Rebuilding a 94 350 LT1, Mods: Crane Gold Race 1.6rrs, I ported polished the heads (Intake and Exhaust) to a mirror finish, CSR elec water pump, EM long tubes, Cloyes Timing set (3145), GM Hotcam, upgrade to 95 timing cover and vented opti and some other minor stuff.
Here is the problem;
The GM service manual says to set #1 cyl to TDC and then it lists a procedure to adjust the rockers, it says to adjust Intake 1,2,5,7 and Exhaust 1,3,4,8. Then rotate the crank 1 turn and do the other rockers.

With the Cloyes timing gear installed and the timing marks aligned, the dowell pin on the cam is at the 3 o'clock position looking at it from the front of the engine. This puts the cam in the wrong position to perform the adjustments to the rockers. If I rotate the crank 1 turn then the timing mark will be at 12 o'clock instead of 6 o'clock. in this position the cam will be in the correct location to perform the rocker adjustments, but it looks to me as if it is no longer at #1 TDC.

This is driving me crazy.
Any suggestions?
Thanks in advance, and I will post some pics one of these days when I get set up to do it.

prattman

 

Just rotate the engine clockwise and follow this procedure EOIC- Exhaust open, intake close, when the exhaust valve begins to open adjust the intake on the same cylinder and when the intake valve begins to close about 1/3 or 1/2 way up, adjust exhaust.

this will insure that the lifter will be on the base circle of the cam.
Have fun and check them again after a few drive cycles.

 

Let me ask you this. Do you know that when the timing marks are lined up (cam gear arrow down, crank gear arrow up) that the SBC is at #6 TDC on the compression stroke, not #1?

 

Corvette Kid NC,
No, I didn't know that.
I thought when the timing marks are aligned the engine was at #1 TDC, the service manual tells how to install the cam, and align the timing marks but does not tell that the engine will be at #6 TDC when the marks are aligned. This is the info that I have been trying to find and it solves my problem as I thought the timing gear had the marks in the wrong place.
Looks like I should follow the advice of eherbst and rotate the crank and make the adjustments as there is nothing wrong, I just don't know what I am doing.

Thanks you guys, you don't know how frustrated I have been the last couple of days trying to figure out if something was wrong.

prattman

 

When #1 is at TDC both timing marks (crank and cam) will be at the 12 o'clock position. Hope this helps you.

 

Just a quick question...have you ever ported heads before? You shouldn't have a mirror finish on the intake ports, only the exhaust ports. A mirror finish on the intake ports can cause fuel droplets to puddle on the intake tract...if you have a rougher finish the air "rolls" around the rough area and will not the let fuel puddle at all...just something to think about...

 

That might be a concern, if the LT1 had a wet intake...

DaveZ.

 

It's the heads, not the intake I am concerned about

 

C&C porting the best way to go.
Leave the top of the intake chamber a little rough.
I also use a drill to prime the oil pump to see if the lifters are all pumping up .I just sent a set of comp cam roller lifters back they would not pump up.
They sent out new ones, but they said the coating on the lifters would only last 6 mths.If the engine was not fired in that time period
the coating would rust the inside of the lifters!They were right.
Saved me a set of intake gaskets and alot of cranking on the starter.

 

I sort of figured that might be the source of your confusion. I've always wondered what their reasoning was in making it that way. Good luck with everything from here on in.

 

Sooooo many ways to go, soooo many $$ differences . Your program is one that I'm considering too as part of a phased approach. I'm all ears as to how it works and what your thoughts are once you get it fired up and tuned.

Thanks in advance!

P.

 

It's funny, because half the expense of a project like this always seems to be the accessory stuff - the things needed to handle additional power and the things that make sense to do "while the motor is apart."

My list of fixed / replaced things got very long when I decided to do a simple motor swap:

New clutch (while I was in there)
Rebuild PS pump (while it was off the motor)
Electric WP and new timing chain set (new cam means no WP drive)
New oil pan (to keep from breaking another motor)
Motor mounts (while they're off)
I would be doing an opti as well had I not just replaced it in July

The list goes on and on...these costs damn near equalled the cost of the parts that add HP.

 

Yes sir, it did help, thank you.

prattman

 

Zix,

The short answer is no.
I have heard much advice on not polishing the intake ports, but have yet to get anything tangible to prevent me from doing it.
As I do know for certain, since I chose to put the extra time into a high polished finish, there is no way I will pull the heads and roughen them. I have a lot of sweat and bad language invested in those heads, so they will either perform, or not.
I have been a machinist in the past, to include CNC, as well as manual machines. I see a lot on this forum about how great CNC stuff is, but I think a person can do a mutch better job manually.
I wonder if the fuel forming puddles is more of a thing from the carb days, as I can't see how fuel could perform such a feat considering the fuel injectors vaporizing it and the high velocity of air in the intake ports.
One last word about my comment on manual work.
I don't think based on the many hours it took me, that a person could afford to get this done as it was many many hours of grinding and polishing, something that most businesess would not do these days.

Thanks for the post, I don't want you to think that I am not following your advice, it is just that I made a decision late this spring to port the intake ports and highly polish them, and of cousre it may be a decision that I will regret.

prattman

 

I'm in no way saying that they will not work, the only thing is I have worked around a lot of people that do head porting and that is something that I've heard from them. How much affect will it actually have? I really don't know, and you'll probably be just fine! I know how many hours of sweat it takes to polish aluminum so I can't blame you for not wanting to take them off again!!

 

In the old day's we always ported until nothing was left of the heads.
CNC porting is what they do today and I have not seen any data that is out on the heads made in the last 5 years.
All I do know is if any obstructions in the intake or heads will hamper the operation in that chamber and will cause hot spots and a ping.
Like I said my heads are CNC ported and I though about polishing the bottom and sides of the chamber to make sure I did not pick up any hot spots when running the nitrous.
With the heated manifolds I don''t think it will hurt anything.
Just the fact that you cleaned them up will make a big difference.
If you look at CNC porting it makes me wounder if it should be smoothed out alittle more for the power adder engines.