I have a 425 Oldsmobile and am trying to figure out what cam bank angle I have whether its a 39 degree or a 45 degree. Can anyone tell me a 100% sure way to figure this out? Also is there anyway of telling if the heads on the engine are the origional heads that came on the engine. Here is some of my eng info.

Block casting 389244D
Heads Casting B 389395
Lifter diameter is .842

 

With the manifold off, put a “straightedge” on the intake surface of the head. Measure the distances (above and below the head) between it, and the pushrod.

If they are the same, you have 45° bores, if the bottom is closer, than the top, it's 39°.

I don't remember the number, but it's more than obvious.

Norm

 

Okay so when you say measure the distances above and below the head i am a little confused. When i measure the distance below the head do i measure from the bottom of the head to the top of the lifter bores, and when i measure above the head where do i measure from the bottom of the head to the top of the head? Let me know when you get a chance and thanks for helping me out on this.

Ray

 

Between the "straightedge" and the pushrod.

Norm

 

This may sound complicated and Norm's method is dead-on accurate, but here goes.

According to Mondello's engine tech book, which has been questioned for its accuracy, a block cast with your number and the .842 lifter will be a 45 degree block. A block with your number and lifter size will be a 39 degree block IF you also have a " drill spot " on the block. I have worked on a couple of these and the drill spot is located on the small raised part of casting that is in front of the oil fill tube and goes from the base of the Intake manifold end-rail forward to the back of the water pump and looks like someone started to drill a 1/4 " hole and stoped after about a 1/16 th of an inch of depth.

Hope this is not too confusing...I still trust Norm's method the most.

Danny

 

Before he retired, Joe sold a tool for that purpose. Don't know if the new guy still sells it, but the difference is easy to see.





The scan is from a '97 Mondello catalog.

Norm

 

Hi, i'm new here, and i live in Austria this is an small country in Europe, i do have the same problem whit the 425 BB i want to put it in an 79 olds cutlass calais, i did found this photo on the internet page from oldspower.com here ist the complet link http://www.oldspower.com/photopost/d...0/425block.jpg as you can see there is an drill spot on the left near the oil tube, i hope that this is what you mean, i'm not very sure, hope that someone can tell me for sure if this is that drill spot! I allso do have 0.842 lifters and the block castingnr is 389244 but my headnr is 548 and it is an C head with small 2.000 intake valves. I hope that Ray will find the drill spot to. Berend

 

Following is from a post at Real Olds Power.


Norm

 

I do have that drill spott on my 425 as seen on the photo i did sent, my engine daycode is 298 on the back of the block near the distributor, witch means it is an 1967 OKT 25 or 26 built 425 the vincode on the right cylinder is P071391L. P= 1967 numbers are assemblycode and L=low comp.9.0:1 so ist an 300HP 425 this is what the american V-8 engine data book says, it came out of an jetstar with an 2BB carb. Hope you are right and ist is an 39 degree block, but i will measure it to by sure.
Ray, yes i know about mondello, i will order there tech catalog! i do know that they are expensive, perhaps somebody can tell my an other shop for olds 425 and A/G body parts but they schould sent there parts to Austria Europe! Thanks to Norm for the photos, they are clear and now i know how to messure it.
Berend

 

Contact one of the following Olds specialists. Any one of them can help you put together the combination that will be best for you.

BTR Performance (Bill Trovato)
http://www.btrperformance.com/

Dick Miller Racing (Dick Miller)
http://www.dickmillerracing.com/

Greg’s Performance (Greg Godon)
http://members.aol.com/gregsperformance/

MJ Proformance (Mark Smith)
http://www.mjproformance.com/

Rocket Racing and Performance (John Stolpa)
www.rocketracingperformance.com

Dave Smith Engineering
25078 Road 196
Exeter, CA 93221
(559) 562-3500

Norm

 

Thanks again Norm, for your information.

Berend

 

Hi, yes its an rare 39 degree 425 i did measure it the way Norm shown on the photos. The drill spot is there near the oil tube shown on the photo i did sent from the oldspower.com page. Hope this wil help others to.

Berend

 

What did you stick in the lifter bore to measue it?

 

Hi, i did presst hard with an straight piece of metal on the lifter, cam muss still be in the engine, and did take an other to find the richt angle. so you don't have to stick something in to the lifter bore, if you push hard enough on the lifter so it wil, muss be straight on the lifter than you can measure the angle with an other piece of metal. did try to put some fotos on here but did not work so far, will try again tomorrow, do have'n new computer and this thing is not doing the way i want to!
Berend

 

For those who find this thread and need this info, here is a pic that will show how to visually tell the differance. Of course measuring is ALWAYS the absolute way to tell, but the pic also makes it fairly simple.

 

i just put up a post about 39*vs.45* B Heads..this thread was helpful to me because all i have is the heads & not the block i do however have a 455 1973 block that i will place my B Heads onto and see what happens pushrod alignment wise..

 

To ad to the this info,I have found 1966 to be the only year that you could get a 425 with both the .842 lifter and the 39* bank angle.However,not all 66 425's were like this.All of the ones I have/had came out of 66 Deltas.All of the other years of 425's(65,67) either had the .921 lifter,or the 45* bank.I hope this helps.

 

I would swear that most non-Toro '67 425 motors were small lifter and 39 degree, based both on personal observation (admittedly small "sample size") as well as what I have heard of other people's experiences.

 

I'd also have to differ. I had a 67 425 block that was both small lifter and 39 degree. Standard bore block, just sold it a few months back for $200.

 

I'm not saying it wasn't done.Just from my experiences with these,all of my .842/39* 425's came from 66 deltas.All of the 67 425's that I had came from Toros,& had the .921 lifter.I sold them all to someone who uses them for a stocker class.I just got one of my 66 425 blocks out last night & looked for the drill spot,but I do not have that.It's leaving friday,so I had to do it anyway.

 

My 67 with small lifters and 39* also DID NOT have the drill spot.