Basic SBC engine build help

[silvermonte]

So Ive put together my very first engine build. Had a good shop do all of the machine work for me and had everything marked. All I had to do was put the thing together. Its nothing fancy, 2 piece rear main, 350 block, that is .60 over, and aluminum pro-comp heads. I have a few questions.

First is, that the cam is a XE268H-10 part #12-242-2 from Comp Cams, it came as a kit with the lifters and valve springs. When I put the cam in I bolted the gear to the cam and attached it to the crank with the timing chain. What holds the cam in place from moving forward and aft? I read a flat tappet cam like this one doesn't need anything to keep its place in the motor. In this true? If it is not what do I need to correct my mistake.

My other question is, how to correctly tighten down the rocker arms. The motor without any of the rockers tightened down spins like I assume it should. By the time I get about half of them done its a real bear to spin the motor over. Ive been using a ratchet and socket on the crank bolt to rotate the motor and I always worried I was going to snap the stock bolt off, the harmonic balancer and pully is installed as I didnt want to have to try and take the bolt back out after the torque I just applied to it. The method I used was to spin the push rod as I tightened the nut till I felt resistance and then I did a half turn more on the wrench. I normally do 3/4 of a turn but that made it almost impossible to turn the motor over.

Extra info that I dont think has anything to do with it but Ill put it out there. The push rods are longer then stock. I dont recall the length but they are long enough that I bought new ones and Im 100% sure that I have the rocker arms in the correct postion. I can post pictures if anyone wants to see.

This is my very first motor that I have ever put together and with it being hard to turn over by hand I dont know if that is normal or if I did something wrong in the assembly. Also do I need any special distributor gear to run with that cam? Once I get these last few problems fixed I have a friend of a friend that has an engine dyno and I will be running the engine at his place to break the motor in and dial it in, instead of my trying to do that while its in the car.

This is the marks from turning over the motor multiple times with the correct push rods. Im pretty sure that about as good as I can get it.


This is a picture of the motor just because I think its pretty, and Im proud of my first real motor.

[bmbrzmn101]

On flat tappets you don't have to do anything special the cam should not walk. As to how hard it is to turn over, do you have the spark plugs in? To turn the engine over with the bolt should take some effort but what length ratchet are you using? Mine is 18" or so. I don't have an issue with the plugs out, just takes more effort with them in as you are working against the compression. If you are using the ARP balancer bolt you should not worry about it. As to torqueing the rockers I have a chart in a rebuild book, but it is in the shop. And I am lazy right now. You might can find it online, it essentially tells you to place a certain cylinder in TDC and which rockers to adjust the rotate to another cylinder and do the other half of the rockers. You can fine tune them after start up and run in. Hope some of this rambling helped.
Chris

here is the chart:

[Typhoon1015]

Great job on doing this yourself!

Do you know what lifters you have? the 850's need a 1/2 turn or so after the pushrod tightens. If you have the 875's it only need a 1/8- 1/4 turn. If they are loose, the motor will run but you will hear them tick a bit, if they are tight, the motor is hard starting due to the valves sticking open.

HTH

[silvermonte]

Bmb - the motor was turned over without the sparkplugs in, they are just in there now to keep dirt out while it sits in the garage waiting for the rest of the project to catch up, and the ratchet I use is a snap-on flex head, its prolly 14" or so and takes a bit of effort, enough that Im on here asking questions

typhoon - here is the kit that i got from summit, http://www.summitracing.com/parts/cc...42-2/overview/ I thought that it came with the valve springs, but I must of just had the machine shop order the correct springs when they did the work on the pro-comp heads and I dont know what they ordered. The listing doesnt mention what lifters came with the kit either, this is why I want to run the engine on a dyno, so that it will be easier to fix and potential issues

The push rods are 8.125" , I seen that as I was looking thru my records. Originally I didn't think I would need longer rods and decided to buy a push rod checker just to make sure since I got new heads. Man was I glad I checked.

[Schwartz Performance]

What have you been using as an assembly guide? There's an older book my dad had, How to build a small block Chevy, that I used for my first few.. Did you check the bearing clearances and turn it over before putting the cam in? What about before you tightened the rockers?

Flat tappet cams don't need anything as stated before, but if you had a roller cam it's necessary to put a cam button in, which is a spacer with a bearing that attaches to the timing cover or the front of the cam/gear.
Flat tappet cams typically require an iron distributor gear, while roller cams use bronze or other soft materials since the cams are a softer material.

Back to the rockers.. Turn it over and look at how they contact the tip of the valve stem.. Make sure it doesn't come off the tip or get onto the edge of it, as this will determine if your pushrods are the right length.

With all of this said, get a rebuild book. All of your questions will be answered in one simple reference guide for the low price of $19.99

-Dale

[bmbrzmn101]

Thought I might want to mention this before you put this in a car. I recently decided to look at an engine I rebuilt but never ran. I did it about 20 years. One thing always annoyed me about this engine. It was difficult to turn over with a wrench on the crank. Fast forward to 2 months ago, my son and I decided to take it apart to clean and freshen it up. When I removed the piston and rods I thought I would remike everything to verify clearances. Didn't make it that far. When the number 4 rod and piston came out I noticed something on the bearing and thought it was debris. Wrong! When assembling the engine years ago I did it by myself and nicked the crank with the rod. Small nick gouged the rod bearings causing stiffness to rotation.

Moral here is that if you feel that the rotational stiffness is too great, it is better to disassemble now and investigate and the reassemble if nothing found than to worry and do nothing until a brand new engine seizes and some parts destroyed.

Find another engine(even on in a car) remove the plugs and turn it over with the same wrench and feel how that feels compared to you new engine. It may help ease your worries. Just keep in mind how many miles may be on the test engine. The more miles may feel a little easier to turn.

Chris