: 397/375hp setting roller rockers and lifter questions
Jan 16th, 00, 02:11 PM
Engine is a 1968 396/375 hp. It has been fitted with a comp cam and roller rockers. The engine has sat for nearly 10 years. It was completely rebuilt 10 years ago, started, run for 10 minutes then shutdown. Previous owner said he took tension off the valve springs for storage. Sure enough the rockers are lose. The engine is out of the car and I still lack a few components (starter, carb, etc). I have taken the intake off and I am replacing with an original one for this year engine.
Since the intake is off, how do I tell if the lifters are mechanical or hydraulic??
How can I set tension on the valve springs with the engine out of the car??
What is the best way to crank the engine while it is out of the car for setting the tension on the valve springs??
What are the best gaskets to use for the intake manifold??
What is the best source for intake manifold bolts??
Sorry for the long post and many questions, but I am eager to get this beast running.
Thanks in advance for the help.
Jan 16th, 00, 03:37 PM
The best way to check to see if the lifters are hydraulic or mechanical is to see if you can compress the lifter with a pushrod. After sitting for ten years they might be stuck so it may be hard to tell. Ten years ago very few people used hydraulic roller cams so chances are it is a mechanical cam. You will need to get the cam part number to find out the proper valve lash setting. What the previous guy meant by removing the tension from the springs was that he loosened all the valves up. All you have to do is re-adjust the valves to get it right.
Please don't take this wrong, but by the sounds of it, you are not real familiar with this procedure. Considering the amount of damage that can be done by having the valves adjusted wrong, especially on a mechanical roller cam, I would suggest you ask around and find someone familiar with the procedure to help you out, at least the first time. If you cannot find anyone, let me know and I will try to locate an engine builder close to you.
Hope this helps,
Advanced Automotive Machine
Jan 18th, 00, 03:08 PM
Bill- unless I missed something, he has a flat tappet cam and roller rockers.
If the intake is off, take one of the lifters out and set it on a bench, and try to work the plunger up and down with a pushrod. A solid lifter will be solid, and a hydraulic lifter will have a springy feel to it. If it is solid, most cams I've seen are lashed at .024"intake, and .028"exhaust. Turn the engine with a breaker bar on the front crank bolt, start at #1 and go every 90 degrees, setting each cylinder in the firing order, 1-8-4-3-6-5-7-2
Use Fel-Pro rectangular port intake gaskets.(they are rectangle posrt heads, right??)
Any aftermarket parts supplier has the intake bolts you need if you are using the correct GM intake.
Jan 18th, 00, 03:27 PM
You are correct, I must have misread it the first time and thought he said roller lifters along with rockers DUH...thats what I get for hurrying through the posts !
Jan 28th, 00, 03:56 PM
Thanks Dave and Bill.
I guess I sounded a little unsure. I had done this proceedure but it was over 20 years ago. I was always told to start at TDC, tighten 1/4 turn for half the valves. Then rotate the crank 1 revolution and tighten the other half. Then turn the crank one more rev and tighten all the valves one more 1/4 turn. Again, this was what I was taught several years ago. The final result would be all rockers would be tightened 1/2 turn from 0 lash. With the intake off, I can see the cam so I know when it is not on the lobe but instead the base circle.
There is no danger of over torquing the crank bolt by rotating the engine in this manner? I work for a diesel engine company and we generally have a gear in the front gear cover which drives the crank when turned externally.
The intake does have the rec. ports. I have been to several auto stores looking for the silicone gaskets (Mr. Gasket or any other) but no one around here carries them. I know you can get them through the aftermarket sources but figured I might find them at the local parts store. I guess I can try a hi performance store in the area before I order them via catalog. In the past I use to put a bead of silicone on the front and rear of the intake in leu of the gaskets in these areas. Is that still common?
Are the intake bolts grade 5 or do they need to be grade 8?
Jan 28th, 00, 05:41 PM
Try Speedtek in Hurst. They are about 20 minutes from you. I have had great luck with these guys. Keith is the owner. They are in the old Super Shops location there.
'68 # matching coupe-frame on restored
'68 assembled in Belgium SS-under construction
Jan 29th, 00, 12:09 PM
Thanks Jeff, I'll give them a try. BTW, what is a BelgianSS? Was this a camaro from Belgian?