Thread: Changing compression ona built motor

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Hey Roger,
Yes Sir,,, I agree Tech has some very good insight and I don't mind the being direct at all,,, actually prefer getting to the nuts and bolts of things to put it simply. Read the article and found it very interesting and makes a really good case for a later model roller block. And with all that,,, it's also pushing me more toward and LS engine,,, just pondering it though at the moment. What caught me most was the end play or shift of the cam on a roller and the .005" tolerance. I'd do a carb intake and only have the ECM for ignition. I'm just not real sure I like having the coil packs hanging on the valve covers. Kind of takes away from the bling of shiny valve covers LOL. Not having to deal with the distributor next to the firewall is an advantage. There is still room to do a swap if I decide to before completing the build. One area I can't picture on doing an LS install is the accessory mounting and if the water pump would get in the way of the radiator fan which isn't mounted at the moment so I could be concerned over nothing.

I am a machinist by trade just not a automotive machinist,,, I make energy related parts which can be much more complicated. Would love to get into some engine machine work though.

Originally Posted by jerry clayton

Having a block that is set up for OEM type hyd roller lifters is a valuble part of the scheme to just sell what you have and build whats best-by the time you get different pistons/rings/pins, balalance them to crank, etc-buy heads and valve train, you can sell what you have as an assembly and build a much more street suitable set up for todays gas

So Jerry,,,, I read the article Roger linked to and am considering your suggestion. Could you recommend a year model range of good blocks to use. I'm looking online for deals but haven't some across one yet I'd consider. Of course nothing happens until I sell what I have LOL... Not a high roller over here,,, dang it,,,, Where's Jay Leno when you need him

Here's a tutorial that was written about the L31 cylinder heads, which bolt onto the L31 5700 Vortec motor that Chevy used in trucks and vans from '96 to '02. It was still the Gen I architecture, but featured a roller cam and one-piece rear seal stock from the factory. The vehicles that used it are listed in the article.
http://www.crankshaftcoalition.com/w..._cylinder_head

Gen II motors (LT1) also came with roller cams and one-piece seals, '92 to '97 I believe, with a reverse cooling system where the heads got the cool water first. Aluminum heads on F body cars. These heads will not work on Gen I motors without considerable jumping through hoops.

Gen III motors (LS1), a return to conventional cooling. Aluminum block and heads.

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Hey Tech,,, hope you get to see this post. I've sold the motor so I'm ready for that wish list to build a simple yet nice 383. I'm looking for 375 to 450 HP that will be slightly economical to operate on pump gas and not break the bank building. There are completed motors out there but I'd prefer to know what's really in it.
I'm also looking at the possibility of doing a 5.7 or 6.0 LS swap that would be carbureted instead of fuel injected. Seems the younger crowd really likes the LS and since I "MAY" sell the car sometime down the road figured it may be wise to consider the type of people who would be buying. Not too many of us really old farts left LOL. Besides,,, from all I've read and talked with others about the LS,,, the bottom end is pretty fool prof and you can get the HP I'm looking for pretty easy. I also like the no distributor thing as it will let me get the engine a little closer to the firewall.

So guy's,,, jump in with all the input you have,,, I'm all ears LOL

If your just looking to get it a little closer to the fire wall???Put a Ford in it!!!!!!!


Or consider LT1 series engine

Ha ha,,, Yea a Ford in a Ford,,, didn't I read about that someplace lol

Oh boy! I love a new engine build. I’ve been watching this thread and now feel like I can really jump in and hopefully, offer some advice that you can digest and use what you believe to be appropriate.

I’ve posted this information several times, but it’s easier to update it and share again so you don’t have to search for it. I have used variations of this combination for a lot of years. It’s proven and should net you well over 450 horsepower and 460 plus foot pounds of torque.

First and foremost – find a good machine shop where you can talk to the person who will be doing the work. The prep on your block is critical. The stroker motor can be a screamer if built correctly, but heaven help you if clearances are not correct as the whole thing will come apart and you’ll have one very expensive door stop! Make sure that the technician has built many 383 motors. I know everyone has to learn somewhere – but you don’t want it to be your engine. As an option, Summit sells a block that has been all prepped for a 383 build for $700 plus another $100 for delivery. I have never used a Summit prepped block as the supply of bone yard engines has always been pretty good wherever I have lived; however, you may want to compare and price. Ordering the block from Summit will get you a nice clean unit, but I’d still want to check everything out – your call.

That said and if you go a complete build route where you start with a used block, have the block cleaned and tested – no need to build a block that has cracks or cannot be squared. Make sure that the machine shop understands that you’ll be building a 383 stroker so you want to have the crank journals align bored. In most builds, I ask the machine shop square the block and cut it to 9.003” – this is an important measurement as detailed a bit later on.

Have the machine shop install new cam bearings and new brass freeze plugs. Also have the machinist go over the location of all the galley plugs with you so you know where they are and that they have been properly installed. When you get the block back from the machine shop make sure you really scrub that baby down with hot soapy water. I like Dawn dish washing liquid and water straight from the bottom of the water heater. Put the block on the engine stand and dry with compressed air really well. Paint the inside of the engine with Glyptal. Its $50 a quart from Eastwood – buy the brush on and a quart will do the job real nice. I buy the China bristle 2” brushes from Harbor freight by the box. They come in handy and are throw-away items. Make sure you fan the loose bristles out before starting to paint. Also paint the exterior at this time too. I use rattle can paint from VHT and have for years. Let everything dry real well – at least 48 hours.

Rotating assemblies are really your choice. I’ve used Eagle cranks and had good success – some here think they’re junk and will tell you so. If you like Scat, that’s fine too. The nice thing about a kit from a top tier company is that you can get the crank, bearings, rod, bolts (and pistons and rings) in one package that should increase the likelihood of everything fitting nicely together. Again, some will differ – but I have used the kits from Eagle, some from Scat and years ago, from PAW (their “in-house” kit) and had good luck. I still check everything with a micrometer but I’ve rarely had to return anything. I have had Summit send me replacement head bolts for free one time when I had an issue. I find if I ask nicely when I have had issues (again, very few) I usually get good support and service.

Back to build – I’ve used a -7cc flat top and with the above deck height (remember that 9.003” measurement?) and that keeps things in the 10-10.5:1 compression ratio with a .041 head gasket (see below for part number). A -12 piston will certainly lower your compression ratio into the 9’s, but IMO - this could cost you some horsepower. You will need to match final hone/size to pistons and press the pistons and rods together – it’s a bit tricky if you’ve not done it a lot and you need a press so this is another machine shop task that’s worth spending a few extra dollars for.

It is real easy to overlook the oil pan assembly. You can go stock, but need to be mindful of clearances here as well. I like the Milodon 30901 as it holds 7 quarts and fits stroker motors – might need a bit of adjustment with Eagle or Scat rods so be sure and check. Use Milodon 18750 oil pump with the 18314 pickup. Use Milodon 23050 oil pump drive shaft and 41000 one piece gasket. Milodon 81300 is an oil pan stud bolt kit – and, in my opinion, worth the $20 for ease of assembly. Many do not like the one piece gasket - especially when working on the engine in the car, but I have found them to be fine – a word of caution – do not overtighten as that’s where most of the leak problems come from. GM torques them to 12 ft/lbs at the factory. Never go more than 15 ft/lbs. I even use a ¼” torque wrench as is helps remind me to do pan bolts very gently. Timing cover is half – i.e., 6-7 ft/lbs.

Top the engine off with the components listed below:
I really do like AFR 195 heads and think they may be good for +/- 25-50 horsepower. Whatever you do, stay away from the Dart 127122 heads – they are less money but have a lot of issues.
Double roller timing set - Summit is fine
Comp Cams 7972-16 chrome moly 5/16-inch pushrods
Comp Cams Magnum Steel Roller Tip Rocker Arms 1417-16 – these are a 1.52 roller tip. Optionally the Comp Cams 1305-16 Pro Magnum Roller rockers are full roller rockers in a 1.60 ratio.
Comp Cams K08-420-8 - Comp Cams Xtreme Energy hydraulic roller - kit with lifters
Depending on the block you get, you may also need a Comp Cams 08-100 lifter install kit that has the spider, lifter guides and camshaft retainer (must have this to keep the cam in place).

There’s a couple ways to go on carburation – my all-time favorite is a combination Edelbrock Performer RPM and a 750cfm Quadrajet. The Demon 5402010 Mighty Demon 850 Carburetor (I have not yet used one, but like the looks and tech specs of the new Quick Fuel carbs, but they are expensive ($6-700) should pair well with the Performer RPM as well, but I have not personally vetted this combination.

Fel-Pro 1205 intake manifold gasket
Fel-Pro 1003 head gasket
HEI Ignition - stock Chevy is a good unit - pair with a MSD ignition (stay away from Accel anything – I’ve never had good luck with Accel and they’re no cheaper than MSD which has always been good to me.)

I’d go with 3.40 (or taller) rear end and a 2500 RPM stall converter if you’re going to run an automatic.


Good Luck,
Glenn

Glenn has put together a good combination of parts, now I'll have a go at it....

First, choose the piston compression height that you will use. 383 pistons for 6" rods can be had with compression heights from 1.125" to 1.133", so you have to coordinate the rod length with the piston compression height and crank radius to arrive at a measured stack of parts. Only then will you know what block deck height to use with what head gasket in order to set the squish/quench to somewhere between 0.035" and 0.045" (thirty five thousandths to forty five thousandths).

If I were going to build a Gen I 383 for the street today, a motor that would run on available pump gas without detonation, here's how I would do it.....

Keith Black KB122-030 pistons...(1.130" compression height)
Keith Black KB Performance Pistons KB122-030 - Free Shipping on Orders Over $99 at Summit Racing
Use 1/16" rings of your choice. Ductile iron moly ring set 4000BD8, Cast iron moly ring set 4000BM8.
You must pay particular attention to the top ring end gap with these pistons. Follow the instructions that come with them.

Scat 2-IRC-6000P 6" rods...
Scat Pro Stock I-Beam Connecting Rods 2-ICR6000P - Free Shipping on Orders Over $99 at Summit Racing
These rods are clearanced to miss the cam lobes, so you can use a standard diameter cam core.

Scat 9-350-3750-6000 3.750" cast steel crank...
Scat Series 9000 Cast Pro Comp Stroker Lightweight Crankshafts 9-350-3750-6000 - Free Shipping on Orders Over $99 at Summit Racing
This is an internally balanced rotating assembly, so budget money for final balancing with a 350 damper and 350 flexplate at the machine shop.

This will make a parts stack of 9.005", so I would cut the block decks to a new block deck height of 9.005" for a zero deck. Then I'd use a Fel-Pro 1003 head gasket that compresses to 0.041" and makes a 0.041 squish/quench with a zero-deck block. Have your machine shop index the block so that cuts are made exactly 90 degrees apart. If the block is square, then the heads will sit squarely on the block and the manifold will sit squarely on the heads and everything will seal up and be happy with each other.

I would use Pro-Filer 195cc intake runner heads, 70cc chambers for a static compression ratio of 10.1:1.
SBC 23 Degree Cylinder Heads
Under $1100 ready to bolt on...

I'd use a dual-plane, high-rise intake manifold such as the Edelbrock Performer RPM intake manifold, #7104, with a rebuilt Quadrajet carb (Cliff Ruggles is the Quadrajet guru, so try to buy one of his rebuilts if you can).
Cliffs High Performance Quadrajets :: Qjet Carburetor Rebuild Kits, Parts, Quadrajet Rebuilding, Quadrajet Parts, Bushing Kits, Carb Tuning
I would not use an Air Gap manifold due to driveability issues in colder climates. There is only a couple of hp difference between the standard RPM and the Air Gap RPM. You'd never feel the difference in hp in the seat of your pants, but you'll sure be able to tell the difference in driveability issues.

I like a Milodon 7-quart oil pan with Milodon oil pump. Position the pick-up screen 3/8" to 1/2" from the bottom of the pan. Use modeling clay on the oil pump pickup and ease the pan down to mash the clay and find the clearance. Do not use Play-Doh, it will not hold its shape. Use oil-based modeling clay from a hobby shop or craft store. If the pickup is too far from the pan bottom, you could run the motor out of oil. If the pickup is too close to the pan, the pump could pull the bottom of the pan up against the pickup and starve the motor of oil.

Howards retro-fit hydraulic roller cam and roller lifter kit CL111145-10
Howards Cams Retro-Fit Hydraulic Roller Camshaft and Lifter Kits CL111145-10 - Free Shipping on Orders Over $99 at Summit Racing
Use an 1800-2000 rpm stall speed torque converter.

1 5/8" long tube headers with an X or H pipe immediately after the collector, then pipes and mufflers of your choice (2 1/4" to 2 1/2" pipes) to the rear bumper. Terminating the pipes under the vehicle smacks of Mickey Mouse and is a pain to drive with the sheet metal reverberating.

Use a 14" x 4" air filter assembly so the motor can breathe.

I'd use a DUI distributor with Taylor wires....
Performance Distributors - Performance Distributors

Crane makes the most precise full roller rocker arms. I would not use the Comp units that use a sliding ball fulcrum.

Follow this tutorial by Scott Foxwell to get the proper pushrod geometry....
https://www.youtube.com/watch?v=o5is9BsH5OU

.

Now this is what I've been wanting to see. I've saved both lists and will got to work on obtaining prices.

Only thing I don't see is the type of block,,, meaning pre-86 or later roller block.

Thanks again guy's,,,, man ya'll gave a lot of info,,, this will tie me up for weeks ha ha ha ,,,,
HotRodN

Another question,,,,, how well do the engines built for this much HP do with long trips,,, meaning,,, are these best for drag racing or local short runs to the car show's,,, or do they also serve well for taking long road trips where endurance is important?
Something I plan on doing with the car,,,, making a few trips to other states and the related car shows and events.

Definitely go with a roller block - in my opinion, they're better all the way around. The Summit part I mentioned (SUM-1500100-30) is a 1996-2000 factory four-bolt roller cam block. For $700 it's probably a good base to start from as the block has been vetted and all the machine work has been done (I'd still scrub it clean and paint the innards with Glyptal and mic everything - but that's just me). I also have this thing about painting Chevy engines Chevy Orange if they're going to be used in a hot rod or a muscle car.

Either of these builds would be good for everything from crusin' to a long jaunt. I have several of these builds with well over 50K miles and they're purring right along. Tech's recommendations are spot on and he stays pretty current on best practice and part numbers. As you've probably noticed, we share a lot of the same component recommendations. While I have not personally used the Pro-Filer heads they look good and the price is right. As Tech recommends them I may use a set on my next build.

Pick your cam after you decide in which generation of block you're going to use. The Howard's cam is a titch more aggressive and is a retrofit roller cam for engines that did not originally come with a roller cam. I have not used this exact part but have used other Howard's products and found them to be good.

If you're going to do a lot of stoplight-to-stoplight you'll want to spend time to make sure cooling system is adequate. The stock GM clutch-type fan with a proper shroud is still one of the best ways to cool an engine - stay away from electric unless you have insurmountable clearance issues.

Don't look for good mileage but pretty much anytime you mash the pedal tires will fry and smoke will appear!

Let us know what you decide!
Glenn

I found the absolute best improvement in gas mileage for both my nomad W/ 383 and the charger W/318 is to drive my Vega W/140.

Ha ha,,, don't have a Vega but I do have a Harley that gets about 45 MPG,,,

I looked up the engine blocks on Summit website and right now they have a special going on for $629 and freight about $110,,, after reading some of the feedback I'm a bit concerned over quality. Seems quite a few customers received blocks that had a lot of rust in the cylinder bores and lifter bores. Also a few complained about dimensional tolerances. I called and talked with customer service and they have a decent return policy so will most likely go that route fro a block.

I stopped by the machine shop I normally use and was surprised with the answers I got from one of the owners about the machine work they do. Seems they do not have a way to index the block when deck machining. Instead,,, they indicate the surface and then machine. The thought was if it was right from the factory it should be right now. To me,,, how do we know it hasn't been decked before and done incorrectly or that it was right from the factory. I would assume a factory never worked before block would be good unless it has a slight warp to it from over heating. Maybe I'm being a bit picky but I don't need and expensive BBQ pit or boat anchor. Also the machine work alone was more than a block from Summit,,, so,,, looks like doing the Summit way is the best for getting a block ready to go and build. Just hope IO don't have to go through several blocks to get what I'm after. I have tools to measure most dimensions except being able to check block square. I'll keep checking shop around here and see if there's a better deal or at least close before jumping off into the Summit block.

More in a few days, I'm going to start a build spreadsheet to come up with a general cost.

Thanks guy's,
HotRodN
P.S Hope you all had a great Thanksgiving !!! Give thanks to the one who gives all,,,, Amen )

Glenn,
I looked at using a stock fan but on my car it wouldn't work because it would sit too low. I think it would be outside the bottom of the radiator. I've gone with a PRC radiator and 16" electric fan. They claim it works for up to 600 HP. I'll have to see. Even with the electric fan it's gonna be real close to the water pump shaft. But it will clear. Right now I'm trying to get happy with the final placement of the whole setup. Hard to get good measurements with the engine in place. But it's getting there. Heck it's taken me all week to get the grille shell mounted to the radiator. Keep getting interrupted and also had to make a special bracket for the top. I had the radiator made 1 inch shorter than stock so the brackets shipped with it didn't work up top. Now to get a shroud mocked up and have my buddy get one made. Will keep all up to date and post pix once this part is done.
HotRodN

Tech,
If I were to decide to go with 5.7" Rods,,, what changes,,, compression length?? I assume I'd go from 1.130" to 1.430" given the .300" difference. I also assume that torque would be slightly lower than with 6" rods.

I noticed you have Hypereutectic pistons chosen,,, would forged pistons be a slightly better choice or,,, do the hyper's perform well enough to not worry about the more expensive forged. Keep in mind this is not going to be a drag car but I will step on it occasionally for the adrenaline rush LOL.