chad":25h2f3w0 said:
may depend on the "sickness"?
Also
ur interest in application (end goal)?
Agreed. As I said though, in the problem winds up being the bottom end, I'll almost assuredly just go for a V8 swap. It just makes better sense.
As for goals, it's hard to say. I've built cars in the past that I always just wanted to be "fast enough" and it never ends there. My first DSM was supposed to "just run good", but is now a low 12 second car even with a junk trans and slipping clutch, and is being replaced by the Galant VR4 currently next to the Mustang in the garage, with a built stroker that I'm hoping to hit 500-600hp on.
Just making the point that plans change, so it's tough to say. Ultimately, I can say that I want the Mustang to be a cruiser with enough power to have fun, but not so much that it's a handful to drive.
Econoline":25h2f3w0 said:
Is there an adjustable rocker set on this engine? It could be the original owner either set the timing 'by ear' and burnt something or he over adjusted some rockers and has one hanging open or even bent. I take proclamations of "rebuilt" with a grain of salt. Who knows what was done, by who and how. Could be a "Tijuana tune up" for all we know.
It's possible, but again, I would expect an engine with a bent/open valve to produce much less than 70 psi. Perhaps I will pull out my leakdown tester and see.
As for "rebuilt", based on what the guy I bought it from relayed to me, it was a reuse of rods and pistons, new bearings and rings, and a rehone. No idea what the tolerances were or anything like that. If this was a motor someone had just "didn't run", I'd be much more inclined to believe it wasn't anything requiring a shortblock rebuilt. However, my experiences with parts that someone else "rebuilt" are not very good.
Econoline":25h2f3w0 said:
You know, it's possible the rings haven't fully seated as well if it truly is just rebuilt...
Those compression #'s won't keep it from starting and running. Get it started and drive it like you stole it
I Agree, that compression isn't so low that it would cause a no start, it's just clearly an issue, and one I'm not comfortable just forgetting about. I mean, I guess if it winds up needing torn out anyway, for a rebuild or a swap or whatever else, then there isn't any harm in beating on it for some fun for a while though.
bubba22349":25h2f3w0 said:
The compression numbers you have are more indicative of a valve seal problem (top end) than the rings! If you have adjustable rockers it maybe as simple as a rocker arm or two on # 6 that needs readjustment, or with non adjustable rockers it might be that a push Rod is too long. Pulling the valve cover and rocker arms (keep the push rods in order and check the lenght of them against each other) also put a straight edge across the tops of the valves to check for any differance in the valve heights especially on those of # 6's valves compared to the rest. With non adjustable rockers it is important that valve stem tops all match closely in height sadly many machine shops don't take the time to check that this is done correctly. All of these above checks are fast to do and very low cost at only the price of a valve cover gasket and maybe a couple different lenght push rods.
You think so? Like I said before, I would have thought that a valve that wont close would produce compression numbers alot lower than 70.
I assume there is a specified range for clearance between the pushrod and rocker arm? Can anyone provide it for verification?
Edited