I am in the process of building a 350 engine. it is bored 30 over, a pro comp 4x4 cam in the 600-4600 rpm range, an edelbrock preformer intake and a 500 cfm edelbrock carb. I curently have 2 sets of heads 1.94s and 2.02s. wich ones do i use? the truck is a 73 k-20 daily driver, on 245/75/16. 4speed trans 205 transfer. i plan on putting it on a set of 38 tsl (after i can figure out how to get them under the old ladys radar) the axles are loaded with 4.11s, what heads will give me the best bottom end?  

The 194s, gotta keep the air velocity up for efficiency,save the 2.02s for the higher rpms engine your gonna build for your wife, when she finds out about the 38s,shes gonna wig! she'll want them for her camaro.maybee..  

I agree on 1.94's and would even strongly consider 1.72's as they will give better low and midrange torque and response. As far as cam I would need to see lift and duration to comment on its match, Carb size is good. Also as far as "loaded" gears, you are loaded way wrong for 38's by any stretch here. Some think 4.10 is holy grail of gears but there is no universal do all gear. The proper ratio depends on tire size and vehicle. With 38's 4.10 are about equal to 3.07's with stock tires which are not a performance combo by any stretch and no SB build is going to make it pull the right. Even a 4.56 would be light here with a 4.88 being better. The smart thing to do here would be to install 5.38's and a NV4500 tranny and scrap/sell NP465. This would give you about 100 RPM less at cruise than 4.10's with 465 and about 30% more pulling power in first through 4th vs 465 and would make that truck run. As a rule of thumb if you want truck to run well, you take tire size and divide by about 7.8 or so with a non OD tranny to get gear ratio that is a compromise between good power and cruise/MPG with a big lift and divide by 7 with a OD tranny. About 25 to 30 years ago I had a 72 GMC 3/4 ton 4x4 that I warmed up a bit it had a 465 and 4.10 with 32's on it and it ran well but I would like to have put 4.56's in it I think if I did it over. I like my truck to run strong in all gears, not just a few of them. I even have a set of 4.56 on the shelf here for my 2000 K3500 that I plan to install this summer and it in not lifted nor with it ever wear more than stock sized tires. I drive a truck when I need hauling/towing power and cut no corners here. Nothing sadder than a big lifted truck with too tall a gears that struggle to get out of its way at speed. They are easy to spot because they are they ones that they are downshifting a lot and winding the snot out of them in lowers gears to try to make up for lower performance in top gears.  

I would go with the 2.02 and do a little work on port matching the intakes. Also do a little work on the turndowns to the intake/exh valves. Anything you can do to get as much air into your cylinders as efficiently as possible is better. Your camshaft is what allows how much air is allowed into your cylinder. If your cam is only allowed to be open so long on intake/exh thats all the air you gonna get in the cylinder. On the low end torque thats all about carbs and cam timing. Cam timing is what tells the engine what it is. Is it a high rev motor or is it a midrange motor or low end torque. It is true you can have two big a port and hurt your low end torque with bad port velocity, but a chevy 2.02 head in stock form is a great little cyl head and does a good job. What is the casting# need last 3 numbers? You don't have to port much just knock off any high spots and smooth out turn downs a little. Keep the ports a little rough and create a little turbulance in ports. Common sense type of situation. Their are some other concerns but not gonna go their. Are you running a header or manifold? Just more stuff to worry about. I know I'm gonna catch some flak but been their done that with ford and chevy's. Engine is a air pump and how much air can you move efficiently at a given RPM??  

wyomingtrailheader:
I would go with the 2.02 and do a little work on port matching the intakes. Also do a little work on the turndowns to the intake/exh valves. Anything you can do to get as much air into your cylinders as efficiently as possible is better. Your camshaft is what allows how much air is allowed into your cylinder. If your cam is only allowed to be open so long on intake/exh thats all the air you gonna get in the cylinder. On the low end torque thats all about carbs and cam timing. Cam timing is what tells the engine what it is. Is it a high rev motor or is it a midrange motor or low end torque. It is true you can have two big a port and hurt your low end torque with bad port velocity, but a chevy 2.02 head in stock form is a great little cyl head and does a good job. What is the casting# need last 3 numbers? You don't have to port much just knock off any high spots and smooth out turn downs a little. Keep the ports a little rough and create a little turbulance in ports. Common sense type of situation. Their are some other concerns but not gonna go their. Are you running a header or manifold? Just more stuff to worry about. I know I'm gonna catch some flak but been their done that with ford and chevy's. Engine is a air pump and how much air can you move efficiently at a given RPM??

You are not quite right here. While it is true that cam timing does play a major roll in engines potential torque curve, valve and port size play a far bigger roll at lower RPMs than you think as to intake runner type and diameter. If you want strong crisp low and mid RPM response and torque, you DO NOT want 2.02 heads. Actually the need for 2.02 heads at all is kinda over rated unless you plan to spend a lot of time above 5000 RPM. How you might build a engine for a fast car vs a heavy 4x4 is completely different matters. Bigger is not always better and same with carbs as to big can hurt performance too (some seem to think the bigger the better here too)  

I agree with the smaller valves and higher velocity theory and I go you one more that kinda proves the point. The reference to the cam controlling the air flow could be compared to the butterflies controlling the airflow in a carb. Put too big a carb on and no matter how lean you jet it it will be a dog until you get to the upper rpm's. Too small a carb will run good on low end but starve for air on the top end. Same thing with valves and ports. There is no substitute for a balance of parts for the correct application so that they work together and the 2.02's are for bigger and higher rpm motors.  

Well from my experience with small block chevy's I've had good luck with the 2.02 in 4wd with smaller cams. Its mainly the cam and cam profile to help out on 4wd cams. Most everything I do anymore is heavytruck 4wd's. I would need to know what cam your running and intake. Sometimes port volume is a issue on dual plane intakes. I like making sure the valve isn't a restriction. Rocker arm ratio is another problem with chevy's 1.6 ratio is ok but sometimes like a little more movement in valve. Currently doing a 400ford with a 2.190 int vlv 1.71 exh 4v head for a 4wd ford 5500lb truck with standard tranny, setting up for midrange. Port diameter is my biggest issue with 4v head their to big. Epoxy up the intake runners some and will be good to go. Every engine is a air pump, but how effieciently they move it is the question. What cyl head are you running on the 350? casting number last 3 numbers. Did a lot of porting back in the day on chevy's for wheelin and muddrags. I'm still learning about camshaft potential. The timing of valves opening and closing are very important and cam profile. On carbs the booster design is important. Is it a downleg style or straight or annular I like the annular for low end because it helps vaporize the fuel on low end a little better. I do know smaller carbs do work great on low end. As I learn about booster design with 4wd stuff the annular type carbs I really like and you can run bigger carbs. Helps broaden my torque curve or makes a longer flatter torque curve. O'yeah forgot sometimes with the 2.02 vlv sometimes vlv shrouding is a issue on 4" bore. Sometimes working the combustion chamber and unshrouding the vlv helps a lot with the 23 degree heads chevy runs from factory. Angle milling is a good way to help unshroud the vlv but also piston clearance is another issue. This is more info than you want to think about but I'm always trying to build a better mousetrap no matter what it is. I usually have my cams cut for me instead of buying off the shelf anymore and I degree them. What type of header and exhaust??  

sbc's are 1.5, bbc's are 1.6..

to prevent the mess and confusion the 1.5 ratio rockers and 1.94-1.5 is the way to go unless yer spinnin over 5 grand.  

Well I sturred up some issues. I never spend over 5 grand on a 4wd motor unless its a big block. Small block chevy about 2500 to 3000 carb to oil pan. Mainly do a lot of fitting of the engine. Big block chevy rocker ratio are 1.7 small block are 1.5 but 1.6 are available. One of the quickest cheapest ways to build a small block chevy is install a set of 305 heads like on a IROK 305 head. More compression smaller combustion chamber smaller vlvs believe 1.84 int. good little combination with a dual plane. But when running a manual tranny I like a broader torque curve than what you'd get from that head. Meaning you don't have to shift gears/push the clutch in and lose momentum. One good thing is this guy now knows a lot more than he knew before.  

wyomingtrailheader:
Well I sturred up some issues. I never spend over 5 grand on a 4wd motor unless its a big block. Small block chevy about 2500 to 3000 carb to oil pan. Mainly do a lot of fitting of the engine. Big block chevy rocker ratio are 1.7 small block are 1.5 but 1.6 are available. One of the quickest cheapest ways to build a small block chevy is install a set of 305 heads like on a IROK 305 head. More compression smaller combustion chamber smaller vlvs believe 1.84 int. good little combination with a dual plane. But when running a manual tranny I like a broader torque curve than what you'd get from that head. Meaning you don't have to shift gears/push the clutch in and lose momentum. One good thing is this guy now knows a lot more than he knew before.

Re-read the last post, he said spinning, not spending. Ya'll are apples and oranges with these motors anyway. I happen to believe that bigger isn't better in this situation as well. You could build a motor like you outlined but it's kinda like going around the block to get there. He can get what he needs with the smaller valves and less mods necessary to support that big flow. BTW- I don't think it matters anyway since he hasn't posted since May.  

On the carb sizing I would have to see a vacume reading at the manifold and carb. I live at 4000ft elevation and play at 8500ft elevation and carb sizing is critical. I'll set up a carb with the best overall vacume reading. I'm currently playing with a 800cfm on a 460 and like it with annular booster setup on a 1 to 1 linkage. Like the 1to1 for lowend torque. I don't have much air to play with up here and carb sizing is critical for broad torque band.  

wyomingtrailheader:
On the carb sizing I would have to see a vacume reading at the manifold and carb. I live at 4000ft elevation and play at 8500ft elevation and carb sizing is critical. I'll set up a carb with the best overall vacume reading. I'm currently playing with a 800cfm on a 460 and like it with annular booster setup on a 1 to 1 linkage. Like the 1to1 for lowend torque. I don't have much air to play with up here and carb sizing is critical for broad torque band.

Bigger carb is not going to solve thin air and even for a 460, 800 CFM is too big. The way you deal with thin air and deeper gears than you would use at sea level and keep average RPM higher. Part of what make a engine work and response well is velocity of air in runners and its mass. In thinner air the mass is reduced so you need more velocity of air to get same kinetic energy in air to help fill cylinders. When intake valve closes, the air starts to stack up a bit against valve from momentum recharging port for next cycle. In thinner air it take more velocity/RPM to do this. BTW, a 460 at 5000 RPM (which is a bit more than you want to regularly turn it anyway) would need about 600 CFM tops. A bigger carb reduces mixture velocities in venturi and reduces response and lower RPM torque. One more thing, you want to use more aggressive timing at elevation too and run at least 6 degrees more than stock setting (the higher you go the more spark you want (this is a very old trick) Try using more spark, smaller carb and 89 octane and better axle gears and you will be pleased with results.  

sno i am gonna have to disagree with you a little bit. a 600 cfm carb will feed 460 big block up to about 4000 rpm. i had a 600 edelbrock on my 454 chevy and thats all about it would let it turn. a big carb lets more air flow thats why it has a bigger rating. i will agree with more timing and more gear.