73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 83HighSierra on January 13, 2008, 08:24:37 pm
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So over the weekend i purchased a 350 thats bored over .40, When i bought it i was told that it had 1 to 10 compression. It has been completely rebuilt everything is new and it has never been cranked. It Has a steel crank, 2.02 closed chamber heads, all new cam,pushrods,rockers, and double valve springs, and performance fuel pump. So i am curoius as to what everyone thinks i should do about a intake, carburator, and tranny ( i have a th350).
Thanks in advance
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I'd do a compression check to see what the PSI is. Also, what cam and specs? You're probably better off with the q-jet but you might use an aftermarket aluminum intake since 10:1 will be pretty hot and that'll pull some heat from the combustion chamber. Alluminum or cast iron heads? Stock th350? You *may* need a regulator with that performance fuel pump to keep pressure down. Some other guys will have ideas too.
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well, you can do a compression check, but i doubt the guy would give him his money back even if it did have a weak hole. i don't think i'd have bought a motor that hasn't even been cranked. that's all fine and well, but what if they did something wrong or heck, had a defective part? you might be d@mn disappointed when you fire that thing up, or try to.
ok, off that topic, for that combo, it depends on what you like. are you a Holley or an Edelbrock guy? you can get a decent aluminum intake from Summit, Jegs or any plethora of places...just get one that goes well for the RPM range you want. as for carbs...again, are you a Holley or Edelbrock guy? do you like tuning a LOT or "Setting and Forgetting"? if you like to tune and retune but have BA performance i'd go holley, and about a 650 DP or so. with an Edelbrock, they don't have a 650 (if they do i haven't found it) so i'd go with a 600...but you might end up a little under-carb'd if your motor is as "hot" as you've been told. if you really think you're Billy Bad*** then you can step up and get a Demon carb. they are more expensive but they are set up for one thing...RACING.
but i'd stay around the 600-700 CFM range as far as a carb goes...i think around 650 would be ideal...700 might be a little TOO much. you can get carb/intake/sometimes cam packages, might be best suited for your purposes since you aren't as knowledgeable in picking and choosing parts...
as for your tranny, you are lucky, you have a Th350 which is a stout tranny. as long as it's in good shape you should be fine. you might wanna consider an auxillary tranny cooler (heat KILLS) and possibly a tranny temp gauge. a shift kit might be a nice addition as well. but honestly, you should be fine. might wanna get a higher-stall TC if you are really wanting to LAUCH this bad boy with authority
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If its not going to be a daily driver, or you dont care about efficiency, go with a single plane high rise manifold with a 1" spacer, or a tunnel ram intake (no spacer) and a Predator 6000PXI carb, mounted bowl forward. That combo will give you the low end torque of an edelbrock or holley on a dual plane manifold, but with good top end HP..You just sacrifice some fuel economy. A predator requires NO tuning after the initial setup. Match the metering cam/fuel nozzle bar to the engine and use, and forget about it til its time for a rebuild (which amounts to a new accelerator pump diaphram, fuel nozzle bar, gaskets, and possibly float and spring). I STRONGLY discourage the use of a predator on a dual plane manifold..they require a lot more space for the fuel and air to mix properly, and a dual plane manifold will actually reduce the torque potential of the carb.
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word! that is some really good advice man...
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Thanks, Predators and tricks with predators is one of the few things I know enough to really give sound advice on ;D
People are scared of them because they seem too good to be true, and are assumed to be complicated..when in reality, theres nothing complicated about em..Initial setup of the bellcrank/detent cable/throttle linkage is the most confusing part IMO (I actually struggle to figure that part out, every vehicle I've worked with one on has been different). The price also tends to drive potential buyers off..its somthing different, and people are afraid to shell out $500-600 to try somthing they haven't played with before.
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I think the 1st thing you need to know is your cam specs.
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well i got all the boxes of the cam and everything that is in it. so ill just have to look at those but there at a friends house. By the way i want this to be a daily driver with a good kick to it
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Use a good intake for your RPM usage, then top it with a predator variable venturi carb.
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If you use a dual plane with any predator carb, be sure to use atleast a 2" spacer under it. I had my PXP (race model) predator on a 355 in a '76 k5 blazer with a dual plane intake, and couldn't cold start it without pouring just a splash of fuel into it. The cold start method would flood the engine, even one full pump of the pedal would flood it. I installed a 2" and 1" carb spacers for a total 3" of added space and the problem went away entirely. A PXI (street model) would probably be ok with a 2" spacer. That blazer with 38" swamper TSLs, 3.73 gears, np203 tcase, TH350, and that carb on that engine got about 6-8 mpg..it got 9-10 mpg with an edelbrock tuned for efficiency, but it lost some of its testicular fortitude by switching from the predator to the edelbrock..The owner at the time didn't like the fact that it had to idle at 1200-1400 RPM, or the lack of an idle circuit could cause it to die while it was idling at 800-900 rpm.
I agree on the cam specs, get that info, then decide what you want to do.
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Personally I would never guess or assume anything on a 'mystery motor', no matter what was said. Get that thing on a stand, pull the heads and oil pan off and do some homework first. Then find a combo for drivability the way you want. 10:1 and 2.02 heads with cam to match in a full sixe truck will be a $#@% to drive around with any regularity. Confirm what you have for your own sake.
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ok i got the spec sheet for the cam but i got lazy so i just scanned it into the computer. Also i checked the block casting and this is what it said
10243880 1995-00 350 2/4 Gen.I crate motors and "ZZ4", roller cam, one piece rear seal
And heres the spec sheet
(http://i46.photobucket.com/albums/f105/C-dog01/cam.jpg)
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I would run a decent dual plane intake with that cam. Just plop an edelbrock 600 on there.
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I would run a decent dual plane intake with that cam. Just plop an edelbrock 600 on there.
Also, you may need to run a fuel pressure regulator if the "performance fuel pump" puts out too much pressure. Edelbrock's needle and seats are REAL sensitive to too much pressure.
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Would a edelbrock victor jr and a 700cfm carb be alright for a daily driver or should i get something more suddle?
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the number is just like you looked it up. you have a Gen 1 small block. what heads are you running? i mean, are they newer centerbolt style or older perimeter-bolt heads? that's what determines what intake you can run. the casting number on the block doesn't really mean squat. it's about what heads you are running, as that's what the intake bolts to. honestly, you can make an '87-up intake bolt onto '86-lower heads you just have to elongate your bolt holes. anyhow, to answer your question, if you have the perimeter bolt heads you want to go with a '86-down intake...if you have the centerbolt heads, then go with the '87-up style.
oh, and in case you don't know what i mean by "perimeter-bolt" and "center-bolt" i'm referring to the way the valve covers are attached to the heads...
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i have centerbolt closed chamber heads
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Your truck is gonna loaf around with a single plain intake. Why do you want that intake?
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i totally missed that Vile. yea, you WANT a dual-plane...trust Vile if not me...he's forgotten more than most of us will ever know about this stuff
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I was wondering about the victor because thats what a buddy of mine mentioned i should get. What intake and carb combo should i get then?
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honestly, since you don't know a whole lot about this, i strongly recommend an Edelbrock Performer package, sans the cam. get their matched intake/carb combo. just match it to what comes closest to what you have. personally, i think a good DP intake and an Edelbrock 600 like Vile mentioned would be great on this combo. Weiand makes a good intake too...a good DP intake from most places will work nicely...then don't put anything over a 650 cfm carb on it...heck, 650 is probably too big...a 600 should be perfect
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I was wondering about the victor because thats what a buddy of mine mentioned i should get. What intake and carb combo should i get then?
What stuff do you have now in your engine compartment? Since its an 1983 it does not have to run through the sniffer but it's supposed to have all the emissions equipment it had on it from the factory. Do you have a charcoal canister? If so, I'd run a Edelbrock Model 1400 which is emissions compliant for 1980 and before. Don't worry, it'll work on yours. It's also an electric choke, so if you have only a manual choke, you will have to run a B+ wire to it (the ground wire just connects to a screw on the airhorn).
If you have problems, I'm in Houston as well. Not that I know anything, but sometimes it helps to have someone else look into the engine compartment and say, "Ah-yep, it's a GMC."
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I would run a decent dual plane intake with that cam. Just plop an edelbrock 600 on there.
Listen to Vile! Victor jr is for a higher RPM motor. You want something that is going to produce good low/ midrange torque/ horsepower. The victors power range starts around 3500 RPM, way to high for a truck, it will be useless (it will only look cool). Look at the RPM air gap or similar, great performance 1500-6500 RPM. You'll be much happier.
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ok so i think im going to go with what vile said because you obviously know what your talking about. So if i get a decent dual plane intake and a 600 or 650 cfm carb will i still get alot of power out of the engine as i can for a decent daily driver or weekend truck?
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Go with the Edelbrock performer RPM or a similar manifold. I made a post a while back showing what the main difference between a dual plane and single plane manifold is. You can search for it... Anyway a heavy truck that's driven on the street will have always respond better with a dual plane. Ideally variable intake geometry would be the best but no one makes one for these engines that would be practical. So again dual plane is what you want