390 block question

[edgarval]

I have a std bore 390 block. I want to bore it over .30 . I also want to purchase the 4.375 . Does anyone have knowledge of putting one in a small bore fe block.will it drop in or a little grinding will be needed, what cam will work and what pistons will I need that is already available. I want to stay with a 390 block I cannot fund a big bore fe yet. Im wanting to drag race this engine. I use the edelbrock heads for now. I know the 4.250 will drop in but Im assuming the bigger stroke will help me achieve good e.t. times.

[blykins]

It will drop in, no problems. 

You will need a custom piston, I don't know of any off-the-shelf slugs out there for that combination, but that's not a deal-breaker.

Any camshaft will work, just pick the grind to match the application of your vehicle. 

[cammerfe]

Very much what Brent said. I'd also note that ET is dependent on the way your chassis works. A longer stroke will give more power which will contribute to higher speed. Good Luck with your project and Welcome!!

KS

[CaptCobrajet]

It will have no issues with hitting the bores, but a solid roller, or a healthy hydraulic roller will interfere with the back four rods most of the time.  I made a jig fixture so I can mill the rods to clear without a bunch of back and forth, but it can be done with a small grinder and cleanup with a cartridge roll.  I would guess we have done probably somewhere between fifteen and twenty of those 458 combos over the past several years.  I keep the piston in stock but it has an 18cc dish.  Like Brent said, it is not hard to get a flat top version.  It is a good way to make a 390 a big incher.  I would suggest planning for a 6500-ish peak at that stroke.  JMO.

Blair Patrick

[edgarval]

What info do  I need to order the customs Pistons . Will a 445 suit for a easier rotating assembly install . I really want the 4.375 stroke . Do I grind the rods on the side ? Will the factory main caps be okay for 700+. I'm planning to use the factory main caps. I'm going to put this motor in a foxbody . Thank you guys . Any off shelf camshaft that will in in without hitting .

[edgarval]

Caption taker. How much are your Pistons ? Are the forged ?

[edgarval]

Capt cobra

[blykins]

I'm not trying to be a jerk, but you will not be anywhere close to 700 hp if that's the goal you're aiming for.  550-600 would be a better guesstimate, especially if you're looking to use out of the box cylinder heads and camshafts.   Around the 600 hp mark on a race motor, I would look into beefing up the factory block considerably.

Also, if you're looking for a drop-in combo that will require no checking for interference, a 4.250" would be a better match.  I've only done 4-5 of the 4.375" crankshaft combinations, but they have all been in aftermarket blocks with mild hydraulic rollers.  I always check for interference, but with a Scat 6.700" I-beam or H-beam rod, I haven't had to grind yet.   

[edgarval]

thank you blykins, the 6.7 rods are the ones i want to purchase . will it be a 600hp engine ? will the long stroke meet my goals? will block filling be okay for now? i will be putting out of the box cylinder heads on.

[blykins]

I think it will take a good bit of cam and compression to get to 600 hp. 

[edgarval]

what off the shelf camshaft hydraulic cam/springs would you recommend.?

[CaptCobrajet]

I agree with Brent.  You will struggle to make it past 500hp with off the shelf cams and out of the box Edelbrocks, no matter which stroke you use.  Thirteen cubes by itself might be worth 20 hp in a healthy combo.  Not too many screw-together engines that make 600+.

Blair Patrick

[Posi67]

You sound like you are on a bit of a tight budget and making 600 - 700 HP with a 390 just doesn't happen without a considerable amount of money. The builders here are your best source of information as well as parts so trust them over whatever anyone else tells you or what you've read somewhere.

My question is.. what exactly do you want to accomplish? 600 HP in a Foxbody car is easily capable of running in the 9's which brings another whole range of expenses to the table. Once your goals are known it will be easier to get the right info from the right people.

[edgarval]

yes im on a strict budget. 390 block is the only one i can afford..i would love to run 9's.Ive seen the 445 ci in the 500 range i was assuming the bigger stroke will help me achieve more power.

[blykins]

Well, as Blair pointed out, the difference in would be about 13 cubes.  At 1.2/1.3 hp/ci, you're only looking at 16 hp difference. 

Your average 445 will be in that 500 hp range, but it also depends on how you're feeding it.  You'll be struggling a little with out of the box Edelbrock heads and a hydraulic cam.