534, it will take you to a GM data page. Refer to the technical note and you will find that GM states that, "The HT 502 is not intended for use with electronic fuel injection." They speak of load and altitude conditions that may result in engine damage from leaning fuel mixture conditions.

Their words, not ours! I have no clue why.

Bob of Bob and Molly
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Old 08-08-2005, 10:39 AM   #39
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Thumbs down Look up KIT#12360893

Quote:
Originally Posted by wascobob
Henry:

No flames here, but if you will refer to post #5 of this thread (my post-wascobob) and go to the link in it and look up engine part #88890534, it will take you to a GM data page. Refer to the technical note and you will find that GM states that, "The HT 502 is not intended for use with electronic fuel injection." They speak of load and altitude conditions that may result in engine damage from leaning fuel mixture conditions.

Their words, not ours! I have no clue why.

Bob of Bob and Molly
Bob,



Thanks for sharing – I wasn’t intending on folks getting twisted or flamed, I was just adding my two cents .



I did go to the link. I did see the note about fuel injection listed under part number 88890533. However I also found Kit 12360893 – please look this up . This specifically states : “This new emission-legal (50 state) Retro-Kit engine conversion kit is designed for 1991-93 Chevrolet and GMC 10, 20 and 30-series trucks with 2-wheel drive, originally equipped with a 454 TBI engine and 4L80E automatic overdrive transmission.” I found this while looking at the web site. TBI is a form of fuel injection and GM is saying this kit is OK to use on part number 88890533. Maybe I have missed something but it appears GM says no/yes depending on which advertisement you review.



I support fuel injection big time. One fellow bragged about the Howell system used with this engine with fantastic results – once the bugs were worked out. My Edelbrock was the same way. I don’t suggest doing anything GM does not recommend and violating the warranty. But – I think this reading would cause me to pursue this further than just coming to a blinding stop when the statement “NOT TO BE USED WITH FUEL INJECTION” appears. I know the benefits to computer controlled vehicles far out way the disadvantages of the carburetor. But I also know that this is not my project .



Regards,

Henry
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Old 08-08-2005, 03:02 PM   #40
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Axleman-Healthy discussion

You are correct also. GM makes two 502 tow motors. One built for FI as you referenced, and one built for earlier carburated, non-emmission applications. Both are rated almost alike in terms or hp. and torque, torque curve.

I believe that waterdawg bought the carburated version. Maybe he will chime in and let us know for sure.

This kind of conversation is healthy and does not detract from his thread. Others are following this thread with interest, and hopefully, this may clarify some points without offending.

Thanks Bob of Bob and Molly
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Old 08-08-2005, 03:17 PM   #41
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Thanks Bob!

Quote:
Originally Posted by wascobob
Axleman-Healthy discussion

This kind of conversation is healthy and does not detract from his thread. Others are following this thread with interest, and hopefully, this may clarify some points without offending.

Thanks Bob of Bob and Molly
Bob,

This was my intention. Additionally, I love to learn (especially if an engine is involved).

Regards,
Henry
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Old 08-09-2005, 02:25 PM   #42
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Update and still no change.

I am about to pull my hair out. Now with the next "Authorized Workhorse" GM service center. 2.5 weeks and they are still working on the vapor lock problem. I have a call into the Service manager since this seems like mechanics 101, but I guess the nature of service centers these days is to drag your feet. I can not tell you how frustrated I am and am really not sure where to turn with this project. Nobody seems to be able to pin-point why I am having a vapor-lock issue and the most frustrating part is that the mechanic has no game plan or isn't communicating with me what it is. So at this time my 502 is 11.5 weeks and counting. Summer fading and I just may buy a trailer........John

P.S. I apologize for getting "as my wife would say snippish", I know you guys are trying to help and inform and I do appreciate the feedback. I need to do my homework on mechanics......
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