valrico_stingray

I am looking for gobs of HP/torque on just 93 octane fuel. I'm not looking for a high rev drag car. My 64 has a 1966 NOM 3858174. I hope to reuse the block, forged crank, and rework the 461 heads for better flow. Everything else will get replaced. I kinda want to go with the '70 LT1 type cam. I would enjoy hearing what those of you have done similarly. I want to keep my SB hood. I mostly need ideas for carb, intake, cam, valvetrain, rods, pistions, exhaust. Who went with stock type parts - who went all modern - what did you use? You can answer here or in an e-mail. Thanks a bunch. Chuck


[Modified by valrico4, 10:44 PM 2/14/2004]

SWCDuke

Your objectives are mutually exclusive! HP = T X N/5252, so to make more power you have to increase revs and increase torque at high revs, both of which will kill low end torque, fuel economy, and driveability. You can't have your cake and eat it too!

There's tons of engine building tips in the archives, some good, some not so good, but briefly here's what you can do to get reasonable street torque bandwidth, good top end power, and high reliability at a reasonable cost.

1. Qualify rods and crank via magnflux, install SHP windage tray and big pan, balance entire rotating and reciprocating assembly. Balance clutch assembly and torsion damper separately.

2. LT-1 cam

3. Target actual measured CR at 10-10.5:1 with either OE type replacement forged pistons or modern hypereutectic cast. Max compression for a given piston is obtained by reducing quench clearance to .035-.040" and tight quench clearance will minimize detonation tendency for a given CR. If shaving the block and removing the numbers is not an issue - go with flat top pistons and minimum quench clearance, which should yield this range CR with 461 heads. Proper planning requires that you measure deck clearance prior to pulling the pistons, so you know your starting point, and you also need the compressed gasket thickness and piston dome/recess volume to compute the new CR.

4. SPARE NO EXPENSE on massaging the heads to include pocket porting, port matching, and a multiangle valve job. (The interior of the ports do not need to be opened up - just smooth down any casting flash.) I CANNOT OVEREMPHASIZE THIS POINT ENOUGH!!!

5. Any OE or aftermarket four-barrel inlet manifold with about a 600-700 CFM carb is fine. The OE SB Quadrajets (750 CFM) work just fine, too, but might need some recalibration if they were originally set up for an emission control engine.

6. Obtain some 2.5" ram horn manifolds and use proper 2.5" piping with low restriction mufflers.

7. OE or equivalent parts everywhere else, and ATTENTION TO ASSEMBLY DETAIL! Measure EVERYTHING! Spend the money you save not buying over-hyped hot rod parts on the heads and qualifying the bottom end.

Use a NAPA/Echlin VC1810 vacuum can with full manifold vacuum on the single point distributor (different can number if HEI), and high breaker tension points. Total initial plus full centrifugal timing should be 36-38 degrees, and get the centrifugal in as quickly as possible without detonation.

The above configuration will provide 80 percent torque bandwidth from about 2000-6000+, useably and safely rev to 6500, idle reasonably at about 800-900/12", return reasonable fuel economy, and make close to 275 RWHP. The limitation on power is the HEADS, not the cam!

Did I mention lavishing maximum attention/effort/expense on the HEADS?! ;)

Duke




[Modified by SWCDuke, 9:03 PM 2/14/2004]

mrg

Duke ..
I'm in the midst of a 327 rebuild project too. A question I have concerns the crankshaft. It's a forged unit that hasn't been ground undersize. Is it a good idea to polish the crank journals using 600 grit sandpaper and the shoestring trick .. ? .. Should the oil hole passages in the crank throws be chamfered, as well .. ? ..

I have forged TRW flat top pistons installed in the engine now and they seem to be in good serviceable condition for reuse. Is it worth it to use gapless style rings with this type of piston .. ? .. I see that Clevite 77 bearings are available in a "P" series that have more eccentricity to them than the standard P suffix available for most cars and trucks. Which style should we use for our street driven engines .. ? .
mrg

aworks

duke is right on target with the bottom end. the heads i beg to differ. i have been this route with 461 heads. by the time you pay for the port work and replace valves and we know that they are prone to cracking between the valve seats. you can buy a set of good aftermarket heads. if you want to save on the money end go with dart iron eagles. i love the high rev 327 over any small block. i turn mine to 8500. rpms all the time. i run canfield heads on this one. i buddy who is also my eng. builder. runs iron eagles on his 327 and his will beat mine every time at the drags. the power is in the heads but you can not be afraid to turn that little eng, thats what it takes to make power with the small cubes.

SWCDuke

It's a good idea to have the crank checked for straightness, journal dimension conformity, and have the journals polished. A good engine machine shop should be able to do this, and it's not a budget buster. I also recommend that cranks and rods be magnaflux inspected, though it's rare to find a crack in a Chevrolet forged crank. They are very high quality and durable pieces. Chamfering the oil passages in the journals is not necessary unless you're building an 8000 rev road racing engine.

My SHP crank was straight, crack free, and all journals measured right in the middle of the OE dimension range. You would never know it had over 100K miles. After qualification I had the journals polished.

Clevite 77 are excellent bearings. I'm not familiar with the P-series. By "greater eccentricity" I assume that they're designed for more crush to hold them in place(?) Assuming standard bearings fit snuggly in the recesses, that's what I'd use. On engines that have been rebuilt a zillion times the bearings sometimes don't fit the recesses snuggly, but more "crush" when the bolts are torqued down will hold them in place.

I've heard mixed reports on gapless rings, so unless I wanted to experiement, I'd stick with standard moly faced rings, and fit them to each cylinder to be sure the end gap is in spec.

Everytime I get involved in a SB system engineering project it always comes down to the heads. HEADS! HEADS! HEADS!

If you're looking for the best torque bandwidth and peak power, you can't spend too much money on heads. If you want to save money or maintain original appearance, the 461, 462, and 186 small chamber heads can be made to work fairly well, but it takes a lot of labor. The hobbiest can do most of the head work on his own time for little out of pocket expense, and there are lots of books out there on how to do a good pocket port, port match, and valve job.

If running an original equipment heads is not important, and you have the budget, aftermarket heads are the way to go, but they will still need prep. There are a zillion out there, and the AFR 190 aluminum heads appear to be a good bet for a street engine.

Beware of big flow numbers at high lifts! A reasonable street cam is going to provide peak lift somewhere between .4" and .45" when you take into account real rocker ratio, and the valve is going to spend most of its time at .2" or less, so it's the flow at low lifts that really counts. This is where pocket porting and multiangle valve seat geometry are going to pay big dividends. On the inlet side at high revs the inertia of the incoming fresh charge will continue to fill the cylinder past BDC while the valve is nearly closed, so the flow at low lift is critical to obtaining good VE at high revs and getting the most out of the cam.

On the exhaust side the pressure ratio is higher than critical (0.528) so as the exhaust valve begins to open, flow is sonic and choked. Flow is a function of flow area and the flow coefficient of the annular area around the valve, so, again, valve seat geometry is critical to allow exhaust pressure to blow down and minimize pumping work on the upstroke beyond BDC.

Duke

MikeM

I am looking for gobs of HP/torque on just 93 octane fuel. I'm not looking for a high rev drag car. My 64 has a 1966 NOM 3858174.

If I take this statement as your primary objective then I would recommend that you look into getting a built 383 engine from an engine builder. The rest of the advice you got on the heads, cam, intake, porting, aftermarket heads, not going too big on port flow at high valve lift is all good advice and can be apllied to the 383. You can build the 383 for about the same money as the 327 and get the 56 cubic inches for almost nothing. That way you won't have to twist the valve springs out of it to get horespower.

Another thing: if you don't do a lot of highway driving, you might consider slipping a 4:11 gear under it. You'll feel like you added 50 horsepower.

mrg

I just miked the crank, pistons, and cylinder bores. The crank checked out pretty good, with no evident taper on the journals - nominal measurement was 2.2985 mains ( #5 smaller by a thou) and 1.1985 crank pins. The cylinder bores are a concern, though. Those miked out across the board at 4.033 with the pistons coming in nominal at 4.0265 with one about a thou less than that. Cylinder taper and out-of-round was between .001-.0015.
With the piston clearance being in the .0065 range, which seems pretty loose, will this be a problem .. ? .. The pistons are forged TRW flat tops .. I will be using the LT-1 cam so if the pistons slap around a bit in concert with the tappet noise, I can live with that .. ! .. My main concern is if the clearance is 'too much' and if it's time to maybe replace them. They look in real good shape, though, otherwise.
Thanks for your earlier reply, Duke ..
mrg

SWCDuke

The mains appear to be in spec except the rear. My '63 Shop Manual shows the same range for all five - 2.2978-2.2988".

There's something wrong with the rod journal measurements you posted. The spec is 1.999-2.000".

The piston diameters should be measured normal to the centerline of the pin axis.

If your measurements are correct the pistons are pretty loose. You can probably put everything together that way, but it may not last 100K miles. It appears that the clearance was set up too loose by whoever did the bore job.

The clearance range for the OE forged pistons is .0028-.0035". For racing up to .006" is sometimes recommended, but I know one guy who installed the OE forged pistons that loose in a street engine and broke a skirt after about 20K miles.

Duke

mrg

Duke ..
After carefully recalibrating the 2"-3" mic with it's measuring rod standard, the rod journals come in at 1.999. I rechecked the mains also and they speced out ok, except for the #5 journal which was slightly under the low end of the journal spec .. Not sure what to do about that one .. Maybe use a .001 oversize bearing after having the crank polished. ? ..

Yes, it appears the machinist who bored out the block cut too much material away, given the .0065 piston to wall clearance. He knew forged pistons were going into this engine. It was quite a few years ago (1974) and if memory serves, I'm thinking he may have went ahead and bored out the block without checking the piston demension. Of course, he didn't 'say anything' ..

I did notice that the cylinder bores each have some light scoring in line with the longitudinal axis of the piston skirts. Not bad, but barely detectable using the 'fingernail' test .. The pistons had some light scoring, also. My guess is this might have been caused by the rocking motion of the piston in the bore .. ? .. These pistons have probably less than 20K mileage on them. They do appear to be in good shape, though. I had thought honing the cylinders for the new rings would take care of those score lines, but this will only increase the bore size MORE than it already is ..

Knurling the pistons seems like a 'band aid' approach. I am more concerned with durability and longevity. So, it looks like the logical alternative is to replace the pistons with new ones and bore out to the next size - .040 .. I think I read somewhere that a 327 shouldn't be bored out more than .030 over .. ? .. Is this true .. ? .. Keith Black offers 327 hypereutectic pistons in the .040 oversize so it seems this size is available. Speed Pro lists special alloy forged pistons that 'fit tight and don't expand as much', so that might be another option. Are hypereutectic pistons the 'way to go' now .. ? .. I have aftermarket connecting rods that will replace the stock units, too. Would it be better to just stay with a forged piston type for strength and 'insurance' .. ? .. I just don't want the thing to BLOW UP . . ! ..
mrg

VetteLT4

:eek:
you spin yours to 8500 frequently? wow. id really like to hear the details of your engine buildup (or any build that can spin those rpms). id love to have a 327 that can reliably and consistently take 8000+ rpm. didnt think such numbers with reliability were possible.


[Modified by VetteLT4, 6:23 PM 2/16/2004]

aworks

Ill tell you what i remember. stock forged crank, small journal.balanced rotating assy, manley 61\4 inch rods,manley light weight platinum pistons, rollercam, specs i dont remember. The heads are canfield alum. 195 CCs, comp cams steel roller rockers. Intake, dual quad tunnel ram with 660 holleys. Trans M22. rear 12 bolt, spool, and 488s. Not much low end but she screams. this motor is coming up on two years old trouble free and way more fun than my big block cars. now when im done with the L88 im building for my grand sport,we will see if they go as good as everyone says. its built to stock specs,no port work on the factory alum. heads, i even left the 12 1\2 to 1 pistons. the bitch will be ill have to run race fuel.

SWCDuke

If the #5 journal is a thou under, you need a thou undersize bearing. I'd recommend doing a plasigage check.

Pistons and cylinders are a tough call. I wouldn't recommend knurling. The old might work okay in the same bore, but maybe not. It's a risk you'll have to decide you whether or not you want to take.

Boring to 40 over should not be a problem; 327s have been bored to 60 over, but sonic testing of cylinder wall thickness is recommended first to make sure there's not a thin spot due to core shift.

Piston choice is a tossup. Both forged and hypereutetic are okay, but both need to be fit to their unique requirments, and cylinder wall finish should be tailored to the type of ring, which is usually moly. It's all in the details.

Duke

valrico_stingray

Duke, I haven't been able to get e-mail through to you. I just wanted to say a thanks for all your help.

Chuck


[Modified by valrico4, 9:05 AM 2/17/2004]

VetteLT4

this brings up another good point that ive always wondered about. so increasing the length of the rod increases the rod ratio which i hear is good for higher revving engines. stock 327 rods are 5.7 right? I thought you could squeeze 6 inch rods in there, but you really went all out huh? how do you know what size rods will fit in there?

mrg

Ok, Duke .. I have it in mind to get with a machinist who's been in the business for many years and have him check over the block and pistons first, then go from there. I'm inclined to go with an overbore and new slugs just to put the 'what if' issue to bed. Investing in precision measuring tools was a good thing. Wish I had done it the first time around ..

Thanks for all your input and suggestions .. Very much appreciated ..
mrg

RGGregory

mrg,

My 67 327/350 is set up much the way Duke describes a good 327 street package, with the exception of my L-79 cam (which is pretty close to the LT-1)...I'm making about 280 hp at the rear wheels with chambered pipes.

Allcoupedup

RGGregory -
Which heads are you using - how about valve size? Are you using domed pistons?

Thanks,
brian

RGGregory

Stock 202 heads with flat-top pistons about 10:1 CR

Viet Nam Vett

Thanks Duke :cheers:

Excellent Reading.... :thumbs:

aworks

LT4. the way we used 61\4 inch rods was to use 350 pistons. if you do the math it comes out perfect with a zero deck height