Big Block guys, Need Help please...... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TP from Cntl PA · 03-05-2006, 07:55 PM

I had a book laying around that gave you everything you needed to know on how to tell the difference between what CI block you might have, but I can't seem to find it. I need to know where/what to look for on my Big Block to verify it is indeed a 454(Truck came OE with a 350, so it is not original)

It isn't running right either. Doesn't seem to have much low end, and it will hesitate some while driving when you get on it and backfire out the exhaust once and awhile without warning. The pervious owner put an Edelbrock on it, and it may need tweaked some, but I have a gut feeling it is ignition timing. I don't have a BBC book, so does anyone have the spec's?

TIA,
TP

**68350** · 03-05-2006, 08:50 PM

points or hei? Almost sounds like bad points or timing, sorry no specs handy.

Robznob11 · 03-05-2006, 10:41 PM

specs on a 454 are 4inch stroke 4.25 inch bore. if it is a 454 the last 3 #s of your casting are likley 445 since this block was produced from late 70 to 90s there are also a few other castings. that are mark 4 I want to say that the last 3 #s are 289 or 389 there are also 2 more. most 427s used the same block but they have a shorter stroke crank althouth the 454 crank can be installed to make them a 454. mortec has all the casting #s you need to identify chevys. just do a serch for mortec casting numbers and you will find there site. i build stroker bbc so i can let you know more if you need just email me..

Robznob11 · 03-05-2006, 10:47 PM

the block casting # is located on the block on the lip right above where the bell housing bolts on. should bo on the driver side if you take a flash light and look down on the bell housing behind the intake you should be able to spot it easy on the lip of the motor.... happy hunting...

TP from Cntl PA · 03-06-2006, 07:00 PM

Thanks Guys...........Looks like they have HEI on it, but I am not sure. Was going to tear into it tonight, but am feeling a bit under the weather so I am going to wait until it warms up enough to get my steam jenny out and blow the crude off of it before I start wrenching. Supposed to be in the 60's here this weekend which will be perfect.

03-05-2006, 07:55 PM	#1
TP from Cntl PA Registered User Join Date: Apr 2003 Location: Central PA....In the Berg of Nisbet Posts: 790	Big Block guys, Need Help please...... I had a book laying around that gave you everything you needed to know on how to tell the difference between what CI block you might have, but I can't seem to find it. I need to know where/what to look for on my Big Block to verify it is indeed a 454(Truck came OE with a 350, so it is not original) It isn't running right either. Doesn't seem to have much low end, and it will hesitate some while driving when you get on it and backfire out the exhaust once and awhile without warning. The pervious owner put an Edelbrock on it, and it may need tweaked some, but I have a gut feeling it is ignition timing. I don't have a BBC book, so does anyone have the spec's? TIA, TP __________________ '72 K-20 EFI'ed 250 Inline/4spd stake body, Farm Truck '71 C-20 Cummins Diesel Powered, In storage thanks to $5.00 diesel! '69 3500 GMC 305V-6/4spd, Still under reconstruction.......... Inlines Rule! 6 soldiers standing is better than 8 laying down!!!!!!!!

03-05-2006, 08:50 PM	#2
68350 Senior Member Join Date: Jan 2002 Location: Williston, ND Posts: 2,999	Re: Big Block guys, Need Help please...... points or hei? Almost sounds like bad points or timing, sorry no specs handy. __________________ 68 Chevy CST/10, 50th Anniversary, 327/th400, 373 posi, buckets 68 GMC Shortbox Stepside, 402/th400, Tilt, Tach, Bucket Seats, 3.08 Positraction 69 Chevy Camaro SS, 383, 4 speed, positraction 70 Chevy El Camino SS396, Triple Black, 454/th400, Tach 70 Chevy Shortbox Stepside 4x4, 350/th350, Tilt, Tach, Cab Lights, Bumper Guards, Tow Hooks 70 Chevy 3/4 Longbox, 350/auto, 70k, SURVIVOR 71 Chevy Blazer, CST, 350/auto 71 GMC Sierra K2500, 454, 4 speed, 4.10 posi, 37s 71 Custom/30, Open Road, 350/th400, tilt 72 Chevy Shortbox Fleetside, 496 Stroker/th400, Tilt, Tach, Bucket Seats, 3.42 Posi 72 GMC Sierra Grande 2500. 427/th400, tilt, a/c, tool and stowage, buckets/console, 3.54 posi

03-05-2006, 10:41 PM	#3
Robznob11 Registered User Join Date: Feb 2004 Location: brownfield texas (west texas) Posts: 1,936	Re: Big Block guys, Need Help please...... specs on a 454 are 4inch stroke 4.25 inch bore. if it is a 454 the last 3 #s of your casting are likley 445 since this block was produced from late 70 to 90s there are also a few other castings. that are mark 4 I want to say that the last 3 #s are 289 or 389 there are also 2 more. most 427s used the same block but they have a shorter stroke crank althouth the 454 crank can be installed to make them a 454. mortec has all the casting #s you need to identify chevys. just do a serch for mortec casting numbers and you will find there site. i build stroker bbc so i can let you know more if you need just email me..

03-05-2006, 10:47 PM	#4
Robznob11 Registered User Join Date: Feb 2004 Location: brownfield texas (west texas) Posts: 1,936	Re: Big Block guys, Need Help please...... the block casting # is located on the block on the lip right above where the bell housing bolts on. should bo on the driver side if you take a flash light and look down on the bell housing behind the intake you should be able to spot it easy on the lip of the motor.... happy hunting...

03-06-2006, 07:00 PM	#5
TP from Cntl PA Registered User Join Date: Apr 2003 Location: Central PA....In the Berg of Nisbet Posts: 790	Re: Big Block guys, Need Help please...... Thanks Guys...........Looks like they have HEI on it, but I am not sure. Was going to tear into it tonight, but am feeling a bit under the weather so I am going to wait until it warms up enough to get my steam jenny out and blow the crude off of it before I start wrenching. Supposed to be in the 60's here this weekend which will be perfect. __________________ '72 K-20 EFI'ed 250 Inline/4spd stake body, Farm Truck '71 C-20 Cummins Diesel Powered, In storage thanks to $5.00 diesel! '69 3500 GMC 305V-6/4spd, Still under reconstruction.......... Inlines Rule! 6 soldiers standing is better than 8 laying down!!!!!!!!

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