Thread: SBC 350 build

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Alright everybody, here's the deal. It turns out I have a crazy awesome dad. I just found out he bought me a 71 C10 and it is sitting in storage for me come spring time. It has a stock 350 other than headers and vortec heads and a stock TH350 behind it. I want to redo the top end of the motor and I was hoping for some insight from the community. This is obviously my first time rebuilding a motor and I have my old man for an extra set of hands and insight but I need help on a few parts. Here's my plan so far:

Motor
Heads: Brodix IK180 64CC combustion chamber- 2.02 in 1.60 ex
Intake: Edelbrock Performer RPM Air Gap
Cam: COMP Thumpr cam and lifters
Duration@.50:In-243 Ex-257
Lift:In-.500 ex-486
Comp Roller Timing Set
Carb: Holley Ultra Street Avenger 670 CFM
1" Carb Spacer
MSD Pr Billet Distributor/Strret Fire Coil/Street Fire Plug Wires/NGK G-Power platinum

Tranny
TH350
B&M Transpak
Hughes 2500 Stall converter (opinions on stall?)
Aluminum deep pan

My boggles are mainly push rods
(length), rockers, (roller worth it) and do I have it way over cammed? Any insight is greatly appreciated. It's going to be my daily driver but I want to have some power. Thanks in advance everybody.

http://www.pinkbike.com/photo/6070164/

How many miles on the engine??? Might want to do a leakdown check on the engine (compression check at least!) All the top end goodies in the world won't do a bit of good if the bottom end is weak or tired.

Got to ask, why the thumper cam???? Probably not the best performance or economy for an engine that will be your daily driver.... I'd also have to suggest going to a hydraulic roller cam...Lots of problems the last few years with flat tappet cams as the Feds took all the good stuff out of the oil that prevents flat tappet cams from grinding the lobes flat.... Yeah, they're more expensive but a retrofit hydraulic roller properly match to the rest of your engine will give you better performance and not cause you a lot of grief (and additional expense) when the cam loses a lobe or two!!!!!

As for the pushrods, get a pushrod length checker then when the engine is al put together you'll be able to order the correct length pushrods for the engine....

I believe there is about 170,000 km on the motor. I will be sure to run a compression test and see where I'm at. I can't get at it for now so it'll have to wait. In all honesty, I just chose the thumpr because I heard they give the engine a nice lope and had decent performance. I really don't know too much about cams. I'll look into hydraulic rollers but I don't think it'll fit into my budget. Any suggestions for rollers? Alright, I have a push rod length checker in my wishlist on summit. Thanks for the input my friend.

are you sure you don't mean 2.02 intake valves???? 2.20 will not fit on a 4 in bore

i did mean 2.02. sometimes my fingers work against me. lol

first post fixed

All you younguns want to start at the wrong end of the truck. Do the rear first. 3.73/4.10 gears, good axles, posi or Detroit Locker or Auburn unit, wider wheels and tires, premium shocks.

Putting a fresh top end on a short block that has 170,000 KM on it is not advisable, it'll blow the rings out. Then, you'll have to disassemble the motor and build it right anyway.

Using a flat tappet cam is not advisable. This is such a touchy situation because extreme pressure lubricants that used to be in oils have been taken out because they clogged up catalytic converters and cost the auto manufacturers money on warranty claims. So the auto makers convinced Congress to eliminate the lubricant from motor oils. They got away with it mostly because all of the current motors being built by the makers use roller tappet cams which do not require any extreme pressure lubricant additives in the motor oil. I got so tired of explaining all the monkey motion you have to go through to get a flat tappet cam to live in a motor today that I wrote this long-winded checklist of things that will frag your install....
http://www.crankshaftcoalition.com/w...ips_and_tricks
You don't have to deal with any of this foolishness with a roller. You just wash the shipping grease off, oil the lifters and cam with off-the-shelf motor oil, install, fire the motor and drive.

Choosing a cam just for the rump-rump is not advisable. Makes you look like a poser.

Building a 350 to haul a heavy truck is not advisable. I would be thinking a 383 made with a 350 block or maybe a 406 made from a 400 block. You need cubic inches and you need torque, not horsepower. Best way in my opinion to build a 383 is to start with a roller block from a '96-'99 Chevy truck or van. These were RPO L31, 5700 Vortec motors, roller cam and one-piece rear seal. You can sometimes re-use the stock roller lifters if you get them with the block and just buy a new roller cam. Much cheaper than doing a retro-fit roller cam on an earlier block.

Using an Air Gap intake in a cold climate is not advisable. Use the standard Edelbrock RPM and make more power and torque than ANY OTHER MANIFOLD.

Using high-buck Brodix heads on a daily driver is not advisable. It would be like hanging a string of pearls on a pig. Spend your money more wisely on a 383 stroker kit or other parts that will make good torque. These iron heads coupled with a good D-cup hypereutectic piston with an 18cc dish on a 383 will make a 9.7:1 motor that will operate well on pump gas with the right camshaft and will rip the rear tires off.
Racing Head Service heads....
http://www.summitracing.com/parts/RHS-12410-01/
Keith Black pistons, use with 5.7" rods....
http://www.summitracing.com/parts/UEM-KB135-030/

The stroke radius will be 1.875", the rods will be 5.703" and the piston compression height will be 1.433". These 3 added together make the "stack" that will fit into the block. Your stack will be 9.011". An unmodified 350 block will measure 9.025" on the block deck height (measurement from the centerline of the main bearing bore to the flat part of the block where the heads bolt on). If you deduct 9.011" from 9.025", you find that the crown of the piston will be down in the bore 0.014" when the piston is at top dead center. If you use a composition head gasket such as the GM 10105117 that compresses to 0.028", then you add 0.028" and 0.014" and find that you have a "squish" dimension of 0.042". Perfect for pump gas and should allow plenty of ignition timing to operate properly on the street and highway.

If you want to play along with what I'm suggesting, we can get into more detail, but I'll wait and see what you have to say. Let me warn you of one thing......DO NOT TELL ME THAT YOU CAN'T AFFORD THIS OR THAT. When I was a young man, I was working 3 jobs at 80+ hours a week in order to make the money required to do what I wanted to do. If you want to learn how to build a motor with 470 hp and 490 ft/lbs of torque that will rip the tires off and run on pump gas, step up to the plate. Otherwise, do it your way.

Oh, and by the way, the cam that I would choose for this combination would be a little lopey.
http://www.summitracing.com/parts/CCA-08-430-8/
You wouldn't have to necessarily use this exact cam. You could use one made by another grinder that used these specs. You'd want to use a 2500 stall converter.

Tech when You and I were younger there were all Kinds of Job's to be had and we could make as much Money as we could stay awake . But Today that's not the case . Yes no way around it a Roller Camshaft and Rockers are the Better Build . But a Flat Tappet Camshaft Engine can be built and run an easy 100K + Trouble Free Miles . I built a Few Last Summer . My Truck Runs one of them Engines every day From High 90's to -10 Deg Weather . And that was not a High Dollar Camshaft . That Engine run excellent .

Yes with 170K Miles your Engine might have so much wear in the cylinders that it will need to be Bored more then 030 . Might be better off to use it for a core trade in on a Built Short Block . Maybe some one has a Reman OEM one piece Roller Block you can Trade it in on .

For a truck like that a 3.55 Gear would be good 2500 Stall Speed . You could Build a High Torque 355 with a Set of High Flow after market 2.02 1.60 Vortec Heads And a Camshaft Max 480" Lift use a Weiand Stealth Non-Air Gap Vortec intake with a 750 Performer Carb 1 5/8" Long Tube Heads .

As Dave suggested and I agree with him,have someone that knows what they are doing,do a leakdown test first.Then let us know what the results are.One other question is how is the engine doing in terms of oil pressure??.

First off, thanks for the replies. Tech, you really seem to know your stuff but I'm not really interested in building a 383 or anything near 470hp 490 ft/lb torque. That's more power than I need and I'm not looking to beat my dad in a race... yet. I see the general consensus is to get a leak down test done on the motor so I will have that done. I don't know if the previous owner played around with the gearing so I'll pull the cover off the rear end and check the rear gears and then go from there. I'm not sure what it's like for oil pressure and I won't be able to do a leak down test or check compression until spring time because it's in the back of a barn blocked in by another 20 cars. I also have another option. It has vortec heads on it right now. Do you think I could make solid ponies and torque with those heads and new cam, intake, carb?

A leakdown is going to give you a good assessment of where you are with the engine at that point.Don't let mileage on the engine allow you to think about anything or assume you need to do any replacements.As for a oil pressure check,consider doing a oil change and oil filter change to a Wix oil filter then do a cold oil pressure and hot oil pressure check at idle and at cruise speeds.

Originally Posted by Louey

A leak down will, providing the valves aren't leaking.

170,000 km on the motor = 105,633.103 miles.Rings are way cheaper to do now, than later.At that mileage, I would advise seriously thinking about checking the cylinder wall condition. And also the main and rod bearings. You will have the heads off anyway right ?
Looks like a real nice pickup though.

Hey Louey-it would give ya a idea of the condition of the rings too.I agree a mod is only as good as the weakest link.But there again has been many top haft mods done successfully on engines that where qualified as being in decent shape.I just ask myself how many rods on this site have 105,000 miles on them or more since built??.I would guess thousands of them.Again the oil pressure check could give him somewhat of the condition of the rod and main bearings.

What has been said makes plenty of sense to me. Since I'm going to have the motor mostly tore down, I might as well go a little further and check over the bottom end. It sure can't hurt to take a look at the bottom end. I will be popping new rings in for sure to improve over stock and I will take a look and the cam, main and rod bearings. Again, all the input is greatly appreciated. Thanks for the compliment on the truck, Louey. I think it's gonna be real sharp when I'm done with it and plenty of fun.

Originally Posted by Bowtiepickups

First off, thanks for the replies. Tech, you really seem to know your stuff but I'm not really interested in building a 383 or anything near 470hp 490 ft/lb torque. That's more power than I need and I'm not looking to beat my dad in a race... yet. I see the general consensus is to get a leak down test done on the motor so I will have that done. I don't know if the previous owner played around with the gearing so I'll pull the cover off the rear end and check the rear gears and then go from there. I'm not sure what it's like for oil pressure and I won't be able to do a leak down test or check compression until spring time because it's in the back of a barn blocked in by another 20 cars. I also have another option. It has vortec heads on it right now. Do you think I could make solid ponies and torque with those heads and new cam, intake, carb?

What you got was my signature approach, to come galloping in like Caligula, lopping off heads and taking no prisoners. I guess that's because I have always built stuff by the old hot rodder's axiom...."If some is good, more is better and too much is just right." I may not always be right, but I will always be opinionated.

There are lots of copy-cat, so-called "Vortec" heads out there in the aftermarket, but the only ones that are worth fooling with, other than the RHS heads I linked in my first post, in my opinion, are the genuine Chevrolet production RPO L31 heads off a 5700 Vortec motor that was in the '96-'99 Chevy trucks and vans. Same motor that I suggested using the block out of to build a 383. These heads can be found under casting numbers 12558062 (induction hardened valve seats) and 10239906 (separate pressed-in exhaust seats in some, but not all of these heads). Some people will tell you that there is a "good" head (induction hardened seats) and a "bad" head (pressed-in exhaust seats). Builders who have flowed both heads will tell you that the heads flow the same after you clean up some sharp edges at the seat and blend them in.

These L31 heads flow better than any other PRODUCTION cast iron head that Chevrolet ever cast up, but they have several weak points as well. It takes some work and some money to get them to the point where you can bolt them onto a motor and get close to the same results as you can from the heads I linked, which come out of the box ready to bolt on.

First, they are thin-walled castings. If you are pirating a set of used heads from somewhere, the first thing you want to do is clean them up and have them magnafluxed for cracks. You might want to make a deal with the guy you're getting them from that you can exchange them for another set or get your money back if they fail magnaflux.

Secondly, the rockers are "rail" type rockers that have an area on either side of the rocker that shrouds down around the tip of the valve to keep the rocker centered on the valve stem tip. These rockers will work ok for short and moderate lift cams and the aftermarket has come up with "roller rail" rockers. Use caution and buy only narrow body rollers so they will clear the inside of the L31 center-bolt valve covers.

Thirdly, the heads have pressed-in rocker studs that might tolerate up to around 250-260 lbs of pressure across the nose of the cam, but any more than that will begin to pull them out of the heads. You can pin the studs into the heads with a low-buck Mr. Gasket kit to prevent pull-out.
http://www.summitracing.com/parts/MRG-806G/

Fourth, the valve guide boss is extremely large on the O.D. because Chevrolet used only a single spring on these heads. There is no room to install a 1.250" spring with damper because the damper I.D. will not clear the boss O.D. And if you're going to use more cam, you're going to need more spring. So, you must cut the O.D. of the boss if you plan to use a 1.250" spring, or cut the seats in the heads for a larger diameter spring to clear the boss. The other main problem is that the bottom of the retainer will crush the valve guide seal at valve lifts exceeding 0.430". I know there are those fellows who will tell you that you can run 0.500" lift with the stock arrangement, but Chevrolet says 0.430" limit. You have to leave a safety margin to account for valve float and that is usually around 0.060" minimum.

Crane Cams makes a spring and retainer that will clear the seal and the O.D. of the boss, drop right in on the seats in the heads and will allow more lift, but they are pricey.
http://www.summitracing.com/parts/CRN-10309-1/

Some fellows have done a "Ghetto Grind" on the bottoms of the retainers to gain some clearance between the retainer and the seal. I have heard of cutting 0.080" off, but have never done it, so have no experience with what works and what does not work. If I were going to do this, I would mount all the retainers on the table of a surface grinder and take off the material that way, instead of trying to do it with a hand grinder.

So, there's the skinny on L31 heads. By the time you get through doing machine work and buying new parts, you could have bought a set of RHS thick-wall casting heads complete and ready to bolt on for less money.

Originally Posted by tango

Tech when You and I were younger there were all Kinds of Job's to be had and we could make as much Money as we could stay awake . But Today that's not the case . Yes no way around it a Roller Camshaft and Rockers are the Better Build . But a Flat Tappet Camshaft Engine can be built and run an easy 100K + Trouble Free Miles . I built a Few Last Summer . My Truck Runs one of them Engines every day From High 90's to -10 Deg Weather . And that was not a High Dollar Camshaft . That Engine run excellent .

Yes with 170K Miles your Engine might have so much wear in the cylinders that it will need to be Bored more then 030 . Might be better off to use it for a core trade in on a Built Short Block . Maybe some one has a Reman OEM one piece Roller Block you can Trade it in on .

For a truck like that a 3.55 Gear would be good 2500 Stall Speed . You could Build a High Torque 355 with a Set of High Flow after market 2.02 1.60 Vortec Heads And a Camshaft Max 480" Lift use a Weiand Stealth Non-Air Gap Vortec intake with a 750 Performer Carb 1 5/8" Long Tube Heads .

Tango, I agree with you on several points.
1. There is no plethora of jobs like there used to be.
2. A flat tappet camshaft will run 100,000+ miles in a motor built today (but only if you follow the precautions that I laid out in my link above). What usually kills cams with these kids is the use of a herculean valve spring and no extreme pressure lubricant in the oil. I have a flat tappet cam in the motor in my truck (300 I6) that I rebuilt 2 years ago. The reason it will last is that I used stock springs and also an oil addivive. So, I'm confident that the motor will serve me for 100,000+ miles without incident.
3. The Weiand Stealth and the Edelbrock Performer RPM are basically the same design, both of them being a knock-off of the aluminum Z28 intake manifold from 1968 302's. Best street/strip manifold ever made for a small block in my opinion.

Haha. That sounds like a solid way of thinking. I read little article and the boys at Hot Rod magazine used vortec heads and used a set of COMP Cam's beehive springs and ran .490 lift. (they say they are good for .560) If i understand correctly, I can put on the beehive springs and retainers and be good for a .560 lift cam. I was thinking I would do this since the heads are already on the motor it would be a decent way to make power and save some serious scratch. Of course, I would check the casting numbers on the heads before I did it.
Link to the article:
http://www.hotrod.com/techarticles/e...ild/index.html
Check page 2
Link to springs:
http://www.summitracing.com/parts/CCA-26915-16/
Link to retainers:
http://www.summitracing.com/parts/CCA-787-16/