hey guys wondering if anyone can give me an answer,have just rebuilt my 348,the pistons in the block are ok,so had block honed, crank ground,heads had some porting and polishing work,new valves rings bearings,cam etc,but when i fired it up and bed the cam in it has not stopped breathing,only has about 50 miles up on it so far does seem to be getting better,any ideas,thankx
motor problems
- Thread starter garey
- Start date
Maybe more time to seat the rings.
Most pistons that I have removed from a old engine had the top ring land wore out and would have to cut the piston for a ring spacer to true up the ring land.
Are you running a PCV system or the road draft tube?
Most pistons that I have removed from a old engine had the top ring land wore out and would have to cut the piston for a ring spacer to true up the ring land.
Are you running a PCV system or the road draft tube?
the pistons are 60 thou over s.f brand dont know if thats a good brand or not,installed edelbrock performer manifold has the hole beside dist for breather only have a hose coming of it down towards the gearbox has 600 holley, goss electric fuel pump replaced all the fuel lines with 3/8 rubber line,isky cam 485 lift,new stainless valves double valve spring scorpion roller rockers everything brand new
If it is .060 over did you check your ring end gap?
A new/fresh engine should not have hardly any blow by, Either the rings have not bedded in properly or you may even have a broken ring.
I would strongly suggest you get the guy who assembled the engine to take a look at it.
I would strongly suggest you get the guy who assembled the engine to take a look at it.
Is it using any oil? I'm assuming that the "breathing"that you're referring to blow-by past the rings.If,as an example,the block was honed very smoothly as one would be for a "moly"faced ring,and cast iron rings were used,it may take forever to get the rings to bed in.
I heard of that Bon Ami trick before. I wouldn't do it and don't know anyone that did, but I did hear it works??? When I first got my 409 back from the machine shop and installed it, it was using about 1 quart of oil every 400 miles or less. Posted a thread on it here and received many suggestions. My issue might have been a little different because my tailpipes were smoking a lot of blue. Short story, when the heads were rebuilt, they never replaced the valve guides. Not sure why they didn't. Took the heads off and had new valve guides put in. Purrs like a kitten. No more oil usage. Have your valve guides been replaced?? Do you have blue smoke coming from the tailpipes?? Just a thought, Carmine.
hey carmine no did not replace valve guides he said they where ok could be that tho,thnx very frustrating you just expect it to work right
I didn't know that. All I knew was excessive oil usage, blue smoke and a substance the consistency of thin molasses in my tailpipes. Yes, it is very frustrating, but I'm sure you'll get to the root of the problem, Carmine.
Get the engine up to operating temperature and then run a leak down test and see if they are all close or if 1 has more than the others to pinpoint a problem cylinder.
If they all check the same try some test drives where you accelerate up to speed and then let it coast back down several time to help seat the rings.
If they all check the same try some test drives where you accelerate up to speed and then let it coast back down several time to help seat the rings.
Rings won't seat without some load. Like uphill in 3 or 4. A trick from the old days, if you can't take it out and beat it up, is to seal up the engine and put a shop vac on the main breather to get vacuum in the engine and pull the rings in tighter as you run it on a stand or in the car. Still best to not Idle past cam break in and get it on the road so as not to glaze up the cylinders and then you really have a problem.