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05-12-2014, 11:42 PM
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#1 |
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Registered User
Join Date: Aug 2013
Location: Phoenix, AZ
Posts: 21
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'86 Silverado engine swap
Howdy,
I was hoping someone could help me because I'm stuck. I have an '86 Silverado which had the original 305 in it when I got it. Instead of rebuilding it, I had a 350 engine from a 1990 Suburban. The 305 was carbureted but the 350 was fuel injected. I was able to have the carb replace the injection and it ran really well for a few weeks then putted out! I was told I'd have to rewire complete with new harness to 1990 Suburban standards. Is that true? Thank for any advice! RFC |
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05-13-2014, 10:37 AM
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#2 |
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BAD BOW-Silverado XST
Join Date: May 2000
Location: Senior Member from Austin, TX
Posts: 6,431
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Re: '86 Silverado engine swap
You don't need the harness unless you are adding FI. What do you mean by putting out? Start with the basics. Fuel delivery, ignition, and exhaust. Yes, exhaust. A clogged cat or muffler will hurt performance. Check carb settings. Check timing. Is timing constant above idle? If timing jumps around, bigger problems exist. Do you have a vacuum guage? Connect one to the carb. Read this to interpret vacuum readings: http://www.centuryperformance.com/fo...a-Vacuum-Gauge
A vacuum guage is $15 at Harbor Freight. It's one my most trusted tools in my garage! |
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05-13-2014, 12:43 PM
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#3 |
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Registered User
Join Date: Aug 2013
Location: Phoenix, AZ
Posts: 21
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Re: '86 Silverado engine swap
Thanks GCHEMIST!
What I mean by "putting" is that it's misfiring and "put puts" out...it no longer remains idled without shaking. I'm not expecting that it be as smooth as a Lexus the way it's misfiring is unsettling considering the carb is rebuilt and the timing has been checked and adjusted and rechecked. All new spark plugs (properly gapped) and wires. New Flowmaster 40. I haven't checked the vacuum...thanks for the heads-up! I'm glad I don't have to get a new wiring harness, I don't have the $ for it just yet. Much obliged, RFC |
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05-13-2014, 01:37 PM
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#4 |
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Getting Old; Going Broke
Join Date: Apr 2010
Location: Owasso OK
Posts: 2,764
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Re: '86 Silverado engine swap
How is fuel being sent from the tank to the carb? In tank pump? External pump?
__________________
Why is every used 350 sbc out of a corvette? There's only two things that excite a man, expensive toys and real expensive toys. VEGETARIAN: That's an old Indian word meaning "I don't hunt so good." When the going gets tough, switch to power tools. |
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05-13-2014, 01:42 PM
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#5 |
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Registered User
Join Date: Aug 2013
Location: Phoenix, AZ
Posts: 21
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Re: '86 Silverado engine swap
RandyP,
In tank pump. RFC |
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05-13-2014, 01:57 PM
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#6 |
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BAD BOW-Silverado XST
Join Date: May 2000
Location: Senior Member from Austin, TX
Posts: 6,431
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Re: '86 Silverado engine swap
How is it regulated? A carb needs less than 7 psi. Too much and a carb will flood the engine.
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05-13-2014, 02:02 PM
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#7 |
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Registered User
Join Date: Aug 2013
Location: Phoenix, AZ
Posts: 21
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Re: '86 Silverado engine swap
GCHEMIST,
Thanks again. That's something I haven't looked into yet. Regards, RFC |
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05-13-2014, 02:51 PM
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#8 |
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BAD BOW-Silverado XST
Join Date: May 2000
Location: Senior Member from Austin, TX
Posts: 6,431
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Re: '86 Silverado engine swap
If it's an Edlebrock carb , over 6 PSI will cause problems too.
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05-13-2014, 05:24 PM
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#9 |
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BAD BOW-Silverado XST
Join Date: May 2000
Location: Senior Member from Austin, TX
Posts: 6,431
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Re: '86 Silverado engine swap
Read this on carb fuel pressure: http://www.73-87.com/7387garage/drivetrain/fuelpump.htm
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05-14-2014, 02:40 AM
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#10 |
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Registered User
Join Date: Aug 2013
Location: Phoenix, AZ
Posts: 21
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Re: '86 Silverado engine swap
Thanks again GCHEMIST,
I haven't checked the pressure yet and now the picture is becoming clearer. I used the carb that was on the 305 (4bbl but not sure of make), had it rebuilt and put it on the 350. I know it's not an Edlebrock but I'm starting to feel that the shop that rebuilt it only half-a$$ed it. That along with possible vacuum leaks (I never replaced the vacuum lines) are the 2 main culprits! Again, thanks! RFC |
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05-14-2014, 10:37 AM
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#11 |
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Registered User
Join Date: May 2010
Location: Mountain House, CA
Posts: 555
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Re: '86 Silverado engine swap
When you say "in-tank" pump is your fuel tank an 87 on up tank? Where exactly is your fuel pump? Your stock tank should have been a draw straw style with no baffle for the fuel pump. If you are running an in-tank pump with out a baffle you could be aerating when the level gets to low.
__________________
My Chevy habit is paid for by Ford diesels... Here is my SLOW LS install: http://67-72chevytrucks.com/vboard/s...55#post6456355 Caliper Rebuild: http://67-72chevytrucks.com/vboard/s...d.php?t=613748 Upper Control Arm Bushings: http://67-72chevytrucks.com/vboard/s...d.php?t=616974 IG mattcrp1 |
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05-14-2014, 10:50 AM
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#12 |
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Registered User
Join Date: Aug 2013
Location: Phoenix, AZ
Posts: 21
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Re: '86 Silverado engine swap
mattcrp1,
You know, I didn't do any homework on this truck because it was so cheap for a short bed with a straight body here in Phoenix. They're hard to find out here almost stock, so as soon as the ad went up I snatched the truck without asking too many questions. The previous owner said he put a new tank in because the original owner before him had the truck sitting for about 12 years. I'm finding out things about this truck as I go. It's very possible the tank is from a later year. RFC |
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05-14-2014, 12:01 PM
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#13 |
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Registered User
Join Date: Dec 2002
Location: Cactus Patch So. Az
Posts: 4,749
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Re: '86 Silverado engine swap
I have a good tank that I removed from my 78, 16 gal that I will pay forward if you are down south 100 miles!
__________________
53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD) 53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25 55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73 62 Solidaxle Corvette Roman Red (327 340hp 4spd 3:36) C4 & C5 suspension tube chassis LS 3 4L70E 65 Corvette Coupe 327 350hp 4spd 4:11 78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42 2000 S-Type 3.0 (wife cruiser) 2003 GMC SCSB 5.3 4L60E 3:42 |
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05-15-2014, 12:22 AM
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#14 |
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Registered User
Join Date: Aug 2013
Location: Phoenix, AZ
Posts: 21
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Re: '86 Silverado engine swap
Solidaxel,
Thanks for the offer but I'll roll with what I have right now...sounds like I'm getting closer with the troubleshooting. BTW, is that your '53 on your profile? Nice truck! I have a '50 3100 that is on the back burner until I get the Silverado back on the road. RFC |
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05-15-2014, 02:04 PM
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#15 |
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Registered User
Join Date: Dec 2002
Location: Cactus Patch So. Az
Posts: 4,749
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Re: '86 Silverado engine swap
[QUOTE=RFC;6674136]Solidaxel,
Thanks for the offer but I'll roll with what I have right now...sounds like I'm getting closer with the troubleshooting. BTW, is that your '53 on your profile? Nice truck! I have a '50 3100 that is on the back burner until I get the Silverado back on the road. RFC[/QUOTE Yes that is the 55 G M C there is a pic of all three of them somewhere the 53 is green
__________________
53 TuTone Extended Cab 350 4-Spd 3:08 (SOLD) 53 Chevy Moldy pearl green ZZ-4 4L60E 9" 3:25 55 GMC 1st Black Mll (ZZ4) ZZ6 TKO 600 5 sp 3:73 62 Solidaxle Corvette Roman Red (327 340hp 4spd 3:36) C4 & C5 suspension tube chassis LS 3 4L70E 65 Corvette Coupe 327 350hp 4spd 4:11 78 Black Silverado SWB (350/350) 5.3 & 4L60E 3:42 2000 S-Type 3.0 (wife cruiser) 2003 GMC SCSB 5.3 4L60E 3:42 |
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