We recently dropped our 62 327 off at a machine shop. I previously had the block cut for Program Eng. splayed 4 bolt main caps. We have a 3.875" stroke callies crank that was turned down from 350 sized rods and mains to fit a small journal block and rods. We have 6.00" Manley SJ rods with the cap screw rod bolts.

When I began gathering parts for the build, I was planning on running a flat top piston and a fairly healthy solid cam to make it livable on CA's 91 octane pump gas. However, since that time, the intended goal of the engine has changed... since that time, I married and the 62 became the wife's to drive. The wife doesn't want a rough idle, and that pretty much dictates I run a milder cam, which won't be compatible with the expected 10.5+:1 compression, based on the use of flat top pistons and my 66 cc heads.

It's my understanding that a dished piston and a 6.0" rod is out of the question with a 3.875" stroke. Is it possible for to use 5.7 or a 5.875" rods, allowing a dish piston to be used?

 

Your biggest concern with considering a shorter rod is crankshaft counterweight clearance. When the piston is near the bottom of the bore the bottom side of the pin bosses come very close to the counterweight. Usually the crankshaft manufacturer will specify a minimum rod length based on how much the counterweights are machined down. Otherwise, it is certainly possible. There are 4" stroke small block cranks machined to clear 5.7" rods.

Dan

 

Dan,

Thank you for your input. I considered this. The machine shop discussed machining the counterweights down for block clearance. This was done when I stroked a 283 with a 3.75" GM crank, but I had balance issues, and had to use a lot of heavy metal.

I would be willing to machine the counterweights if it would still allow the assembly to be internally balanced.

BTW, do you see any issues with using a 5.875" rod with a dished piston?

 

I'm not really familiar with any clearance issues between the small end of the rod and the bottom of the piston crown, but I see that JE makes an "inverted dome" (i.e. dished) piston for a 3.875" stroke crank and 5.850" rod. It's a 14cc volume.

Dan

 

Thanks Dan, I will look into it. I'm sure someone makes a SJ rod in that length. If I could get an off the shelf piston, that would be a huge plus.

 

check out je pistons web site the srp piston just might be what you need.

 

I ran a 3.875 crank, 5.850 rod, dished JE piston and still had almost 11:1 CR but with a larger bore. Your deck height and gasket thickness also comes into play with any combo so do your homework.

Good luck,
Dave

 

Hi Wes, stay with the long(er) rod, the 6.000". The longer rod fits the crank profile easier when the piston is at BDC. More clearance at that point between the piston-pin bosses and the counterweights.

I believe you said you already had the rods, if not I would choose a S/J, lightweight, +.300" piece. Keep the reciprocating weights down some. We use a "featherweight" (530 Grams) on this platform, 6.000" H-beams, ARP 2000 series bolts, and bushed.

Important: When you lengthen the stroke and make the mains "smaller", you start to encounter some "rod-overlap" issues. This is when the distance between the C/L of the crank-pin (rod) and the C/L of the mains starts to reach a critical dimension! This is also the reason we've gone over to the "Honda" rods in some "high-end" platforms. Much smaller (lighter) at the bearing end!

You will need a piston with 1.060" C.H., a 10 cc dish with a 66 cc head, and a 9.015 deck for approx. 10.2. This will yield about an .055" quench with an .038" gasket.

The "target" C.R., 10:1/10.5:1, may become an issue with a "short" cam in "large" 396" SB. Personally I would lower the target to around 9.75:1 and stay with the cam. With iron heads I would not go anywhere near the 10:1 in this unit. With aluminum's you should be OK.

Short cam+iron heads+"big" inches+10:1=probable detonation!

Thanks, Gary in N.Y.

P.S. The problem you have is the C.H. The 1.063" size is a "stocking" piston height for the SB 400" bores only. They would most likeky have to be made to order for the 3.85" stroke and the SB 350" bore size!

 

200FRCZ19, thanks, I will check them out.

hookedup, I will definitely be paying attention to the deck height and quench. I looked at their site, but I couldn't find a dished piston, for use with the 3.85" stroke, and a 5.85 rod.

GoFast, I already have the Manley 6.0" SJ rods. They're a nice looking set, with cap screws, rather than rod bolts. If this becomes too cost prohibitive, I may have a 350 crank turned down, or go with a SJ 3.75" stroke and an off the shelf piston. prior to my taking the engine to the machine shop, the wife said she would be happy with a stock GM target motor. So, I have to be careful how I cam the motor, while keeping detonation in check.

Crane recommended a couple cams to meet my idle requirements, and still work with @ 10.5:1 and 91 octane:

1. A hydraulic cam with .467/.494", 222/234 @ .050", on a 112* LS (didn't write down the advertised)

2. A HR #119701 Small Base Circle .518/.539, 222/230 @ .050", on a 112 LS, 288/296 Adv

3. A HR #119661 Small Base Circle .539/.558, 230/238 @ .050", on a 112 LS

4. I also have a Comp 274 XS that was ground on a reduced base circle .501/.510, 236/242 @ .050", 274/280 (this was purchased for my stroked 283, before it spun a rod bearing)

The first two cams look plenty streetable, but I don't think they will bleed enough of the compression off to allow the car to run on 91 octane. The third cam will probably be choppier than the wife likes, and would require a 2800 - 3000 stall converter.

When I started gathering the parts for this build, my goal was to run 12s at LACR's 2700" elevation, through the factory block, heads, intake, and with a GM cam. I wasn't concerned about the compression, because I was planning on running a 30/30 or similar cam. Here is a link to the heads http://www.picturetrail.com/gallery/...617&uid=649897 .....a mildly cammed stroker, or even worse, a low-po 350 seems like a waste at this point.

I'm going to speak with the machinist this week, and see what the different options will cost me.

 

Ok i'll admit i have never done this but i read all the time of fly cutting the pistons for clearance - normally for vlv clearance. And once i talked with Bruce Fulper of Rock and Roll Engineering he said sometimes that he would just cut-down flat-top pistons for clearance/reduce compression so i know it can be done. But u would want to leave enough surface material for quench (cut out a dish) if possible. By cutting down off the shelf forged pistons this may be cheaper than replacing crank and rods. Only the machine shop can really tell you though.

And looking at the pix of your cyl heads i see the chambers still could be opened up to reduce compression. Unshrouding the vlvs will not only open-up the chamber but improve breathing. It looks from the pix like the the vlv's are still shrouded. And i think a little more chamber contouring is possible too. Those bumps below the plug holes can be improved. Not for amatures but a skilled head porter will know where he can remove metal and where not to. Contouring the chambers and have them volume matched is a good thing for performance.

Well just my 2 pennys and hope this can help save you some $$$.
cardo0

P.S. i vote for cam #4 (if u get c.r. <9.5) - Comp 274 XS - well because i' m partial to solid flat lifter cams.

 

with 10.5 this cam would be very streetable with 396 ci

3. A HR #119661 Small Base Circle .539/.558, 230/238 @ .050", on a 112 LS

I used it's Crane solid brother with 1.6 RR's in my first 383 and I could go to lockup 4th gear OD at 2000 rpm and floor it. In a 396 it would even be tamer. I had a smooth idle @ 900 rpm with 13-14 inches of vacuum. It was to mild for my taste and upped the duration 8 more degrees I&E @.050.

I have 20 cc dished pistons 6 inch rods 4 inch stroker in my 427 small block

 

Just got off the phone with the machine shop. The crank cleared the block, but the rods hit. The shop will do their standard 383 cnc machining on the block, and recheck rod clearance. I should have an answer about pistons by this time next week.

cardo0, if a dish piston were available, I would consider it. Regarding re-working the chambers, I would hesitate to do so. The guy who did the heads got some decent numbers out of them, and I don't want to hit water or possibly do something that would negatively affect flow.

I may get lucky, and not need a reduced base circle cam. If so, that opens up a lot of possibilities. The wife said a stock cam would be nice, so I guess that makes a 30/30 cam an option...

gkull, I like the specs of the second cam, but Crane recommended a 3000 stall converter to go with it. I'm currently running a stock TH 350 and converter, with a B&M modulator and governor. We have a fresh TH350 that will be swapped with the engine. I have a 2200-2400 stall converter that will go with it. Due to space constraints, I use a deep aluminum pan and a 2 pass, 30" frame cooler. I will also use synthetic fluid with the new trans to help reduce heat. However, I'm afraid that a higher stall converter would lead to a short trans life, especailly as much time as we spend in L.A. traffic.

BTW, I just picked this up, and may run it instead of the 461 dual plane.


Thanks again,

Wes

 

Wes, I used to work for Summit Racing tech/sale line. 1/2 of the people on the tech line drove rice cars and have never turned a wrench on an american V-8. They encouraged everybody to read every car magazine in the break room to keep up on currant ideas. Most of them only knew as much as you do from reading the paragraph on the parts page.

When they rate a cam they are talking about a run of a mill 350 ci. So when it says rough idle 3000 stall they are talking about some 350 ci. You install it in a 302 ci and it would be animal, but install it in 383 or near 400 ci and it's very tame.

I also install only small base circle billet cams in my motors. The more lobe to rod clearance the better

 

gkull, I understand about the larger stroke requiring less stall, and smoothing the idle somewhat. However, my wife wants a mellow idle. Her car currently has an 82 305 with a 264 Isky Mega cam (108 LS). It idles decently in park/neutral, but is pretty choppy in gear, with the stock converter. She doesn't like driving it. Rather than rebuilding the 327, she just wanted a stock GM Target motor. I couldn't imagine driving a Vette with something like that, so I convinced her to let me build the 327. So, if the idle is rougher than she wants, I will catch hell for it.

That said, if we did go with a HR cam, the HR #119661 looks pretty good. The FI unit we picked up is supposed to have better driveability vs a carb. Unfortuanately, the cost of the FI unit makes a flat tappet cam more appealing.

Thanks again,

Wes

 

I had a 63 - 64 FI sytem on my 61 Vette when I bought it. I fought it for a couple of years. Mechanical FI from the early 60's left allot to be desired. An evaporative carb with an oil bath air cleaner from the 1920 is a neat looking item also, but not really very functional.

 

gkull, I understand your point. The FI should make more avg power than the #461 intake and carb I planned to run. If I can't make it work well, I can always switch back to a carb or swap an aftermarket EFI. At that point, the Rochester unit would make a real purdy door stop.

 

At big car swap meets those Roch. early 60's FI units sell for as much as $4500. I can't believe it. I sold my running unit for $2500 because I didn't know how much it was worth.

They only have about a 2500 some foot change in elevation range or air density. If your driving elevation or air doesn't change much from summer to winter they can be made to work.

 

gkull, we're planning to drive from L.A. to Bowling Green in may. We will probably take the 40 through Flagstaff and Albuquerque. How much worse will t likely be at elevation? Will the car still hold an idle?

Also, our nearest track is LACR. We are at sea level. LACR is around 2700'. Any idea what kind of effect a sea level tune will have on the performance at LACR?

Thanks again,

Wes

 

like I said, my 63 or 64 FI unit could keep me going within a 2500 foot window or so elevation change. Then I had to get out and screw with the adjustment because it would run very good.

My house is at 4400 the mountain pass is 7000 on the way to the Sacramento valley. I had to stop before the top and fiddle and then stop again about 1/2 way down and then again near sea level.

 

You mean everyone doesn't have a 350?

It seems like Crower is the only cam mfr that describes how a cam will perform in various engine sizes. For example they show one of their cams having powerbands of:

1900-5500 RPM in a 406
2000-5700 RPM in a 383
2400-6200 RPM in a 305/350
2700-6600 RPM in a 307/327

So, like gkull says, a high rev cam in a 302 is a high torque cam in a 406. And I'll bet a stock stall converter would work in the 406, while the 302 might require 2600-3000.

On another note, I'd be concerend about using small journals on a 3.875" stroke crank. That's not very much journal overlap. GM decided to go with large journals even for a 3.48" stoke, and larger still (mains only) for 3.75". I guess if you keep the revs down it will be OK. And it is a Callies crank.