73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Performance => Topic started by: TexasRed on May 15, 2009, 10:15:02 pm
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I'm building a 383 with around 9.5:1, 3.42 rear end, shortbed 84, four barrel carb, vortec heads, and dual exhaust with manifolds (hopefully with some cash a set of shorty headers).
The cam will probably be
http://northernautoparts.com/ProductModelDetail.cfm?ProductModelId=18646
but if that requires me to get a new converter with higher stall, I might get
http://www.jegs.com/i/Crower/258/00915/10002/-1
Will either require a higher stall? Which cam would you recommend? I'm leaning towards speedpro because I think it'll be much better for my application.
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No and actually that cam isn't much bigger than stock. Why such a mild cam? I'd build some more lift into the cam personally.
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I'm cheap and don't want to go over the max lift on vortec's without doing more work. Lazy and cheap I is.
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Tex, You can get real close to .500 lift stock & with careful spring/retainer choices (beehives), you can go over that. Put some more cam in it. My Two cents, mid-high 220's @.050 & .480-.500 lift at least. It's 380+ cubic inches! What transmission do you have? Lorne
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+1. You'll be disappointed with that motor. It'll pull real nice from idle to about 3500 and then run out of puff. That said, you should also try real hard to get some headers on the engine, even if they are shorties. If you cannot, then you may be better off with a small cam (though maybe not as small as the one you spec'd). Increasing overlap on an engine with a restrictive exhaust is not a good idea.
With headers, a cam along the lines of a Isky 270 Megacam (http://store.summitracing.com/partdetail.asp?part=ISK%2D201271&autoview=sku), would be my smallest choice, even if low-end torque was a major priority. I would also clearance the heads (pushrod holes) for 1.6:1 rockers on the intake valves. Note: Always check for proper rocker sweep across the center of the valve tip, especially after installing high-ratio rockers and adjust pushrod length accordingly.
If you are going to all the trouble building a 383, why cheap out on a little machine work to the heads? But like HAULIN IT said, I've also read that the superior beehive springs increase retainer-to-guide clearance. They are about $185 a set (that's for the springs alone), so it won't save you any money, but you'll end up with better springs. Why are they better? In the case of a flat tappet cam they can offer better valve control with less over-the-nose spring pressure, which translates directly into longer cam life and less chance of break-in problems along with more rpm potential. This is due to the spring's lower mass, the much lower mass of the retainer (steel beehive retainers are lighter than titanium retainers for traditional springs), and higher resonate frequency of the tapered beehive design.
Check out this article: http://www.carcraft.com/techarticles/vortec_valve_spring_upgrade/index.html
Since this article was written, Comp has released a beehive spring designed specifically for flat tappet cams (the ones in the article are originally designed for roller cams). The part number for the new springs is #26986-16 for the set.
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Well, I want it to idle pretty smooth and mostly be a sleeper. Also I'd like to be able to do a small amount of towing with it. It's got a lot of memories from pulling a popup around Oklahoma with my grandparents when I was a kid. It'll lose puff around 3500? LOL, just like the 305 it's replacing?
I'm running a 700r4. Came from the factory with a th350c.
Also, I'm thinking of these shorties: http://www.jegs.com/i/Edelbrock/350/65273/10002/-1
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Well 3500 was a bit of an exaggeration, but you get the picture. My CamQuest program predicts that an engine similar to the one you spec'd would make peak hp around 4500.
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It'll be a sleeper alright....because it won't wake up. The price is no different because the grind changes. You want a cheap cam, here : http://store.summitracing.com/partdetail.asp?part=SUM%2DK1105&view=1&N=700+150+
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Will that allow me to still get decent mileage with my overdrive? I figure I'll be cruising at 1500-1800 rpm on the highway.
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yeah and you can run your stock converter
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Actually I think I prefer that Isky cam. Tighter Lope Separation angle. I don't mind spending money but I'd like to at least not overspend where not needed. So for more lift I can get the beehive springs AND the retainers? That's it? I have the stamped steel rockers that were stock on the vortecs. Also, will it hurt if the intake manifold I have is for idle and up? I do plan to upgrade the exhaust system, but I"d rather by the headers and get new mufflers at the same time. These old glass packs are loud!
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It'll be a sleeper alright....because it won't wake up.
LOL, I like that one!
Actually I think I prefer that Isky cam. Tighter Lope Separation angle. I don't mind spending money but I'd like to at least not overspend where not needed. So for more lift I can get the beehive springs AND the retainers? That's it? I have the stamped steel rockers that were stock on the vortecs. Also, will it hurt if the intake manifold I have is for idle and up? I do plan to upgrade the exhaust system, but I"d rather by the headers and get new mufflers at the same time. These old glass packs are loud!
Regardless of the spring you choose, you'll need to do a guide to retainer clearance check. To confirm that beehive springs will do the trick for you, you could just buy one beehive-style retainer and a checking spring, install it on the valve at the proper height, and measure how much lift you can achieve. I have not run beehives on vortecs myself, so I can't confirm that it works, but the author of that article I posted seems to think so. But beehive retainers are significantly smaller than traditional retainers, so it makes sense that they would add a little clearance here.
But like I said earlier, if a low budget reigns supreme, you should check into the total cost of machining down the valve guides and running traditional springs. Also, the cam/lifter kit Vile recommended will be some $100 cheaper than my recommendation, and would definitely make your motor healthy. Also summit offers a Street/Strip line of cam/lifter kits for about $140 and they are ground on a tighter 110 LCA. Leaving some power on the table maybe be worth it to you, if your goal is just to get a healthy SBC for minimum cash outlay. You'd be surprise how quickly the little costs sneak up you, when you start making little allowances here and there. Just something to consider. But I'd personally be more inclined to go with the Isky 270 cam and cut costs elsewhere.
Here are some books I wish I had read before sinking my money into a crappy crate motor:
How to Build Max Perf Chevy Small-Blocks on a Budget (http://www.amazon.com/Build-Perf-Chevy-Small-Blocks-Budget/dp/1932494847/ref=sr_1_1?ie=UTF8&s=books&qid=1242581874&sr=8-1)
How to Build Horsepower, Volume 1 (http://www.amazon.com/How-Build-Horsepower-David-Vizard/dp/0931472245/ref=pd_cp_b_0?pf_rd_p=413864201&pf_rd_s=center-41&pf_rd_t=201&pf_rd_i=B000X5526O&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0S4AQ00RRT9Q2XRZEGZ0)
How to Build Horsepower, Volume 2 (http://www.amazon.com/How-Build-Horsepower-David-Vizard/dp/1884089143/ref=sr_1_1?ie=UTF8&s=books&qid=1242582046&sr=8-1)
How to Build and Modify Chevrolet Small-Block V-8 Camshafts and Valves (http://www.amazon.com/Chevrolet-Small-Block-Camshafts-Motorbooks-Workshop/dp/0879385952/ref=sr_1_9?ie=UTF8&s=books&qid=1242581874&sr=8-9)
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If your staying with the 700R4 and you get a stall stay away from lock up converters,they cause the transmission to cycle between shifts to much exspeacially on 4x4 with bigger tires and not enough gear,it will cause premature tranny wear.
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I would personally never use a 700R4 without a lockup converter (except for on a dedicated race machine). But I do agree that the TCC cycling excessively can be a real problem. Fortunately, the TCC being electrically switched, there are many ways to tune exactly when you want it to lockup (speed, throttle position, transmission gear, etc.). I was actually thinking about adapting a TPS sensor to my carb and a speed sensor to my tranny and then making my own adjustable control curcuit to fine tune the lockup conditions on my truck. Sounds like a fun project, huh? Also Transgo makes a hydraulically controlled TCC kit, but I think you have to remove the VB to adjust it.
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Transgo makes some good modifications that are simple to eliminate converter lock/unlock/lock/unlock etc. If you're running a 700R4 with 35" Tires I'd run 4.11"s
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Just a little update, I've got the block back from the machine shop. You know the phrase, measure twice, cut once? Well, what I thought were factory standard pistons (everything else looked factory) turned out to be .040 over already. . . so my .030 pistons were gonna have to run a lot of clearance. :-X.
So they sold me a 2-bolt core that I could use. Then a day later they tell me my stuff is ready but I gotta pick it up today, they're closing the shop that day. They did what they call a "Vat Special"- cleaned, checked for cracks, bored, cleaned the deck, installed cam bearings, freeze plugs. Do I need to clean the bores for any grit? I think not cleaning a motorcycle block after boring messed up some rings one time.
If I use that Isky cam do I need to use an oil pump over stock? That 270 looks almost like a little too much for the gear I'm running. I think I'll run the beehive springs if it gets me a little less cam wear in the future and allows a lot easier revving. Now if I could only get paydays closer together.
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why not get a custom built converter they cost as much as an off the shelf unit but are exactly made to fit your cam. i sent my friend down to a shop down in houston (who does grave diggers converters) and costed about 250- 300 (4l60e) for a converter built for his car (lbs) and cam. you cant buy that off the shelf. it runs great and his original converter was back in his car within 24hours.
clint
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I can get performance converters for cheaper than that. There's not much too them.
Clean the engine again yourself. As the builder it's your responsibility to check all of their work. Wipe the cylinders clean and apply a fresh coat of conventional 10w30 to the cylinder walls. Soak the pistons once the rings are on in a container in the oil also.
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If I use that Isky cam do I need to use an oil pump over stock? That 270 looks almost like a little too much for the gear I'm running. I think I'll run the beehive springs if it gets me a little less cam wear in the future and allows a lot easier revving. Now if I could only get paydays closer together.
Now don't think that I am advocating a "fancy parts fix-all" with those beehives. They represent a significant investment and I would buy a retainer and checking spring first to verify they clear the valveguides at the lift you want to run. Remember the article I posted was testing the #26915 and #26918 springs. The one I'd use for a flat tappet cam is a #26986. Another thing that concerns me is the bottom OD of the two springs in the article is 1.29" whereas the bottom OD for the #26986 is 1.412". This may mean it will still be necessary to machine the valvespring pockets larger with this spring. Check you spring pockets' diameter before ordering. Also, the "potential" for decreased cam wear comes from setting them up with less pressure than a typical spring.
For example: the valvesprings that Isky recommends for its 270 Megacam will have 115 lbs at an installed height of 1.7" and approximately 259 lbs at .465" valve lift. The #26986 beehive spring will yield 123 lbs at an installed height of 1.75" and 253 lbs at .465" valve lift. This isn't a significant enough difference to justify the increased cost. But when you set the #26986 to an installed height of 1.78" the seat pressure drops to approx. 115 lbs (like the Isky recommended spring) and the pressure at max valve lift of .465" drops to 245 lbs. And this decrease of 14 lbs (over the Isky spring) at max valve lift can result in dramatically decreased cam wear over the long haul and less chance of break in issues. But is this worth the extra $100 to you? When you add in the fact that they might just drop in without machining the valveguides, yes would be a perfectly resonable answer. But at this point it should be clear that you should also check your maximum available spring installed height on your heads (dependent upon the depth of the spring pockets and the length of the valve stem). Machining may be required, making this spring less of a sweet deal.
Here is a pic that illustrates one of the reasons why beehive springs have superior capabilities over traditional springs. The spring/retainer pair weighs a heck of a lot less.
(http://image.popularhotrodding.com/f/8990230/0607phr_31_z+camshaft_basics+valve_springs.jpg)
Source: http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/index.html
Also there is no reason why your choice of cam would have any bearing on your choice of oil pump. The cam lobes' lubrication comes from oil spash off of the crank and what oil falls on it on the way back to the oil pan. So the cam doesn't see the difference between 5 psi or 65 psi. Your bearings are another story, but high volume oil pumps rob power, can suck a stock pan dry, and are probably overkill in most cases. If I were building an engine from scratch, I'd buy a stock replacement Melling pump, disassemble it, and blueprint it (check/correct all clearances and relieve/smooth all passages).
If you are concerned about the cam being too large, it is always better to err on the side of too little cam than too much cam. Read the article I posted above to become more comfortable with selecting a cam.
Keep us posted.
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I'm still working on 'er. I started cleaning the bores, but it's taking forever with purple power, hot water, and a scotch bright pad. I guess I'm supposed to do this with dishwashing soap and lots of hot water? Anybody have any tips on making this easier. Don't want to spend 4 hours trying to get grit outta the bores.