01-04-2017, 10:48 PM | #26 | |
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Re: Lets talk Small Block
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01-05-2017, 10:54 AM | #27 |
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Re: Lets talk Small Block
Another thing that I remember is that it is supposed to have higher compression pistons. Flat Top I presume, but I'm sure there are many differences. The guy I bought it back from told me that they actually had a harder time finding the pistons because they did not bore it, than if there were to bore it. Seems as though most of the company's had plenty of oversized in stock but not the stock bore size.
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01-05-2017, 04:05 PM | #28 |
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Re: Lets talk Small Block
It would be worth finding out which version head you have, flat tops with the big chambers might be workable with a smaller cam. The small chambers may have too much compression for a smaller cam.
Are there casting or model numbers on those?
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01-05-2017, 05:11 PM | #29 |
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Re: Lets talk Small Block
I had a 69 K10 with a manual transmission (SM465) and 4.11 gears, 33x12.50x15 MT tires on steelies
The engine: 350, bored 0.060" over (=360) Weiand 180* dual plane intake Holley 650 Double pumper Cam was Crane 113901 for towing, off road, and low-end torque Pistons were 8.5:1 compression flat top. Heads: 1.92 Truck heads ported, polished, and gasket holes matched Exhaust Manifolds: rams horn cast iron manifolds (also ported, polished and matched) Exhaust was 2-1/2" duals with DynoMax turbo mufflers The engine was ported, polished, and balanced to 10,000 RPM. It was VERY smooth running. I was pulling around 350 HP and this truck did VERY well for towing and would get no less than 12 MPG no matter what I was pulling. On the open highway, treating it nice, I would get 14 MPG. Over time, I did a rebuild and the machine shop junked my heads, so I installed a set of STOCK (not ported, polished or matched) 1.92 truck heads. I lost at least 75 HP, the truck dropped to 8-10 MPG, and the carb was way over-jetted. I was starting a family so I sold it. Anyway, the biggest difference you have here is that if you are actually at 10 or 10.5:1 compression, you COULD install a less radical cam, but you will have to run premium or above fuel. I agree that the engine the way it is currently set up would not be much fun to drive unless it is at WOT. I set up my truck for driving and being a workhorse and it did that VERY well. Good luck! I was first thinking a simple cam swap until I read the compression ratio. that combination would push me more toward one of the crate engines. Make sure you get it cammed appropriately for an automatic or manual transmission. (It can affect shift points) http://www.cranecams.com/56-67.pdf
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01-05-2017, 05:12 PM | #30 | |
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Re: Lets talk Small Block
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A question though... Regardless of the chamber size (which if I understand you will be important in determining which cam I can successfully run) If these World Products Stock Replacement heads are just as they claim, a decent stock replacement head. Then what can really be expected out of them? Is for example, 400 ft lbs of torque at say 2500 to 3500 rpm realistic? An open question to anyone... |
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01-06-2017, 10:55 AM | #31 |
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Re: Lets talk Small Block
The truck runs nice now, right? I thought that's how you started out. You don't need an engine or any changes, you need more vacuum or brakes that don't use vacuum (hydro-boost). Diesels make virtually no vacuum, they come in heavy trucks, and they stop.
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01-06-2017, 11:28 AM | #32 | |
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Re: Lets talk Small Block
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I have definitely thought about a hydroboost system. But after thinking about it for quite some time I'm now considering tackling the issue through the engine rather than the braking system. There's really no reason that the current power brakes shouldn't stop it if it had the correct vacuum. I know you run 4x4's. Do you run small blocks or big blocks? 350's or 383's just curious. I've rebuilt a few small blocks and other motors but don't know enough about them to know what combination of heads and cam and pistons work best together. I don't really know of the correct resources other than to ask here on this forum, that can help give me an idea of what kind of power potential there is for my 350 vs buying a 383 and yet keeping it at a range that will still allow it to make enough vacuum to be streetable. Honest real world feedback is sometimes the most valuable. That's why I really appreciate your feedback and that of the others on this forum. |
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01-07-2017, 12:44 AM | #33 |
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Re: Lets talk Small Block
I think someone mentioned it but a vacuum reserve canister would be something to check out before tearing into the motor. If the brakes are your biggest issue and you don't want to convert to hydroboost then it seems like it'd be the way to go. That is if its really about the brakes and not about you just wanting a new motor. Let me be clear, I don't mean to imply theres anything wrong if you do want a new motor but a new motor is not at all necessary in order to get your power brakes to work correctly.
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01-07-2017, 08:32 AM | #34 |
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Re: Lets talk Small Block
There is a lot of speculation here about your engine specs. You won't really know what's in it unless you tear into it and see for your self what pistons, cam lift, duration etc it really has. It sounds like a fun engine for off road adventures but maybe not so good for the street.
So far no one has asked just what shape your brake system is in. Have you rebuilt the complete system or just know it doesn't feel right? If the truck once stopped good but now doesn't I would pull the wheels and inspect the whole system. Low vacumn will diminish power brake performance. If I recall correctly the factory system needs a minimum of 9 or 10" of vacumn to operate right. There could be a small vacumn leak in the brake booster reducing it's effectiveness. If it is an original brake booster it would be suspect due to age. There is a coil spring inside the booster that can break and rub a small hole in the diaphram bleeding off vacumn. I've had that very thing happen on an 82 pkup. That truck had a stock exhaust and I could not hear the vacumn leak. You could remove the vacumn line from engine to booster and plug it and see if the vacumn signal goes up at the engine. If so it can indicate a vacumn leak in the booster. A vacumn reserve can from the salvage yard could be a good tool to narrow the cause to either just a low engine vacumn or worn/weak vehicle brake system.
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01-07-2017, 10:09 AM | #35 | |
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Re: Lets talk Small Block
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I wish I could tell you the specs on my '72 350 I built in '91. I believe I used an RV range cam and bumped the compression a bit. It's no monster but runs out nice. I had a cracked head this summer and put a fairly fresh pair of 1.94s on and it runs better yet. I was concerned the bigger valves would mess up the combination, but they were cheap. Turns out it runs better. I was about to build a 383 before I found those heads. That is still the plan for some day. I have another engine for that.
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01-07-2017, 10:29 AM | #36 | |
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Re: Lets talk Small Block
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I get onc good pedal than very hard pedal because I'm not getting any help from my the booster. It's pretty scary in town. You are right it would be great for wide open fun. It needs a lot more power between 2000 and 3500 is my guess. I think more vacuum would help the idle and trans kick down also. I realize I need more info from what I currently have to really make the best decision. I guess I didn't realize the puzzle would be so complicated and that's why I appreciate all the feedback so far. It doesn't seem as easy as saying ...oh put this cam or this cam and change to these heads and you'll be happy with it. Or even ...I doubt you'll be happy with anything but a 383. Assuming that I do have flat top pistons and going up from there. Is it ignorant to asuume that I can get a close idea of what a good cam would be for my stock replacement heads. And what more potential I could get with cam and heads? And what I might be able to expect in tourque from either of those combinations. The drop in 383s I was looking at advertise their specs so I could then compare to that. |
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01-07-2017, 10:38 AM | #37 |
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Re: Lets talk Small Block
I'd junkyard crawl for a vac pump and can.. and be done with it..
Unless you are just looking to rebuild or replace the engine.. just because.. then go for it. But even the vac pump won't fix a bad booster.. new does not = good put a hand held vac pump on it and see if it holds vacuum.. Many oem pumps ford trucks mod motors (most) all non hydro boost oil burning trucks caddy's g.m. small cars sunbird/sunfire/cav/ colbalt |
01-07-2017, 11:58 AM | #38 | |
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Re: Lets talk Small Block
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01-07-2017, 07:18 PM | #39 |
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Re: Lets talk Small Block
Sounds to me like a set of vortec heads and a mild cam is what you are looking for.
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01-08-2017, 11:43 AM | #40 |
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Re: Lets talk Small Block
I agree, Vortecs and a mild cam would probably be a great solution. It really depends on the current pistons, the Vortecs have a 64cc chamber so it's easy to get too much compression with no-dish flat tops made for 76cc chambers.
It would be nice if it's a roller cam compatible block. Google images can help with the ID, it's pretty easy to see the difference with side by side pics. Easy enough that you can tell by looking thru the head casting holes with just a valve cover off.
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01-08-2017, 05:34 PM | #41 |
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Re: Lets talk Small Block
Mine has 64cc chambers with dish tops. Those heads gave a noticeable bump in power and I run regular. Actually, regular 10% ethanol crap
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01-08-2017, 06:01 PM | #42 |
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Re: Lets talk Small Block
I have a worn out 1972 350 with headers and an RV cam that runs good but uses a quart per every tank of gas. I'm hoping to replace it by spring with a fresh 350 but with Vortec heads. I am exited to see how they will perform in a truck such as this.
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01-08-2017, 08:34 PM | #43 |
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Re: Lets talk Small Block
The truck has new headers on it now. I would be a little worried about spark plug clearance with the Vortec heads. From what I read, the plug is closer to the exhaust port.
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01-08-2017, 10:52 PM | #44 |
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Re: Lets talk Small Block
Maybe that's why Vortec heads tend to crack
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01-08-2017, 11:05 PM | #45 |
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Re: Lets talk Small Block
No kidding didn't know that. I think I'm leaning toward sticking with my heads and trying to come up with a cam that will work well with them. I'd still love a 383 I'm pretty sure of that. But that's another several thousand. I don't at all look forward to process of breaking in a cam and adjusting rockers and all that. I think I'm becoming lazy as I get older. Gotta do something though.
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01-09-2017, 12:41 AM | #46 |
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Re: Lets talk Small Block
The iron Vortec heads have the spark plugs in the original or at least very close location. The Fastburn heads have angled plugs. Both the iron Vortecs and Fastburn heads have raised exhaust ports.
The Vortec heads cracking issue is due to 2 things. 1) lightweight castings 2) The original factory intake manifold gaskets were prone to failure and leaking coolant. If this was not caught and the vehicle continually driven, the engine could overheat. This would cause the cracking.
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01-09-2017, 12:49 AM | #47 | |
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Re: Lets talk Small Block
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Also, carb tuning can make a big difference. Have you tuned the idle mixture screws with a vacuum gauge attached? A small turn of the screw could add 1-2" of vacuum. And might actually make it idle better. Count the turns so you can reset it if you aren't happy. Another trick is the vacuum advance on your distributor. What is that attached to? If it's on ported vacuum now, you can attach it to manifold vacuum. That will give you a bump in idle, allowing you to back off the throttle stop screw. That may also give you another 1-2", especially if you are idling on the power circuit now.
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01-09-2017, 10:53 AM | #48 | |
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Re: Lets talk Small Block
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01-11-2017, 12:17 AM | #49 |
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Re: Lets talk Small Block
I still think you might be able to gain 1-2" using full manifold vacuum on the distributor and retuning the carb for that. But every engine is different. It'd be more of an experiment than a promise. Keep in mind a few things if you switch this. 1) You have to make the switch with the engine warmed up to see correct results. 2) You will have to lower the idle at the carb with the stop screw. 3) You should retune the carb with a vacuum gauge after making these changes. Otherwise it will seem like you have no gain and perhaps even develop a stumble without that type of retune. It does change the vacuum profile of the engine. Screw the debates about which is better (ported or vacuum), the engine profile tells you this. Stock profiles might like one type. Radical profiles might like another. It's a trial and error process. Nobody can tell you which is right or wrong (which is why this is so heavily debated). But your engine can tell you if you listen.
I'd also be tempted to try a vacuum canister next. Not uncommon to need one with a radical cam. Or last resort, as discussed, change the cam.
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01-11-2017, 01:40 AM | #50 |
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Re: Lets talk Small Block
Is simply ditching the booster and going manual brakes a bad thing for a 4x4? I have manual disc/drum on my two wheel drive and it's no problem.
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