345cc dart iron eagle head any good for boat?
 

6272990 are the casting number on the ones I got now 2.19" intake / 1.88 exhaust valves, 118cc combustion chambers, 318cc intake runner

The ones im looking at are Dart Iron Eagle Cylinder Heads as my 990s are cracked 15200132 casting number 2.30'' Int/1.88'' Exh Valves 345cc Intake Ports, 119cc Combustion Chambers

Would the dart heads work on my engine it's a mark iv big block bow tie block 502 bored 30 over 4.500 bore
l2513f 030 speed work forged piston with single valve relief I believe the crank and rods are stock
thanks for any help

Deleted...double Post

The direct answer is yes, it will work. But definitely not the best choice. At 345cc on the intake it's too big unless your adding compression and cam and plan on spinning it 6000rpm. IMHO, You'd be way better off going with a large oval port from Flotek, AFR, etc. The superior flow of this type head won't kill torque and will significantly boost torque and HP in the standard operating range.

I will be the contrarian to this conversation. I believe the addage of going "too big" with intake runner size and it will "kill" torque is overblown. You may not be utilizing the full potential of the head but I don't believe you will make less power than the ****ty stock heads. If you go to small on the runner size you will be leaving power on the table. Now I'm not saying the Iron Eagle is the best head out there, but they are pretty good and durable.

Ya I figured the the bigger intake port wouldn't be an advantage but there a reasonable price from a buddy that had them on his camaro and has upgraded to different heads just lookin to get my boat runnin my bigger concern is if the bigger intake valve and maybe different valve angles will cause the valves to hit my pistons?

The good news is that head doesnt flow so great so it`ll be just fine on a smaller engine. :D
You can`t be sure unless you throw some puddy in there and see how close everything is .

I had em on a 8.3:1 flat top piston, .680 lift

As long as the heads haven’t been decked and your cam isn’t installed 2-4 deg advanced you should be sufficient on clearance but as dan stated - clay it up To be certain.

Ya I'll will check piston to valve clearence when I get the heads just wondering if anyone would know if the .11 bigger would change piston to valve clearence much before I spend the money and buy them

And u consider a 502 a smaller engine? I guess there's bigger engines but still lol

I should have clarified, smaller engine for that application not that it`s a small engine.:drink:

ya gonna clay em if buy them just just wanna be 90 precent sure they will work before i buy em also fort to mention i got 1.7 rockers

1.7 is std on bbc. Heads will work ok just not ideal for your application as you’re basically hearing. I doubt you’ll have any clearance issues but what a perfect time to get a good flowing set of aftermarkets tailored to your CI. (290-315 cc) Mentioned in earlier post.

But then it’s cam, intake and exhaust but pending your end goal it may or may not be worth it. JMO

I bet if combined with an edelbrock rpm or rpm air gap dual plan manifold, it would make great torque.

That would be a interesting dyno test, throw a set of heads on a engine that are by all means too big of runner then band aid it with various intakes, including maybe some oval ports. Ive already seen how bad a perfomer rpm can kick a Victor jrs ass on anything from about 515 down thruout majority of power band. Smitty

Thats interesting, what outcome would you expect if the reverse were done? As in running 325 heads on a 615 ci that has a high flowing intake such as profiler snipers?

Then test the two in a small light single boat like a velocity 22 to see what makes better power in actuality. Man, i miss going to the drag strip to test parts/theories/ideas :)

ya not looking to buy new heads or exhaust only Plain on keeping it maybe anther 2 summers than upgrading but would consider a new cam for the heads I'm looking at if u have any recomendations. Since i ownded the boat it would never rev much over 4500 its a 1986 27foot nova iii single engine i have a 21p prop and a23 would do 50 to 52 mph with the 23 at 4400 to 4600 ish rpm should I be able to get more rpm out of it?
https://cimg7.ibsrv.net/gimg/www.off...6cf8f7c3d1.jpg

Nice looking! Based on what you said I’d find another fresh set of 990’s and leave all else alone unless you’re willing to do the whole combo - heads, intake, cam and exhaust. You’ll thank me later 😉

Believe me I'd have a set of 990s of i could find em been looking for months and dont want to buy a used set off the internet cause ya never know what your getin. can't imagine you'd loose mutch more than than 20 to 30 ft lb of torque with these heads and I bet the boat may still work better than it has sine I owned it I put prob 60 hrs on it my self and would bet they both been cracked since i got it that's prob why I got it for 7k. I would say the only reason it lost enough power for me to notice an issue was because enough coolant got in the oil to Rase the oil pressure enough to pop the rocker off
https://cimg0.ibsrv.net/gimg/www.off...dcedfc4af9.jpg

Who said that? :picard1:

Looks like int and exh rocker got switched at some point also but relevant and no biggy as your covers evidently clear.

BTW - you sure you don’t have a collapsed lifter or bad cam lobe? Did you identify the cracks in heads? I’m assuming you didn’t but just asking. If it’s from freezing the blocks almost guaranteed to be cracked before the heads. A little more history might open the door to other things to check and confirm.

Did you recently notice a drop in rpm or always been the same last 60 hours? I see a 200-300 more rpm at least.

Most generally (for me anyway) those cracks on the underside are difficult to see without magnafluxing.

that clearance rocker is in the correct location needs to be that way to clear the stud boss

Ya there was some self clearing going on who ever put it together last with the roller rockers forgot to cut the oil dripers off the valve cover and she did some self clearing found the pieces in the oil pan lol

Dont think the block froze as it has a closed loop cooling system had the heads at an engine shop and its cracked between the valve on one cyl on each head cam don't look new but no lobes are ground off from just looking at it maybe a collapsed lifter never thought of

seemd to be loosing a very small bit of rpm all the time last summer than lost 200 or 300 all at one the last day it ran and I Knew something was up came of plane and it never had the power to get back up

Back in September I dynoed a 548 with tiny little 290 afr oval ports BUT a huge cam even though the flow goes flat then backwards at .650+ lift, made 750+ hp and if i remember right 680 ft lbs of tq (might have been 660) but had a Chinese oval port copy of a vic jr and a modded 4150. But, was a non marine engine with lots of lift, duration and compression. We expected MORE tq then it made, we never finished extracting every bit of power from that engine before dyno waterbrake broke. Im just know getting the new dyno setup in place, Smitty

When you have up and running you think? Jim and I like to bring over one of the 565,s

At what RPM were the peaks and was it a long broad torque band?

https://cimg7.ibsrv.net/gimg/www.off...4fa5ad6c51.jpg
so to answer your question the hp peak was at 6500 then flattened out to 6800 or so, even at 7300 it wasn't falling off face of earth. (for those that missed earlier comments was talking about a 548 with compression with large cam BUT a set of AFR 290 cc oval ports because they were what customer had left off his 496 he blew up) The heads were like a "governor".on top, had enough cam, in the high 270s/280 (@50) range with lift approaching 800.
This was partly thru the dyno session, we had top end tune about dialed in, our torque was lame at slightly less then 650 at 5000 I expected to see 700. In subsequent pulls changing cam timing, bleeds, ignition timing, carb spacers, we got tq closer to 700 when the dyno impellers started screeching on casing from coming loose on main shaft so we never found full potential of this one, Smitty

https://cimg2.ibsrv.net/gimg/www.off...63aeb2411a.jpg
This picture with the tq peak was after playing with cam timing, tuning changes, carb spacers . I forgot that we saw 691 on last pull.
the graph below is the same pull as post 26 with the 757 hp, before picking up tq from tuning changes.https://cimg6.ibsrv.net/gimg/www.off...3e432bc25b.jpg

The two cams I'm looking at are both comp cams exteram marine

1000-5000 rpm range COMP Cams Xtreme Marine CamshaftsCamshaft, Hydraulic Flat Tappet, Advertised Duration 262/268, Lift .505/.515,

COMP Cams Xtreme Marine Camshafts 1600 to 5800 rpm range

Camshaft, Hydraulic Flat Tappet, Advertised Duration 270/286, Lift .544/.547, Chevy, Big Block, Each

Which one would be best would for my boat it's got a 1.5 bravo one drive and ran 52 ish with 23p prob @ about 4600 and 49 with 21p prop but like I say idk if the engine was ever at its best since I owned it. So what I'm wondering is if I got the bigger cam (5800 rpm) and it still would not rev above 5000 would it make less power than the 5000 rpm cam below 5000

I belive I should be around 8.6 to one with my pistons with the 119cc heads I'm looking at if thats what this chart means. My end goal is to have a running boat so not really interested in changing from the stock manifolds and through hulls i have now consider intake if enough gains but the boat dynoed @ 420 hp when that engine was put in in 2006 if I'm with in 20 ish hp of that I'll be happy but will take cheap hp if possible while I have it appart
https://cimg4.ibsrv.net/gimg/www.off...86c3b5b868.jpg
Highlited is the pistons i have