So close but so far away.... ALMOST ready to fire our 250 inline
 

Havent posted much in the way of builds lately, but figured id post some pics of the engine some of my students and i did as part of the advanced engines class i teach. Its a 250 bored .030, flat top forged TRW L2314 pistons, Tom Lowes HYTORK cam, heavily ported and with lumps and 1.94/1.60 valves all done here at the school. This is destinted for wifeys 68 stepper here in a few weeks. Almost got this thing ready to fire for the kids tomorrow morning as it is our seniors' last day, but still missing a few things and a few wrong parts...ugh... But figured I'd throw some pics up for everybody before we hung more wires and hoses on it.... Also one of my seniors asked to restore the Merc valve and side covers for me...Did an awesome job, makes those bad days not so bad when they wow a person like that...very proud for sure! Here are the pics....

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Congrats! Looks very nice

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Nice! wanna trade? :)

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Question, heavily ported with lumps? What's a lump? I'm a dummy when it comes to 6 cyl mods.

Is that a stock or high performance exhaust manifold?

Possibly a Clifford intake with a small 4bbl in the future? I does not appear to be an integral head so maybe?

That senior did an awesome job on the covers! :metal:

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Man - those Merc pieces are nice. How hard are they to find? Do they bolt right on?

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Wow Mike, those covers really make it look good.

A one lunger has got to choke the life right out of that thing. Now, where's that web page showing blowers for inline 6's? Yeah, 5 psi. boost with multi-port injection and CD ignition. That'll do it right. You don't mind eating mac-n-cheese and raman noodles for 6 months do you?

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

liking the colour combo along w/ the detail(s) to it

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Very nice!

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Cool/

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

That motor looks really good. That engine compartment will look clean with that in there.

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

No joke, one of my greatest regrets in owning my truck the past 18 years is pulling the butter smooth, nothing wrong with it, 250 for a 350 about 12 years ago. I should have just put a T5 behind it....

Beautiful looking motor. One of the best GM ever produced.

Thank you for teaching kids to do more than play with their phone.

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Gotta love the simplicity of a pre-smog 250.

Which transmission will be in the 68?

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

That looks amazing.

That thing will run like stink.

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Just my style.........I mean just my style if I wasn't incredibly broke lol. That's about to change though, just got my degree! Seriously though, your motor reminds me of mine, just better!Attachment 1405438 been using my old beater as a fun way to help me learn new stuff while I was getting my AST degree. I think this old stuff makes learning a lot of fun. To much working on minivans and sunfires can make you want to switch to cosmotology!

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

I assume he is talking about a cam shaft with larger lobes?

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

No it's actually a lump that goes in the head. 250 guys are always talking about installing lumps. Supposed to be a great upgrade. Changes air/fuel flow.

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

"Lump Port" is actually a modification of cylinder head. A wedge is installed into the intake passages, kind of looks like the top of an airplane wing, or a lump, hence the name. Because the 250 and 292 (and I assume 230's as well) each cylinder shares the intake port on the head and manifold the air velocity is decreased over all due to the large port in relationship to volume of air each cylinder will take. Only one valve opens at a time so the speed at fuel/air mix is in drawn in is on the slow side. The lump is supposed to increase the air velocity and mixture efficiency with in the head prior to the intake valve. The stove bolt guys have touted the lump port modification has the way to go. Want to try out a lump port on one of my spare cylinder heads.

Paul

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

tkeduk8r, I have a question about your PCV system. The PCV valve with vacuum line is top center. I can't see where the fresh air intake is for the system.

An internet search for "MerCruiser 250" produces plenty of valve covers and complete engines. Most are on Ebay. I can't see on any of those pictures either, what provision is made for PCV air intake.

Lump ports on the inline head, involves cutting out the head bolt boss and raising the intake port floor. Each of the three intake ports feed two valves. The boss for the head bolt provides restriction and the area inside the port is large and causes the velocity of the air/fuel to slow just before the valves. Removing the boss increases the port volume even more.
Adding a large lump to the port floor with brazing, epoxy or an aluminum insert, reduces the volume and directs the flow toward the valve pocket.

There are a couple of different aluminum inserts, but they all involve removing the boss, installing a short hex head bolt and plugging the old hole on top.


Sorry, ironduke, I didn't know you had posted as I was a little slow. These images should help.

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Good info from these guys, I also saw some cool vids on YouTube with guys installing lumps!

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Thanks! You learn something every day, makes a lot of sense.

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

"The boss for the head bolt provides restriction and the area inside the port is large and causes the velocity of the air/fuel to slow just before the valves. Removing the boss increases the port volume even more."



Thanks for the correction.

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Thanks guys... Was at school that night till about 11.... Didn't know the flu was waiting until about 230 am and have been home sick the past two days...gonna be missing graduation tonight too.... Oh well...

Anyway... The lump port mod is due to the fact that a head bolt passes right through the three siamezed (?) Intake ports. Basically you cut and machine the bolt boss out of the head and insert a aluminum "lump" that directs the intake charge more efficiently to the valves.. Very cool and disgustingly common sense....

The exhaust manifold is a stock c60 with a larger 2.5 inch outlet.... Found out the hard way that neither my Clifford intake nor my factory power steering brackets are compatible with it :(.... So we cleaned up the stock intake n carb just to get it running before school gets out....

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

Oh... And yes the merc covers are bolt on... I had to use to use two gaskets to clear the ARP head studs...as far as the pcv system goes there is only one port and it had a hollowed out pcv valve in there when I got the covers... So I don't know how "it should" go....I'll have to figure out how I want to make it work on the truck yet...may have to drill into cover for connection to air cleaner yet well see...

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

And it'll have a 4speed OD MY6 trans out of an 84 c10 behind it with a 3.73 gear turning 31 inch tires...
--Mike

Re: So close but so far away.... ALMOST ready to fire our 250 inline
 

That a833 ought to keep your RPMs down. Nice engine.