Engine GT40P questions and advice

So my car is losing coolant and it’s not leaking it and it’s 100% burning it because im leaving puddles in my driveway from the exhaust every time I start the car. It’s been doing it for a while now and im not sure if it’s a head gasket or if it’s an intake gasket but either way it’s time to address it and I figured I’d go ahead and throw some heads and a cam in while im at it.

Im able to get some GT40P heads for a decent price. I also already have an explorer upper and lower with explorer 4 hole 19ib injectors. The car will never see a track and I don’t really care about squeezing the extra power that AFRs and TFS heads can. I also can’t afford those types of heads so I’m sticking strictly old school budget since the car is a cruiser/driver. I haven’t really decided on a cam yet but it’ll probably be something really mild

I know the GT40P heads are finicky with spark plug boot to header clearance so my question to you all is, would I be able to run the 9mm Ford performance spark plugs and just put 90 degree boots on the ends of the troublesome ones? If so, does anyone know of any good 90 degree boots for the 9mm plug wires? If not, does anyone have any advice on what plug wires and boots to run? I’m running BBK shorty unequal length headers.

Next thing is, obviously I’m going to have to upgrade the valve springs, so which valve springs would be good for a mild cam like an e303 or Anderson n41? Im not looking to go crazy or anything. I’ll also be running the scorpion 1.6 5/16 roller rockers.

Lastly, I’ve got some lifter tick on the passenger side so I’m going to replace the lifters and I saw the ford performance racing lifters that are 1/16 inch taller than OEM lifters and I’m wondering if I’ll need to run shorter push rods or if I’ll need to run different push rods regardless because of the head change and roller rockers. I would get the OEM ones but I’m not sure when they’ll be back in stock and with the way ford is with their stock I don’t really feel like waiting for 6 months to maybe catch them back in stock. Any advice and help would be greatly appreciated

Mustang5L5 said:

Alex Parts also has GT40P springs.

FORD, SMALL BLOCK 302 HO w/ E7, GT40P & GT40 - Alex's Parts Sales

alexsparts.com

Really there is only 1 spark plug that is the issue on the 40P's. You just need a 90* boots to clear on most of the plugs, but this will also depend on what headers you are running. You also might need to pull headers to change plugs in the future. Again...depends on what header you have.

Highly recommend you mock it up on the bench with head, header, spark plugs and wires before put in car and do it all bending over the fender.

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I’m running the bbk shorty unequal length part number 1515. That is a good idea to get it all done before putting it in the car I appreciate it

AeroCoupe said:

TFS spring kit for the GT40’s:

https://www.trickflow.com/parts/tfs-2500100

Excerpt from Ford Racing with regards to the M-6500-R302’s:

These lifters are 1/16" (.0625") taller than stock. Removal of heads is necessary for installation. Lifters M6500R302H does not require the removal of the head for installation."

So looks like you want the “H” model. I run these in the Coupe.

Have zero experience with the P heads but someone will chime in on the headers and plug wires.

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I appreciate the link. I thought the “H” models were the ones that were 1/16 taller? If I’m removing the heads anyway to replace them what else would I have to worry about in regards to clearance?

Mustang5L5 said:

When i had GT40P heads, i had a set of BBK 1515's, and they worked well in my mockups.

I never installed the heads however. Ended up going with Al heads and sold the 40P's for $50. I regret that sale.

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Yeah with the prices of even the 40p heads now I’d imagine it hurts to think about selling them for $50. I remember when explorer intakes and heads could all be had for a fraction of what they’re going for now. Shame I couldn’t get in the game a little earlier lol. I appreciate the info.

AeroCoupe said:

I have them and can get them in and out with the Edelbrock Performer RPM heads. What I would do is call Summit Racing and see if they will measure the R302's and the R302H's length. The other thing is if the P heads have the relief above the lifters then the lifters will install with no problem with the heads on the motor.

Ford Racing lists them as OEM replacements so my guess is there are some folks that have cylinder heads without the reliefs and had issues.

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I picked up the H set. Since I’ll have the heads off I’ll pop them in then that way there won’t be any type of fitment issues.

So I got the heads and the coolant port on one of the heads looks a little rough. Not sure how much cause for concern it is but does anyone have any advice as to deal with it? Should use a little bit of RTV around it when putting the gasket on?


I’ll have to see what the other head looks like when I get home. Let me know what you all think

Mustang5L5 said:

For pitting like that, i've filled the pits with JB weld and then hand-sanded it flush with the surface of the component.

However, what you are seeing there is likely inside of the gasket sealing area, as you can clearly see a defined square of pitting with a border region. Would need to lay a gasket on there to confirm. Regardless, i'd prob fill the pits with JB weld, (very thin) let it dry and then sand it flush. I did this exact repair on my lower intake as the t-stat housing had the same damage.

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I didn’t think about that but that makes complete sense. What grit would you recommend? I appreciate the advice

Mustang5L5 said:

If you start sanding it down before it fully hardens, you don't need much to get it smooth. I had an assorted pack so I don't recall what I used. 180-600 grit range.

Given that they are iron heads, I doubt you'll get aggressive enough to start removing the head material. Just use as little as possible to fill the holes and carefully sand smooth and give it time to cure. Just make sure you mask off the area you don't want debris to get into. Tape off the ports and slap a valve cover on.

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Solid info I appreciate it