stevesxm

smitty, thats a GREAT catch on that oil hole height... i won't even ask how long that took... but wonderful job

articfriends

iTrader: (1)

Steve its a long story but basically when I put my motor on the dyno after the oil was warm it would hold 30-35 psi at idle at 1000 rpm's but dropped below 5psi to 2-3psi at 700 rpm's. Drained oil out,no metal. At that point we put thicker oil in which did virtually nothing for the problem once warmed up. I chose to continue the dyno session as oil pressure was fine from 1000 rpm's up. When I brought motor back to my shop I started looking real hard,I knew what my clearences were as I had double checked them as assembling. Pulled the oil pan off and intake off,dissassembled oil pump thinking the bypass was hanging open but I had it apart already when assembling motor so I wasn't convinced it was the problem either.Took oil gallery plugs out of the back and noticed if I blew air in the gallery on the even numbered side of the block while the cam was on peak lift on rearmost lifter a awful lot of air woul blow up around the lifter body into the valley. If you rolled motor so that cam took that lifter slightly off lift it would stop. I also ran oil pump with a priming tool while rotating motor with intake off and had alot of oil flooding the valley (although I don't really know how much would be too much as I never had to try that on anything before). I dug the old comp lifters out of my scrap barrel and started comparing them very closely,you could see using verniers there was about a .018 difference in total height to feed hole that was at top of the center band. Consulted with Cam motion that had a similar problem going on but hadn't found the answer yet,merlin rep who claimed he had never heard of any problem with their blocks and Bob madera who hadn't seen the problem yet but was as helpful as possible. At that point I tore the cam out and sent it back to be reground smaller. Installed it and immediately did a test with my oil priming tool and a drill,motor had 1/8th as much oil flooding the valley and would build up 50-60 psi of oil pressure at a slower speed. When I first primed motor before going to the dyno it had 40 psi cold with drill so I didn't think much of it but it was when it was hot at a slower oil pump speed that the problem would emerge. Rigged up a test stand vs going back to the dyno (my fuel mapping for the efi was all done so it only needed to be ran to make sure it had oil pressure at idle hot). Fired the thing up,warmed it for 15 minutes,had 60 psi at idle vs less than 5psi,oil wasn't super hot as you can't get one real hot unloaded on a test stand.
So back to this thread-I had a merlin 2 block,a 615 lift cam with std base circle and morel hyd roller lifters.Due to a slight difference in the lifter construction the oil feed hole into the lifter body was placed about .018 higher,this caused a near zero oil pressure condition at idle. If anybody ever builds a similar combination they will want to play close attention to this. I don't blame Morel lifters as they work as drop ins in any other block and are very high quality,Smitty

Strip Poker 388

iTrader: (6)

Also if the block or heads have been resurfaced.Like .020-30 head and maybe 20-30 on the block that will change the length.

Like Chris said ck it

bobl

Interesting. I have a Merlin 2 block and a set of Morel and Crane lifters here, so I just went out and did some checking. On this one, the Morel lifters stay inside the lifter bore by about .100 of an inch. The Cranes are quite a bit further down. That is with a Crane 741 cam stuck in it. I wonder if the base circle on this Crane is smaller than the cam you had ground...hmmmm. I also have a Dart block so I'll check that over the next few days. I've got a Cam Motion cam going in that block so I'll do some comparing. Very good information!

KNOT-RIGHT

Measure the morel lifter then measure the crane lifter this is what I beleave is what Articfriends said.

fbc25el

Does anybody know what the diference is between a merlin 2 and a merlin 3 block is? I though that it was C N C machining. Also the cam that i am going to install is a crane 139021.

bobl

I did. No question they are different. It just didn't come out the top of my block like it did in Artic's.

bobl

I asked that question to Bill Mitchell(of World Products) at the SEMA show. He said the only difference was the bosses for extra head bolts.