merlin big block lifters.
 

I presently have crane hyd. roller lifters. I am planing to swich to morel lifters. Will i need to change my pushrods. thanks.

Re: merlin big block lifters.
 

when ever you change any part of the valve train, you should check the geometry and adjust as needed. Buy an adjustable pushrod set, and check them.

Re: merlin big block lifters.
 

Make sure you double check the lifter bores on the Merlin block, Have heard horror stories of them coming out too tight and grabbing lifters. Another reason to buy Dart blocks....BBB :D

Re: merlin big block lifters.
 

More than likely yes , do the magic marker trick after you think you have the right pushrods, and see if the roller in the rocker runs in the center of the valve tip. This is very important we don't want to side load a valve stem. BBB

Re: merlin big block lifters.
 

Be VERY careful with a merlin 2 block/morel lifters and std base circle hyd roller cam. When I put my last combo together I used a merlin 2 block w/morel lifters. The oil holes on center band in the lifters were approx .020 higher than other hyd lifters which resulted in virtually no oil pressure at idle hot under 800rpm's.The chamfer on the lifter bore top hid the fact oil hole was partially exposed,I ended up reducing the base circle on the cam .060 which moved lifter down .030 which fixed the oil pressure issue,Smitty

Re: merlin big block lifters.
 

Maybe that's the real story why the lifter bores would get scuffed. I won't have to ever experience this or all of the other shortcomings of those blocks because, I prefer Dart, or even a Bowtie. BBB

Re: merlin big block lifters.
 

BBB,the oil feed hole height didn't cause the lifter to scuff,it just caused a vast amount of oil to bleed off at 700-800 rpm's idle. Howewver,the machine work on a merlin 2 block like mine has to be re-done OFTEN,my lifter bores were also tight along with cam tunnel being dimensionally wrong,mains being to tight when it came to bore size,etc. My block though was a blem,I spent more on it and strightening out the machine work than a prepped one would cost new but I'm leery of how good the "prepping" actually is because the blem on mine was 2 little spots of cast iron that had slight imperfections on the fuel pump boss and back edge where intake bottom had to seal. It seemed strange that ALL the machine work would be wrong TOO,Smitty

Re: merlin big block lifters.
 

Thanks for the reply. I have crane lifters in now. I just though since I am changing the cam i would up grade the lifters. I know now that a dart block would of been a better choice but the person I had do the machining(Steve Schmidt in Indy)said we would go ahead and use it.Also it is a merlin III. thanks again.

Re: merlin big block lifters.
 

Most merlin blocks can be considered blems unless re-worked and proven otherwise.... BBB

Re: merlin big block lifters.
 

When Morel designed the retro fit hyd rollers for the GM engines they located the pushrod seat of the lifter to fit OEM pushrod length. The body of the lifter is .300" tall to work with the late model blocks and aftermarket blocks taller lifter bores. So the Morel lifter will work in early, late, or aftermarket blocks.

You should check your pushrod length to prevent premature wear.

Chris

Re: merlin big block lifters.
 

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

Re: merlin big block lifters.
 

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

Re: merlin big block lifters.
 

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 :drink:

Re: merlin big block lifters.
 

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!

Re: merlin big block lifters.
 

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

Re: merlin big block lifters.
 

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.

Re: merlin big block lifters.
 

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

Re: merlin big block lifters.
 

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.