Help with 383 Build

[pennyduke]

Re: Help with 383 Build

The heads are stock 1996 5.7L Vortec heads from my Suburban's blown motor. They were Cleaned and tested, Had a 3 angle valve job, replaced the push in studs with new screw in studs (1076 Mr Gasket) , New upgraded springs (GM Performance 12499224), New Retainers (COMP Cams 787-16), New Valve Locks (COMP Cams 648-16), and new oil seals. The heads were not machined for valve lift or shaved. The machine shop did say they checked the heads for flatness and did a very slight mill for cleaning the gasket surface only.

Head part links: http://www.summitracing.com/parts/MRG-1076/ Studs
http://www.summitracing.com/parts/NAL-12499224/ Springs
http://www.summitracing.com/parts/CCA-787-16/ Retainers
http://www.summitracing.com/parts/CCA-648-16/ Keepers

Now for the block. I tried to reuse the 1996 roller vortec block but the main bearing was spun too bad. I bought a 1994 5.7L block from a friend for $100. The machine shop cleaned it, pressure tested it, and measured it and found it to be a good block. I dont think the block is a roller. I really don't know how to tell. Is this something the machine shop can tell me? We were trying to get the bottom end done before we got into the roller cam part.

 

[John_S]

Re: Help with 383 Build

Now for the block. I tried to reuse the 1996 roller vortec block but the main bearing was spun too bad. I bought a 1994 5.7L block from a friend for $100. The machine shop cleaned it, pressure tested it, and measured it and found it to be a good block. I dont think the block is a roller. I really don't know how to tell. Is this something the machine shop can tell me? We were trying to get the bottom end done before we got into the roller cam part.

A '94 block would be roller capable (since '87). It would have drilled and taped holes in the lifter valley for spider retainer. It would also have two taped holes for the cam retainer at the cam gear location.

 

[pennyduke]

Re: Help with 383 Build

John_S, I like what you are saying about the whole Perfect Quench thing. Everything I've been reading in other threads stress the 0.042 and the zero deck. I will have the machine shop check the deck when the kit gets here and go from there. I would like to hear from others on the subject of Quench related to my big boat. I know it will be much easier to get to 9:1 without worrying about the perfect quench.

 

[greg82255]

Re: Help with 383 Build

PM Sent.

 

[wca_tim]

Re: Help with 383 Build

talk to your machinist. It's likely that you could experience more detonation problems with a 9.5 compression ration and a poor quench than you would with a 10:1 and a tight quench. Dialing the timing back just a little bit would have the same kind of impact on performance and be something you could reverse when you wanted to... Just some things to think about... have fun with it

Regarding roller vs non roller cam. What kind of lifters do you have, etc... again, I would ask your machinist about this too.

Something else to consider, is that a well designed engine build with matching components, will get better fuel economy and run better throughout the rpm rangethan a lower performance engine. case in point, my daily driver is a corvette. It gets significantly better fuel mileage than the Honda crv I sold a few years ago. both in town and on the highway (ie.22 ish and 30+ on the highway). IF I keep my foot out of it.

Not saying you're on the wrong path - I like the way you're going about this. Sounds like most of your plan will work well together. Your intake, heads and the 260's duration comp xm cam will work very well together.

 

[John_S]

Re: Help with 383 Build

John_S, I like what you are saying about the whole Perfect Quench thing. Everything I've been reading in other threads stress the 0.042 and the zero deck. I will have the machine shop check the deck when the kit gets here and go from there. I would like to hear from others on the subject of Quench related to my big boat. I know it will be much easier to get to 9:1 without worrying about the perfect quench.

When you talk to your machinist, whom you think does not have allot of boat engine building experience, make sure that he understands that your heavy cruiser is the equivelent of an extreme duty towing application, not a performance car. Do some research on compression ratios for that application, also use a calculator to see what the HP diff between 9.5 - 10:1 is worth it over 9:1. Figure the fuel cost differences from your yearly bills, see if it is worth it. I would not count on any fuel mileage improvement from the higher compression engine.

Vortec heads in themselves, made good strides in avoiding detonation, over standard heads, even with ideal quench. I have yet to see any dyno results with vortec heads and only a quench change, to see what the improvement is, and at what rpm band. If someone has a link to such info, please post.

For your cam choice, you do not want to move the powerband above 5K rpms. You need the power to plane the cruiser. Given the alpha, you still got to go into the throttle gradually. In a heavy boat, the alpha is more at risk with a high torque 383 than on a lighter boat. You are typically running larger diameter and more surface area props to get the barge out of the water, which are not conducive to high wot speed, anyway.

 

[Tail_Gunner]

Re: Help with 383 Build

 

[pennyduke]

Re: Help with 383 Build

I just found out that the block is not Roller Block. The casting number is 10054727. It looks like it's a 1988 Silverado truck Block, 2 bolt main, 1 piece rear main seal. There is another number K0424USA. The machine shop looked at it today and said it's not a roller. I plan on using a roller cam, and a roller lifter package with push rods and 1.5 roller rockers. Also he says that if I do the Piston switch to -23.00cc he would have to weigh each piston to match the kit. he says he can reduce the weights of the new pistons but it would be harder to add weight to the new pistons. Something about adding lead to the wrist pins. I'm really getting lost now. lol

 

[Tail_Gunner]

Re: Help with 383 Build

I have an xm-270-H12 grind comp in a 383 and although I kind of wish I had been more aggressive, it has great manners and would be perfect for most folks purposes... it would likely be really close on reversion with stock manifolds, the next one down in duration (specific cam depending on whether using hydraulic roller or flat tappet) would be fine with stock exhaust and would still make a good bit more power than the other cams being considered. If you wanted to use aftermarket risers or manifolds / risers or even add extensions to your risers to put the water a bit further back and allow you to run the 270 for a nice step up in power. (reversion is where the overlap between intake and exhaust valves being open creates a little suction in the exhaust and draws water back into the engine - not good).

running the -18 cc pistons, you MAY have to run premium gas or retard your timing a little bit for cheap gas to avoid any detonation, but it should be no problem at all running premium. With that kit, your heads, an xm-270 or similar cam, ideally with 1.6 ratio rocker arms, edelbrock airgap rpm and an edelbrock or holley 750 cfm marine carb, you should wind up with 375-400 horsepower with a peak at 5000 - 5200, have a tame enough idle around 600 rpms to keep from trashing your drive and an all around great running package. It's a tried and true combination of parts...

look up posts by mkos1980 on vortec heads and related builds too, good information and a sharp guy from what I can tell.

If you decide to have a custom ground cam ground, word on the street is and has been for years - Bob Madera at Marine Kinetics is "the man". Period.

http://www.marinekineticsonline.com/index.html

Cheers!

Agreed the 270 is a great cam..Even in a v6 there is no sudden power pulse or reversion. I cannot say that would be true for every application but its a far better cam than the stock cam..and most of the new power comes 3500 and runs out at about 5500 in my case...After installing this cam i monitored its performance carefully..The boat doesnt even move well under power until 12-1500 and most of planing is at 3500. If were going to do water sports its always has been a prop change..The only thing that stands out is the midrange punch and maybe 5 mph on the top end.

 

[Tail_Gunner]

Re: Help with 383 Build

I dont know how far you are in with that block...But stroking a 350 and using it in a boat...with a two bolt main. Now your stressed in engine and drive. You may inquire about splaying the caps..That would balance things up a bit. And not at 10.1

 

[pennyduke]

Re: Help with 383 Build

That chart puts me at 210 to 220 at 5000 rpm. The cam i'm looking at is 212 to 218. Is that Chart for marine use?

 

[John_S]

Re: Help with 383 Build

I just found out that the block is not Roller Block. The casting number is 10054727. It looks like it's a 1988 Silverado truck Block, 2 bolt main, 1 piece rear main seal. There is another number K0424USA. The machine shop looked at it today and said it's not a roller. I plan on using a roller cam, and a roller lifter package with push rods and 1.5 roller rockers. Also he says that if I do the Piston switch to -23.00cc he would have to weigh each piston to match the kit. he says he can reduce the weights of the new pistons but it would be harder to add weight to the new pistons. Something about adding lead to the wrist pins. I'm really getting lost now. lol

Retrofit roller cams are fine. If the cam doesn't have a pressed on cast gear, you will need a melonized or bronze distributer gear. Assuming you are running a mech fuel pump, need a fuel pump push rod for the steel cam. And need a cam button to limit its back n forth movement in the block. I think there was a bunch of info on this in Greg's thread.

Since you are putting an older block in a newer boat, spend some time figuring out the flywheel, starter, and coupler, you going to need. There were a number of changes when this transition happened.

 

[Scott Danforth]

Re: Help with 383 Build

buy a newer block if you want a roller crank. the blocks are cheap, and if your machine shop does a lot of engines, he probably has 3 or 4 core blocks there. a retro-roller cam is about $600 more than a standard roller cam. the block will be about $150

 

[Tail_Gunner]

Re: Help with 383 Build

That chart puts me at 210 to 220 at 5000 rpm. The cam i'm looking at is 212 to 218. Is that Chart for marine use?

Makes no difference its a chart that show's how cam grind's function..Takes a lot out of old wives tale's. As you can see a lot has been plotted..Little side note your boat is not even going to begin getting ramped up until about 1500 rpm..Lots of slip going on real power in most i/o's begins at 2000 rpm. Under that your in the no wake zone.

 

[pennyduke]

Re: Help with 383 Build

buy a newer block if you want a roller crank. the blocks are cheap, and if your machine shop does a lot of engines, he probably has 3 or 4 core blocks there. a retro-roller cam is about $600 more than a standard roller cam. the block will be about $150

This is the first I've heard of a roller crank. Am I missing something?

 

[Scott Danforth]

Re: Help with 383 Build

correction, roller cam :facepalm:

 

[pennyduke]

Re: Help with 383 Build

correction, roller cam :facepalm:

Scott, Don't scare me like that. I'm confused enough. lol. With that said, I do see Marine Roller Cams for around $295 for blocks 87-96. Is this not the Cam i need? Or do I need a $600 retro fit?

 

[Scott Danforth]

Re: Help with 383 Build

Scott, Don't scare me like that. I'm confused enough. lol. With that said, I do see Marine Roller Cams for around $295 for blocks 87-96. Is this not the Cam i need? Or do I need a $600 retro fit?

you will need a $900 retrofit cam since your block is not a roller block. that would indicate you have a block for flat tappet cams. ($900 - 300 = $600 delta that I mentioned)

I just found out that the block is not Roller Block. The casting number is 10054727. It looks like it's a 1988 Silverado truck Block, 2 bolt main, 1 piece rear main seal.

 

[pennyduke]

Re: Help with 383 Build

The Machine shop did ask if I wanted to have it converted to a 4 bolt main. Everything I read on here said a 2 bolt main was fine. Does the 4 bolt really help with the balancing?

 

[Tail_Gunner]

Re: Help with 383 Build

Here comes the MARINE part..built 350 2 bolt main not my cup of tea at this point..Marine...read heavy duty cycle motor..If it were me a new block is in order,,,to much monkeying around..where's Jowie he should give you the detail's.