I am looking for some advice on a rebuild of a 427. It's an L-88 Short with 990 iron heads. It is a 4 bolt main, foged crank, 7/16 rods, 12:25 compression, Crane L-88 Bluprint cam, crane roller rockers, high volumn oil pump, windage tray. Here are my questions:

1. What compression should I drop to, to run on 94 octane? (Right now it runs on VP C-12)

2. What is a good cam choice? I do like the sound of the L-88 cam.

3. What stall speed torque converter should I use? ( the car is driven 3 nights a week to crusie nights in the summer with occasional trips to the drag strip. I am unsure of the exact vehicle weight, It is a restification of a '72chevelle, the car currently has 4:88's which I will change to match the new cam power range.)

A buddy and I ran that same cam in the late 80's. I did love the sound. I had mine I a 65 Impala 11 to 1 454 with a 4-spped and 4.33's ran pump gas all the time. My Buddy had a 427 in a 66 Chevelle with 11 to 1 he also ran pump gas. They were or daily drivers. That cam sonded great with turn downs and turbo mufflers. That cam cost 59.95 back then. That is just what I have done.
John

Boy, sure would love to hear an 88 cam again! Thinks I forgot?

Although I love the modest 'lumpiness' of my Ultradyne solid ( now Lunati ), I can't remember the old 88 cam ( ran back in 1978 btw) to compare.

The Crane solid I ran was a dual pattern LS6 type cam, so you could get it to idle at 14-15". This one is more like 10-11" and rings the headers like you can't beleive!

To wit, does a tighter lobe center, intense lobe, modern small race cam, have the same idle quality as the wider center, looooong seat duration old 88 cam?

I don't know, but I think my Lunati A7 would come darn close if it had slightly tighter 107or 108 LSA.

Most of us with street/strip 427s are running from 10-10.5:1 compression and cams with 276-295 seat durtations on 93 octane. One way to get that lumpiness back is to tighten the lobe centers.

No matter what, the 427 is going to want more gear to "meet or beat" the pull of a 4" stroke motor. So while 4.88s are excessive ( needing , what 7700+ redline crossing the 1/4 mile stripe!), I think you'll find that 4.10 to 4.33 is about right for strightline use, especially if you'll be using the 'natural' range of those heads on a 427, which is 4500-7000 rpm.

My 435 HP clone turned out real good IMHO. That Lunati cam, medium dome SRP's, 112.5 cc chambers = 10.51:1 ( too high with such a small cam!). The same cam at a 10:1 compression ratio would be nice, but I'd go to a custom 107-108 lsa version if you really want the L88 lope. The motor gets the car to 118+ mph in the 1/4 and can bang out 16mpg on the highway, so superb street strip compromise imho.


Man, I can't beleive I haven't seen your Chevelle around. You weren't at the Grand island show, were you? Only 2 tripower cars there, Ray's 69 and mine I thought.

BTW, I have some videos, incl sound, of the car ( in the Grand Island Holiday Inn parking lot!), if you wanted to hear it idle. I think you'll want more roughness than I have, and I think I have too much!


Your's a 3X2? I know I havent seen a 72 like that. COOL!!!!!!!

Oh, nearly forgot. Sir, if you RPM this motor near 7000, which it DESERVES TO BE! smile.gif , I;d ditch that HV pump in a hurry. THe old L88 pump is awesome, slightly larger than stock. I run a standard Melling. I would NEVER run a HV pump again , unless the motor's internal clearances warranted it. HV is fine for your typical 5500 rpm mill, but , just like crank stresses when you get north of 6500, the stresses on the cam gear etc have to be ridiculous at RPM when your spinning a whole bunch of oil that you don't need to. At least use 7 qts of oil if you stick with it.

My opinion, your professional machinists' may differ!

427L88 No its not a 3x2 though I think that if it was it would turn some heads. Currently I am running a Race Demon 825 cfm. Yes the high volumn pump has been a problem, I was hoping that someone would reply to that. What rear gear are you running in your '67 and what tranny? How many rpms on the highway? I was not at Grand Island I was at the Super Cruise in NT and I did see your car, looks great. Do you think solid low 12's is possible with this set up?

L-71 that 66 chevelle my frind has would run 12.05 with a wore out 26x9 slick leaving a 3000rpm and 4.56's. With 3.55's and western auto g-60's street tires it would run 12.80's.
John

Low 12's!?!? My friend, the little 435hp motor I built mph's enough to run 11.60s with an optimal launch.
Yup, I do. Unless you gear it way back.

Gears- long answer - When I did all the math on the motor, the M20 needed 4.33s to get the rpms right. Well, some time ago, right here on TC, a bunch of Richmond 5-sp road race boxes came up for sale and the ratios, combined with the 3.31s were spot on. I mean the numbers were perfect. I had to get a 5 speed!

Being that the M20 and the T400 have similar ratios, 4.30s would be perfect 1/4 mile gears with a 3500-6800+ powerband. 4.10s would be ok.