Rebuilt engine only idling at 40 degrees advanced (new question 8/19)

[Grey owl]

I would be looking for vacuum leaks, and timing by ear real common.for SB fords back in the day. Find TDC set distributor right on #1 plug wire and start, advance distributor till you hear it running on the next cylinder then back it off. If it pings or cranks hard back it off a little mor

 

[EPB72]

Ignition timing isn’t growing to correct a low compression issue at 105 psi ,,, worn engine poor rebuild , heads combustion chamber size ? Valve timing ,cam profile,,, I’ll say it was this engine originally a reverse rotation engine ? Mix matched parts ? A vaccum leak doesn’t cause low compression issue.. I think the op is just curious at this point ,, I think his explorer engine may be a better option with some checking first,

 

[joshua]

Ignition timing isn’t growing to correct a low compression issue at 105 psi ,,, worn engine poor rebuild , heads combustion chamber size ? Valve timing ,cam profile,,, I’ll say it was this engine originally a reverse rotation engine ? Mix matched parts ? A vaccum leak doesn’t cause low compression issue.. I think the op is just curious at this point ,, I think his explorer engine may be a better option with some checking firs

I think I’m just going to play with the timing and drive it for a while, see if possibly a stuck ring pops loose or the rings bite( Bite if it was really honed) I will say, I don’t see anything on the pistons saying .30 indicating larger pistons. But I just don’t understand putting all that money on the top of the engine if the bottom was garbage. But idk, maybe they were convinced it was a head issue and thought they didn’t have to do anything to the short block.

I will start taking the explorer apart asap.

 

[joshua]

Ok, so this explorer is a 1998 I’m pretty sure that means p heads. That’s not going to work with my headers I’m pretty sure. Anyway.

I wouldn’t mind using these brand new aluminum heads off the boat anchor, but they were on a flat tappet cam cam block Other than changing valve springs and push rods, what do I need to look for (check) in order to see if these aluminum heads will work ?

Edit: I also was never able to find any info on the heads by their casting numbers.

But these look exactly like them, with that checkering and rocker arms. Also the tiny plug holes.

https://www.ebay.com/itm/2323996848...d=link&campid=5335857059&toolid=20001&mkevt=1

 

[DirtDonk]

Like any head (but especially imported aluminum heads) I would also check that the valves mate squarely to the seats.
Any testing might be as simple as filling the combustion chamber with liquid to see if it flows out or stays in.
I remember cleaning up a set of heads once, that were thought to be in OK condition. The looked good too. I only started to question that description when I was cleaning them with kerosene and it would leak out of the combustion chamber and out through the ports!

And not to point the finger only at imported stuff, because the Edelbrock heads are getting a bar reputation for leaky valves/seats right out of the box.
I have a set for an engine I'm building ("building" being an optimistic term right now) in the box still and have not tested them. But the Tube of Yuze has produced several videos highlighting this issue.

Paul

 

[ntsqd]

It is likely that such a cylinder head is going to have small combustion chambers. I've no idea what the normal CC of a P head is, but the odds are that the AL heads are at least the same size and probably smaller. This could affect piston to valve clearance, so I'd check that. If they are smaller then you're going to gain some static compression ratio, which isn't a bad thing unless it pushes you into too high of a CR for pump fuel. I be surprised if the Explorer short block has anything other than flat-tops in it, so this shouldn't be possible unless the chambers are really tiny.

Given that nothing is known about those heads I'd send them out for a rebuild. Maybe they need nothing, and maybe they need some work. Either way you won't be repeating the same error that the guy before you made. While the machine shop has them ask them to check the CCs of the chambers so that you know what you've got. And they can set up the appropriate valve springs for the cam that you want to use.

While I'm thinking about it, water is a terrible choice for checking the valve seal or any leak for that matter. It's surface tension is too high and it won't leak thru as small of a hole as mineral spirits solvent, diesel, or even ATF will leak thru.

 

[Timmy390]

Ford GT40P cylinder head combustion chamber size is nominally 59 cc, typically measuring between 58 cc and 61 cc

Those heads are more than likely china knockoffs of XYZ head. China was for sure doing a GT40 knockoff. They flowed well HOWEVER the valves, seats, springs and such were total garbage. The Stang guys would buy them bare and build them with good parts as a cheaper option to the real thing.

Tim

 

[joshua]

I did get a hold of that eBay seller, and he did confirm that they are his heads. So are GT40esk copies with 64cc chambers.

I also dropped the heads off today to have them checked out at my machine shop. It’s not a ton to of money to have them checked. But the real issue I noticed is the guide plates are eating the push rods. I’m thinking the plates are a harder material than the rods, but it’s just chowing on all of them.

I have maybe an hour of run time on these heads. Even if the metals don’t like each other, should they be hitting the guide plates like that in such a short amount of run time? It’s every single one. Or do I really just need harder push rods.

Also I bought a rebuilt 87 roller mustang motor with paper work. I’m done with this boat motor. The new rebuilt engine is a long block.(aka rebuilt heads as well)

I would like to use the aluminum heads from the problem flat tappet motor on the new rebuilt roller block. Can I simply take the springs off the new roller block heads and transplant them on the aluminum ones that currently have the flat tappet springs on them now?

Edit: I also ordered and received these pushrods for the roller motor(In additional pics) Are these Hardened? Or do I have to get chromoly ones? I ordered before I discovered this issue.

 

[DirtDonk]

Yes, for guideplate heads you almost always need hardened pushrods. They're not uncommon, but they're not made automatically for engines that typically don't use guideplates from the factory
The exception(s) are with kits like Crane put out (don't know if they're still available?) where the guideplates themselves had nylon(?) "bushings" as guides to eliminate, ore at least reduce pushrod wear.

The rods should not be in hard contact (as in, binding) in the slots, but they do come in contact so do in fact need to be special hardened versions.

At least that's how I understand the workings at play here.

Paul

 

[73azbronco]

you really need hardened rods.

You really need to work with a machinist who knows his stuff when you start talking swapping springs willy nilly between heads.

That is a lot of metal shavings on that head, like a lot......

Have you checked the pushrod length to spec? Are the pushrods the right length?

The add says works with guidplates, I assume they are hardened. But are they made to work with those specific guideplates? What does the machinist say?

What is buying a motor with paper work mean?