39 degree 425 Engine

rt38 classic engines · 05-07-2006, 07:08 PM

Hi All: I reciently rebuilt a 425 from a 1966 Dynamic 88 for a customer and it has severe valve noise, but runs OK. I am in the process of rechecking the valve stem highth, and will install adjustable push rods, but I think I may have the wrong camshaft. I've been told that somtime mid year 1966 Olds changed to the 39 degree engine and this one could be 45 or 39 degree. How can I tell which one I have?

Oldsguy · 05-08-2006, 10:45 AM

Wow, this is a tuff one. If you don't get a reply from someone here in a day or so try realoldspower.com There are some people over there that might be able to help you.

VegasDelta · 05-08-2006, 01:32 PM

Short of tearing it down again, the 39* blocks usually had a drill spot on the web to the left of the engine code. The 39* blocks were used in the Toronado & the 45* were used in the other models. The Toro blocks also used the .921" lifters.

Oldsmaniac · 05-09-2006, 05:28 PM

I believe that nearly all 66 425 engines had the 45 degree cam angle unless it was a Toronado engine with the large lifters....Mondello sells a checking tool and also gives ways to check cam angle....A cylinder head from 39 degree engine will sit atop a 45 degree block but pushrod holes wont be straight thru....Ive found this out the hard way....

05-07-2006, 07:08 PM	#1 (permalink)
rt38 classic engines Junior Member Join Date: May 2006 Posts: 1	39 degree 425 Engine Hi All: I reciently rebuilt a 425 from a 1966 Dynamic 88 for a customer and it has severe valve noise, but runs OK. I am in the process of rechecking the valve stem highth, and will install adjustable push rods, but I think I may have the wrong camshaft. I've been told that somtime mid year 1966 Olds changed to the 39 degree engine and this one could be 45 or 39 degree. How can I tell which one I have?

05-08-2006, 10:45 AM	#2 (permalink)
Oldsguy Administrator Join Date: May 2004 Location: Lees Summit MO Posts: 2,553	Wow, this is a tuff one. If you don't get a reply from someone here in a day or so try realoldspower.com There are some people over there that might be able to help you. __________________ Dan '46 2 door

05-08-2006, 01:32 PM	#3 (permalink)
VegasDelta Member Join Date: Aug 2005 Location: Henderson, Nevada Posts: 34	Short of tearing it down again, the 39* blocks usually had a drill spot on the web to the left of the engine code. The 39* blocks were used in the Toronado & the 45* were used in the other models. The Toro blocks also used the .921" lifters. __________________ 1966 Olds Delta 88 Convertible 1939 Buick Century 2004 Dodge Hemi Ram 2002 Kawasaki Vulcan 1500 FI

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05-09-2006, 05:28 PM	#4 (permalink)
Oldsmaniac Senior Member Join Date: Oct 2005 Location: NJ Posts: 350	I believe that nearly all 66 425 engines had the 45 degree cam angle unless it was a Toronado engine with the large lifters....Mondello sells a checking tool and also gives ways to check cam angle....A cylinder head from 39 degree engine will sit atop a 45 degree block but pushrod holes wont be straight thru....Ive found this out the hard way....