sbc 350 rebuild questions

where should i look for a dual point distributer, summit? will a new one work as well? and then how would you reccomend i dial it in?  
STAND ON IT!!!

stick to the HEI, most people including mechanics can't even set up a single point correctly.
the HEI from 74-81 is free of crap....and trouble free compared to the points, If you were building a drag boat or car then the dual would be worth messing with.
also don't go advancing or retarding the cam unless you know how to use a degree wheel and are dialing it in to the manufacture specs. they come out of the box nearly correct depending on the quality of the timming set.

the 240 cam will work but will be lacking big time in the  upper mid range and top end, I've used them to warm up 305's and even had a 240 grind in a sbc400 that had small valve heads. you'll be very disapointed in the mileage and the  power out in the mud and hwy. the 252 will prove to be strong and have plenty or torque used with with stock heads and exhaust.

if you want some mileage and a broad power range and enough vacuum to operate your brakes, look more into the 110-112 degree range on the lobe center.

Tighter lobe centers....
more peak power,
higher fuel consumption
rougher idle
more torque at low RPMS,
peak power occurs at LOWER RPM,
higher emissions,
power RPM band gets narrower and moves DOWN

longer duration....

more peak power, rougher idle,
higher fuel consumption,
higher emissions,
less torque at low RPMs,
power peak occurs at higher RPM,
power rpm band widens and moves up

your stock cam gm Part # 968711 has a 114 degree lobe center, 195/202@.050,.390/.410" lift, the same cam was used for 200-300hp engines, the heads, valves, carburation and compression made the hp differences.
even that would be a wise choice to use.  
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hey mud!!! it's like the gangs all together huh? so you think i should run the 252H also? i'm not convinced that it's worth the money right now to do this kind of upgrade but probably by next spring i will be doing this so i want to thoroughly research it and put my money where it will be best spent.  
STAND ON IT!!!

also if i were to install this cam could i run the stock intake, distributer, heads and carb? i could do it little by little if it wouldn't adversely effect anything.  
STAND ON IT!!!

HEI is not emission crap free. Starting is 73 they severely modified timing curves and max advance on engines as well as chopped CR ratios and restricted ports in heads. Most 73's on were pigs compared to 72 and earlier even when new. Also for what it is worth, single or dual points are not hard to setup, it is child's play. Furthermore Mudds suggestion to use a stock cam here is not a good one. The whole concept with a 252 is that is flows so much better and has more power because of asymmetrical lift yet is crisp and response because of limited duration. The quicker you open a valve and the further you open it, the more air you will flow in same period of time. Stock GM cams have very slow lifts and a lot of overlap below .050. I would never use a stock GM cam on a rebuild or re-cam when some aftermarket solutions can make such a big difference especailly with 73 on carbed motors. Furthermore, I would not change heads because again you want higher mixture velocities for good lower RPM power and bigger ports and valve are not for this. Stock intake would work but a dual plane would give you better low speed response due to higher mixture velocities as part throttle. Dual plane is not a must have but it can sharpen up lower RPM power. What some do not realize is that what works for max HP and RPM can suck for lower RPMs and Mudd kinda muddied the water here because I was focusing on lower RPM power and response and his is just general and there is a difference.  

just get the cam and put it in with the stock heads if they're in good shape.
use the HEI not the points distributor, they are also easily adjustable....a mild cam doesn't need extreme curves, simply sticking centrifugal advance weights, the same as are needed to adjust the points distributor, just a different shape, LMAO.. special timming curves...

chopper isn't building a race enginge here, just a occational wheeler and daily driver with a family to think about.

any Idea on the specs of the cam thats in the engine of the "stock" suburban your always braggin about snoman?  
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see me at robsoffroad.com

Any distributors made 73 and later were neutered, They limited total advance and retarded curve. You can install weaker springs on advance weights so it advances sooner but total advance is still limited. Pre 73 distributors were not limited like this. There is some power to be had with a properly curve distributor and I mention older ones because they were curved as such from factory. See you can make a engine run with a retarded curve as they have been doing it for years and do it today with knock sensor to keep consumers happy running 87 octane. The result is reduced max power and MPG. Anyone that was driving when 73's cam out (like I had been for several years) would remember what a hit power and MPG took in 73 in cars and trucks. BTW, I still have that cam around here somewhere I think (one from my GMC) SB's like about 38 degrees of advance WOT around 3800 RPM or more for best power. This generally needs more than 87 octane though. Max engine EFFICIENCY (ie work per amount of fuel consumed) occurs when you develop peak combustion pressure at correct point in rotational cycle for max energy transfer (this is usually around 15 to 20 degrees ATDC). Retarded timing lowers peak pressure and point it occurs at and reduces efficiency. And as I stated earlier, open exhaust valve too soon or to little back pressure lets pressure blow down too quickly and less is coupled to crank at lower RPM's. I studied IC design and theories in college and wrote a few papers on it. What works for max peak HP and make usable HP at lower RPM's is two different matters but some think one theory does all. The concept of asymmetrical cam's goes back to 70's. Back then they were called MPG cams because the reduced overlap while increasing flow so that power was good while improving MPG from less fuel loss at overlap and improved effective CR at low and mid RPM's(shorter duration of valve opening) which means more power is extracted from mixture at lower and middle RPM's. When you are talking about power at higher RPM's, cam and intake dynamics change because weight of air mass in port and its energy from motion plays a role in best cam duration for desired RPM. At these speeds you start thinking of air mixture as a continuous flow rather than pulses.  

in 73 the power didn't exactly decrease, the way it was measured changed...along with decreased compression in favor of emisions and economy.  
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see me at robsoffroad.com

Im tearing done my 350 in my 72 chevy pickup and i would like to know how to get the max torque out of it from idle to 5 or 6 grand  

mudb8-.:
in 73 the power didn't exactly decrease, the way it was measured changed...along with decreased compression in favor of emisions and economy.

YOu are in error here, yes they changed the way it was rated but power to a big drop as they retard timing, reduced compression, restricted exhaust ports and increase exhaust overlap to dilute incoming mixture more to reduce peak pressures and temps to help control NOx generation. (the whole reason behind retarded timing and lower compression was for NOx control before they was 3 way CAT's) The result of this was reduced power and lower MPG. Detroit timed the new rating system with new emissions so they could have better ammo to explain the loss. (had they done it sooner they would have had a hard time selling the power loss in 73) My 72 GMC was rated at 255HP gross and 210HP net. (that year GMC rated then both ways) In 73 it went to about 160 HP net.  

Buchoz72Chevy:
Im tearing done my 350 in my 72 chevy pickup and i would like to know how to get the max torque out of it from idle to 5 or 6 grand

You need to make a choice here, make torque from idle to about 3500 RPM or so and then failing off or max torque from about 3500 to 6000 RPM with torque declining at lower RPM's. You cannot have both short of variable valve timing. Best you can hope for is a compromise were torque peaks at the RPM's you use most. Many years ago I ran a H260 grind mentioned earlier in this thread in a 350 and it pulled good from about 1500 to 5000 with a manual. If it had a automatic the lack of torque below 1500 would not really been much of a issue.  

snoman, i just finished looking at the 500cfm edelbrock square bore performer and they reccomend it be used in a 305ci or less. could i consider the 600cfm? and if so how might this effect my optimum torque peak range?  
STAND ON IT!!!

also might someone suggest a good stock and/or aftermarket head to go with the low end torque theme?  
STAND ON IT!!!

There is a lot of misconceptions out there on carb needs as to size. Also when you change the valve and head porting you change the effect of the cam placed in engine. Type of fuel system too plays a roll in what configuration you need too. Since were are dealing with a carb and and wanting strong low end and mid range power this post will deal with this subject. First, the carb. If you are lucky you might reach 90% VE (volumetric efficiency) with your engine and this will be at the speed where its torque is the greatest, not at peak RPM when torque is falling. If we use this 90% VE we will find that a 350 turning at 5000 RPM will use 455CFM (actually less with a torque cam because it will be well past peak VE) This is well within a 500CFM carbs ability. You will need a much warmer cam and RPM's of 6000 and more to really begin to use a 600 or more CFM carb on a 350. The 500 will flow better at lower RPM and have higher mixture velocities in bores which leads to better fuel/air mixing and a better burn and efficiency. (this is important with a carb for good response and power)Same with intake, you want smaller ports to keep mixture velocities high to better mix fuel and air at lower RPM's. Also, you have to consider the velocity and mass of air in intake and as it is moving in intake and when valve closes the air does not stop instantly but rather starts to stack up against port and valve for next cycle from the mass and momentum of flowing air which helps fill the cylinder for next cycle. Smaller runners and ports are best for this at lower and mid range RPM power. Large ports and runners at best above 4000 RPM or so. Same with valve size. Many think 2.02 or 1.94 here but again if low RPM torque is the focus here you kinda want 1.72 valves because velocity of mixture into cylinder will be higher and it will mix and burn better and yield better lower RPM power. Use a small valve head with a cam with a aggressive lift on a short duration and it will fill cylinders nicely below 4000 RPM. If you go with bigger valves, you need to consider shortening duration of cam even more because larger valve increases the effective duration of cam because they increase the effective flow vs lift compared to a smaller valved head. (it starts to flow sooner at a lower lift because of greater surface area of valve seat so it has to open less to create the same effective surface area opening into cylinder and will start to flow a few degrees sooner and stop a few degrees later than a smaller valved head. I hope I did not muddy water for you but again this as all about low and mid range torque and we are not building a 5000 RPM plus power house here. I come from old school in that I believe a good 4x4 engine should have great low and mid RPM power. Modern V8's in 4x4 have some impressive rating at 5000 RPM or more power peaks but unless you are mud racing or sand dragging at high RPM's you will never see that power peak and that high rating at high RPM's is achieved at the cost of lower RPM torque and HP is torque times RPM divided by 5252 and the more torque you have at lower RPM's the more HP you are getting to flywheel and load. Most of my driving off road and on and even towing my RPM never gets above 3500 RPM or so and if so only briefly and because of this, I want my best grunt/torque available at lower RPM's where I can use it. This is why at old 350's with a lower HP rating can out tow/pull a 4.8 or 5.3  which both have higher peak HP rating but less flywheel HP below 3500 RPM or so were most of this work is done.  

My question deals with displacement.  I just rebuilt the 400 small block in my '77 Chevy.  I was in a hurry picking parts and wanted a very mild engine.  The cam I chose was a 214/224 @.050 with 443/465 lift.  I put a Perfomer intake on with a 600 cfm Holley.  Truck also has Summit headers and crappy 2 1/4 inch exhaust through glass packs. I know that the 50 more cubic inches make a difference in the performance but how much of a difference? With this set up should I have gone with a smaller cam?  The truck sees logging trails, mild mud, and a little towing.  Its a 1/2 ton with 33's and 4 inches of lift with a 350 th and full time 4x4