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Big block Chevy engines | Last updated on September 26, 2013 |
Introduction
When I started
this Web site back in 1996 there wasn't much information about big block Chevy engines on the Web, so I
decided to create this page. I don't claim to be an expert about
engines and am simply sharing some of the information that I've compiled from many different
sources.
Eventually I'd like to be able to provide some good technical information, especially about cylinder heads, and also make the casting number lists as complete
as possible for those of us that are hunting around for old blocks, cranks and heads.
I'd also like to be able to provide more information on is the maximum bore size that can be reliably used on various big blocks. I've heard of people going as
much as .125" over stock on some early 396 blocks, although you'd certainly want to check the wall thickness of the block with a sonic thickness tester before
taking one out that far. Aftermarket pistons are available for .090" 454s and in some cases as much as .125" over.
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Preparing an engine block for machining
The first step in preparing a bare block is to get it clean. Begin by scraping off any gasket adhesive and the worst of the built-up grease. Even with all of
the right tools, tearing down a block can test your patience, and I recommend having the shop that's going to clean the block also remove all of its plugs. If
you want to do it yourself, here's how:
All of the freeze plugs need to be removed with a hammer and punch. Pull them out with pliers before you knock them all the way into the water jackets.
(Otherwise, since they're non-magnetic, you'll have to keep moving the block around until the plug lands over one of the holes for them, getting a grip on it
with the pliers, and pulling it out. This is how we learn humility.) Now out come the oil gallery plugs, which have weird square female heads that even with
the proper Snap-On tool still often have to be carefully drilled out.
The lifter galley and the entire inside of the block were then fully deburred to remove all of the "pockets" where casting sand and metal may come loose,
something I'd suggest to anyone building an engine. I used a die grinder with emery cloth cartridges, which makes it possible to reach into all of the block's
contours.
Once you've got the block completely bare (except for the leaving main caps in the right places) and deburred, you're ready to call the local engine rebuilder
and find out when they're changing their solution so you can get it in their tank when it's not full of sludge. The shop I took the block to for it to be hot
tanked let me bring it in right after they changed their tank's solution on a Friday afternoon, and we lowered it in and let it spend the whole weekend
thinking over how badly it wanted to hang onto the last of its grease. Monday morning I was there early to hoist it out of the tank, and spent a full fifteen
minutes running water all over it and through all of the passages, ending up with something that was clean. Then I got an air line and got the entire block
completely dry, and it was ready for machining.
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Big block Chevy bore and stroke
| Engine Size |
Stock Bore |
+.060"-over |
Stock Stroke |
| 366 |
3.935" |
3.995" |
3.760" |
| 396 |
4.094" |
4.154" |
3.760" |
| 402 |
4.125" |
4.185" |
3.760" |
| 427 |
4.250" |
4.310" |
3.760" |
| 454 |
4.250" |
4.310" |
4.000" |
| Mark 5 — 502 — Mark 6 |
4.468" |
4.530" |
4.000" |
| 454 Engines |
3.760" |
4.000" |
4.250" |
4.500" |
4.750" |
4.875" |
| Stock bore = 4.250" |
427" |
454" |
482" |
511" |
539" |
553" |
| Bored .030" = 4.280" |
433" |
460" |
489" |
518" |
547" |
561" |
| Bored .060" = 4.310" |
439" |
467" |
496" |
525" |
554" |
569" |
| Bored .090" = 4.340" |
445" |
473" |
503" |
533" |
562" |
577" |
| Bored .100" = 4.350" |
447" |
476" |
505" |
535" |
565" |
580" |
| Bored .125" = 4.375" |
452" |
481" |
511" |
541" |
571" |
586" |
| 502 Engines |
3.760" |
4.000" |
4.250" |
4.500" |
4.750" |
4.875" |
| Stock bore = 4.468" |
472" |
502" |
533" |
564" |
596" |
611" |
| Bored .032" = 4.500" |
478" |
509" |
541" |
573" |
604" |
620" |
| Bored .062" = 4.530" |
485" |
516" |
548" |
580" |
612" |
629" |
| Bored .092" = 4.560" |
491" |
523" |
555" |
588" |
621" |
637" |
| Brodix, Dart & Merlin Blocks |
4.000" |
4.125" |
4.250" |
4.375" |
4.500" |
4.625" |
4.750" |
4.875" |
5.000" |
| 4.500" bore |
509" |
525" |
541" |
557" |
572" |
588" |
604" |
620" |
636" |
| 4.530" bore |
515" |
532" |
548" |
564" |
580" |
596" |
612" |
628" |
645" |
| 4.560" bore |
523" |
539" |
555" |
572" |
588" |
604" |
621" |
637" |
653" |
| 4.590" bore |
530" |
546" |
563" |
579" |
596" |
612" |
629" |
645" |
662" |
| 4.600" bore |
532" |
548" |
565" |
582" |
598" |
615" |
632" |
648" |
665" |
| 4.625" bore |
537" |
554" |
571" |
588" |
605" |
622" |
638" |
655" |
672" |
To calculate the displacement of an eight-cylinder engine: bore x bore x stroke x 6.2832
Cubic inches x 16.387 = cubic centimeters. Cubic centimeters x .061 = cubic inches
The five largest Bonneville Salt Flats engine classes
| AA / Fuel and AA / Gas |
501 cubic inches and over |
8.21 liters and over |
| A / Fuel and A / Gas |
440 to 500 cubic inches |
7.21 liters to 8.19 liters |
| B / Fuel and B / Gas |
373 to 439 cubic inches |
6.11 liters to 7.19 liters |
| C / Fuel and C / Gas |
306 to 372 cubic inches |
5.01 liters to 6.10 liters |
| D / Fuel and D / Gas |
261 to 305 cubic inches |
4.27 liters to 5.00 liters |
BBC Engine block casting numbers
| Number |
Size |
Rated Horsepower |
Production |
Main Caps |
| 340220 |
427 |
|
1968-1976 |
Four-bolt (tall-deck) |
| 346236 |
454 |
|
1975 |
Two-bolt |
| 361959 |
454 |
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1978-1987 |
Two-bolt or four-bolt |
| 364776 |
427 |
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1974-1976 |
Four-bolt
(tall-deck) |
|
364776 |
454 |
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1977-1990 |
Four-bolt (tall-deck) |
| 364779 |
366 |
|
1968-1990 |
Four-bolt (tall-deck) |
| 473478 |
427 |
|
1977-1990 |
Four-bolt (tall-deck) |
| 1014183 |
366 |
|
1991-1992 |
Four-bolt (tall-deck) |
| 3855961 |
396 |
325 and 360 |
1966 |
Two-bolt |
| 3855962 |
396 |
360, 375, and 425 |
1965-1066 |
Two-bolt or four-bolt |
| 3869942 |
427 |
390 and 425 |
1966 |
Two-bolt or four-bolt |
| 3873858 |
396 |
375 |
1966 |
Four-bolt |
| 3902406 |
396 |
325, 350, and 375 |
1967 |
Two-bolt or four-bolt |
| 3904351 |
427 |
425 |
1967 |
Four-bolt |
| 3916321 |
427 |
425 and 435 |
1968 |
Four-bolt |
| 3916323 |
396 |
325, 350, and 375 |
1968 |
Two-bolt or four-bolt |
| 3935439 |
427 |
435 |
1968 and 1969 |
Four-bolt |
| 3935440 |
396 |
350 and 375 |
1969 |
Two-bolt or four-bolt |
| 3937724 |
366 |
|
1968-1976 |
Four-bolt (tall-deck) |
| 3955272 |
396 |
325, 350, and 375 |
1969 |
Two-bolt or four-bolt |
| 3955272 |
402 |
325, 350, and 375 |
1969 |
Two-bolt or four-bolt |
| 3955274 |
366 |
|
1968-1976 |
Four-bolt (tall-deck) |
| 3955276 |
427 |
|
1968-1973 |
Four-bolt (tall-deck) |
| 3963512 |
454 |
360, 375, 425, and 460 |
1968-1971 |
Two-bolt or four-bolt |
| 3969852 |
366 |
|
1968-1976 |
Four-bolt (tall-deck) |
| 3969854 |
402 |
360 and 375 |
1972 |
Two-bolt |
| 3969854 |
454 |
360 and 375 |
1972 |
Two-bolt |
| 3969858 |
427 |
|
1968-1973 |
Four-bolt (tall-deck) |
| 3999289 |
454 |
|
1972-1979 |
Two-bolt |
| 3999290 |
402 |
240 |
1972 |
Two-bolt |
| 3999293 |
366 |
|
1968-1976 |
Four-bolt (tall-deck) |
| 3999294 |
427 |
|
1968-1973 |
Four-bolt (tall-deck) |
| 10114182 |
454 |
|
1992 |
Four-bolt (tall-deck) |
| 10114184 |
427 |
|
1991-1992 |
Two-bolt or four-bolt |
| 14015445 |
454 |
|
1978-1987 |
Two-bolt or four-bolt |
BBC oval port cylinder head casting numbers
| Number |
Engine Size |
Year |
Combustion Chambers |
| 336781 |
454 |
1973-1985 |
Open chamber |
| 346236 |
454 |
1975-1978 |
Open chamber ("peanut" ports) |
| 353049 |
454 |
1970-1973 |
Open chamber |
| 3872702 |
396 and 427 |
1966 |
Closed chamber |
| 3904390 |
427 |
1966 |
Closed chamber |
| 3904390 |
427 |
1966 |
Closed chamber |
| 3909802 |
396 and 427 |
1966-1967 |
Closed chamber |
| 3917215 |
396 and 427 |
1966-1969 |
Closed chamber |
| 3931063 |
396 and 427 |
1966-1969 |
Closed chamber |
| 3964280 |
427 and 454 |
1966-1970 |
Closed chamber |
| 3964290 |
427 and 454 |
1966-1970 |
Closed chamber |
| 3993820 |
402 and 454 |
1970-1971 |
Open chamber |
| 3999241 |
402 |
1970-1972 |
Open chamber |
| 6272292 |
402 and 454 |
1971 |
Open chamber |
BBC rectangular port cylinder head casting numbers
| Number |
Engine Size |
Year |
Combustion Chambers |
| 3856208 |
396 |
1965 |
Closed chamber |
| 3904391 |
396 and 427 |
1965-1967 |
Closed chamber |
| 3919840 |
396 and 427 |
1965-1969 |
Closed chamber |
| 3964291 |
396, 402, and 427 |
1965-1970 |
Closed chamber |
| 3964292 |
454 |
1970 |
Closed chamber |
| 3994025 |
454 |
1971 |
Open chamber |
| 3994026 |
454 |
1971 |
Open chamber |
| 3996074 |
454 |
1971 |
Open chamber |
| 6258723 |
454 |
1971 |
Open chamber |
| 6272990 |
454 |
1971 |
Open chamber |
Big block Chevy valve covers
Here are some of the cast aluminum big block Chevy valve covers that I've collected over the years.
Among the very first aftermarket valve covers for the 396 and 427 engines were these from Cal Custom, in Gardena, California. These were die-cast parts that
were high-quality and very popular. The early versions say "Gardena, Calif. No. 40-2100". The later versions say "Carson, Calif. No. 4701-4028". The only
difference is in the logo, which is on the breather knock-out.
These were one of very few aftermarket valve covers to have oil drippers located above the rocker arms. Although Cal Custom made valve covers for many
different engines, the big block Chevy version was the only one that I know of, and the only aftermarket big block Chevy valve covers that I know of other than
Edelbrock, that had drippers.
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Edelbrock has made several different styles of cast aluminum valve covers for the big block Chevy, and this pair is probably the earliest.
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Here's another style of Edelbrock cast-aluminum valve cover for big block Chevy engines that was similar to the ones shown above, but with a straight Edelbrock
logo.
A third version was essentially a Mickey Thompson valve cover with the Edelbrock name on it, along with a mirror-imaged Chevy bow-tie logo.
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These sand-cast Keith Black valve covers were made in the late 1970s and early 1980s.
Although KB has made several styles of their own breathers, the pair shown here has been fitted with aftermarket "no-name" breathers.
These came fully polished, complete with ruts and waves courtesy of a polisher who was in too much of a hurry. I sanded them smooth, bead blasted them, and
then coated them with
Gibbs Brand to protect them.
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These sand-cast Eelco valve covers were probably made in the late 1960s. I only bought them because they were oddball and cheap. They were on eBay, and I was
the only bidder.
Every Eelco part I've seen was a copy of something that somebody else had already done a better job of.
The quality of these castings is the worst that I've seen on any valve covers.
Even after I sanded the worst spots, bead blasted them, and coated them with
Gibbs Brand, they're still ugly.
These things weigh about three times as much as Cal Custom valve covers. They are the heaviest one-piece big block Chevy valve covers that I've ever seen or
heard of.
Leave it to Eelco to make "performance" parts that could actually make a race car slower.
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Gennie Shifter valve covers were designed to make a rat look like it had 16-valve heads. Also, the end caps can be bolted on to give the look of overhead
cams.
A lot of thought went into their design. Die-cast and exceptionally good quality, they were probably made sometime in the 1980s.
This pair is NOS, bought on eBay.
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This is a rare pair of die-cast aluminum valve covers that were made in the 1990s by Advance Marine in Monrovia, California.
The tops of these are angled like many Ford valve covers.
The Advance Marine valve covers were good die castings, with clearance for virtually any rocker arms.
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Milodon cast aluminum valve covers were made in the late 1970s.
These are among the hardest big block Chevy valve covers to find.
This pair is NOS, bought on eBay from
Pat Musi for $55.
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Big block Chevy engine resources
Big Block Chevy Engine Parts Identification
Mike Maciolek has put together a site that is packed with information about engine codes for both rats and mice.
http://www.nastyz28.com/bbcmenu.php
Big Block Chevy Engine Projects
This page describes the engines that I'm building for my roadster and my truck.
http://www.roadsters.com/power/
Chevy Talk
This is the most popular online forum for exchanging information about
high-performance Chevy engines as well as just about everything related to all years and models of Chevys. The site is large and very active.
http://www.chevytalk.org/
MorTec, Inc.
The creators of "Engine Math For The Rest Of Us"
software provide a great deal of information on their site, including Chevy bore and stroke,
casting numbers and their locations, and crank journal sizes.
http://www.mortec.com/
The Stellings timing cover that is shown on the right was made in the 1960s.
In 2005, I bought it from a veteran
racing engine builder who was selling it on eBay, and then cleaned it up with fine abrasives.
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All text and images on Roadsters.com
are Copyright 1996-2013 Dave Mann
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