What's the difference? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Mrturner1 · 08-14-2016, 11:18 AM

So I have a 1970 C10, and it came from the factory with an L6 and 4 speed but somewhere along the lines it got swapped for a 355/th400 setup by the previous owner. I got an oil pan gasket for it yesterday and the arch that goes over the timing cover wasn't big enough. I took the gasket back (fel-pro permadry btw, the blue one peice) and ordered one for a 75-85 Chevy small block and it fits perfectly. What does this mean for my block and rotating assembly? Is it gen 1? Something else maybe? The crank journal is clearly bigger

truckster · 08-14-2016, 11:46 AM

It's Gen 1 - Everything up to the LT1 engine is considered Gen 1. There were manufacturing differences over the years.

Mrturner1 · 08-14-2016, 12:03 PM

Quote:

Originally Posted by truckster

It's Gen 1 - Everything up to the LT1 engine is considered Gen 1. There were manufacturing differences over the years.

So what's different about this one? The larger journal is a plus correct?

truckster · 08-14-2016, 01:42 PM

As far as I know, the journal size changed to 2.45 some time in the early 60s and stayed the same. There were a couple of different thicknesses of front cover/oil pan gasket, but I believe that was due to the difference in the channel in the front cover.

The biggest difference between earlier and later Gen 1 SBC blocks would be the later change to 1-piece rear main seal and provision for roller cams.

Mike C · 08-14-2016, 04:34 PM

There were two different versions of oil pan stampings. Regular gasket sets usually come with both sizes of rubber pieces and use the same cork side pieces.

In late '70's (1978 I think) GM switched dipstick to passenger side of block from driver's side and in '86 went to 1 piece rear seal.

All of these things require a different oil pan gasket.

GRX · 08-14-2016, 05:21 PM

Crank journals are the same. Like Mike said ^^. Difference is in the pans. First one was for the older type pan. Thicker gasket required after 1975.

08-14-2016, 11:18 AM	#1
Mrturner1 Registered User Join Date: Nov 2015 Location: Colfax California Posts: 1,644	What's the difference? So I have a 1970 C10, and it came from the factory with an L6 and 4 speed but somewhere along the lines it got swapped for a 355/th400 setup by the previous owner. I got an oil pan gasket for it yesterday and the arch that goes over the timing cover wasn't big enough. I took the gasket back (fel-pro permadry btw, the blue one peice) and ordered one for a 75-85 Chevy small block and it fits perfectly. What does this mean for my block and rotating assembly? Is it gen 1? Something else maybe? The crank journal is clearly bigger

08-14-2016, 11:46 AM	#2
truckster Registered User Join Date: Jan 2001 Location: Orem, Utah Posts: 7,978	Re: What's the difference? It's Gen 1 - Everything up to the LT1 engine is considered Gen 1. There were manufacturing differences over the years.

08-14-2016, 01:42 PM	#4
truckster Registered User Join Date: Jan 2001 Location: Orem, Utah Posts: 7,978	Re: What's the difference? As far as I know, the journal size changed to 2.45 some time in the early 60s and stayed the same. There were a couple of different thicknesses of front cover/oil pan gasket, but I believe that was due to the difference in the channel in the front cover. The biggest difference between earlier and later Gen 1 SBC blocks would be the later change to 1-piece rear main seal and provision for roller cams.

08-14-2016, 04:34 PM	#5
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,727	Re: What's the difference? There were two different versions of oil pan stampings. Regular gasket sets usually come with both sizes of rubber pieces and use the same cork side pieces. In late '70's (1978 I think) GM switched dipstick to passenger side of block from driver's side and in '86 went to 1 piece rear seal. All of these things require a different oil pan gasket. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

08-14-2016, 05:21 PM	#6
GRX Registered User Join Date: Jul 2010 Location: MD Posts: 1,937	Crank journals are the same. Like Mike said ^^. Difference is in the pans. First one was for the older type pan. Thicker gasket required after 1975. __________________ 1969 c-10 Step Side Long Bed. I-6 250cid = = 1969 Pontiac GTO hard top. 400, 4-speed.



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