[Don66GTO]

I have been slowly upgrading the parts of my 66 GTO.

I have reworked the suspension (OPG G kit stage 4)

Reworked the drum brakes ('till I can afford to convert to disk)

Replaced the th375 tranny with a bullet proof TH400 (the old trans died)

Dougs headers and 3 inch flowmaster exhaust w/ supper 44's (I was planning to upgrade the motor later)

I have a 74 455 with 4X heads in the car that needs a rebuild now.

It has the cast intake on it and the Q jet on it still.

I was thinking about upgrading to a crower 60916 cam now while it is being rebuilt and running it like that until I can afford to upgrade the heads later.

would it be stupid to run the new cam now and upgrade the heads later? and could I run that cam with the 4X heads? I am planning on boring it out 30 over.

I had been planning to go through the engine within the next 2 years but I guess the car wanted it sooner.

I guess what I am really asking is should I do all the upgrades to the engine all at once or can I do it in more affordable sections?

sorry about all the crazy questions... I am trying to learn as I go.

[Will]

Am I understanding you?

You want to completely rebuild the engine you have now and are wondering whether you could run the 60916 cam in it, then upgrade the heads later?

I don't see any problem with that plan. You'll need new valvesprings for the 60916 so might as well get those installed on the 4X heads. I think the compression of that engine is about 7.5:1, right? When you're having the engine rebuilt if you zero deck the block and have the heads milled you can easily get that up into the mid to high 8:1 range, which will make a difference. It's not optimum but a 455 should have no trouble making power with that cam even with a lower than optimum compression ratio. Then, later on when you can afford better heads you'll be all set.

However, a set of core 6X or 5C heads shouldn't cost all that much and the cost to rebuild them is the same as your 4X heads plus you wouldn't need to mill them (you should still zero deck the block though) so the cost differential between getting the new heads now vs. rebuilding what you have is only going to be a couple hundred bucks.

[screamingchief]

With a cam like that I would'nt be real worried about the future head upgrade plans.

As Will says,find some better cores to begin with,I agree the 5C or 6X heads would be top of the list,I would opt for the 400 castings (-8/98-100cc) myself and not push the CR envelope too high with todays pump fuels being what they are.

With those heads I would definitely want new 1pc. valves,and some good valvesprings (crower),and adjustable valvetrain,also I would definitely machine the heads for the "good" viton PC style VS seals,so those items would be SOP for any heads I had built.

Seems natural that there will be some guide work to go with the valvejob too.

I'd likely fill the exhaust crossovers with aluminum,and slot the heads for 1.65 rockers too as more SOP.

I would'nt worry much about the ports,maybe some very mild cleanup to get some trash outta them,nothing serious,that and maybe match the ports to the stock gasket size.

I'd be much more concerned about building a nice stout bottom end if future upgrades are in the cards.

I would absolutely insist on using some forged rods and pistons,even if they were on the "budget" end of the scale,and were a bit on the "porky" side of this stuff.

A well built and tuned 455 like that will be a lotta fun,you may find you like it just fine "as-is" and decide to leave well enough alone and forget about the head upgrade,so dont go too cheap on the iron heads you use on this.

Just stick to sound building practices,and spend wisely,and all should work out pretty well for you.

Tuning usually make a much bigger difference than some more "glamorous" mods/upgrades do.

JMO/FWIW.

[440GP69]

you can usually find some great deals on cyl heads in the for sale section on the forums, just BE carefull and ask lots of questions before buying if that is the route you take, FWIW not all 4x heads have th huge chamber my 270cfm 4x's have 98cc chambers from a 73 400 i believe.

[baron_]

since you asked for advice...

I'd probably upgrade to discs on the front before you started doing the engine upgrades
around $300 to do it yourself, $400 if you just buy a kit

even 400 horsepower and drum brakes can be kinda scary