Hello listers, I'm actually closer to the end than the beginning of a 351C installation in a '78 F-150 Explorer whose 351M was getting pretty wheezy.

The small pattern C-6 has been rebuilt as has the Cleveland and after lots of bead-blasting and parts painting assembly is underway.

I'm trying to install the Edelbrock Performer I bought for it and have run into a snag. I have a complete FelPro gasket set, but when I went to install the intake, it seemed to sit down too low in its cradle. That is to say, the intake bolts seem to be supporting it on the outside edges of the bolt holes and it doesn't press down on the gaskets on the block very well.

I didn't go past finger tight, and I have purchased a FelPro 1240 intake gasket set (which Edelbrock calls for). It seems to have a little thicker gaskets where the intake meets the heads and has cork block gaskets instead of the rubber ones in the full motor kit.

Is there a reason for FelPro's making two different intake gasket sets? I don't have the motor here, it's in a shop about an hour away, so I'm trying to arm myself with info early on. I wonder if the seemingly thicker 1240 gaskets could make much of a difference in stack height? Finally, assuming these intake-to-head gaskets work, should I stick with the rubber block-to-intake gaskets or use the cork ones?

Thanks in advance,

Califasbob

 

No good advice on the first part but I gave up on the supplied end seals long ago and went ala GM.... a bead of RTV, and never looked back.

 

Has the intake been milled?

 

First, sorry to be so slow to look at the thread I started, it's been a crazy week!
I took the manifold out of the box myself, so it's the only part I know wasn't milled. The machine shop said they didn't mill anything, and that everything was in spec, but since the last Cleveland was made 20 years ago, it's hard to know where it's been and what's been done to it.

As for the suggestion regarding RTV, the Edelbrock directions said the same thing: instead of the block-to-manifold gasket, to use a bead of RTV. But I feel I need all the foundation I can get to compensate for the fact that the manifold wants to sit so low.

I know this is impossible to diagnose online, and I'd be better off if my motor stand were in my garage and not so far away. I appreciate your suggestions!

Respectfully,

califasbob

 

A picture would help if possible.

 

Bear Tracks, I won't get down 'til next weekend to mess with it, but if something is still goofy, I'll take a picture & post it.

Thanks again, Califasbob

 

Hello, I got to spend a couple of hours with my motor on the stand trying to get the intake to bolt on more smoothly with the Fel-Pro 1240 gasket set. It still wants to sit a little low.

Now for what I forgot to mention...The motor is a 351C with 400 heads (they were in better shape than the Cleveland heads). I know their combustion chamber is slightly larger, but would this cause them to stack higher than the Cleveland heads? I told the machine shop what they were working with, but they may not have taken this into consideration. I know the thing to do is disassemble and remeasure, but can anyone confirm my suspicion?

Thanks again for helping the rookies!

Califasbob

 

I'm not positive about this, but I believe since you are using 400 heads you need an intake made for the 351M\400 instead of the cleveland intake. Maybe some of the more experienced guys here will confirm this.

Good Luck!!

 

Nope, the Cleveland manifold should fit just fine. It sounds like there has been some milling done somewhere most likely on the block to 'square it up' although it's certainly more common to see heads milled to eliminate warpage.

 

Yes 2v C and M heads should mount up exactly the same on the outside. That's an odd problem because the usuall case seems to be the manifold wont go down far enough if the heads and deck have been milled without milling the intake side of the heads or the manifold. Maybe someone did the corrective mill on the heads or manifold wrong.

 

I'm not sure about the correctness on the fit, but Bubba will let us know. From what I know, the M series engines have longer rods, so therefore the deck stands about an inch taller than the motor. The first question that comes to mind is, is the motor actually a "Cleveland" or is it a 351-M/400? If it is, that would explain the gap. There are also "adapter" kits available that will correct this problem from "C" blocks to "M" blocks, but an "M" intake will not mount to a "C" engine. Hopefully Bubba will joiin us to enlighten.

 

If you were trying to install a 'C' manifold on an 'M' block you'd have more than a "little" gap to fill. It's hard to say for sure without some sort of visual but as near as I can tell from the description the intake is sitting too low which indicates that the heads are sitting higher than they should be. It is a very strange problem since removing metal from the block or heads would make the intake actually sit higher.

 

Thanks for the flurry of replies. First, there'd be a huge gap between between a Cleveland intake and M motor. I know the block and manifold are Cleveland, and I know the heads are M heads. The bolts all drop into the holes, but as you tighten, they seem to want to go toward the outside edge of the manifold bolt holes. As you've pointed out, it sounds like someone milled the block where the manifold meets it, but not the head mounting surfaces of the block.

It sounds like the heads need to be milled to compensate for an unmilled manifold?!?!

Sorry again for the rookie play-by-play description of my problem, and as always appreciative of your suggestions!

Regards, Califasbob

 

I just read through this thread for the first time. Your problem sounds screwy. I say the intake manifold is bad. Do you have a stock intake manifold to try?

There's a guy in Oregon selling Australian iron 4v intake manifolds that fit American 2v heads. Iron intakes are better than aluminum intakes in the first place, and iron intakes always have heat shields on the underside to prevent oil from coking in the exhaust crossover. You might want to return that POS Edelbrock intake and get the Oz part instead.

 

Thanks, Paul. That's what my much more experienced buddy who's helping with assembly says. He has a stock manifold and that's our next step..."screwy" is right, Jeesh!

As always, I appreciate the input.

Bob