Hi. The Z28 I bought has a 350 with a cam I guess, and an aftermarket intake manifold. It's got no ***** below like 3000/3500 rpm. After that it tears off pretty nicely. I kind of bought it hoping for more low end grunt.

I'd like to find out the cam specs without tearing the motor apart or taking it out. Can this be done? Can't I just get lift #'s by measuring pushrod lift by taking the valve covers off? And what about lobe separation and duration? The most I want to take off is the intake manifold (I dont know if its a single or dual plane yet, if it's single i'll switch to a dual and hope for the best).

Thanks,
Oliver

 

You can check lift with a dial gauge on a pushrod but I'm not sure how accurate it will be with hydraulic lifters. Probably close enough to get a rough idea on how much lift is on the lobe. There's no way to check duration or LSA without putting a degree wheel on the balancer. It can be done with the engine in the car but it isn't easy. It would probably be easier to just pull the cam and see what markings are on it.

Lack of power at low rpms can be any number of things. A low stall converter matched with a long duration cam will cause problems. Ignition timing, timing curve, highway gears in the diff or any other thing could be a problem.

Too many people buy or build an engine that isn't suitable for the driving conditions they intend to use it for.

 

i havnt done a chevy motor, but with the old for 302's i did, pullin the cam didnt involve pullin the motor. does the cam go in the rear of the motor on these things? i just assumed they did since the distributor was back there.

can i see anything about my torque converter from underneith? its missing the belhousing bottom cover so the converter is in plain sight. i think 383 gears in back, nothing aftermarket. turbo 700 tranny

 

Cam goes out the front on all engines.

Remove water pump, balancer and timing chain cover.
Remover valve covers and rockers. Pull pushrods out.
Remove distributor and intake so you can remove the lifters
Unbolt camshaft gear from camshaft and pull camshaft out. You'll probably have to pull the rad out to get the cam out.

That's the basics. It depends on how easy or hard it will be to remove any of those things. Add on all the extra accessories and it becomes a long weekend job.

There's a possibility that there's some numbers on the end of the cam behind the timing gear but they're usually on the back side and the only way to see them is to pull the cam.

Too big of a cam could have caused more problems. Factory heads can barely support .500" lift. More than that and problems with the valve train can occur. Coil bind, rocker bind, the underside of the spring retainers hitting the top of the valve guides etc.

Looking at the torque converter will tell you very little. Unless you know someone has changed it, it will probably be stock.

If the previous owner can't tell you anything about it, you'll either have to live with it or tear it down to know exactly what's in the engine.

Distributor is on the rear of a Chev because it also drives the oil pump which is at the rear down in the sump of the oil pan.

 

awesome. when you say unbolt camshaft gear, im guessing you mean the sprocket the chain goes onto? or is there something separate on that side of the cam to move the fuel pump or somethin. the rest is familiar ground though, just never done a chevy, so i expected some slight variations.

thanks alot,
Oliver

 

3 bolts on the cam gear then the onlt thing holding the gear on is a dowel. I forgot about the fuel pump. You'll have to unbolt it so the pushrod will fall down away from the cam. It's been years since I've used a mechanical fuel pump.

After removing the cam gear, the easiest way to pull the cam out is to put a long 5/16" bolt back into one of the bolt holes to use as a handle.

 

Awesome, thanks for the help. I will procede to tear this sucker down tonight.

Another question that I just thought of. Can I measure compression ratio without pulling the heads? I guess I could use trig and put a stop thru the spark plug hole and measure the distance from the outside of the head to the top of the piston, measure the angle of the stop against the head (angle theta, it would be a right triangle since the piston top is square against the cylinder) if i made a triangle, with the adjacent being the distance from stop to piston top, and had a known hypotenuse which is the distance from the head to the piston top measured by the stop length, i could solve using the cosine of the angle between stop and head multiplied by the hypotenuse distance to get the triangles adjacent side length, which would be the distance from the center of the piston stop to the top of the piston.

which this distance from stop to piston i could subtract the distance from stop to deck of block ( at 90 degrees )and the difference would tell me how much past the deck the piston is sitting aka deck height.

I can assume a stock 350 bore and I'll measure stroke distance by above method to be safe, then measure gasket thickness, find a code on the heads to hopefully tell me compression chamber cc's.

then finally determine volume with piston at tdc and at bdc, and divide bdc volume by tdc volume and that ought to get me compression ratio.

but if there is an easier way, please, please, let me know.

Thanks,
Oliver