Merlin 345 Grumpy Jenkins flow numbers... Stock and ported??
 

AS fall is here I need to refresh heads this winter since valve seals are leaking really bad, wondering what someone might have gotten for flow numbers fully porting and cleaning up 345 Merlins? I know these heads suck and are old school but I own them as they came on the boat, not looking to chase numbers with this boat really but before I do a valve job now would be the time if porting them is worth it....When I need a full refresh is when I will add some CI possibly and more aggressive solid rollers and better heads unless I can get numbers from these heads.

Anyone have ported flow sheets?

I don't see Merlin heads....

OMG DUH!!!!!! I didn't scroll tat far LOL

So those numbers are fully ported it looks like

My old Valako ported Merlins were wedged to 316 cc's and my flow #'s. Maybe not a true comparison, but hope it helps.

Lift___in. ex.
.200 151 133
.300 213 165
.400 277 222
.500 326 251
.600 362 254
.650 371 260
.700 377 262

Thanks, I have to refesh heads this winter so I thought about porting for cheap HP,Joe (Mild thunder) ran my engines on his Dyno sim and with a much better flowing head they made 50 more HP each, that may be worth it if I can get the numbers where they need to be...

my engines are 548 Dart tall deck shortblocks 11CC dome pistons
Merlin 345's
10.6:1
254/[email protected] .595/.595 LSA114 cams 1.7 Crane golds
Brodix HV2005 4500 intakes
Holly HP 1050 Dominators

Not sure yet, but savings of buying new castings, I get my work done fairly cheap as it's a friend also.

I do not know your combo, but 345's are large for normal size(468-509) boat engines, unless I'm off on this opening up the ports a bit more not going to give you much at the RPM's we usually see ?

Saw that, Didn't see numbers.. ugh

How old are the heads? The decks on those heads were notorious for caving in on the combustion chambers and getting holes. Had it happen to me two times on my engines many many years ago. If the heads need seats and guides anyway it might not be worth the fuss to fix them and then have them ported. But I guess you'll find out soon enough!

They have a 26* valve angle. Most aftermarket performance heads have a 24* valve angle.

https://cimg7.ibsrv.net/gimg/www.off...af74c0814c.jpg
Heres some flow numbers from my head guy. All flowed on same bench, same fixture, etc

Looks like the EQ heads are killer for the money. Also looks like if one was to spend time porting them, focus on the exhaust runners......

i should note that the 'stock" flow numbers on the eq heads, had a non tulip exhaust valve, and intake valve without a 30* backcut . Ported numbers had a tulip ferrea ex valve, and back cut intake. The "stock" numbers would have been a tad better with a tulip style ex valve. No pipe on the exhaust. The intake ports are basically untouched, the exhaust had just a little blend at the seat. Most of the work was in the chambers.

Ive seen some numbers on some fully ported versions of them, with some big cfm numbers .

Well refreshing heads and my head guy says there is a cheap and easy 30 cfm to be had, so I am going to clean these up for now, not fully working them but since I need to do valve job why not pick up a few HP as merlins leave a lot to be desired... 30 CFM or more has to gain something...

duration yes, lift questionable, cams are .600

Ported 345's almost the same as stock Merlin 320's?

Will be a good before and after comparison.
I was looking at the comparison that MT posted. Not especially interested in the #'s, more interested in the comparison using the same test equipment. Looks like the Darts were knocked in the dicl< after porting.

yea, they will be better but not going full working, just getting some things done, should see 30 CFm or so..