Building a 350 Vortec motor

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

Pay attention to Johns Advice on the Head modifications for the increased cam lift... Cut the tops of the guides, install screw in studs, maybe guide-plates and drill the push-rod tubes for clearance. Add a set of roller rockers and you are off and running. You should have around 330hp and over 400 ft lbs of torque.

If you switch to guide-plates you need new hardened push-rods. If you don't use guide-plates you need the proper self aligning rocker arms. if you are really trying to not spend money you can use stock type rockers.

Also you might need to clearance the block a little to use the double roller timing chain, they hit on the backside of the top gear.

I will double check all of that. thanks! I'm using NAPA's machine shop. They've done really good work for some friends so i trust what they're doing.

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

As far as staying cheap, you lucked out on the block as concerns the fuel pump. Most late roller blocks are not drilled for the fuel pump rod.

This block (by checking numbers) is virtually the same block as my old motor except for the holes drilled in the heads for the intake. They are the vertical style. I also lucked out with the block having a cover plate where the electric fuel pump was mounted. Pulled of the cover plate and it is drilled for the pump rod.

 

[Scott Danforth]

Re: Building a 350 Vortec motor

my recommendation is the self aligning rockers vs guide plates and expensive pushrods, however that is my personal opinion.

 

[joewithaboat]

Re: Building a 350 Vortec motor

Hey, Im not in any way being critical, just asking,...to the folks constantly talking about the importance of a d-shaped dish for use with the vortec head. Where are you getting that it is so vital. I'm not saying it wont help and i understand quench, swirl, flame travel, deck height etc but are you making reference to it because someone did some testing that shows it is more important on vortec heads than any other head. I would think because the vortec has a better placed spark plug that it would be less important than other small block chevy heads.

Thanks, Joe

 

[Bondo]

Re: Building a 350 Vortec motor

I would think because the vortec has a better placed spark plug that it would be less important than other small block chevy heads.

Ayuh,... You can run higher compression ratios with proper quench, Without the threat of Detonation....

Full dish pistons, Don't take the vortec design to where it Should be...

 

[billbayliner]

Re: Building a 350 Vortec motor

Hey, Im not in any way being critical, just asking,...to the folks constantly talking about the importance of a d-shaped dish for use with the vortec head. Where are you getting that it is so vital. I'm not saying it wont help and i understand quench, swirl, flame travel, deck height etc but are you making reference to it because someone did some testing that shows it is more important on vortec heads than any other head. I would think because the vortec has a better placed spark plug that it would be less important than other small block chevy heads.

Thanks, Joe

Joe, the quench is a benefit for all SBC cylinder heads, not just the Vortec heads.
All SBC heads have the wedge area off to the side of the combustion chamber. Same with Chrysler's wedge head motors.
The full dished piston doesn't have enough flat surface to come up under the wedge area and is a recipe for detonation.

The D dished is better suited for the early heads and some say that the Low Compression Quench or Reverse Dome pistons mirror the Vortec wedge better. Since GM continues to use the full dished pistons, it's hard to break old habits I suppose.
The automotive machine shop guys don't quite understand marine engine loads, unless they specialize in building sbc marine cruiser engines.
Most all of the quench effect testing that you might read about is done for track and street use. Those engines don't see marine loads, so the results might not be as impressive. The marine tests are fewer and further between.

Dennis Moore talks about the full dished pistons and detonation, then goes on about the quench style in his SBC Marine Performance book. I think it's Jeff Smith who talks about LPCP and how the quench helps with low end torque.

Quench piston C/R calcs were just done in a thread over at ME.com Volvo Penta forum using Sick's C/R calculator and United Engine and Machine C/R calculator. You can read there without being a member. Bondo posted in that thread.
There's quite a bit about this on the Bayliner Tech forum, but you have to be a member to read certain forums there.

 

[joewithaboat]

Re: Building a 350 Vortec motor

Ayuh,... You can run higher compression ratios with proper quench, Without the threat of Detonation....

Full dish pistons, Don't take the vortec design to where it Should be...

Joe, the quench is a benefit for all SBC cylinder heads, not just the Vortec heads.
All SBC heads have the wedge area off to the side of the combustion chamber. Same with Chrysler's wedge head motors.
The full dished piston doesn't have enough flat surface to come up under the wedge area and is a recipe for detonation.

The D dished is better suited for the early heads and some say that the Low Compression Quench or Reverse Dome pistons mirror the Vortec wedge better. Since GM continues to use the full dished pistons, it's hard to break old habits I suppose.
The automotive machine shop guys don't quite understand marine engine loads, unless they specialize in building sbc marine cruiser engines.
Most all of the quench effect testing that you might read about is done for track and street use. Those engines don't see marine loads, so the results might not be as impressive. The marine tests are fewer and further between.

Dennis Moore talks about the full dished pistons and detonation, then goes on about the quench style in his SBC Marine Performance book. I think it's Jeff Smith who talks about LPCP and how the quench helps with low end torque.

Quench piston C/R calcs were just done in a thread over at ME.com Volvo Penta forum using Sick's C/R calculator and United Engine and Machine C/R calculator. You can read there without being a member. Bondo posted in that thread.
There's quite a bit about this on the Bayliner Tech forum, but you have to be a member to read certain forums there.

Thanks guys,
Like i was saying i get all of the basic principals of quench, flame travel,... detonation and pre ignition sensitivity. I worked for a couple years in a very good performance/competition machine shop. We worked on some pretty cool stuff.

Ive flipped through D.M. book a few times (I don't own a copy).

From the way some folks were always saying "make sure you use a d-dish with vortec" I just thought maybe someone had done a series of back to back dyno tests where vortec heads showed some super sensitivity to these basic engine building principals.

Thanks, Joe

 

[billbayliner]

Re: Building a 350 Vortec motor

Joe, I think what you're hearing is how much better the Vortec heads perform if a quench is added, whether a D dish, LCQ or Rev Dome.

Something that I forgot to post.
The original SBC 265, 283, 327 and I think the first 350's, all used a flat top quench piston. Many were single valve reliefs also.
They also used cylinder heads had the wedge area as they do today.
Eventually the intake runners became larger and the combustion chambers became smaller. There are many other small changes, but basically the design is similar today.

It wasn't until the 70's when GM was forced to reduce auto emissions. To comply to emission standards, they did so by using the full dished piston and it worked well for automotive daily drivers.
The full dished piston is cheap to manufacture, and when they have double valve reliefs, one p/n does all 8 cylinders. When you go to a quench piston, you now need two p/n's.

btw, Dennis Moore refers to the full dished pistons as smog control pistons that should never be used in a Marine engine. Lots of the hot rod guys agree.

 

[joewithaboat]

Re: Building a 350 Vortec motor

Joe, I think what you're hearing is how much better the Vortec heads perform if a quench is added, whether a D dish, LCQ or Rev Dome.

Something that I forgot to post.
The original SBC 265, 283, 327 and I think the first 350's, all used a flat top quench piston. Many were single valve reliefs also.
They also used cylinder heads had the wedge area as they do today.
Eventually the intake runners became larger and the combustion chambers became smaller. There are many other small changes, but basically the design is similar today.

It wasn't until the 70's when GM was forced to reduce auto emissions. To comply to emission standards, they did so by using the full dished piston and it worked well for automotive daily drivers.
The full dished piston is cheap to manufacture, and when they have double valve reliefs, one p/n does all 8 cylinders. When you go to a quench piston, you now need two p/n's.

btw, Dennis Moore refers to the full dished pistons as smog control pistons that should never be used in a Marine engine. Lots of the hot rod guys agree.

Thanks Bill,
At one time I was into cars/engines 24/7. I was moving on to other things about the time the vortec casting was gaining its fame.
My favorite casting to hunt was the "041". It was the best combination of qualities... port, chamber, bowls, short-side radius, deck thickness, etc. Today aluminum heads have gotten so reasonable i would never spend that kind of time/money on cast iron other than to use a mostly stock vortec head.

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

Well, the cam and intake came in this past Friday. Problem is, i didn't read the fine print well enough so the cam has to go back. It is not designed to work with an LT1 block and that is what i have. So, the wait continues.

 

[joewithaboat]

Re: Building a 350 Vortec motor

Well, the cam and intake came in this past Friday. Problem is, i didn't read the fine print well enough so the cam has to go back. It is not designed to work with an LT1 block and that is what i have. So, the wait continues.

What do you mean LT1... do you mean to say that you ordered an early "12" style instead of a late "08" style that used a cam retention plate. The LT1 "07" is a completely different animal and uses a front mount distributor/ignition system.

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

What do you mean LT1... do you mean to say that you ordered an early "12" style instead of a late "08" style that used a cam retention plate. The LT1 "07" is a completely different animal and uses a front mount distributor/ignition system.

I was told my motor is an LT1 motor. The distributor is at the rear of the block. It's a 1996 motor.

 

[joewithaboat]

Re: Building a 350 Vortec motor

I was told my motor is an LT1 motor. The distributor is at the rear of the block. It's a 1996 motor.

The LT1 moniker was originally used in the 70's then again in 92-97. The later used front mount distributor/ ignition "optispark". They had gear driven water pumps.
I never owned one but everyone i know that did hated them.

They also had reverse cooling (heads first). Some components interchange, some don't.

I'm thinking you don't have this... but probably do have the late model block which used the "08" cam blank type. It has a retention plate with two bolts on the front

You can run the old style camshaft but will have to use a cam button kit to retain the cam. It would be better to return it if you can.

 

[John_S]

Re: Building a 350 Vortec motor

Well, the cam and intake came in this past Friday. Problem is, i didn't read the fine print well enough so the cam has to go back. It is not designed to work with an LT1 block and that is what i have. So, the wait continues.

A '96 LT1 would be a gen II smallblock, and not the same as the gen I in your boat. Gen II LT1's did come in '96 Caprice police cruisers. Either you just sent the right cam back for the wrong one, or you have a bigger issue of making a gen II work in a boat.

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

A '96 LT1 would be a gen II smallblock, and not the same as your gen I in your boat. Gen II LT1's did come in '96 Caprice police cruisers. Either you just sent the right cam back for the wrong one, or you have a bigger issue of making a gen II work in a boat.

I havent sent anything back yet... Waiting to decipher what i really have before doing so. The new motor has a little retention plate on the front held on by the 2 bolts described. What numbers on the block do i need to look at to determine further???

 

[John_S]

Re: Building a 350 Vortec motor

Look at this link: http://www.nookandtranny.com/Info_LT1.html

Does your timing cover look like that?

If not, that is a good thing (Not a LT1). It should have only one hole for the crankshaft. If so, post your cam part number.

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

SWEEEEET!. My timing cover looks NOTHING like that. It is abs plastic. The original had a hole for the crankshaft sensor but stamped on the inside of the cover is a part number for one without the hole. I bought a new one without the hole. The front of the oil pan mounts in a groove on my cover. So then its not an LT1???

This is a link to Summit and the cam i ordered. Under the application tab, it says not for LT1 or LT4.

http://www.summitracing.com/parts/CCA-08-416-8/

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

Also noted, my heads are cast and end in 906 (if i remember correctly, i havent seen the heads in almost 2 months)... So again, not matching LT1 head casting numbers.

 

[Scott Danforth]

Re: Building a 350 Vortec motor

did you order new lifters with your cam?

 

[John_S]

Re: Building a 350 Vortec motor

I'd say it is NOT an LT1. Might want to ask who told you it was, and why? Cam looks correct for a sbc gen I.