302 with 351w head problem

[Abroadwa]

I have a major problem with engine coolant leakage. A brief description of what motor I have.

1970 302 mustang block and most components.
1978 351w heads.
Offenhauser 302 intake manifold
I used 351w intake manifold gaskets.

The problem I have is on the driver side cylinders 5-8 are all ingesting antifreeze/coolant. I have replaced gaskets a couple of times now to no avail. I cannot locate even the smallest of loss through the intake gasket. With the manifold off I can see antifreeze sitting on the intake valves like I said, only on the drivers side. I am also unable to locate a crack or any issue with the manifold. I have antifreeze in the valley AND ingesting into all four cylinders on the drivers side with no leakage visible through the gasket area. Where could that much coolant be coming from? What do I check? Has anyone else had an issue like this?

I thought that it would have to be through the intake manifold since it is all four cylinders but I plugged the two sides and flooded the cavity with no leakage. It couldn't be a head problem with all four cylinders receiving antifreeze right?

I have a dual plane offenhauser manifold and have verified no issue on the passenger side 1-4 cylinders. I am at wits end trying to fix this. Is there something that I am missing???

[JerryGLX]

That head might be cracked internally. cant see it from the outside sometimes. If you are sure that all your gskets lined up perfectly then i would start with removing the head and having it checked out.

[mark a.]

According to my book, you need a special head gasket for this conversion.

[Blurry94]

If you're sure you have the correct HG's, then I would lean towards a cracked/warped head. The heads can usually be resurfaced in that case.

[Ford427Strokr]

Sounds like cracked head. I have an 89 302 with 78 model windsor heads. If you have just put the heads on it and its leaking they might not have cut the intake side of the heads. I had mine cut for 11 to 1 compression and they had to cut the intake side on the heads so the intake would seal.

[umdstang]

mark
i was thinking about doing a conversion from a 302 head to a 351 head on a 302 block i know that i need special bolt kit but what else am i going to need

i see you said that your book says i need a special head gasket what book r u talking about does it include anything else needed to do the conversion

any help would be great

[Ford427Strokr]

I used just a 302 head gasket in mine and bought inserts from Crane Cams for the heads.

[umdstang]

sorry for the late answer but what kind of insert from Crane Cams???

thanks
brian

[Ford427Strokr]

inserts for the bolt holes in the head. The 302 head bolts are smaller than the 351 head bolts. You can use a washers for this but I have never done it.

[pud]

i wouldnt swap 302 heads off for 351w heads unless A) I had a pair of 1968-9 windsor 4v heads. or B) I had a 302 built in 1986 or prior. ...look for some E7TE 302 heads, you wont regret it.

[Ford427Strokr]

The 4v heads are a lot better. I would go with a set of GT40 P heads over the E7s. Out of the box the will give you better flow and a little more compression. You can get them out of salvage yards from 97,98 Explorers with the 5.0 engines. A new set will run you about $260 but I think they are not made anymore so finding a new set might be difficult.

[umdstang]

Hi Pud,
thanks for the response,
I do have an older block from 68 or 69 and they were the 69 Dooe heads. Would i have to get a new intake manifold to accomidate the exrta intake bolts or just leave them there and plug them

thanks
brian

[pud]

get gt40s, explorers and mustang cobras had them. I wouldnt waste time on old 351w heads (unless they were 4v 68-69). Most 351w heads are the same as 302 heads anyways, and if you have a 351w truck head they just 302 heads with gigantic combustion chambers.