panchop

i hurt the little high spinning 327 i built for my 65. I am thinking of putting the original block back in but built as a 383. do you think i can use the original 461 heads and cast iron intake and still make decent power. has anyone completed one of these. guess i'll keep the car for a bit longer.

Hitch

It can be done but beware of core shift when you are grinding the block to clear. I know of one 327 that is now a paper weight because of this. I wouldn't do it with a numbers block. Dave

BarryK

a buddy of mine used a 327 and made a 383 stroker out of it. He than used all the "correct" heads, intake, carb, exhaust manifolds, etc to dress it up as a "correct" L76 motor. He's been running it for the last two years in his '65 and it runs great. Even took first in his class at the local "Corvette Challenge" at the local strip last year running that motor.

Scott Marzahl

Greg,
Besides Wes having one, qwik-tripp has one too. Last I heard he was working on another one.

http://forums.corvetteforum.com/show...post1560705677

Donny Brass

Barry, what kind of times did he run ??

BarryK

Donny, I don't remember his times but I did make one run against him myself and besides him having a lot more power in his 383 than I have in my 100% stock L76 it was my first time ever at the track and he blew me out of the water. It wasn't even close. He KILLED me on launch time. 60', 1/8 mile, 1/4 miles, ET and MPH

He is a sometime poster on here so maybe he will respond to this thread if he see it. It's actually Qwik-Tripp that Scott referenced above that I'm referring to.

Yes Scott, Tripp is working on a new motor based on the last couple conversations I had with him. Since he builds his own motors and usually has plenty of extra blocks and parts around it doesn't cost him an arm and a leg to build one and he tends to get bored with a motor after a few years so I guess it's time to replace the current one.

Scott Marzahl

Donny,
This is from Tripp's post.

"xe274s comp cam. w/3.36 gears it ran 13.22@105 "

Donny Brass

that is a really nice time for a 3:36 gear

63 340HP

I'll be building a 388 in the next few months (4.060x3.75). I have heard the same reservations and warnings about 327 block core shift (good to go, or paperweight risk). I have a few 870 blocks to try (with hopes that the first one will be good).

The stock 461/462 heads are the choke point. No guessing there when the C3 guys all encourage running CNC ported 210cc+ intake runners on 383's. The stock heads can be ported to work (461X heads are easier to make work) but don't expect wild peak power past 6000 rpm without a radical cam and much better than stock intake & exhaust mods. Modern large-port aluminum heads cannot be beat for flow performance.

With stock manifolds and a stock intake the 383 power peak is likely to remain below 5500 rpm (below 5000 rpm for most matched cams). Stock exhaust manifolds and mufflers pressurize the back of the exhaust valve enough to negate any potential for beneficial overlap tuning. The result of the backpressure is that narrow lobe center cams just kill low rpm torque with no benefit, so typical solid-flat tappet circle track grinds fail to work well. A cam in the LT1 or 30-30 style (114-116+ LSA) will get the most power from the cubes when your blowing through manifolds & mufflers (something we have heard many times before).

Good power through manifolds and mufflers can be achieved with modern lobe profiles, better power than with the LT1 cam (IMO), but there are very few off the shelf grinds that do even a slightly better job (leaving a custom grind in your future if you choose the manifolds and mufflers challenge).

Regardless of the challenge to make power through the old iron heads & manifolds, the 383 will easily make 30-50 ft.lbs. and 20-30 hp more than the 327 from off-idle to 5000 rpm (with the same heads & cam). This increase in hp per dollar spent is hard to beat if you already have the engine apart anyway. If you want power from the 383 past 5500 rpm expect to spend money on porting and or good flowing heads.

Good luck on the build up. Let us know what you come up with as the challenge of using old iron heads and manifolds & mufflers is not all that common (it's too easy to buy a crate 383 that will deliver 25-50hp more through open headers).

KyleDallas

Right on 63 340hp... the reason many 383's can't make 400hp
while others scream past the 500hp mark.... heads.

Stock double humps... even the 461X variety aren't enough head
for a 383 in stock configuration (unported)... you'll run out of air in
the 5000rpm range....

For a 383 you need a 195cc runner minimum up to 227cc's...
ideally you want a head that flows over 250cfm @ .500 lift...
with this hardware you'll go 450 to 550 hp depending on cam/tuning/exhaust.

Stock double humps have runners in the 160cc range and flow
around 200cfm.... this is why all the cam in the world won't help a
383 when it starts gasping for more air in the 5000rpm range...
200cfm of air is all you're going to get... even when the engine is asking
for more.

for 383's, 395's, and 400 ci's

1. Bowtie Vortec Large Port 215cc's
2. Dart Iron Eagle Platinum's in 200cc or bigger
3. AFR's
4. Canfields
5. Brodix IK's

Edelbrock Victor Jr. heads can often be found on Ebay cheap
and will fit the 250cfm- 195cc up needs of a 383.

panchop

I'd like to keep it stock looking. I have a set of ported , big valve 292s around. ,maybe they will work a little. not looking to make a screamer.

MikeM

I built up a 400 SBC years ago. It was a '70 model with the higher compression pistons than later 400engines. 10-1 rated, I think. I put in a L-79 cam, '69 Z-28 carb and intake. That's it. Stock 2 barrel 400 heads/valves. That engine is much stronger than a stock L-79.

I'd have to agree it runs out of wind at some point because of the heads but by the time it does, the 327 wouldn't even be in the smoke. Now, I like 327's and I have no ax to grind. Just giving you an example of what you might expect.

wesmigletz

If you're going to stroke your SJ 327, I'd strongly recommend a set of splayed 4 bolt main caps from Pro Gram Engineering. Get a dedicated cap screw SJ stroker connecting rod to minimize block grinding. A nicely ported set of factory heads should support your 383 nicely. Aside from the bolt holes on the ends of the 292 heads, they will look at home on your 327 block.





Our 62 was a low horse 327/300 HP car. We built a 6" rod stroker using a 3.85" stroke, with a .040" overbore. Our 62 461X heads received a little clean-up work, and were cut for 2.02/1.6" valves. We used dished pistons and a cheap, fairly mild re-ground solid flat tappet cam.

The 62 is my wife's weekend, putt-around car, and our stroker was built accordingly. The car has a mild lope at idle, starts right up, can be driven anywhere, including L.A. traffic in 100* heat. Driven normally, it's as docile to drive as a carbureted grocery getter can be. On the other hand, violent wheel spin and sideways acceleration is just a blip of the throttle away...

With a stock TH350 trans (left in D upshifting at 4500 RPM), I went 13.2 @ 106 uncorrected (12.88 @ 109 if you believe in altitude correction factors) at LACR on 7-29-07. The car was spinning well past the 60' mark, and it was 95* when I arrived at the track in the morning. The above pass was on 235/70/R15 radial TA tires. I ran a 2002 C5 Vette with intake, custom tune, and cat back mods. I beat him by 4.5 MPH, FWIW.

There's more in the combo, but LACR shut down on 7/29 and I haven't raced since. At the time I ran, the engine only had about 200 miles on it, and was a long way from being sorted out.

AZDoug

What failed on the 327?

Doug

panchop

i blew the first to second shift at about 6500+ RPM with my foot all the way in. I have a couple bent and proken pushrods, a couple boogered up shaft style rockers. I haven't pulled the heads yet but i imagine i will have a couple funny looking valves. I have decided I want an engine in milder tune anyhow for this car.

sub006

[QUOTE=panchop;1563430134]I'd like to keep it stock looking. I have a set of ported , big valve 292s around. ,maybe they will work a little. not looking to make a screamer.[/QUOTE

You could always PAINT the aluminum heads ORANGE.

63 340HP

except... the unported small valve 461X heads on my bench have ~185cc intake runners. I thought X heads had 172cc runners (at best, like the X-head "sandbagger" urban-myth claims) but the uncut intake runner volumes measured from 183cc-190cc. I had wondered how wesmigletz achieved intake flows of 263cfm on his ported X heads, and it motivated me to blow the dust off these stock eliminator legal June 63' X heads. The X-heads offer a bit more intake volume than the large valve 462's currently on my 327 .

While not ideal for a max power runner, these should be good for 375-400 peak horsepower through L76 manifolds & mufflers (with the right cam, 450hp+ through uncorked headers if a stock look is not desired). The X-head 383's increase in peak hp & torque is not much to brag about (with modern cover article $4,000 crate engines delivering over 500 hp) but achieving an average horsepower from 2000-6000 rpm that is close to the original L76's advertised 340-hp is not all that weak either.

63 340HP

Thanks for the recommendation. I followed your build up and learned from the experience (your success is good motivator).

A main stud kit is the minimum improvement plan for insurance, and I have been looking for a main cap girdle that fits the 327 main cap bolt spacing. I may have to weld and redrill a 350 or 400 main cap girdle to fit (or abandon the idea). I could not get a straight answer if a 2-bolt 350 and 327 have similar main cap bolt spacing (anyone)?

The 292 head comment reminded me of a set of heads I found on the shelf near my X-heads, a set of ported 186 heads that have the bolt holes filled with JB weld with the ends ground to look like stock low performance heads (not like camel humps, cheater heads, but I understand they were effective at the track until the owner got caught). There are a lot of old "cheater" circle-track parts sitting on dusty shelves that may come up short compared to new castings but they still flow 15% better than stock iron heads.

wesmigletz

63 340 hp,

Here is a source for SJ splayed main cap kits. I think Milodon make them them for the SJ blocks as well.

www.pro-gramengineering.com

They're not cheap, neither is having the machine work for them. However, they do provide some insurance for your bottom end. I think dedicated splayed caps for the SJ blocks is a better alternative to cutting a block for 350 sized main caps, because you may be creating other issues. Be sure to keep your rotating assembly light and internally balanced.

Wes