Hello all. I’m kind at my wits end and hoping to get some insight before tearing down my engine. 70 olds cutlass with a 350 rocket bored .030. The car sat for 12 years before I got it back and I needed heads. Bought a set with rockers, lifters, pushrods all in included from a shop that manufactures aluminum heads. Got everything back in order, but the only way I can get the car to start is if I set the initial timing to 50+ degrees. I do not have the vacuum advanced connected while setting the timing. I’ve gone over all my steps twice with the same result. My last resort I can think of is my pushrods are not long enough so my valves are not staying open during their cycles. If anyone has any further insight please let me know.

here’s the cam specs

 

Once it starts does it run ok ?

Before tearing it apart you need to do a couple of things.
1. Do a compression test
2. Make sure that your balancer is correct as far as TDC goes. The outer hub might have spun. You should be able to check it close enough by pulling the #1 plug and looking in with a flashlight as you turn the engine over by hand. When the piston is all the way at the top your timing mark should be very close to "zero"

Start with those two things and report back.

 

Timing marks do line up to 0 at TDC. When set there, the car doesn’t even ignite a little. I get some combustion when set to at least 25 degrees but won’t run and often blows back out of the carb. When I am able to get it to run it only likes to be at 1000 rpm or higher and timing is 50-60 degrees. As far as how it sounds, lower RPM almost sounds like a misfire occasionally. I have verified spark on every cylinder and have gone through firing order, even marked my wires at the cap so there’s no mistake. New distributor and wires.

i only suspect the pushrods because when i watch them operate it doesn’t look like the valve springs are being compressed very much. When I take the valve covers off you can’t really tell which cylinder is on what cycle until I turn it by hand and watch for movement. My pushrods at 8.5” length

 

Here’s a clip of it running.

 

If the pushrods were too long to the point of holding the valves open you would not have a lot of compression Thats why you need to do a compression test.

What cylinder heads are on the engine ? How did you adjust the valves, if they are adjustable ? Can you post a picure of the valve springs and rockers etc ?

It actually does not sound that terrible. Somebody that build more Olds engines might chime in but I think that camshaft is going to have a pretty rough idle in a 350 engine.

 

As said, do a compression test, probably very low. Are those heads and cam from Olds Rocket Parts? What .030" pistons were in the motor? Those heads end up at more CC than their advertised 69CC.

 

At rest

Intake

Exhaust
Here’s the valves for cylinder 3. Set to 0 lash plus 1/2 turn. Using poly locks. 1.6 ratio

 

A camshaft with duration such as yours needs to idle at 1000-1100 RPM. This is a "high strung" high RPM cam that needs at least 9.5:1 compression, 2600+ RPM stall torque convertor, 4:11-4:56 rear axle gears. IMO this not a good choice for 355 CI street engine.
Let's look at the rest;
You have a "rebuilt" engine but you did not include, and perhaps you don't know the engine block deck height, the installed piston height, and the cylinder combustion chamber volume. I'll assume you used a standard replacement head gasket with .040+ compressed thickness. What I'm getting at is we don't know the engine's compression ratio. Then we add in a camshaft on crack.
In summary and IMO we may have Frankenstein engine with a high strung cam. It is difficult to offer any tuning advice until we have verified the prior listed measurements.

 

That’s what I was afraid of. Back in 09 I was under the impression I had high compression ratio based on what my dad told me as he was a master GM tech. Now running the numbers based on what I remember (standard stroke, .030 dished pistons, block was decked, 69cc chambers) I’m looking at 8.1. So to save me headaches in the long run, I’m better off getting a cam with specs that better suit my current equipment.

 

Alright I did some further digging. I bought the cam/lifters/heads from old rocket parts on eBay. After going to their site and specifically looking at just the camshaft I learned it’s for a 39 degree block, not a 45. This info is not in the listing and was not mentioned when I sent them a message with more questions. So looks like I’ll be tearing it down and putting in a camshaft after all. I’ll reach out comp cams with my engine specs to find a camshaft that will work best for what I have.