[64speed]

I have stripped one of the bolt holes for my valve covers from bolting and unbolting trying to fit the valve covers. Can I drill and tap them safely or do the bolt holes lead to an oil gallery or water jacket. I am going put a lot of double sided tape down to catch chips from drilling going onto the head

[hurryinhoosier62]

Originally Posted by 64speed

I have stripped one of the bolt holes for my valve covers from bolting and unbolting trying to fit the valve covers. Can I drill and tap them safely or do the bolt holes lead to an oil gallery or water jacket. I am going put a lot of double sided tape down to catch chips from drilling going onto the head

Use a drill bit to find the bottom of the hole. Mark it with a scribe or a Sharpie. When drilling for the Helicoil or Time-Cert, do NOT drill deeper than the index mark you made on the drill bit. In most cases, the valve cover bolt hole bosses are blind and do not enter the water jacket.

[Scott Stoneburg]

In my Edelbrock heads, the top bolt hole is open to the intake port. I think my iron D ports were too, but they were ported .

[Half-Inch Stud]

Both Upper Valve Cover Bolt hole are ready to break into Intake Runner ceilings. No drilling any deeper than stock.

[Bill Hanlon]

Originally Posted by hurryinhoosier62

Use a drill bit to find the bottom of the hole. Mark it with a scribe or a Sharpie. When drilling for the Helicoil or Time-Cert, do NOT drill deeper than the index mark you made on the drill bit. In most cases, the valve cover bolt hole bosses are blind and do not enter the water jacket.

Don't just mark it. Use a drill stop.

[64speed]

Wonder if I can tap it without drilling cause it’s soft aluminum

[64speed]

I will measure the point the helicoil threads in and drill no more

[Cliff R]

In most cases you will be able to tap into aluminum for a heli-coil w/o drilling. You may have to open up the very top of the hole slightly to get the tap to start. I install heli-coils just about every day and almost NEVER drill the hole out for this procedure in softer materials.......Cliff

[mgarblik]

Originally Posted by Cliff R

In most cases you will be able to tap into aluminum for a heli-coil w/o drilling. You may have to open up the very top of the hole slightly to get the tap to start. I install heli-coils just about every day and almost NEVER drill the hole out for this procedure in softer materials.......Cliff

Well, you have yourself in a little jam on this one. The hole isn't very deep and you want to install a heli-coil to fix it. So basically you have one shot if the head is installed. Like Cliff said, do not drill it. start the helicoil tap straignt and tap to the bottom. Clean the shavings out and run the tap in again to make sure you have nice clean threads. The possible issue is, the hole is so shallow, I doubt a full length typical 5/16" heli-coil will go in deep enough. So if that's the case, do the following. First use a caliper or a coat hanger wire to measure the depth of the hole. Subtract the 3-4 lead threads length from the helicoil tap to estimate how deep it will go. If there is not enough depth, you can cut the helicoil BEFORE you install it. Use a very sharp pair of diagonal cutters and cut between the coils removing a few coils. Dress any sharp end left with a good file. I am mentioning all this because if a helicoil is installed and it stops 1 coil to flush with the hole, they are a real bitch to remove from aluminum. The coil needs to be in the hole 1/4-1/2 turn beyond flush to hold. BTW, valve cover bolts/studs do not need to be very tight. 120-150 inch lbs. is plenty tight with a cast cover.

[78w72]

that stinks, should be able to install a heli-coil without drilling to the next size up.

but i gotta ask, how did you manage to strip the threads installing valve covers? did you cross thread the bolt? valve covers use very little force & should not be tightened anywhere near tight enough to strip the threads... even after multiple times. they are pretty deep threads & with proper torque should not have stripped out.

& e-heads top v/c bolts are open to the intake ports, you need to use thread sealer on the final install or there will be a vac leak.

["QUICK-SILVER"]

This a top bolt or bottom bolt that's stripped out?

With ported E-RPM's, I wouldn't do a top bolt without removing the intake.

You can go an inch or more deep on bottom bolts with no problems.

Top bolt on mine measures less than 3/8ths inch from top of hole to roof of intake runner.

Clay

[grivera]

Originally Posted by 78w72

& e-heads top v/c bolts are open to the intake ports, you need to use thread sealer on the final install or there will be a vac leak.

Is this the case with their DPorts as well?

[Skip Fix]

On my E heads that is part of why I used studs and Loctite so no leaks into the port and I could set them so they did not go into the port too much.

[78w72]

Originally Posted by grivera

Is this the case with their DPorts as well?

sorry should have said round port e-heads. cant confirm on the d-ports but i recall reading they do too, unless they were ported as one guy said above. but for sure on stock O-port e-heads.

[78w72]

Originally Posted by Skip Fix

On my E heads that is part of why I used studs and Loctite so no leaks into the port and I could set them so they did not go into the port too much.

studs are a good option too. on mine i checked the depth of the holes & cut the bolts so they didnt protrude through. & used thread sealer. next time they come off i think i will stud them though.

[JSPONT]

I have cnc ported KRE D ports, yes the hole is in the port, I use a sealer on the top bolts.

[Skip Fix]

5/16" Allen "set screws" work good an Fastenal has them in different lengths for different thickness valve covers or cover spacers.

[64speed]

The threads in one of the heads got weak from constantly screwing and unscrewing them trying to get valve covers to fit. I went outside just now and was able to get one of my set screws to grab and go in straight. They are 1 inch long and I’d say about 1/2 of it sticks out. It threaded in a thread or two more than the rest of the studs but it’s tight and I’m just gonna leave it alone. Thanks guys for all the help