Rebuilt 351W starts, runs FAST, then dies - help wanted

[foothilltom 33]

4 minutes ago, barnett468 said:

Take the lifters out and look at the bottom. They should be perfectly smooth, if they are scored at all the cam is likely dead. Look at the cam as well. Put the same lifter back in the same hole it came out of.

 

I'm seriously afraid to find out.  I think I'll do that first thing tomorrow.  Why ruin a Sunday evening.  :)

[barnett468 418]

I would also lay the intake side gaskets on the heads then set the intake on it and measure how much clearance there is on the ends. It should be around 3/16".

[barnett468 418]

1 minute ago, foothilltom said:

I'm seriously afraid to find out.  I think I'll do that first thing tomorrow.  Why ruin a Sunday evening.  :)

lol

[foothilltom 33]

Well, some dang good news for once.  I pulled the lifters one by one and inspected for any signs of wear.  Happily, there are as smooth as the proverbial baby's butt, so I don't think I did any detectable damage to the motor during that 40 seconds of running with coolant in the oil.  Put them all back in the same hole.

My Fel-Pro 1250S-3 gasket is on its way and I'll clean up the block, manifold, and heads before re-installing.

I'm going to do the "dry fit" test as Barnett suggested to see how much gap I have in the front/back.  I remember thinking originally "that's a big gap", but I didn't realize then that a 1/4" was normal.   I was expecting a pretty tight fit, but I'm educated now.  :)

I'll keep you posted on the progress, but meanwhile, please accept my sincere thanks.  I learn so much here and I don't give back a damn thing.  I hope to change that.

Tom

[barnett468 418]

1 hour ago, foothilltom said:

I learn so much here and I don't give back a damn thing.  I hope to change that.

Tom

Donations are cheerfully accepted thru paypal or bank wire transfer.

[1969_Mach1 333]

Nice to hear some good news!  Take your time reassembling the motor and new intake gaskets.  Maybe take a look at Edelbrock's website for instructions and torque specs to install that manifold.  Often with aftermarket manifolds the instructions will recommended to use something like Gaskacinch and literally glue the gaskets to the cylinder heads (but not the intake manifold side).  Did you recoat the lifters with some assembly lube before reinstalling them?  I don't know that it's needed, but might be a little extra insurance.

[skidmarky 50]

I hate to put bad thoughts in your head, but if you ran it with coolant in the engine, I would be more worried about wiping out the bearings. Always run a new engine with straight water til you know there are no leaks.

[dcm0123 15]

You may want to test fit the intake, head and gaskets and inspect for excess clearance before you fully assemble..

If you have a gasket which goes between the front and back of the intake and the top edge of the block, leave it out for this test. With only the two long gaskets installed along with the intake manifold there should not be clearance between the head, gasket and the intake.

If there is clearance, you have a problem. Unfortunately I do not know how to tell if it is the head or intake. If there are clean machined surfaces on a used part, I would suspect someone machined the surface and may have done it wrong. I believe if the long sides of the intake are machined, the surfaces on the ends which mate with the block have to be machined to or the intake will bottom on the block before there is correct compression on the sides to the heads.

If you are using aftermarket heads, I suggest you verify what manifold they were designed to be used with. Possible they require aftermarket manifolds made by a specific supplier.I have trick flow heads and their intake on my 351W.

Remember to take apart and install the end gaskets before tightening everything down. I believe many people replace the end gaskets with RTV if you are concerned they will not compress enough to allow a good seal between the intake and head.

[DocWok 30]

On 8/12/2019 at 2:17 AM, foothilltom said:

I'll do that right now.  Thanks!

And yes, based on my smoke test, the manifold was leaking pretty much from front to back, both sides.  Very strange.  I can't wait to see what the culprit is.

Update: I could get my smallest gauge through from front to back (.0025).  Color me ignorant.  I had no idea it could be so "off".  I wish I would have been more vigilant about that part of the fit.  I was hyper-concerned with the RTV gasket I made in the front and back.  Ironically, that didn't leak at all.  Just the Felpro gasket side.

The plot thickens.

The observation from the OP that a feeler gauge could be slid along between the the Edelbrock manifold and intake gaskets on the alloy heads while it was correctly torqued in place would suggest the Edelbrock had been machined.