Building a 350 Vortec motor

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

You have alum heads????? What grind is the cam aka a 268?

No. Cast iron 906 vortecs. Cam is the 264 marine extreme from Comp Cams. I can't tell if i need a bronze distributor gear with it. The gear on the cam looks cast, not steel. I'm going to call Comp Cams tomorrow to be sure.

 

[pennyduke]

Re: Building a 350 Vortec motor

Did you replace your push in studs on your heads? I see alot of posts saying to replace them. Very confusing subject...

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

Did you replace your push in studs on your heads? I see alot of posts saying to replace them. Very confusing subject...

No, i left the studs alone. I'm not going high enough in hp i dont think to worry about it.

 

[joewithaboat]

Re: Building a 350 Vortec motor

No, i left the studs alone. I'm not going high enough in hp i dont think to worry about it.

The hp is not what makes them pull, it is the open spring pressure and constant high rpm. Id call comp cams and ask them what your open pressure will be. Give them your spring part number, your installed height and your cam grind. I bet they are borderline.

If we start a pool my money is on them pulling out. Sorry to be a kill joy.

 

[Tail_Gunner]

Re: Building a 350 Vortec motor

The hp is not what makes them pull, it is the open spring pressure and constant high rpm. Id call comp cams and ask them what your open pressure will be. Give them your spring part number, your installed height and your cam grind. I bet they are borderline.

If we start a pool my money is on them pulling out. Sorry to be a kill joy.

Agreed XM lobes are very agressive along with a heavy duty cycle motor...ls6 spring's and a cam that will reach .500 lift your asking for trouble not doing the apr studs...


http://www.youtube.com/watch?v=3isVcqtCn6E

 

[Scott Danforth]

Re: Building a 350 Vortec motor

the studs are $45 and the local machine shop will charge less than $100 to install them. I recommend going with the screw in studs.

 

[pennyduke]

Re: Building a 350 Vortec motor

Summit recomended the Mr Gasket straight studs for my build with the same Cam you are using and Vortec heads. The heads only need to be taped and threaded. Here is the link.

http://www.summitracing.com/parts/MRG-1076/

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

Well that sucks. Especially since the motor is almost all back together...

 

[pennyduke]

Re: Building a 350 Vortec motor

I did read somewhere that if the heads were hot tanked, The studs have a better chance of pulling out. I'm no expert, But you have to make the call on that one. If it were me and the motor was together, I would replace them just to protect my investment. I really dont know what would happen if they do pull out, but gaskets are way cheeper that bent valves of busted pistons. Just me 2 cents...

 

[Tail_Gunner]

Re: Building a 350 Vortec motor

Well that sucks. Especially since the motor is almost all back together...

http://www.youtube.com/watch?v=3isVcqtCn6E

Watch how easy they pull

 

[Tail_Gunner]

Re: Building a 350 Vortec motor

Summit recomended the Mr Gasket straight studs for my build with the same Cam you are using and Vortec heads. The heads only need to be taped and threaded. Here is the link.

http://www.summitracing.com/parts/MRG-1076/

A word of caution...This a very spefic modification with very spefic parts. Do not assume buying a look alike will get you into the needed tolerance range. Even after proven part numbers are used there can still be toruble. Now if you have miced them out and they are in spec go get it.

 

[pennyduke]

Re: Building a 350 Vortec motor

Tail_Gunner, Are you saying that these parts recomended to me by Summit may not be to spec's. I just took them to my machine shop and they are installing them today. I'm sure they will check everything before installing them. What exactly could be wrong with a set of 350 rocker stud? I'm not doubting you, I just want to gain more knowledge about what I'm doing.

 

[Tail_Gunner]

Re: Building a 350 Vortec motor

I should have said hi first me bad....:redface: Pennyduke you should start a new thread everyone benefits and less confusion

http://www.chevyhiperformance.com/techarticles/148_0208_vortec_heads_valve_lift/index.html

Once the heads are machined and the new springs are in place, it's a good idea to replace the weak press-fit rocker studs with screw-in types. Be careful--the type of studs or rocker arms you choose will determine whether or not guideplates are needed. The GMPP screw-in studs don't require guideplates when used with rail-type rockers. ARP screw-in studs require guideplates. To prevent binding, do not use rail-type rockers with guideplates. It's also wise to enlarge the pushrod holes to a 1/2-inch diameter for increased clearance. This is required when using 1.6 rocker arms to prevent scuffing the pushrods against the pushrod hole in the head.

Read more: http://www.chevyhiperformance.com/t...tec_heads_valve_lift/index.html#ixzz1vp2HbyTq

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

It's done. Here are a couple of videos of its initial startup...

http://www.youtube.com/watch?v=2uxm8Zc0Eg4

http://www.youtube.com/watch?v=dzLHitiemQk

Setting timing on Saturday and adjusting the carb a little followed by a sea trial. If all goes well, me and the family will be out on it Sunday. If not, I guess i'll get towed back to the dock somehow...

 

[greg82255]

Re: Building a 350 Vortec motor

Looks great! Good work - I hope anyone on this site who wants to build a new motor can learn from both of our threads.

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

Thanks! I am however just a tad bit worried that i didnt use screw in studs. I've been give opinions going both ways (they'll be fine vs. get screw ins)... Talked to the head shop and got a "they'll be fine"... I guess we'll see what happens this season. Praying nothing goes wrong.

 

[joewithaboat]

Re: Building a 350 Vortec motor

Thanks! I am however just a tad bit worried that i didnt use screw in studs. I've been give opinions going both ways (they'll be fine vs. get screw ins)... Talked to the head shop and got a "they'll be fine"... I guess we'll see what happens this season. Praying nothing goes wrong.

I have had a small block engine that i built as a young poor teenager years ago. It had a reasonable big (biggest RV) split duration flat tappet cam. It had around 120lbs of seat pressure, cant remember the open pressure. It didn't take but a few hard cruises around the block to pull the studs. It was a manual trans car and pulled to about 6,500 rpm. Lucky for me about half just pulled a little and the valves started clattering.

A few years later, while in College and working in a machine shop, i saw more than one catastrophic failure. The stud(s) pulled half way out under WOT the rocker banged a retainer, popped a keeper, dropped a valve, ate a piston, scored the block....

If I were in your position, Id make a few passes at progressively higher RPM's, then idle back down a listen for clattering valves.
I'll be pulling for you, Hope I'm wrong about you needing them.

Sounds good in the vid, Keep us posted.

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

Will do... I believe that was the plan Sunday anyway. My family will be on board and i'm sure my wife, 4yr old, and 20 month old don't really want me testing out WOT with them in it anyways....

As for timing adjustments, we're going out with a mechanic friend of mine and his family. He recommended setting my timing while underway to make sure everything is right at higher throttle points. Does this sound correct?

 

[Tail_Gunner]

Re: Building a 350 Vortec motor

What type of ingtion system...

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

Thunderbolt IV.
We went out today and ran it a good bit. Got the timing set, carb adjusted, etc. Made a couple of hot runs. Hit 57-58 on the speedo @ 4800 rpm (with a little to spare) using my new Michigan Wheel 21P Rapture. It ran well all day. Here's a vid of us coming back to the dock after hanging out...

http://www.youtube.com/watch?v=Hd4VK09FPYo