Part of my 65 project is to replace the 350 with a correct in apperance 327 / 350 hp. I'm in the parts gathering process, some I have, some I need, some I will leave to the machine shop. My plans are to let the machine shop build and dyno the engine with my direction on what goes in it. Thats where you guys come in. Here is what I have so far:

Std bore block

462 heads, 2.02 / 1.60 SS valves, cut to 58cc, (everything is new on heads)

461 Intake with 2818 Holley (600 cfm)

Used 327 Rods

Steel Crank (std, needs turned 010/010) snout is not taped??

Car has 2.5 Side Exhaust

What cam and pistons should I be looking at? Should I go with ARP Main Cap Studs?

This block will get the full monty in machine work, rotating assy balanced, ect. I'm waiting on my New updated Desktop Dyno (lost DD 2000 during Hurricane Wilma) to play with some numbers.

Thanks for an help and pass along any other machine shop advice.

 

A hydraulic cam will limit revs to about 6200 due to lifter pump up. Consider a LT-1 cam.

The early OE 327 rods are weak - marginal on a L-79 and a good way to destroy a mechanical lifter engine. I recommend Crower Sportsman because they are both very strong and only marginally heavier than the OE rods, so heavy metal usually doesn't have to be added to the crankshaft to achieve dynamic balance.

Look up all posts by "Dave McDufford" on the C1/C2 board if you want to learn how to build a good vintage correct 327.

Dave and his machinist did all the work. I was the system engineer.

The 80 percent torque bandwidth on the lab dyno test was 1600 to beyond the 6500 RPM imposed redline. It will pull usable power to 7200 and the bottom end and valve gear will take that rev limit. It doesn't get much better than that. Dave's machinist did a very nice job pocket porting/port matching, multiangle valve job on the OE 461x heads based on the flow test data, which I used in the simluations. Similarly massaged 462s might not flow quite at well since they start out with a little less port volume.

I also recommend the Engine Analyser program over DD2000 or any of its various derivatives. EA was within a fraction of a percent of predicting peak power, but was about 10 percent high on peak torque and 10-20 percent low on bottom end torque.

I have files of all the OE cam data and rocker geometry data that will work with EA.

Use the OE replacement Speed Pro forged pistons. You need to pay very close attention to dimensions that affect CR, like deck clearance, so you can select a head gasket to achieve no more that 10.5:1 CR if you want it to run on pump gas. Such is usually achieveable with OE machined decks and and a typical .038" composition head gasket. You don't need aftermarket main bearing bolts. Everything on Dave's engine, except the rods and Felpro head gaskets, is OE L79 or OE equivalent replacement from Tier 1 vendors like Federal Mogul.

A non-tapped 327 crank is not Tufftrided, but it is still forged. Look into a surface hardening process - Tufftriding or similar - after it is machined. It should be Magnaflux inspected prior to machining to ensure it is not cracked. Same for used rods, but even a NEW 327 rod is a fool's game. A crack-free Tufftrided crank is essentially indestructable as long as you don't oil-starve the bearings. I believe the non-drilled 327 crank can be modified to accept the 8" balancer, which I recommend. I also recommend the 5-qt. baffled/trap door oil pan, which will preclude the use of the manual steering damper or the power steering boost cylinder.

With the exception of the rods, SHP 327s have a lot of premium parts and nothing else needs to be replaced with hot rod stuff.

Duke

 

Why all the effort to "give away" 23 cubic inches? The pistons and crank are all that HAVE to be different between the "correct" 327 and the much more accessible, 350.

RACE ON!!!

 

Not sure I follow you on that, Dropping a Large Journal 350 crank into a Small Journal 327 block would be hard to do.

 

Duke,

The current engine I have in the 65 is a 1974 LT1 CE engine with 60K. The engine smokes but I'm guessing that is from valves seals as the compression is 205 on all Cyl's. The engine runs fine other than that so I could just pull that LT-1 cam / lifters / push rods / rockers and move them to the 327 and save myself some money. ???????

What is involved in Tufftriding a crank and what does this cost? Sounds like something I will do. Also, do I need to have the snout drilled and tapped?

I read the build up tread, great info, Thanks.

 

As long as the cam is not worn you can transfer everything to the 327 block, but make sure everything, especially the lifters, go back on the exact same cylinder/valve.

Tufftriding is a surface hardening process, generically called "nitriding". The following web page provides an overview.

http://www.heattreatment.co.uk/bowmic/tufftride.asp

There are other surface hardening processes available, too. I don't know costs, so ask your machine shop about Tufftriding or other surface hardening processes that they know of.

All Chevrolet SHP/FI cranks were Tufftrided. All 327 cranks are forged, but only SHP/FI cranks were Tufftrided. This or similar surface hardening on a crack free crank will increase fatigue life and make the crank virtually indestructible as long as the bearings don't get oil starved.

If you have a Tufftrided crank the journals should not be ground unless absolutely necessary. Minor flaws can usually be removed by polishing. When I rebuilt my 327/340 at 115K miles the crank journals all measured right in the middle of the OEM dimension range. It was crack free and straight, so I just had the journals polished.

You don't "need" to drill the crank and install an 8" balancer, but I recommend it both for durability and "original appearance" reasons if you are building a period correct SHP engine.

Duke

 

Im sure you can buy a small journal 3.75 strke crank. Probably forged too.

 

speedomotive
http://www.speedomotive.com/327%20SM...0383%20CID.htm

 

The Chev L-46 350/350 hydraulic cam is a nice choice. about 222 degrees duration at .050" lift, and .450/.460 lift.

My L-79(1976 large journal crate short block) 327 with the L-46 cam (Bowtie heads) will spin to 6800 RPM without problems,and the cam has been tested at Chev to go to 7200 RPM with (new) stock springs and lifters.

Hydraulic lifter pump up is usually tracable to weak valvesprings, that cause the valves to float if this happens, the hydraulic lifters take up the slack, causing what is called pump up. It doesn't happen with new or near new springs, as the lifters are continuously purging thru the pushrods.

That being said, if you are serious about your RPM, you gotta change springs every few thousand miles, or years, depending on how much you drive the car. It is getting time to change my springs at ~ 4000 miles, as i used to get 7K with brand new springs before the valves started to float, now float is starting below 6700 RPM.

Doug

 

First, you never mentioned that YOUR 327 block was for the small mains. Second, why not just turn down the 350 crank? Where do you think the 383 came from?

RACE ON!!!

 

On most 350 cranks turning the mains down to small journal you end up moving the oil hole closer to the radius of the crank do to the angle of the oil hole. It can be done with the right crank.

 

Forget any stock cam. Why would you put a 35+ year old technology in a new motor?

I had a .060 over 327 large crank motor in a street rod. I used Sportman II's with 2.055/1.60 200 cc. in one of it's variations over the years.

If your getting new valves the manley race flows with their narrow stem design are a flow enhancement over stock SS valves

With 58 cc I would use flat top pistons. Because of your short stroke you could get awy with KB Hyper pistons. They actually have some better properties than a forged piston in non racing applications.

I don't recomend stock rods. Why use them when you can get Eagle I beam bushed rods for @ $260 a set or pressed for $240

I would ask the machine shop how much to install 4 bolt main caps. I use fully studded motors.

 

I could go out and spend the money to make everything in the engine brand new aftermarket go fast stuff so I could cruise 55 around town.

I agree with the new rods and pistons.

The 462 heads I have are fresh out of the machine shop ($700 worth of work) new SS valves, seats, guides, ect etc. cc to 58cc. Picked them up for $300 from a guy that didn't use them.

I have a steel crank, so I might as well use that one. Turn it 10/10 and nitrate it.

As for the LT1 cam, worked in 1970, will work in 2006, and it is in good condition. This is a cruiser not a pavement pounder. I'm old school and grew up with this cam, old technology was once new technology.

 

The basic laws of physics haven't changed in the last fifty years, and Chevrolet had a pretty good handle on valvetrain dynamics and head flow back then and what valve timing points were required to get the most out of the available head flow. A "modern profile" that features more aggressive acceleration than the OE profiles will require higher rate springs and maybe stiffer valvetrain components and reliability will likely suffer. "Modern profile" is just aftermarket marketing BS, and there have been a lot of reports of wiped lobes on aftermarket cams.

The more I work with these vintage Corvette engines, both refining my simulations and correlating to actual dyno test data, the more I appreciate how well they were engineered. You can build a vintage SHP engine using all OE components except the connecting rods and it will run all day at 6000 revs and last at least 150,000 miles before it needs a major refresh. In addition, it will have broad torque bandwidth (like pulling from 1000 revs in top gear) and very respectable specific peak power output.

Duke

 

Your heads might be a good deal if they are not to thin. From 64+ cc to 58 cc a lot of material.

Older cams have a very small nose and low lifts because spring technology was poor 35 years ago. So they spend very little time at or near your heads max CFM of flow.

I also don't buy the Chevy stock valve train for the masses being up to date. The heavy retainers, rotator cups, and spring caps that kept the oil from cooling the springs That is the first stuff we through out when building heads back in the early 70's.

I helped Lt1er rebuild his 71 about 12 - 14 years ago. New solid cam and 10.7 compression. P&P heads 186 casting heads with all the goodies. Other than headers it apears to be bone stock. He said that it is night a day difference.

 

He said .030 was cut?? If need be, I will strip the heads and re-install all the parts in a set of uncut 461's. From a cost standpoint it would still be a wash.

 

I didn't mean for any of this to be taken as an argument

I just looked this up to make sure of my memory and check the figures. From the Dart head sight and you could check most heads sites. they claim 1 cc for evey .0065 of milling when you said 58 cc's i was thinking 64 - 58 = 6 6 X .0065 is .039. that's nearly a 40 thousants cut.

I'm not a head machinest and I don't know that much about each casting number. But i do know that stock heads don't have allot of meat between the piston and water on the quench side. the other problem is the outer head bolt holes. The cast iron has less meat. I've had heads surfaced and trued. The only reason i can think of machining .040 off a head or .030 in your case is if the head was warped from over heating. I have a basic distrust of most venders.

Around here I've had heads refurbished for $240 for the resurface, guides, seats, assembly, and hot tank. parts are extra on the bill. seals $50 or so . Springs and chromoly rets $150. Depends on what they are 16X8 = $128 I've had heads done for around $500

http://www.dartheads.com/manager/upl...IRON%20SBC.pdf

 

The heads were cc'ed to 58 because they were a backup set for a race car and the rules changed and he had to now run vortex heads. Thats the story I was told me anyway. I talked to to the seller several times and he's a stand up guy.

No reason to belive at this point there is anything wrong with the heads, it will all figure out in the buildup if the piston to valve clearance is too tight.

No argument here, I enjoy the input

 

The issue with heads that have small chambers due to machining is final CR. Piston valve clearance should not be an issue with an OE cam, but cutting .030" may effect reliability on a race engine and is marginal, but probably okay for a street engine that will not see sustained hard running.

For Dave's engine I set the target CR at NO MORE than 10.5:1, and the RH deck could not be touched in order to preserve the stamp pad. The left deck was .005" higher, so it was cut down to the same level as the right. Both were reasonably parallel to the crankshaft axis. Most OE machined decks are .010" to .015" higher than the nominal 9.025" (SBC) from the main bearing centerline, which is why as built CRs are usually about half a point lower than spec.

Ideally, if you were willing to cut the blocks decks, I would recommend a flattop piston with a shim gasket, which would yield about 10.5 with minimum quench clearance, but both the head and block surface must be dead level, so you're better off running a composition gasket on a rebuild. Since the OE heads and block decks were freshly machined, gasket seal was rarely a problem. Compostion gaskets will easily seal with .0015" warp and will usually seal up to .003" warp - at least on a street engine that will not see sustained hard running as in racing.

Once you know your deck height/clearance, piston volume, and head chamber volume, you select a head gasket thickness to bring your CR into the target range.

The following is an, easy to use CR calculator:

http://www.csgnetwork.com/compcalc.html

On Dave's engine it ended up at 10.35 +/- 0.1 across all eight with a common .038" Felpro composition head gasket, which was okay, and it operates detonation free on pump premium. The dynamic CR is only 7.26:1 (as calculated by Engine Analyzer) because the LT-1 cam has a relatively late closing inlet valve. SBCs will usually operate without detonation on pump premium if the DCR is kept below 8:1 as long as the ignition map is not too aggressive.

With a L-79 cam in Dave's engine the DCR is 7.37, which is still okay but it would be 8.52 with the 300 HP cam - NOT okay. With a 300 HP cam the static CR should be limited to about 9.5:1, which will yield a DCR of 7.84:1.

Duke

 

Duke,
Have you entered a L-82 cam into our model to see what the DCR would be?