New L31 - HT383 Cam - COMP Cams 1418-16 Roller Rockers - Rubbing

[Supercharged111]

Oh, no ****? So now the GMPP ones, i.e. Crane Gold, are on forever backorder? Isn't that what GM puts into their crate 454s? FWIW I went with Comp Pro Magnum chromoly rockers in my 1500 and love them. Damn near quiet as stock, just had to trim the valve cover gussets a tad. I admit I was lazy and didn't check geometry, it bugs me a little in the back of my mind.

 

[m002922]

Update / reviving the thread. Everything is now in (cold air intake, and exhaust system finally done), and with that done I finally got the 0411 MAF tuned (figuring that out took a lot of youtube watching . . . and a lot of the videos out there are on much later ECMs, so figuring out what applies to the 0411 with HP Tuners can be challenging) . . . with the new engine and good tune it's like a new truck.

So now I can start worrying about the Rockers issue which I screwed up, which was the genesis of this thread.

Slowburb, with the Scorpion 1.6's, did you go with longer pushrods, or no? Did you bore out the pushrod holes, or not?

I'll get the tool to check rocker geometry, but I want to be very confident that I'm not going to have to bore out the pushrod holes to put on the Scorpion 1.6s on . . . as confident as I can be without actually installing them. If there's doubt I'll just do the 1.5s.

Thanks to everyone for all their input.

 

[Hipster]

Heads can have core shift from the manufacturing process and then there can be machining tolerances or stack-up so what works for one person heads may not work for another. Rocker manufactures shorten the pushrod cup to fulcrum side to achieve the increased ratio so .100 pushrods and another set of rockers might end up right where you started.

You didn't give all the particulars but if this is a stock L31 longblock the retainer to guide clearance should have been checked when the springs were changed?

 

[m002922]

Hipster. Yeah, you have a good point. Probably safer just not to gamble with it and go with 1.5s.

I'm just kind of ticked about the whole thing because somehow I missed that going from 1.5s to 1.6s would even raise the slightest of issues (I had only done this on sb fords before, and if memory serves no one gave this a thought on fords) . . . when I bought the 1.6s there was nothing from Summit about longer pushrods or possible contact (whereas there were lots of warnings about the Vortec's rather weak valve springs . . . which strikes me as a less serious issue - I digress) . . . and then the salesperson was like "well of course you should have thought about longer pushrods and a louis tool . . . ." OK.

Also, sorry, but I'm not sure what you're asking with this sentence:

"You didn't give all the particulars but if this is a stock L31 longblock the retainer to guide clearance should have been checked when the springs were changed?"

It is a stock longblock except for stiffer valve springs which were installed in the head, and the HT383 cam. Are you talking about retainer to valve guide clearance?

 

[slowburb]

I did nothing to allow the Scorpion 1.6's to fit. Factory pushrods dropped right in.

 

[Hipster]

Hipster. Yeah, you have a good point. Probably safer just not to gamble with it and go with 1.5s.

I'm just kind of ticked about the whole thing because somehow I missed that going from 1.5s to 1.6s would even raise the slightest of issues (I had only done this on sb fords before, and if memory serves no one gave this a thought on fords) . . . when I bought the 1.6s there was nothing from Summit about longer pushrods or possible contact (whereas there were lots of warnings about the Vortec's rather weak valve springs . . . which strikes me as a less serious issue - I digress) . . . and then the salesperson was like "well of course you should have thought about longer pushrods and a louis tool . . . ." OK.

Also, sorry, but I'm not sure what you're asking with this sentence:

"You didn't give all the particulars but if this is a stock L31 longblock the retainer to guide clearance should have been checked when the springs were changed?"

It is a stock longblock except for stiffer valve springs which were installed in the head, and the HT383 cam. Are you talking about retainer to valve guide clearance?

I didn't see where you stepped up from the stock cam so you're probably pretty safe but anytime you alter the lift you should check for retainer to guide clearance and coil bind.
I have had stock Vortec heads in my hands that run out of room @ .450 lift. Some have more room some don't. Bolting on 1.6's and slamming the retainers into the guides can get really ugly. The clearance between the bottom of the retainer and the top of the guide accounting for the thickness of the valve stem seal +.050 inch or more is what you need to avoid damage or cutting the seal. if there is not enough room the best case is you destroy the seals. Worst case you bend pushrods, destroy lifters, camshafts, and maybe break a few rockers sending metal throughout the engine requiring a tear down.

 

[L31MaxExpress]

I didn't see where you stepped up from the stock cam so you're probably pretty safe but anytime you alter the lift you should check for retainer to guide clearance and coil bind.
I have had stock Vortec heads in my hands that run out of room @ .450 lift. Some have more room some don't. Bolting on 1.6's and slamming the retainers into the guides can get really ugly. The clearance between the bottom of the retainer and the top of the guide accounting for the thickness of the valve stem seal +.050 inch or more is what you need to avoid damage or cutting the seal. if there is not enough room the best case is you destroy the seals. Worst case you bend pushrods, destroy lifters, camshafts, and maybe break a few rockers sending metal throughout the engine requiring a tear down.

I have had several sets of stock vortecs that had more than 0.510" clerance. GM had 1.6s on the older Ramjet engines. .461/.481" lift on stock vortecs with stock production vortec springs, retainers, seals, etc.

 

[Hipster]

I have had several sets of stock vortecs that had more than 0.510" clerance. GM had 1.6s on the older Ramjet engines. .461/.481" lift on stock vortecs with stock production vortec springs, retainers, seals, etc.

I've never had a bone stock set in my hands that's had .510 + clearance for the seal, plus a safety margin. You can get there with certain spring kits. I've seen .470-.480 a few times with bone stock stuff but never those kind of numbers.

GMPP Vortecs are clearanced.

Are you suggesting someone throws in a .510 lift cam without checking and possibly destroy their engine?

I've seen them as low as .450 and that's enough for me to check every set. Don't take my word for it. Do some research. The clearance issues with stock Vortecs are well documented.

 

[L31MaxExpress]

I've never had a bone stock set in my hands that's had .510 + clearance for the seal, plus a safety margin. You can get there with certain spring kits. I've seen .470-.480 a few times with bone stock stuff but never those kind of numbers.

GMPP Vortecs are clearanced.

Are you suggesting someone throws in a .510 lift cam without checking and possibly destroy their engine?

I've seen them as low as .450 and that's enough for me to check every set. Don't take my word for it. Do some research. The clearance issues with stock Vortecs are well documented.

I never suggested that. I have checked probably 15 sets myself. Never run across a set that would take less than a .480" lift with a 0.030" margin to spare.

As for the GMPP heads. They are not clearanced. I have personally pulled a part a Ramjet with the 1.6 rockers. It had production GM Vortecs on it.

 

[L31MaxExpress]

Also forgot to mention. The 0.510" number I mentioned is with the seals fully seated. Will not hurt a thing having them fully seated either. I know of another guy that found the same thing. Then added beehives, retainers and locks and got to 0.600" clearance.

You must be registered for see images attach

You must be registered for see images attach