7.4L and merlin heads
 

i have a mark IV motor and i am thinking of buying these merlin heads from someone. will they work on this engine? i just dont want to buy something that wont fit i have herd that some heads wont fit some blocks and will leak water. i dont know if this just applies to gm heads? and not aftermarket? :cool:

Re: 7.4L and merlin heads
 

Most aftermarket heads are designed to fit either block. I have a pair of Merlins on my Gen VI engine. World Products say their Merlin heads will work on Mark IV or Gen VI blocks.
The stock head bolts will not work on Merlin heads. I bought a set of ARP bolts for mine. I think they were about $100.

Re: 7.4L and merlin heads
 

is there a special gasket set? or just a mark IV gasket set will be fine?

Re: 7.4L and merlin heads
 

I believe you just need a Mark IV gasket. I have yet to build a Mark IV engine with aftermarket heads....

Re: 7.4L and merlin heads
 

You need the ARP head bolts and Feel Pro gaskets for the Mark IV block. Check the gaskets on the block first but they should work fine. The good gasket retail at around $100 per set but they are worth it if you run in salt. Are these the raised exhaust port heads?

We just built up a pair of 496 strokers with the Merlin heads. They scream and make for a pretty reliable set up.

If you need the PN for the gaskets let me know, I'll look it up.

Fionn

Re: 7.4L and merlin heads
 

Just picked up my Fel Pro gaskets. I`m using #1037. They were $42 each. I have a Gen VI block, Merlin VR heads.

Re: 7.4L and merlin heads
 

The heads will fit, but if your engine is a 330HP 454 with flat tops (8:1 compression and wimpy cam), you may not gain a whole lot without making other changes... :(
With 9:1 compression and a bigger cam, you can gain 100HP with those heads... :D

Re: 7.4L and merlin heads
 

Think COMBINATION!! Heads, intake, cam, carb {or re-jetting}, maybe pistons for more compression...........on and on and on.....

Don't buy a part here and a part there just because ya get a good deal on one. Discuss your hp/tq/goals with someone who knows their chitt ...rmbuilder, cstraub, Mesa, just to mention a few here on OSO. You'll be much better off and save allot of BS down the road. Just my .02 :drink:

Re: 7.4L and merlin heads
 

see thats the thing, i dont want to buy these heads and make very little power gain. in the deal for the heads this is whats included-2cast iron merlin ported heads (Porting was done by Todd Goodwin at www.goodwincompetition.net) a matched and ported dart intake and holley 800cfm carb. i then would have to buy a roller cam setup and a nice aftermarket exhuast setup (which i intend to do with or without heads) and also i was told that it wont be reliable anymore and its really hard to tune and dail in.

Re: 7.4L and merlin heads
 

It takes a little work but it's not really that difficult. Put a roller cam in it similar to the HP500 cam and prop it to turn 5200-5400. It can put out 500+ reliable horsepower.