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Old 04-25-2010, 09:59 PM
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1st time engine building questions

Hey there i was a part of this website for a while under a different name and ended up no longer working on a project i had at the time, now im on a new one and need some advice. I have an 86 chevy crew cab i stumbled across for a great deal and has a fresh virgin 350 in it and on the 3rd start up, it started a rod knock. Its just a stocker with 041 heads performer intake 650 holley double pump vacuum secondaries. Despite the knock and the need to re-bearing everything new crank i wanna know if this set up has potential to have more low end pulling power cuz im gonna use this truck to pull a mud bog truck and its goin on 38" tires with 4.56 gears turbo 400. Whats a good cam that will work with my set up id love to have a chopy idle but at the same time id rather it work good and have low end torque than just sound good and not move. Thanks alot for any assistance and you guys always have good advice.

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Old 04-26-2010, 06:27 AM
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Yes it can be good for towing. When you go with a cam big enough for a choppy idle you have an engine that makes power at a higher RPM. So go with a towing or RV cam,it will give a slight lope at idle but will increase low end torque which is where you need it for towing.Hope this helps.
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Old 04-26-2010, 10:39 AM
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Thanks that helped get my mind set off wanting a drag car sound haha but what is a good lift/lobe seperation cam to run on stock valve spring heads? I dont want to put alot of money in this but i want to have a lil more botom end then what a RV cam puts out and if i do need to have head work done;opening up the ports and what not; what kind of cam will work? This will be a drive when i need it kinda thing not necessarily a daily driver but more of a show off kinda thing that is still functioning for pulling. Keep the advice coming. Thanks.
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Old 04-26-2010, 11:03 AM
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Why stock springs?
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Old 04-26-2010, 11:35 AM
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i agree with AP, why the stick with the stock springs, this will limit you. since this will be just a mild enigne i would say a 110-112 LSA would be good, i guess i'm kinda confused with your original post, is this truck going to get 4.56 gears and 38" tires? or is that what's on your mud bogg truck. start your question again and ask about this truck and exactly everything you know about it as well as the thing you want to do to it and then we can give you some better advice
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Old 04-26-2010, 12:22 PM
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I also agree with everyone...but my question is, WHY a double pumper for a tow veh?....and as far as I know Holley has never made a DP carb with vac. sec. It's probably a dual feed but not a DP.
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Old 04-26-2010, 02:17 PM
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you're right 327NUT Holley never made a vacuum secondary double pumper what he has is a dual feed like the 0-8... series holley carbs, many think that they are double pumpers but they are just dual feed
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Old 04-27-2010, 10:55 AM
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That was definatly my fault guys it is a dual feed not a DP. Im only using it cuz i had it off my other motor before i went to a 750 DP mechanical secondary. The crew cab as of right now has 4.10 and bone stock 350. I was told it was just built and had an RV cam but on the 3rd start up it knocked and smoked like a freight train so i pulled the motor last night going now to tear it down but while i have it down putting a crank, rod and main bearings, oil pump, rings and valve seals i just wanted to know if there were any fairly cheap ways of getting more torque out the motor. In the future the crew cab is geting converted to 4x4 and will have 4.56 gears and 38" tall tires. If i have to change valve springs do i have to do any additional head work or should i just go with a different cam and drive it? Thanks alot.
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Old 04-27-2010, 01:48 PM
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the best way to pick up the extra power you need is to stroke it to a 383, this will only cost you about 300-400 bucks more total over the 350 and will be well worth the added torque. this would be the only route i would go if i were planning on building a 4x4 truck with 38" tall tires. as far as head work, the heads you have should already be cut for 1.250" springs, and like i said you can find 1.250" springs to handle as much as .550" lift, i would probably still have them looked at and possibley have some slight guide, seal, valve, and bowl work done, you should be able to get the springs and all the machine work done and assembled for around 500.00 (as long as the you dont need new valves, that would be about another 85-100) then i would look for a better cam and lifters

personaly if i were going to run a 38" tall tire i wouldn't run any less than a 4.88 gear, if you calculate it out then the 4.56 gear with a 38" tire would be about the same as a 31" (stock for most trucks) tire with 3.55 gears (less than stock for most trucks today) now a 4.88 gear with with a 38" tire would be about the same ratio as a 31" with 3.73's, and then a 5.13 gear would be about the same ratio as a 31" with 4.10 gears.

if you were to go with a 4.88 or 5.13 gear and a 383 i would probably recomend a cam with about 220-226 @ .050 and around .470-.480" lift but you would also probably need to go with a about a 2500 stall as well, this is just what i would do. if you stick with the 350 and 4.56 gears i would recomend a cam around 210-214 @ .050 with about .450-.460" lift and you would probably be able to use a stock stall. i still say with that much tire and that heavy of a truck that a 383ci motor is the least amount of motor i would go with, it is very heavy and you are planning on turning a very heavy tire as well
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Old 04-27-2010, 07:55 PM
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That makes alot of sense. Let me throw this at you......would a 454 be any beter of a choice as far not having to work as hard to get that kinda power and torque and would either be any beter on gas than the the other between big block and small block? I started gathering parts today and found a 350 010 2 bolt main virgin block today and a set of dart iron eagle heads for 400 and also know of a 396 heads to oilpan but no brackets for accessories for 300 bucks so not sure which one would be beter than the next. I do know the big blocks are alot more expensive to build and not sure if its worth it. Also being that big of a truck with that big of tire and still pulling a trailor wouldnt a stall burn the transmission up? Im still learning so bare with me.
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Old 04-27-2010, 09:18 PM
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If I wanted to make a cheap tow engine that wouldn`t see high revs or high end power was not important, here`s what I`d do. I`d build the 350, and use true flat top pistons with 2 valve reliefs. I`d also use a edelbrock performer plus camshaft or the summit eqiv. Next, a Rochester Quadrajet carb on a performer intake. Small tube 1 1/2 headers, and here`s where I`ll get told I`m crazy, I`d use TBI swirl port heads. This combo would give it explosive out of the hole torque and mid range pulling power. The down side is, it won`t have any grunt past 4000 RPM, but, the reason it was built like this was for exclusive low end power and economy. One of the most critical aspects of a new build is scrubbing the bores after the block is honed, on the stand and ready to go together. Doing a regular wash job won`t cut it. Hone grit gets impregnated in the cylinder bore and it`s gotta be scrubbed with a strong cleaner to be gotten out. After you clean one cylinder, let it dry and give it the wipe down, spray WD40 on a paper towel and wipe the cylinder, if you see gray on the towel, the bores not clean.
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Old 04-28-2010, 06:40 PM
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That would be a fairly easy build i already have the rv cam the performer intake and a budy of mine just did a 454 swap in his 88 shortbed so i have the throttle body 350 in the floor i could use the heads of for nothing. Now i guess i need to save a few bones and go to the machine shop. Any cheap trics to do to the heads to get any more out of them or just leave them alone? Thanks alot im hopefully heading in the right direction now.
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Old 04-28-2010, 06:43 PM
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Whats the benefit of the what i call quadra-junk over lets say a holley 650 or the edlebrock 600? I only ask that cuz ive attempted to get 2 quadrajets rebuilt and they always turn out boat anchors. I usually throw them away literaly. Ive heard they are the best carbs especially when they are right.....especially for fuel economy and reliability but ive just had no luck with them.
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Old 04-29-2010, 08:01 AM
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i cant lie i have had horrible luck with Q-jet carbs, but i think that is was really the person rebuilding them. i've seen these carbs do all kinds of things from people using them on race cars to people using them on street cars and getting 20mpg
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Old 04-29-2010, 08:17 AM
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the Q-jets have smaller primaries, which for some is the most amazing thing since sliced bread. For others (like myself) its just something different and carries no real advantage. Most people that want a good street carb go after the Edelbrocks. I have ran a LOT of different carbs and Edelbrocks are one of the easiest to tune. Minuki's are easy too, but that's for an IR setup.
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