351 4v Intake question, can this be right?

[Jim and Jutta]

OK, putting my closed chambered 4V heads on my 71 M code Mach tomorrow. I repainted them the proper dark Ford blue after it was pointed out that's the correct color. After comparing the weights of the standard 4V intake with an Edelbrock Performer 4V intake, I decided to go with the Edelbrock. I noticed that the ports of the Edlebrock 4V Performer are smaller than the ports of the heads, the original cast iron intake has the same size as the heads. Shouldn't the Edelbrock 4V ports be the same size or is it not an issue?

 

[droptop73]

The ports on the Performer are intentionally smaller to provide better flow velocity. It will not be a problem. If the port were smaller than the manifold it would create turbulence at the port inlet which would be a problem. You could port match the manifold but would not likely gain much performance.

Some performance/race manifolds like the Edelbrock Victor are quite a bit smaller to provide more meat for port matching.

 

[turtle5353]

On my old motor I used a gasket set to port match both my heads and intake. Put some blue machinist die on the head and traced the gasket same with the intake then took die grinder to them and matched them up. Not sure how much I gained but figured it couldn't hurt.

 

[Jim and Jutta]

The ports on the Performer are intentionally smaller to provide better flow velocity. It will not be a problem. ...

Thanks Jeff, that's a load off my mind!

Those puppies are going on tomorrow and off with the 2V heads that the prior owner had put on it.

 

[kidwithfastback=fast]

+1 the smaller ports keep them from loading up as easily.

COOL PROJECT!

 

[goodnigh]

Just a rhetorical question, but why would you want

to use a smaller/mismatched intake on a Cleveland?

mike

 

[Jeff73Mach1]

to compensate for the oversized ports at lower RPM's (in theory I suppose)

 

[droptop73]

Exactly, throttle response comes from flow velocity not flow volume. When an air column is moving faster it fills the cylinder better.

 

[JimNiki]

I didn't notice any valve stem seals?

 

[droptop73]

They're there... the blue things inside the springs.

 

[Jim and Jutta]

OK guys, got the heads off and noticed there's no signs of cross hatching on the cylinder walls but there is signs of oil in a couple of the cylinders , I just had the whole engine rebuilt 5,200 miles ago by a local machine shop, forget the oil leakage, shouldn't there be cross hatching if they did a proper rebuild? Wanted to ask you guys for your input before I discuss this with the machine shop.

 

[droptop73]

Cross hatching can disappear if there is a fine bore finish. The only way to know for sure on the rings is by performing compression and leak down tests. That requires a complete engine though. If you do a "dry" then a "wet" compression test and see if the numbers change. By "wet" i mean squirt some oil in the cylinders and sipn it over a few times, if the rings are not sealing properly the compression will go up on the wet test.

 

[Jim and Jutta]

Cross hatching can disappear if there is a fine bore finish. The only way to know for sure on the rings is by performing compression and leak down tests. That requires a complete engine though. If you do a "dry" then a "wet" compression test and see if the numbers change. By "wet" i mean squirt some oil in the cylinders and sipn it over a few times, if the rings are not sealing properly the compression will go up on the wet test.

Thanks Jeff, I had thought cross hatching was a requirement in a rebuild, as far as testing compression the old heads are off and I haven't put the new ones on until I addressed the concerns with the bottom end. The machine shop owner agreed to take a look at the engine to give his opinion prior me to putting the new heads on.

 

[Totalled]

Are you doing this at your house, or did you find a shop like you were asking about?

 

[trainey]

Looks just like my build. Sitting on the engine stand waiting on me to get it put in.

 

[Jim and Jutta]

Are you doing this at your house, or did you find a shop like you were asking about?

Hey Pat. The car is now in the shop that originally did the work (you know who they are just don't want to mention any names on the net), they agree a poor job was done by the machine shop they contracted it out to and will be rebuilding the bottom end under warranty.

The owner of the shop is being a stand up guy, he was not a happy camper when he saw there was no signs of cross hatching after just 5,000 miles, plus he verified there were signs some oil was getting by the rings in a couple of the cylinders. After rebuilding the bottom he's going to put my 4v heads on and complete everything at no cost.

 

[MechEng]

Hey Pat. The car is now in the shop that originally did the work (you know who they are just don't want to mention any names on the net), they agree a poor job was done by the machine shop they contracted it out to and will be rebuilding the bottom end under warranty.

The owner of the shop is being a stand up guy, he was not a happy camper when he saw there was no signs of cross hatching after just 5,000 miles, plus he verified there were signs some oil was getting by the rings in a couple of the cylinders. After rebuilding the bottom he's going to put my 4v heads on and complete everything at no cost.

Glad to hear the shop is standing by the work they performed and taking responsibility for the bad contract work. I would bet that shop isn't going to send work to them anymore, or at least be more scrutinizing of work that comes back from there.

Hope you get it back in good shape soon!

 

[Jeff73Mach1]

I'm sorry to see you having to deal with this. It is a stand up shop that will do something after 5000 miles though.

 

[Totalled]

Ah, nice! Is the machine shop the one that starts with a "J" and ends with "s"?