I noticed today when I pulled the intake off my 408 exactly how far the rocker bolts actually go into the intake runner. Id say a good 3/8 of a inch. Is there really any reason why I couldn't cut at least the amount that sticks into the port off.

 

I don't see why it would hurt anything considering that the extra length left protruding isn't going to help hold anything.

 

I don't see why not. but I'd probably error on the side of still being a little too long to guarantee you still have maximum thread engagement.

 

I ground down mine on a bench grinder, just make sure to put a thread sealant on the threads so you don't suck oil from the threads.

 

The bolts that come with the comp trunion upgrade were shorter than the stock bolts and don't hang down in the runners. Not sure what rockers you are using, but this might be an option for you.

 

Exactly. I wouldn't want anything hanging down IN the runner.

What rockers are you running OP?

 

I'm running stock rockers with the summit trunions that use the stock bolts. I've got some comp trunions laying around I'll measure off those bolts and cut my stock ones.

 

Why not just use the comp bolts? That's what I did with my AFR's and it worked out fine. Either way you'll be fine. But definitely shorten them.

 

Why not use the stock bolts and grind them off to fit the runners after being torqued down? This way they fit the runner shape exactly and dont leave a void for turbulent air to flow around. Just mark them for the runners they are ground to fit and reassemble them in that order.

 

I didn't want to use the comp bolts because that set of trunions I plan on using in my other car. And I actually thought about pulling the intake off and marking the bolts one at a time and contouring them to the port but I was afraid that having half the bolt grinded off might make it alot easier to cross thread and mess a bolt hole up.

 

Start them by hand. You'll be fine.

 

I havent personally tried the idea I suggested but I dont think it would have any better chance of cross threading than making a head bolt thread chaser out of a stock head bolt and using it to clean the threads out in the block. I was thinking that youd have to remove and dissassemble the heads to do the grinding on the head bolts to get them matched to the ports anyways. The rockers and bolts would need to be torqued down and you would probably need access to both sides of the runner to get it perfect.

Like suggested your gonna start them by hand anyways so they should start threading just fine.

 

Another thing I noticed today was that the comp bolts were not only shorter but threaded a lot higher up. If I did end up cutting almost half inch off the bolts I'll only have maybe half inch of threads holding the bolt in. Idk if since these are prc 247s and the port is just larger or what but these had probably half inch of bolt in the port. I may be better off getting more comp bolts and cutting them to fit.

 

Edelbrock sells intake rocker bolts already shortened. I haven't compared them to the OEM's or Comp's, but that is another option to consider.

Kerry

 

It doesn't matter if the bolts are threaded all the way to the fastener head, as the space between the rocker trunnion, and the pedestal has no threads. The threading on the boss is what it is as it has been raised toward the port ceiling. Blending the current set-up will have no ill effects over what was currently run from the fastener strength perspective, unless it becomes counter sunk into the port.