87 c10.. is it 305 or 350

[cyberpine]

When I purchased my truck a few months ago I was really surprised at how strong it was running and so pressumed it to be a 350. Later, i found out the sticker said 5.0. duh.

I just got back from the shop where I had them do a compression test, check the oil pressure and pop the lids to see what condition the engine was in.

The mechanic was very impressed with the engines condition given the year.
He is reading 200lbs of psi (on average) compression! and 80psi oil pressure. He pull up the lids and found new gaskets and a super clean heads - no sludge of any kind.

He's telling me he thinks the engine was rebuilt not too long ago or is not the original engine because of the bolts on the covers?? He's going to call a machine shop to see if he can figure out for sure.

How can I tell for sure? The oil stick is on the passenger side. The thickness of the fly wheel? The serials .. which he was unable to read.




more pictures to the truck can be found here:

http://sites.google.com/site/1987C10

[Greg84]

Have any more pics from under the valve cover? If you can find the casting number under there then just find it on this list and it'll tell you what size it is.

http://www.mortec.com/castnum.htm

[85 Silverado]

VIN # if the original engine is still installed.

[maxpower_454]

Like Greg 84 said, find the casting number of the heads. If they are 305 heads, it could be a 305 or 350 (since some people put 305 heads on to bump compression) but if they're 350 heads, it's most likely a 350 since 350 heads on a 305 would run like crap. The safest way is to get the casting number on the back of the engine. Maybe you can read it since the other guy couldn't. Or, pull a head and measure the cyl diameter. If it's roughly 4", it's a 350.

What does it matter anyway if you like the way it runs?

[2COR517]

First of all you need a new mechanic. GM went to the center bolt valve covers with EFI in 87. The only way to know for sure what the engine is will be to get the casting number off the back of the block. Sometimes the 305s have a 305 casting number on the right side too. And you might as well get the head numbers under the valve cover too, to put all the pieces together. The intake is not stock. It's possible a new cam was put in the motor which would give it a little more snap.

Running the VIN is useless in this situation