conanhomer
Donation Time
i need to know if there are any clearance issues when you install 2.9 valves into the 2.8, specifically between valve and piston. i am using Jose's cam and stock pistons.
Last edited:
-
Welcome to the new SAOCA website. Already a member? Simply click Log In/Sign Up up and to the right and use your same username and password from the old site. If you've forgotten your password, please send an email to membership@sunbeamalpine.org for assistance.
If you're new here, click Log In/Sign Up and enter your information. We'll approve your account as quickly as possible, typically in about 24 hours. If it takes longer, you were probably caught in our spam/scam filter.
Enjoy.
2.9 valves.
- Thread starter conanhomer
- Start date
conanhomer
Donation Time
very succinct Dan, thanks
conanhomer
Donation Time
i don't quite understand the relief bit. can you explain?Just make sure you do the "other" mod's I suggested
DanR
Diamond Level Sponsor
Drill between the exhaust valves to allow cooling of the water passages as suggested by Sven Pruitt.
Drill and plug the emission port in the bottom of the exhaust ports, then drill and tap 1.5 mm 1.5 thread about 3/4" depth to secure the bottom of your heraders.
My Straight Back Headers come slotted for this option.
Drill and plug the emission port in the bottom of the exhaust ports, then drill and tap 1.5 mm 1.5 thread about 3/4" depth to secure the bottom of your heraders.
My Straight Back Headers come slotted for this option.
conanhomer
Donation Time
got that done already. some day i need to change to your headers.
conanhomer
Donation Time
i started to adjust my tappets today- excessively loose- maybe .60 instead of .14
now i need to figure out if the new 2.9 valve stems are shorter, or are the hardened seats thicker.
do i remove the oil deflector to tighten the clearance, get longer pushrods, or install lash caps?
any ideas?
conanhomer
Donation Time
that was my plan Dan, but i run out of thread on the adjusters before i get the proper clearance.
i guess i'll talk to the machine shop tomorrow to find out what went wrong.
Barry
Diamond Level Sponsor
Hope you mean 0.060" and 0.014"; over a half inch of valve lash would be .....
A quick online search indicates that Ford 2.9 Cologne V6 valves are about 0.75 mm / 0.030" shorter than Ford 2.8 Cologne V6 valves. How the larger valve seats were installed / cut / ground can also affect the "installed length" of the 2.9 valves.
I suspect that "Jose's cam" was re-ground from a stock core. If so, the camshaft base circle was reduced to increase the total lift. That moves the lifters / pushrods "down" when the valves are closed and requires longer pushrods (or lifters) to get the valve train geometry back to "normal".
The technically correct solution is longer pushrods to make up for the reduction in the cam base circle and lash caps to make up for the shorter 2.9 valves. Lash caps have to be the right size (inside diameter, effective thickness and overall length) and there has to be enough exposed valve stem above the valve spring retainer and keepers to install the lash caps. IF the reduction of the camshaft base circle and the reduction of the installed valve length are close to the same, it MIGHT be possible to "take up the slack" by shortening the rocker arm shaft stands and avoid having to use longer pushrods and lash caps.
Something else to consider is "installed" valve spring height; depending on the combination of parts, there could be an issue.
The valvetrain is a complex system; all of this stuff should be carefully considered before any changes are made.
Last edited:
conanhomer
Donation Time
i just talked to the machine shop. he suggested tearing the engine apart and grinding the heads to set the seats deeper. i would like to avoid that. do you have any idea what size of lash caps and pushrods i would need?
conanhomer
Donation Time
the shop likes the idea of shortening the stands. any idea how much off?
Barry
Diamond Level Sponsor
The 2.9 valves are shorter by about 0.030". The 2.9 valve seats might be "thicker" than the 2.8 valve seats, but the difference is probably not huge. The real question is the reduction in the camshaft base circle diameter and that information will have to come from Delta Cams.
My best SWAG would be to reduce the height of the rocker arm shaft stands by 0.030" to 0.040" to compensate for the shorter valves / thicker seats and eliminate the need to use lash caps. Doing that would also shorten the pushrod (and lifter) side by 0.030" to 0.040".
If the camshaft base circle diameter was reduced by a similar amount, you might be able to use the stock pushrods.
If the camshaft base circle diameter was reduced by a significantly larger amount (than 0.030" to 0.040"), then you would probably need to use longer than stock pushrods.
If the camshaft base circle diameter was reduced by a significantly larger amount (than 0.030" to 0.040"), then you would probably need to use longer than stock pushrods.
I would start by checking the position of the rocker arms tips on the valve stems with everything "as is". The rocker tips sweep across the ends of the valve stems as the system cycles, but the rocker tips should stay pretty much in the middle of the valve stems. I like marking the end of the valve stem with a black magic marker and then cycling the system which will remove the black where the rocker tip rubs. If the rocker tips are significantly off-center, some heavier thinking will be necessary.
You need to carefully examine and think about the rocker arm system (stands, shaft & rockers) to make sure that shortening the stands will not cause another problem.
I have never worked on a Ford 2.8 Cologne engine, so take everything I have said with a large block of salt. Shortening the rocker stands should work, but .....
MikeH
Diamond Level Sponsor
I’m surprised this hasn’t come up before, as this has been done several times by others. I had my heads done by Jim Ellis, including 2.9 valves. And he did not mention any issues with the valves being shorter. The issue may be wear on the rockers them selves. Did you have the rockers refurbished?
conanhomer
Donation Time
i did not refurbish the rockers, because they functioned ok with the old valves. i was able to easily adjust the clearance.
really was not expecting this at all.
really was not expecting this at all.
Yikes! I’m sure your machine shop is very good, but if that were my engine, I’d become fully informed about valvetrain geometry and set it up myself.
Thanks to Barry for bringing up the issue of reground cams and base circles. Decking blocks and shaving heads will also alter valvetrain geometries. Head gasket thickness, too.
Here’s a link that discusses rocker arms and valvetrain geometry; http://www.eatonbalancing.com/2007/...-ratio-by-varying-the-length-of-the-pushrods/
Paul M.
Thanks to Barry for bringing up the issue of reground cams and base circles. Decking blocks and shaving heads will also alter valvetrain geometries. Head gasket thickness, too.
Here’s a link that discusses rocker arms and valvetrain geometry; http://www.eatonbalancing.com/2007/...-ratio-by-varying-the-length-of-the-pushrods/
Paul M.
conanhomer
Donation Time
thanks for all the info guys. i'm taking the whole engine into the shop today. my machine shop is bringing in another machinist who they say specializes in valvetrains. i hope see it they will be able to put their heads together and come up with the best solution. the picture shows one tappet (intake) adjusted to approx .015, but running out of threads.
