Lets talk Small Block

[BrianG]

Originally Posted by clay68c10

It would be worth pulling a valve cover and putting a dial indicator on your rocker arms to figure out your current cam valve lift specs, just to have a baseline to compare what cam you may want to change to.

Since it's a one piece seal block, look thru the pushrod and drainback holes and see if it's a block made for the factory roller setup (lots of them are). If you have a flat tappet cam in a block that has the provisions for roller it's a cheap upgrade to put the factory roller lifters in it. You could run a factory Vortec cam or HT383 cam, that would get you in a better power band for your use.

What's the chamber volume on the World heads you have? See if you can find that out and borrow/rent/buy a borescope to look at the piston tops. A lot of the new ones are video capable so you cold post a pic here and figure out what you have. Then you'll have a fair guess on CR and whether you need to do anything about it.

I know that the heads are the S/R or the Stock Replacement heads. They have a 170cc intake runner and either a 67 or 76cc compression chamber. I don't have a dial indicator but it is something I should probably add to the tool box.

[BrianG]

Originally Posted by BrianG

I know that the heads are the S/R or the Stock Replacement heads. They have a 170cc intake runner and either a 67 or 76cc compression chamber. I don't have a dial indicator but it is something I should probably add to the tool box.

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.

[clay68c10]

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?

[BILT4ME]

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

[BrianG]

Originally Posted by clay68c10

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?

I was able to find some casting information under the valve covers. I could not find any exact number when I had it out when the truck was getting painted. The general casting information just tells me that it is their base S/R head and according to the website they come in two different chamber sizes.


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...

[special-K]

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.

[BrianG]

Originally Posted by special-K

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.

The motor runs good, but I can't help but feel that it could definitely be better, especially at lower rpm. When I bought the truck back almost six years ago and drove it home, it seemed great. But I think that I was probably overly excited about the prospect of getting my truck back. It had been rebuilt not too long before I bought it back so I didn't tear into it. Now that the truck is done, I wish I would have opened it up and at least figured out what it was put together with. I've tried to ask the guy but he doesn't seem to know what was put in it.

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.

[TheCougarine]

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.

[Boog]

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.

[special-K]

Originally Posted by BrianG

The motor runs good, but I can't help but feel that it could definitely be better, especially at lower rpm. When I bought the truck back almost six years ago and drove it home, it seemed great. But I think that I was probably overly excited about the prospect of getting my truck back. It had been rebuilt not too long before I bought it back so I didn't tear into it. Now that the truck is done, I wish I would have opened it up and at least figured out what it was put together with. I've tried to ask the guy but he doesn't seem to know what was put in it.

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.

I've never run a big block in these 4wds. Mostly 350s, built a couple 383s, and had some with a 400. I have no use for a big block in a 4wd. I look at them like tractors, where power comes through gearing more than HP. I like the 400 SBC in a 4wd. That's why I like 383s. It's about that stroke.

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.

[BrianG]

Originally Posted by Boog

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.

The brake system has been completely gone through. The booster and reservoir are new along with most everything else. No leaks anywhere, everything bled properly, check valve checked. Etc.

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.

[James the III]

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

[BrianG]

Originally Posted by special-K

I've never run a big block in these 4wds. Mostly 350s, built a couple 383s, and had some with a 400. I have no use for a big block in a 4wd. I look at them like tractors, where power comes through gearing more than HP. I like the 400 SBC in a 4wd. That's why I like 383s. It's about that stroke.

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.

Good info! Thank you. From how I read this, I read that with the right cam even stock heads can make good 4x4 power. However, the 383 would really put a smile on my face. I need to figure out which cam I have I guess. I don't want to end up with a situation where I drop in a cam and end up not being happy and then go heads and bigger cam or whatever. Not like test driving a car where you know what you are getting. The more information I can get from others like you will definitely help.

[garyd1961]

Sounds to me like a set of vortec heads and a mild cam is what you are looking for.

[clay68c10]

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.

[special-K]

Mine has 64cc chambers with dish tops. Those heads gave a noticeable bump in power and I run regular. Actually, regular 10% ethanol crap

[TwoFiftyShifter]

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.

[BrianG]

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.

[special-K]

Originally Posted by BrianG

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.

Maybe that's why Vortec heads tend to crack

[BrianG]

Originally Posted by special-K

Maybe that's why Vortec heads tend to crack

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.

[Captainfab]

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.

[storm9c1]

Originally Posted by BrianG

That is a good question. I have tried a few different things with the PCV. From everything I read, it's pretty much a necessity. I have tried manifold vacuum and the port on the bottom of my Carb, which is also essentially manifold vacuum. No real difference since they were both manifold vacuum. The PCV does eat quite a lot of the vacuum. I switched to the PCV from a 302 Camaro since that was supposedly a low vacuum engine. It didn't really make that much difference if any

Let's revisit this. Different PCV valves are available for different vacuum profiles. Have you tried different valves?

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.

[BrianG]

Originally Posted by storm9c1

Let's revisit this. Different PCV valves are available for different vacuum profiles. Have you tried different valves?

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.

I have tried a few different PCVs and ended up with one from a 302 small block. I found quite a lot of references to this online and that's what I ended up with. As far as tuning, I have a vacuum gauge and have tuned it for optimal vacuum using that. I've also tried no vacuum advance which is where the motor was when I got it and he was told by the engine builder that it didn't need it. I've tried ported and I've tried full manifold. There are enough discussions on this forum and other's online that debate that. I've read and read on about them. I think currently it is connected to ported vacuum. I have checked for leaks and there are none that I can find. I was curious if maybe I had a brake issue or if something had happened to the motor while it sat when I was working on the body. I ran across the guy I bought it back from and asked him about the brakes. He said..."Yes, you only really got one good pedal out of it" and that's how it is now. So, I don't feel that anything has happened to it. I just think that the particular cam that is in the motor now, is not necessarily a street friendly cam. When he bought it from me 10 years ago, he bought it strictly for off road use. I had used it for both on and off road prior to that, but now it will be pretty much an on road vehicle unless I decide to take it to the dunes some day. I need to sacrifice some wide open throttle horsepower for torque and street drivability.

[storm9c1]

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.

[AcampoDave]

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.