[davisenvy]

Should there be washers under the intake manifold bolts? Especially the lower ones. I'm having a heck of a time keeping them tight. GT40P heads, 22 ft lbs and I followed the torque sequence. They loosen up after each drive and its just the drivers side that loosen up. All I can think of is that the missing washers are causing a problem.

 

[sour]

The OE bolts are flanged and don't take washers. It's difficult to find long shoulder bolts with flanges in the aftermarket so most of the time when people replace bolts they are just hex head or machine and those do need washers.

 

[strokeme]

The intake gasket will eventually stop compressing from the hot and cold cycles. The bolts aren't loosening, the intake gasket is becoming thinner, so the bolts appear to be loose. Washers have no bearing on this.

 

[davisenvy]

Thanks for the info, this is what I have read except this has been happening for at least 5 heat cycles. I'll keep tightening and see what happens.

 

[90MarkVII]

Next time around use one of the steel core intake gasket sets.
You still need to recheck the bolts, but the squeeze stops sooner.

 

[Blown85GT]

I agree it's likely the gasket compressing.
You could do what I did, put a small mark on the bolt heads and see if they turn.
I did that and saw that the bolts did not rotate, but lost torque due to gasket compression set.

I think mine took a good 5+ heat cycles to really stop losing torque.

 

[65fasback]

Gasket compressing. Been there and done that. Just be careful you haven’t re-torqued them to the point they are crushed and have started to tear. Way back in my late teens. I went through this with my first intake manifold swap. Now I simply torque the manifold to spec and take it through a few heat cycles. Come back and re-torque them one more time and call it good. A third time if I get carried away.

That was with paper Felpro gaskets. Maybe the new stuff is tougher.

Also, if using aluminum heads, I would much rather have a little extra thread engagement than not quite enough when using intake manifold bolts. I’ve stripped a couple out before due to the extra height of my Funnel Web intake even though I was using ARP bolts. Now a firm believer in intake studs.

 

[toddturbo]

Use studs if possible. On windsor-based engines it's easy but not so much on the Clevelands and 385 series. Also you'd be wise to use good studs (like ARP or similar) as even grade 8 bolts will stretch. And they stretch quite a bit. I just threw a set of grade 8's away because of it, if you look just below the shoulder of the bolt you can visibly see the OD of the threaded area becoming narrower and the threads becoming further apart. Those are stretched beyond yield and are now trash. ARP studs going back on it. BTW those bolts I tossed had 4 re-torques on them from new. Yes I use washers on em, for whatever that's worth. No flange. There's probably better hardware out there than Lowes/Home depot bolts but that's what I had to deal with and that's what I used at the time.

 

[ndmp40]

I will often make my own studs from grade 5 or 8 bolts (cut the heads off). I have never had any fail, stretch, or break. But I only hand tighten the manifold down, it doesn't need lots of clamping force if you do it right. In fact, I am still using studs I made from over 10 years ago, having been on several engines with hundreds of heat cycles. I dont understand how a bolt can fail on an intake manifold. Hell I reuse main and head studs and bolts all the time.

 

[Mustang5L5]

I do studs as well. Stainless with some 12-point ARP hardware. I do have a washer underneath the nuts, but not under the flanged bolts. I did one retorque sequence after running the engine and that was it.