5.0 with early 351w heads

[ajfriz]

I have a 1990 5.0 H.O. that I am putting in my 64.5 and I have some 1969 351 heads that have screw in studs and guide plates as well as some minor porting. Would it be worth it to put these heads on the 5.0? I'm planning on doing a cam swap before I install the 5.0, but I'm not going to rebuild it for a year or two when I plan on building a 347.

[scripts]

They wouldn't hurt. "some minor porting" is definitely going to be better than factory pre-Explorer heads.

[Rickmaan]

Pro's;
-Slightly better intake port flow

-smaller chamber will bump compression up a little (around .5)

-already converted to screw in studs for a stable, adjustable valvetrane

Con's;
-exhaust port flows no better than any other 302 head, and probably just a little less than the stock 5.0 E7 head.

-'69 castings did not come from the factory with hardened valve seats, so the seats will wear quickly with unleaded gas

-adjustable valve trane means you'll have to spend money on new rockers and push rods because the ones from the pedastal mount system used on the '90 5.0 won't work.

Depending on the quality and extent of the "minor porting", they are probably worth a good 20-30hp over the stock heads, but my main reservation would be the valve seats. Double check to see if hardened seats were ever installed during the work that was done.

[ajfriz]

The seats were replaced when the heads were rebuilt. I believe the intakes are 1.94. Is that what they were stock? I was planning on using some roller rockers and pushrods that I have as long as the pushrods are the right length. They are stock 289/302 pushrods.

[jetnoise]

You might want to check to see if you will be loosing compression with those heads
1.94 was not stock.
Pushrod length will most likely not be stock anymore

[gotstang]

You'll need head bolt washers, TFS made a nice/inexpensive set last time I looked. Other than that and some STRANGE length custom pushrods, that should be it.

I agree with the others, I'd CC the heads and try to guesstimate how much compression you're going to loose. A syringe, $1 bottle of colored rubbing alcohol, vaseline, plexiglass and a sharpie should work well for that.

[Huskinhano]

A minor problem possibly with the 351W heads. On your 5.0 with those heads or any other non roller cam head, you will not be able to install or remove the roller tappets with the head on. The E7, GT40 or P heads have reliefs for the roller tappet installation/removal with the heads on.

The 1.94" valve is a Chevy valve. It's slightly taller then the Ford valve and may effect rocker arm geometry. Since it is bigger in diameter then the stock 351W valve, the piston valve reliefs may not be big enough with a high lift cam.

[ajfriz]

I could be wrong with the valves being 1.94. I measured them before I put them back on the little 260 that is in the car now, and that's been a couple of years. There is a good chance they are the stock valves and I just remembered them incorrectly.

When I bought this car the heads were on it, but they didn't torque down the driver side head so there was water in the oil. When I pulled the valve covers off to start the tear down I was pleasantly surprised with seeing the screw in studs and guide plates. I then checked them out and they were rebuilt with no miles on them. The only run time they have is after I put new headgaskets on and ran it for a little while to make sure I didn't have any leaks and to power brake it a couple of times

Would I be able to find a common pushrod if I used standard rockers? I'm just hoping I can easily use these heads since the combustion chamber should be a little smaller and increase compression. Combine the higher compression and a better cam, I should have a 5.0 with significantly more power than stock (I hope).

[66gt350]

IIRC, the stock valve size for '69 heads were 1.84".

[Rickmaan]

Stock 351w intake valves were 1.84", exhaust valves were 1.54". This compares to 1.78" Int./ 1.47" Ex in vintage 289/302 heads as well as production 5.0 heads other than GT40's. It was common practice for many years to install chevy 1.94" valves when reworking these heads for screw in studs. Since you say new valve seats were installed, I don't doubt 1.94" valves were installed at that time. I doubt the larger valves would've done any good at all on a 260 due to shrouding from the small bore diameter, but they are definitely beneficial on 289 and 302 blocks. If the short block has been rebuilt and new aftermarket pistons are used, the 1.94" valves shouldn't be a problem, most new pistons have reliefs large enough for those valves. But if you still have the oem '90 5.0 pistons a little piston notching may be needed for valve clearence depending on the cam you end up with. If you have the stock 1.84" valve size you should be OK with any piston as far as the "eyebrow" diameter on the piston, but valve clearence still needs to be checked when an aftermarket cam is used.

For the pushrods, you are going to have to get aftermarket. Stock length 289/302 pushrods are too long for your roller lifters. You might be able to get by with stock length 5.0 pushrods, but you need to use hardened pushrods because of the guideplates in your 351 heads and stock 5.0 pushrods are not hardened. Since you need to get aftermarket pushrods anyway, you'll be a lot better off using a length checker to make sure you get the correct length. It doesn't make sense to pay for a set of hardened pushrods only to find out the length is not right for correct rocker geometry. Don't be surprised if a non-stock length is needed, you're combining a '90 block with '69 heads, and the heads have been modified. Things like block deck, head deck thickness, rocker arm style, lifter type and cam measurements all affect required pushrod length for proper geometry, and all of these things were changed several times between the production years of the parts you want to put together. Don't worry about the price of custom length pushrods though, they don't cost that much more than good quality oe length pushrods, and the better brands usually list part numbers for several non-stock lengths so chances are good there's a pushrod length sitting on the parts shelf to suit your needs.

BTW - '69 351 heads had a 60cc chamber, late model 5.0 heads have 64cc chambers, so you will get a boost in CR, but not a drastic change.

[ajfriz]

I pulled the heads off of the 260 tonight and they have 1.84 valves. These heads were completely rebuilt with new valve guides and exhaust seats, but they machined the guides wrong because there is a lot of slop in them. You can clearly see that the holes are round and not oval like a worn out guide. The guide itself has the machining marks for the oil passages and they look brand new but are completely screwed because they aren't the right size for the valve stem. Very upsetting since I have the receipt from the machine shop stating what they did and when they did it.