nice build bad advice

[Joel@lavinconstruction.co]

Hi I am hoping somone can help me with this. I had a 383 rebuilt, the guy did a great job we used Kieth Black pistons and a Hughs 510 lift cam. I got some wierd advice and went with it, I had the machinest install 440 valves and seats. I think this was a mistake, since then I was told that it shortens your power band I think my car is suffering from that. Can I switch back? Can I just put a 440 top end on my 383? One other thing, it there a better carb to use than a carter AFB? Thanks

[CAT-TECH]

How would it shorten your power band? Bigger valves=more flow, I dont know about a 440 top end on a 383, It might fit but your deck height will change and so will the angle. Yes there are plenty of carbs other than a Carter AFB. Whats the CFM rating on your Carter? That might be why you lose your top end.

[Joel@lavinconstruction.co]

I am not an engenieer, but I have come to belive that the men who designed the enginge made the valves the optimum size. I would imagine that it had somthing to do with air speed and volume passing into the cylinder. The carberator I am currently using is a Carter 625, I am not a fan of this unit at all.

[440roadrunner]

Factory 383hp and 440 heads were essentially the same, at least for a few years, so I doubt that the valve size is a problem

It may be more likely that the cam is way too big for what you want

Can you post some more specs?

Weight of the car? (and model)

Transmission, rear gear ratio, and tire size?

What RPM do you see at a true 60mph?

Are you running headers? a good free flow exhaust?

What is the EXACT model and specs on the cam you are running?

For example, if you took a fairly stock 383 with factory manifolds, and put in a big, 300deg, .5 lift cam, it might actually SLOW THE CAR DOWN from stock!!

[Bret]

As a general rule in any motor smaller intake will produce more low end . and a huge intake will produce great top end . And yes a radical cam will likely not give much low end

[Russ toy]

I rebuilt my 383 a couple years ago and I put in a 284/484 mopar cam. It was way too much for the stock (2barrel) engine. My engine also ran very hot. The heat and a bad oil pump caused a spun bearing. I have re-rebuilt my 383, 30 over bore and 30 over crank, RV cam. It runs great, doesn't over heat, and is way faster than before. My car is a 69 Charger, 727 trans.