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75 3/4 t 350 mods..will they help??

Discussion in 'Chevy Trucks' started by Hankster, Sep 4, 2002.

  1. Hankster

    Hankster Junior Member
    Messages: 16

    I'm new at chevies so...We are doing a total rebuild/restore of my wifes truck.New body etc. We've already had the tranny rebuilt for towing by a local shop...now I'm looking at the engine while the body is off.....
    It has duals and factory intake and a 1970 q-jet.
    will a newer rebuilt q-jet,Edelbrock Performer Intake and 1 5/8 headers make a noticeable improvement over what we have now??It's a 2wd we use primarily for towing a horse trailer weighing close to 7000 lbs loaded. It tows fine now on flat roads,but could use some extra power in the hilly areas we come to.If the headers won't add much over the duals we now have....what about the new intake??? any other ideas???
  2. CT18fireman

    CT18fireman Banned
    Messages: 2,133

    Wait for 75 to respond. He is working on a simliar project right now.
  3. TLS

    TLS PlowSite.com Addict
    Messages: 1,425


    What is the condition of the engine? If it's OK, then I would suggest a set of Doug Thorley Tri-Y headers. They are 14 gauge heavy wall industrial chrome plated tubing with nice thick flanges that will not bend or warp. They will dump into a nice single 3" exhaust. This will flow better and give you better low to mid rpm power than regular headers and duals.

    The Edelbrock performer is a nice manifold, and a good rebuilt Q-Jet or a Edelbrock Q-Jet is a nice choice.

    I wish I had the time/money to restore my '75 Suburban, as restoring my old '76 pickup was a nice rewarding project. Sure wish I wouldn't have sold it!!!

    Here's a pic...

    \'76 chevy1.jpg
  4. Hankster

    Hankster Junior Member
    Messages: 16

    Thats a fine looking ride!! Got a few that look good like yours running around town here....Hers is a tu-tone like that,but she is considering painting the new one white with black accents...
    Thought a set of ZZ stripes down each side..like the ZZ Top eliminator rod has would be different!!!

    Anyway,the Thorley tri-y 's sound like just the ticket. We are looking for low to mid range torque...not a drag racer!! It already has 3.73's out back...(looking to put in a limited slip,but that is yet another question!!! )..and the Edelbrock Performer is designed along the same lines.....we have some BIG steep hills to climb getting into and out of some of the parks and National forests we go to,as well as some rough roads (if you can call some that!!)..so thats where the posi traction idea comes in....as well as why I'm staying with the q-jet....they're better on hills and in the rough stuff....(less fuel slosh) than a Holley etc....

    This is a good site...lots of info here....thanks for the comeback....Hank in Missouri....
  5. TLS

    TLS PlowSite.com Addict
    Messages: 1,425

    Thanks for the compliments!

    The truck above was a real basket case when I bought it. It was a one owner, K-10, 350, 3 on the tree, Silverado, no factory air (aftermarket though!) with 3.08:1 gears. I later planted a 350hp 350, and a HD 4 speed manual replaced the 3 on the tree (shoulda went with an automatic though) . It would reall get up and go. Shifting was not quick with the HD 4 speed though. An automatic would have had this truck in the low 15's. I had it in the tripple digits on the turnpike a few times (3.08's will allow this!) It ate 5.0 'Stangs for breakfast!

    Both bedsides were replaced, rockers, cab corners, doors, and fenders all new. Only the cab and the hood are original. Frame was blasted and painted. Thinking back, when I bought this truck, it was only 10 yo. Now my "new" truck is almost 13 and is in much better shape.

    I had a Meyer MANUAL angle plow for it at first. Thats NOT as fun as it sounds!

    It took 1st place in a local car/truck show the year before I sold it.

    Here is a GOOD pic of its GOOD side in 1986 when I bought it from the original owner.

    They are a lot of work, but a pleasure when you get them nice!

    \'76 chevy before.jpg
  6. speedracer241

    speedracer241 Senior Member
    Messages: 325

    In my opinion I wouldnt put headers an anything I was going to drive on a daily basis. I always had trouble blowing out the gaskets at the head.
  7. Hankster

    Hankster Junior Member
    Messages: 16

    Also meant to say that the motor is sound..last owner dropped a GM Goodwrench motor in a little before they sold it..

    Wish our truck looked as good as yours did "before"!!!! Between the road salt....The notorious rust problem Chevy's had in that time period....and the fact that it was stolen from the previous owner..and some kids went fencepost busting with the pasenger side.....it's kinda ugly!! We got it all fixed up underneath.....but since beauty is skin deep!!!! YEECH!!! hahahaha.....but we're gonna fix that!!!! Post a pic when we get it "Right"!!

    This one has a modified turbo350 trans....with a cooler....just want to get the rest of the drivetrain up to par!!!!
    Last edited: Sep 4, 2002
  8. TLS

    TLS PlowSite.com Addict
    Messages: 1,425


    Well, then you've never had Doug Thorley headers then. I have them on my '90 for the past 9 years with the original header gaskets! NOT leaking! I have replaced the collector gasket once though when I replaced the exhaust. I had the original cast manifolds expand and shear off the manifold bolt flush with the block.

    The trick to good headers is the finish and the mating surface thickness.
  9. Hankster

    Hankster Junior Member
    Messages: 16

    Speedracer....towing for a horseback trip....the lumberyard....or hauling a new appliance home or a trip the the feed store is all it does.....sits more than it moves!!! It's the third car in a 2 driver family!!
    When weather is bad....we use the toyota 4X4....sorry!!
  10. Hankster

    Hankster Junior Member
    Messages: 16

    TLS...thats what I've heard....it's a too thin flange that causes leaks....3/8 or better won't leak..but on cheap ones they use thinner metal..and it warps and you blow out the gasket....been a while since I did this kind of stuff..but it's coming back!!! This will be the car (truck!) I never got to build as a kid!!!!
  11. 75

    75 PlowSite.com Addict
    Messages: 1,382

    The mods you've mentioned all sound good, if I could make one more suggestion, how about changing the cam (which I'm assuming is currently the stock one) with one designed for the towing application you describe. (Sometimes referred to as an "RV grind" cam)

    I'm fairly certain Edelbrock makes one to be used with their Performer intake so you could get them as a "matched set". Other manufacturers make similar cams as well, in my own case I have a 350, 4-bolt block (casting # 3970010) with Q-jet, Performer intake and a Cam Dynamics "RV grind" cam. Rather than headers, I have a set of the old center outlet or "ram horn" manifolds into dual exhaust.

    For the application you describe, I think the Performer intake, "RV grind" cam, Q-jet and Thorley headers mentioned will give you decent results and the $ figure will be pretty reasonable too. Good luck with the project and hope to see some photos when it's all done!
  12. Hankster

    Hankster Junior Member
    Messages: 16

    75..thanks for the comeback. You are the second person to mention the "cam" idea..and tho I was trying to avoid it(probably the only thing i've never done to an engine) it makes good sense.I'll already be "in there" anyway with the manifold off...so pulling the water pump and timing cover isn't a big deal....and yes Edelbrock makes a matched cam ....
    just as an aside....how are those exhaust manifolds working for you??? and why not a set of headers??? just curious....what model did they come off of??? I like the toughness of cast manifolds....but all i've heard is they are too restrictive of exhaust gases....
  13. ShafferNY

    ShafferNY Junior Member
    Messages: 16

    I'd do as 75 said, I'd go with the RV cam, a set of headers, a new Edlebrock carb and a Performer intake. I don't have an Edlebrock carb, but my uncle does an it runs excellant, plus I've heard nothing but good about them. I've got the original quadrajet on my '78 K-10 and it runs pretty decent.

    75, "super moderator", (that's funny, good one!) what years did they use the "ram horn manifolds. I just think they look cool, even if they don't perform any better than my stockers.
  14. 75

    75 PlowSite.com Addict
    Messages: 1,382

    Hankster - manifolds worked out well, no complaints there. I had headers on for a few years, biggest problem was the salt got to 'em - I generally only use the truck in the winter and they love to use lots of salt here in Ontario. Couple of the plugs were a little difficult to change (needed a wrench as opposed to a socket for acess) but it wasn't really a problem. I'm not certain exactly when they phased out the "ram's horn" style manifolds, I believe it was around 1970 or so. They can be a little hard to find at a wrecker's but they do exist. Cam isn't too big a job once you're that far into the engine, so now is as good a time as any to swap it!

    ShafferNY - I have a picture in one of my engine books showing a 1970 350 cid 370 horse engine, it's got the ram's horn manifolds on it, so I think through the 60's was when they were commonly used.
  15. Hankster

    Hankster Junior Member
    Messages: 16

    75....taking your advice...pulled old cam out,and replacing with the edelbrock 2102..on order from Summit....but have another question for your guys....
    My old truck was a Ford (I hear the boo's, LOL!)..anyway,they were notorious for main bearings going at 100 thousand miles or so..and the quick fix was high volume oil pump ..theory being if you can pump it faster than it leaks past....pressure will stay up.

    Was considering putting one on this truck..350-V8...
    The old mechanical factory gauge read about 30-35 psi all the time before I tore it down(wish I had checked it against a new gauge first)..but since I have the oil pan off....would it be a good idea to put a high volume (not pressure) pump on??? Are there bad drawbacks to doing this?? I heard someone say too much volume can cause other things.....any opinions???
    Do not know the exact mileage this engine has on it (I know it's relatively low..30/40 thou maybe??) ...but the pan,valve covers,and engine "valley" etc are spotless!!! lifters and cam almost clean as new!!! Crank etc has no sign of any sludge buildup at all.......block is clean looking up in there.....
    only thing I saw was some buildup on the intake valves looking at them thru the intake ports..probably caused by the carb being out of adjustment....
    so any opinions???
  16. raceman6135

    raceman6135 Member
    Messages: 61

    Hey Hankster:

    A high volume oil pump is not usually recommended for a small or big block Chevrolet because the design of the oil system is quite good right from the factory. The mains (and through the crank, the rods) get oiled first, then the cam and valvetrain.

    Installing a high volume pump can actually pump so much volume that the oil can't drain back fast enough to "refill" the pump, so the pump sucks air. Air is not a good lubricant.

    Putting a shim or two on the spring, or replacing it with a new one (either standard or high pressure) is all that's needed, unless the clearances are excessive on the rods and/or mains. If they are 0.003" or tighter (and they probably are as it sounds it's been well looked after), go with the standard or high pressure pump, bolt it together, and let it go another couple hundred thousand miles.

    Ten psi of oil pressure per 1000 rpm is all that's required in the pressure department.

    The buildup on the intake valves could be carburetor misadjustment, but more likely it's oil seepage past the valve guides. Chevrolets are bad for this, primarily due to the design. The valve stem rides directly on the cast-in, cast iron guide instead of on a bronze (or other material) replaceable guide. Also, the factory o-ring style valve stem seals tend to get hard and brittle from the heat and break off easily. Check them out, replace them if they're hard, and wait for the rest of the engine to wear out.

    Sounds like you have a gem there. Congrats!

  17. Alan

    Alan PlowSite.com Addict
    Messages: 1,393

    I can't lay hands on my reference book right now, but I'm thinking that teh "rams horn" manifolds are the best flowing of any manifold. Granted, headers will give you more, and supposedly the Tri-Y Thorleys are the best in that respect, but iron manifolds are quieter and last longer.

    LMC Truck has new reproduction rams's horns. Not cheap, I'm thinking about $180 each, but they can be had.
  18. Hankster

    Hankster Junior Member
    Messages: 16

    Thanks for the info Raceman....you talked me out of it. Knew someone here would have the lowdown on this....Yeah,we lucked out..previous owner dropped a "Mr. Goodwrench" engine in...and it never has had a lot of miles on since.....and wife kept oil changes up(before I met her)so.... I'm just spoiled on the oil pressure deal....our Toyota 4X4 pickup with 231,000 miles still runs 60 psi at highway speeds.....and the Ford went downhill way to fast as far as I was concerned....and this is the first Chevy I've dealt with. But we tend to be long term owners....so I want to do it right....I expect to run this truck for at least 10 more years,hence all the bodywork going on right now!!! Just about got the cab whole again....now want to get the motor closed up so the front end can be replaced. Winters coming!!!! and I still have to paint it yet!!!!
    The rams horn type manifolds sound cool...but unless I lucked out at a junkyard....headers are WAY cheaper!!!! I wanted the Thorleys..but may have to settle for Hedman tork steps....
    almost half price..I'm holding off to the last minute to see how the bucks hold out.....theres NEVER enough!!!! hahaha!!!!
  19. ShafferNY

    ShafferNY Junior Member
    Messages: 16

    Here, read this. I just rebuilt the 350 in my '78 K-10 and used a High volume pump. Haven't had a problem yet. It WILL NOT drain the oil pan dry. The only time that happens is if your drain backs in the engine are plugged, and then it will even happen with a stock pump. The link below will dispell any myths about oil pump and the oiling system.

    Sorry, don't mean to rock the boat here.

  20. raceman6135

    raceman6135 Member
    Messages: 61

    Hey ShafferNY, thanks for the link. Interesting read.

    First off, let me say that I like and trust parts manufactured by Melling. I've run their oil pumps in a number of engines and have not had a failure or problem related to their parts.

    However, this quote comes from the very same web site:

    "The high volume pump just delays fixing the real problem. High volume pumps are for increased demands on the oil system such as higher RPM usage, racing, remote filters and or coolers, etc."

    I stand by my point that for stock engines and even mildly modified ones, there is no need for a high volume pump.

    Keeping in mind the normal small block Chevrolet runs 5 quarts/litres of oil, and that one quart/litre is going to be in the filtre at all times, that leaves 4 quarts/litres in the pan.

    The oil passages, pump, lifters, etc. will easily hold another quart/litre. We now have 3 in the pan.

    Another quart/litre to 1.5 quarts/litres will be in the process of draining back into the pan and being thrown around in the engine (off the crankshaft, camshaft, pistons, rods, etc.) That makes approximately 1.5 to 2 quarts/litres available at the pump pickup.

    This assumes, of course, that the engine began with the proper quantity of oil in it. If you're down a quart, you're "down a quart."

    To me, that doesn't seem like a lot of oil available, especially when you look at the size of the sump in most pans.

    Running a higher-than-stock volume oil pump is a risk that I personally won't take.

    On another automotive-related message board, a person asked about putting titanium valve springs in his barely-warmed-over Honda engine. I asked him/her "Why? Are you going to race the engine or spin it at a much higher rpm?"

    His/her reply was "No. I just know a lot of guys who told me I needed them."

    After he/she found out how much more expensive they were than steel springs, and how they weren't going to make his stock cam any more radical, he gave up on the idea.

    Just because a part is for sale, and "bench racers" have told you to run it, does not make that the correct decision. The world is filled with people running too big a carburetor, too much torque convertor and too lumpy a camshaft because "their friend" told them to put that part in.

    Unless "your friend" is paying for your engine, do what you think is right for you and your engine.