'71 429 cobra jet engine - correct cam shaft to use today...

Page 2 of 2 Previous  1, 2

Go down

Re: '71 429 cobra jet engine - correct cam shaft to use today...

Post  rmcomprandy on July 14th 2016, 10:38 pm

Scott Foxwell wrote:
rmcomprandy wrote:
Super Snake Steve wrote:This would be a good time for the  professional engine guys to clear this up as far as the roller set up's go's I've read a few times on this board that a roller set up in the 385 series that a roller up is a lot of  maintenance and for a street set up it is normally recommended to go solid and sometimes  hydraulic can't remember just how its go's but its recommended to use either hydraulic lifters with solid roller or solid lifters with hydraulic roller like I said can't remember witch way I don't know why you wouldn't use say solid roller cam with solid roller lifters with that said I stopped by Jon Kaase shop about a year ago and I asked him about running roller set up on the street and maintenance and he said not a problem anymore and he had that all worked out and a roller for the street was  reliable  of course he didn't go into  detail of what all he has done to  achieve this so anyone wanting to share please do thanks


There WILL be rapid wear on the valve guides or valve stems of a high usage engine when stud / guideplate rocker geometry is used with that extra pushrod side angle.
Why is that?

With the extra side angle of the pushrods, (because of the higher pushrod seat in the hydraulic roller lifter), when using a readily available guideplate type rocker set-up with existing stud locations and the boss angles, the rocker tip/roller will exert sideways motion upon the tip of the valve.
In mid 90's Ford Motor Company testing, the sled type friction, bolt down rocker arm fulcrum and stamped rocker arm would wear beyond allowable limitations simply resisting that rocker from twisting during valve opening and closing.
At just 1,600 RPM this happens 12 times every second.

Bronze guides with stainless valve stems don't wear near as much as cast iron guides with O.E.M. valve stems but, after 20,000 street miles and heat cycles, you'll still be required to resize guides in those heads because of that sideways motion.

EDIT: The less the valve spring pressure will help this situation as the valve tip will not be exerting as much force on that rocker arm tip.
If you're not worried at all about needing a high mileage engine, then have at it.

The short deck Cleveland type engines have the same pushrod angular issues but, none seem to be used for anything requiring "high mileage".
A "BALL" type fulcrum saves the that part but, the sideways motion of the rocker arm tip is still present if valve cant angle is much different than the pushrod angle or, with a sled type fulcrum the boss location and its angularity have not been changed to minimize this happening.

rmcomprandy

Posts : 5176
Join date : 2008-12-02
Location : Roseville, Michigan

View user profile http://www.rmcompetition.com

Back to top Go down

Re: '71 429 cobra jet engine - correct cam shaft to use today...

Post  Scott Foxwell on July 15th 2016, 2:48 pm

Thanks Randy. Appreciate the response.

Scott Foxwell

Posts : 398
Join date : 2011-06-23
Location : N/E Tennessee

View user profile http://www.straubtechnologies.com

Back to top Go down

'71 429 cobra jet engine rebuild...

Post  Pastel Blue on July 15th 2016, 3:47 pm


That is pretty close to the stock cj cam? looks like it. Would they sell a matching valve train kit for this? After reading all of these posts, giving consideration to the restoration build I am doing, it may be wise just to go stock valve train to avoid any possible issues with roller installation. i havent giiven up on this, would need to know that my machine shop undertands all of the variables before moving forward on a roller install. I will have to discuss with my machine shop when the engine goes in to see what they are aware of when it comes to BBF engines. Not a lot of options in my area for engine rebuilds...

Pastel Blue

Posts : 47
Join date : 2016-02-21
Location : Niagara, Ontario, Canada

View user profile

Back to top Go down

Re: '71 429 cobra jet engine - correct cam shaft to use today...

Post  SLord82 on July 15th 2016, 4:18 pm

Pastel Blue wrote:

That is pretty close to the stock cj cam? looks like it. Would they sell a matching valve train kit for this? After reading all of these posts, giving consideration to the restoration build I am doing, it may be wise just to go stock valve train to avoid any possible issues with roller installation. i havent giiven up on this, would need to know that my machine shop undertands all of the variables before moving forward on a roller install. I will have to discuss with my machine shop when the engine goes in to see what they are aware of when it comes to BBF engines. Not a lot of options in my area for engine rebuilds...

No it is not close to the stock cam. The one Randy mentioned is about as close as you can get with a shelf grid.

SLord82

Posts : 124
Join date : 2011-07-02

View user profile

Back to top Go down

Re: '71 429 cobra jet engine - correct cam shaft to use today...

Post  Super Snake Steve on July 15th 2016, 5:19 pm

Crane cams makes blueprint replica OEM Musclecar Cams

Super Snake Steve

Posts : 141
Join date : 2012-07-18

View user profile

Back to top Go down

Re: '71 429 cobra jet engine - correct cam shaft to use today...

Post  DanE on July 15th 2016, 5:41 pm


For your stated usage of this engine, why go to the expense and trouble of converting to anything but the factory valve train. You will not see any gains that are worth it. IMHO

DanE

Posts : 83
Join date : 2010-04-01

View user profile

Back to top Go down

Re: '71 429 cobra jet engine - correct cam shaft to use today...

Post  68galaxie on July 15th 2016, 5:53 pm

A copy of the 429 CJ cam would work well imo.

I have used that in a 460 build and it ran very well - way back in the 80's
avatar
68galaxie

Posts : 294
Join date : 2010-04-13
Location : Edmonton AB

View user profile

Back to top Go down

Re: '71 429 cobra jet engine - correct cam shaft to use today...

Post  rmcomprandy on July 15th 2016, 10:24 pm

This is directly from Ford Motor Company Engineering documents:

 429CJ hydraulic lifter cam .. FMC part number C9AZ-6250-A
lobe lift ... 289"/.289"
theoretical valve lift ... .500"/.500"
SAE duration ... 282/296
Lobe separation ... 115.5 degrees
intake lobe centerline ... 116 degrees

 460 Marine hydraulic lifter cam ... FMC part number D3JE-6250-AA
lobe lift ... .283"/.290"
theoretical valve lift ... .493"/.502"
SAE duration ... 288/292
Lobe separation ... 115 degrees
intake lobe centerline ... 115 degrees

Both cams are right around 216/220 degrees @.050" lifter rise

rmcomprandy

Posts : 5176
Join date : 2008-12-02
Location : Roseville, Michigan

View user profile http://www.rmcompetition.com

Back to top Go down

Re: '71 429 cobra jet engine - correct cam shaft to use today...

Post  supervel45 on July 15th 2016, 10:29 pm

Pastel Blue wrote:

That is pretty close to the stock cj cam? looks like it. Would they sell a matching valve train kit for this? After reading all of these posts, giving consideration to the restoration build I am doing, it may be wise just to go stock valve train to avoid any possible issues with roller installation. i havent giiven up on this, would need to know that my machine shop undertands all of the variables before moving forward on a roller install. I will have to discuss with my machine shop when the engine goes in to see what they are aware of when it comes to BBF engines. Not a lot of options in my area for engine rebuilds...

I am about sure Lunati can hook you up on spring's ect. A comp Cams 926 single with damper or even a Comp Cams 972 single with damper if you want a little lighter spring would likely work fine too with the right retainers. It's not that complicated like Lem said. Pick your poison and go with it.

PS: Comp Cams list's the 926-16 spring for their 270 Magnum BBF cam which is pretty close to the Lunati CJ Repop. Might be the ticket for it also.

Comp Cams Spring 940-16 for the BBF 268 H-10 which is .494 Lift.

supervel45

Posts : 3085
Join date : 2013-09-04

View user profile

Back to top Go down

'71 429 cobra jet engine rebuild...

Post  Pastel Blue on July 16th 2016, 10:39 am

Thanks all for the continued replies... I am learning.

Randy, I have sent you a personal e-mail message (off your web-site submission page) regarding the rebuilding of my engine. Please take a look at it and let me know your thoughts. Thanks

Pastel Blue

Posts : 47
Join date : 2016-02-21
Location : Niagara, Ontario, Canada

View user profile

Back to top Go down

Page 2 of 2 Previous  1, 2

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum