Building a 350 Vortec motor

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

Wow... you guys are busting my budget. I guess i should have mentioned at the start of this thread i have a $1500 budget. Thats why i went with the motor i went with so i wouldn't have to do a helluvalot of changes to make it what i want. HAHAAA.....

 

[billbayliner]

Re: Building a 350 Vortec motor

Ayuh,.... Accordin' to Dennis Moore, 'n everything else I've read,...

It should be between 109? 'n 112? LSA...

If you've read anything from Dennis on the SBC Marine build, you'll know that using the GM type full dished pistons is the wrong way to go.
Your local library can bring in Dennis Moore's Small Block Chevy Marine Performance book for you.
Read what Dennis has to say about pistons and his suggestion for building a quench or squish into your build for marine use. Other than your mentioned mods, you won't need to change any other part of your build.
There's lots of information out there on the quench build that lets you take better advantage of the Vortec chambers.

 

[Bondo]

Re: Building a 350 Vortec motor

Wow... you guys are busting my budget. I guess i should have mentioned at the start of this thread i have a $1500 budget. Thats why i went with the motor i went with so i wouldn't have to do a helluvalot of changes to make it what i want. HAHAAA.....

Ayuh,... My only Point is,... A motor is a package of parts that have to work Together....

Pump up 1 side, 'n it'll fall flat, on the other side....

If ya don't look to the Total Package, yer wastin' money...

'n,... I agree Bill,... D-dish pistons are the Only way to take Full advantage of Vortec heads....

 

[FreeBeeTony]

Re: Building a 350 Vortec motor

Wish I knew about the D-dish pistons when I had my set-up being built.

How much is gained/lost by using/not using them?

 

[Tail_Gunner]

Re: Building a 350 Vortec motor

http://forum.grumpysperformance.com/viewtopic.php?f=53&t=726

have a read all you ever wanted to know and maybe something you did not..

 

[Tail_Gunner]

Re: Building a 350 Vortec motor

Ayuh,.... Accordin' to Dennis Moore, 'n everything else I've read,...

It should be between 109? 'n 112? LSA...

There is much more on this subject that never is discussed...Different bore and stroke along with timing events require differnt angles...Lot of people my self included believed longer lsa reduced reversion that is incorrect

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=4065

I'm no expert, but my understanding has always been that a tighter LSA, also increases overlap which bleed cyl. pressure. This is not ideal for a street car as it would need more compression to compsensate for the cyl. bleed down caused by the cams tight LSA? The more compression you need the less streetable the car becomes. Also my understanding is the tighter the LSA, the more RPM's you need to turn to take advantage of it, hence normally tight LSA's are in race cars? This is a basic explanation, but I am trying to keep the cause and effect simple.

Phil



THATS PROBABLY one of the MOST COMMON MYTHS
(that overlap with a tight LSA bleeds off compression)

"EXAMPLE, OF A
very common mis- conception, is that a cam which is ground on a 108 degree lobe center. which has more overlap and will reduce your DCR due to greater overlap."

PROBABLY one of the MOST COMMON MYTHS
( is that overlap with a tight LSA bleeds off compression)
Overlap has nothing to due with DCR. A cam with 108 LSA will close the intake valve sooner on the compression stroke and create MORE cylinder pressure than a cam with 112 LSA. That assumes durations and cam lobe designs are the same of course "

this is correct

example
LOOK heres TWO cams IDENTICAL EXCEPT FOR THE LSA,(LOBE SEPARATION ANGLES) assuming both cams are installed with identical LCA (LOBE CENTER LINE ANGLE)remember lobe center angles can be changed thru indexing the cam when degreeing it in, LSA is ground into the cam during manufacture, the tighter LSA of the crane 110921 builds a bit more cylinder pressure and results in slightly more torque over a NARROWER rpm band so its better with a manual transmission, the crane 114681 with its wider LSA tends to work better with an auto trans with its wider torque band but very slightly lower peak torque, the crane 110921 has more overlap and better savaging in the mid rpm band, but it idles rougher at low rpms and that overlap doesn,t help if you use nitrous
COMPARE the TIMING

 

[billbayliner]

Re: Building a 350 Vortec motor

Bondo, from what I read, the D dish works well with the pre Vortec heads. There is piston with a deck that looks more like the Vortec wedge. If you look at what RM posted on ME.com in the Other Gas Inboard Mfgs section, you'll see several pictures of these. Dennis Moore also shows several piston types in his book.
Read what these guys have to say about LPCP.

I read Grumpys article some time back. RM also left a comment about grumpysperformancegarage over at ME.com.
Sounds like Grumpy is into the street version stuff, not marine. He sounds like he knows his stuff. But if you give any credit to DM or the other pros, we should not use the same exact sbc build for a marine cruiser engine.

 

[joewithaboat]

Re: Building a 350 Vortec motor

Bondo, from what I read, the D dish works well with the pre Vortec heads. There is piston with a deck that looks more like the Vortec wedge. If you look at what RM posted on ME.com in the Other Gas Inboard Mfgs section, you'll see several pictures of these. Dennis Moore also shows several piston types in his book.
Read what these guys have to say about LPCP.

I read Grumpys article some time back. RM also left a comment about grumpysperformancegarage over at ME.com.
Sounds like Grumpy is into the street version stuff, not marine. He sounds like he knows his stuff. But if you give any credit to DM or the other pros, we should not use the same exact sbc build for a marine cruiser engine.

Who is "RM".... and what is "ME.com"

 

[John_S]

Re: Building a 350 Vortec motor

Does anyone have a link to any dyno testing where the only variable changed was quench? I have read allot of articles on it, but any tests I've seen included other changes. Not quessing if it works, but trying to understand the magnitude of the benefit.

If that testing was with a sbc 350 and iron vortecs, you get extra points.

 

[greg82255]

Re: Building a 350 Vortec motor

PM Sent.

 

[Bondo]

Re: Building a 350 Vortec motor

Who is "RM".... and what is "ME.com"

Ayuh,... RM = Ricardo, a guy from over Northwest way,... Know 'im pretty good...

ME is Marine engines...

Rick, 'n I have discussed this, at length over there,...
Rick's got a bunch of pictures, 'n some graphics on the topic of SBCs...

Bill,.... The Quench helps alot with the old style heads, but is the Key to Vortecs...
Ya can flirt with 10:1, with alot less threat of Detonation...

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

THis all started with me deciding to put a vortec in th boat instead of rebuilding the original 5.7. I found a 1996 vortec from a police cruiser that was pulled for a bad lifter (warranty issue) back in 1997. I have the paperwork from the dealer who pulled the motor...

It had a whopping 3500 miles on it so it was barely broken in. I decided to tear it down to verify condition and replace what needed replacing. The block had no signs of wear but i had it cleaned and checked anyway. Pistons, rings, rods, bearings, crank are all good and are being re-used. I am on a really tight budget for this so.... don't hate.

I needed a cam and intake so i've now ordered the comp cams marine extreme 270 and appropriate springs for it, an Edelbrock Performar intake, and various other parts.

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

So far, the block has been cleaned, new rear seals installed, pistone, rings, crank, etc. are back in, added a high volume oil pump.
Purchased a true double roller timing set, new timing cover, all new gaskets, new circulating pump. I'll be using the oil pan from my old motor for added volume, and the stock Weber marine carb from my old motor (600 cfm)...

The heads are at the machine shop waiting on me to get them the springs so they can be finished and the 202 valves were left out as previously mentioned in this thread.

Overall, i only have a little over a grand i can spend so that's why i've chosen the route i've chosen.

Thanks for all your comments/concerns/recommendations but i figure i'd better let ya'll know the whole story instead of getting into an extensive motor build.

Thanks again.

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

I'll be using a manual fuel pump because the block allows for it and i don't have the funds to switch to fuel injection, and i've read in other threads recommended to me here that i may need a fuel pump rod with a brass end... Why?
I've also read a recommendation to change the distributor gear to brass... again, Why?

 

[John_S]

Re: Building a 350 Vortec motor

I'll be using a manual fuel pump because the block allows for it and i don't have the funds to switch to fuel injection, and i've read in other threads recommended to me here that i may need a fuel pump rod with a brass end... Why?
I've also read a recommendation to change the distributor gear to brass... again, Why?

Because you are using a steel roller cam. You do need a melonized distributer gear, unless the aftermarket cam has a cast gear ring pressed on. Not sure if the distributer gear is compatable from the police engine, to your marine distributer. Need a fuel pump push rod for steel cams. Check cam to make sure it has the lobe. I am pretty sure it does, but a few have eliminated it.

Given the stock engine, performer intake, would have gone with slightly less cam, ie a more balanced pkg. Remember to have the head shop work them for the lift. If you don't, you will probably end up with crushed oil seals, bent push rods, or broken rockers, or worse. You can probably forgo the roller rockers, but screw-in studs, given the heavier springs, might be worth it.

Probably want a tune kit for the carb. Your fuel lines from the original boat motor should fit with just some slight bending. Check the water circ pump. The vortec engines use the composite cover, and the circ pump needed to have some additional clearance. Some of the brackets mounted to intake will need slight mods, bending, etc. Check your accesory braketry fit. Should be OK. I didn't have any issues, but I have the latter serpentine belt config.

 

[Maddoxsdaddy]

Re: Building a 350 Vortec motor

One of the first things i did was compare the 2 blocks. From what i can see, they are the same block. They have the same numbers stamped on them and a big fat 808 stamped on the side. Hopefully i won't need to bend anything. I was planning on using the distributor from my old motor since it is marine vs. non-marine. All of the mounting holes for the accessory mounting brackets are identical. Yet another reasin for me doing things this way... an easy transistion (hopefully).

 

[joewithaboat]

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.

 

[joewithaboat]

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.

 

[John_S]

Re: Building a 350 Vortec motor

One of the first things i did was compare the 2 blocks. From what i can see, they are the same block. They have the same numbers stamped on them and a big fat 808 stamped on the side. Hopefully i won't need to bend anything. I was planning on using the distributor from my old motor since it is marine vs. non-marine. All of the mounting holes for the accessory mounting brackets are identical. Yet another reasin for me doing things this way... an easy transistion (hopefully).

If your original boat motor had a roller cam, then the distributer gear is fine. If not, it might be a melonized, but not sure how to tell visualy. Maybe a part number stamped on it.

The bracketry check is for the change in heads and intake. The intake mounting bolts on vortecs are smaller, and more verticle. Usually this is minor stuff, like relocate coil, etc. Just giving you a heads up so you can check it ahead of time.

 

[billbayliner]

Re: Building a 350 Vortec motor

Ayuh,... RM = Ricardo, a guy from over Northwest way,... Know 'im pretty good...
ME is Marine engines...

Rick, 'n I have discussed this, at length over there,...
Rick's got a bunch of pictures, 'n some graphics on the topic of SBCs...

Bill,.... The Quench helps alot with the old style heads, but is the Key to Vortecs...
Ya can flirt with 10:1, with alot less threat of Detonation...

Bondo, that is who I was talking about. I'm not a member there but know Rick from another forum. He and I talk once in a while if I have a V/P question.

Maddoxsdaddy, you're only a few hundred bucks away from LCQ style pistons. Might not be quite as important for a 21 footer, but it does make a difference in low end torque and defense against detonation. You might want to read some of the stuff on this.

Check with the high performance SBC people regarding the distributor gear. The cam gear is an integral part of the camshaft so there is no changing that.

John makes a good point about the fuel pump cam. Make sure that the camshaft has this fuel pump cam on it.

Ditto Joe on the valve lift and also if you were to change the rocker arm ratio.
The roller tip rockers are also a good idea to reduce the push-pull action against the guides and stems.

Some say to not go too crazy on valve spring pressure for the lower rpm marine motors.