283 disassembly cam ID

[Lynn L.]

1960 290hp motor, rebuilt in 1990, never started motor after assembly, I purchased car this fall and just tore down to bare block to have machine shop evaluate components. The cam is a GM, with 6098 part number, no wear appears new, Any help identifying cam appreciated. Lynn

[David L.]

Re: 283 disassembly cam ID

1960 290hp motor, rebuilt in 1990, never started motor after assembly, I purchased car this fall and just tore down to bare block to have machine shop evaluate components. The cam is a GM, with 6098 part number, no wear appears new, Any help identifying cam appreciated. Lynn

My 1963 Chevrolet Parts Catalog (Oct. 1962) lists the following in Gr. 0.519, CAMSHAFT:

57-61 PASS., CORVETTE w/H.L. Cam (283)
62-63 CORVETTE w/F.I., Sp. H/Per...........................special performance (cast 3736098)................3736097

The same part number and casting number is listed in my 1982 Corvette Parts Catalog (Nov. 1981) for the same models listed previously.

GM # 3736097 is also listed in my 1957 Chev. Parts Catalog (Mar. 1957) for the 1957 PASS., CORVETTE w/H.L. Cam.

I would say that your "6098" camshaft is the right one. The "6098" casting is just a shortened version of "3736098".

Dave

[Duke W.]

Re: 283 disassembly cam ID

3736098 is the finished camshaft part number. It is also referred to in the P&A catalog as the "ID number". The was no "casting number" for GM camshafts, but the finished camshaft drawings have rough as cast lobe dimensions, which were close to finished dimensions in order to minimize grinding.

3736097 is an ASSEMBLY of camshaft and dowel pin. OTC camshafts were ONLY sold as the ASSEMBLY of camshaft and pin.

Nowadays, all flat tappet small block camshafts regardless of manufacturer are ground from a single blank supplied by the CWC division of Textron Corporation. This blank includes the pin and all machining is done by Textron except lobe grinding. So the scores of different camshaft designs currently available from a dozen or so "manufacturers" are all ground from this same blank.

The 3736097 is commonly known as the "Duntov cam", and was used on all mechanical lifter small blocks from '57 to '63.

What you have is a GM manufactured Duntov cam.

BTW if engine has the original type spindly, prone-to-break 283 connecting rods I highly recommend you replace them with a set of Eagle SIR 5700 rods that you can obtain for about 250 bucks. They are a little heavier than the OE rods so rebalancing the rotating/reciprocating assembly will be required, but they will give you a bulletproof bottom end that will be good for over 7000 revs, and the only thing that could hurt it is oil starvation.

Duke

[Lynn L.]

Re: 283 disassembly cam ID

Thank you for ID help, and I will Purchase the eagle sir 5700 rods. The motor was assembled with GM connecting rods, and Ross Racing HC375 pistons. (standard bore) The pistons are extremely domed which damaged 4 spark plug tangs due to turning the motor over by hand. ( the plugs would have to indexed to prevent compression damage to plugs) Compression ratio? Piston recommendation appreciated!! Lynn

[Duke W.]

Re: 283 disassembly cam ID

That was a poor piston choice. I'm sure the CR is waaaaaay too high for premium pump gas.

You should measure the current CR then target a new CR of no more than 10.3:1 for the Duntov cam. See the Fall 2009 Corvette Restorer for an article on how to manage your compression ratio, and you should also go through my presentation from the 2012 San Diego convention, which is online.

I recall seeing a reproduction of the 10.5:1 283 FI piston at a show a few years ago. I think the seller was Danchuck, but I don't know who manufactures this piston. Check KB and Sealed Power for offerings. I'm sure you can come up with a piston/head gasket combination that will get the CR into the proper range.

If you massage the heads and install 1.84" inlet valves (see the Fall 2010 Corvette Restorer) it will be a reliable 7000-rev screamer.

Duke

[Joe R.]

Re: 283 disassembly cam ID

That was a poor piston choice. I'm sure the CR is waaaaaay too high for premium pump gas.

You should measure the current CR then target a new CR of no more than 10.3:1 for the Duntov cam. See the Fall 2009 Corvette Restorer for an article on how to manage your compression ratio, and you should also go through my presentation from the 2012 San Diego convention, which is online.

I recall seeing a reproduction of the 10.5:1 283 FI piston at a show a few years ago. I think the seller was Danchuck, but I don't know who manufactures this piston. Check KB and Sealed Power for offerings. I'm sure you can come up with a piston/head gasket combination that will get the CR into the proper range.

If you massage the heads and install 1.84" inlet valves (see the Fall 2010 Corvette Restorer) it will be a reliable 7000-rev screamer.

Duke

Hi Duke,

Here's a link to the compression ratio article (starting on page 5) that you mentioned:

http://www.stlouisncrs.org/news_files/St_LouisNCRS_ChapterNewsletter2ndQuarter2012.pdf

and here is your presentation from the San Diego convention:

http://stlouisncrs.org/news_files/DukeWilliamsEngineTuningPerformance&EconomySeminar.pdf

Joe

[Duke W.]

Re: 283 disassembly cam ID

Thanks for posting those links, Joe

[Lynn L.]

Re: 283 disassembly cam ID

Just printed Compression Ratio Explained, appreciate help. Thanks Lynn

[Richard M.]

Re: 283 disassembly cam ID

I'm in the process of rebuilding a '61 315HP 283. I've chosen the Duntov equivalent CS113R camshaft and AT 992 lifters, both from NAPA made by Sealed Power.

I'm also in the process of piston selection, and I'm looking at the Keith Black Hypereutectic domed piston, KD-166. Dome height is 0.170".


Specs here.....

http://www.summitracing.com/parts/uem-kb166-030/overview/make/chevrolet