Jump to content
Server maintenance Read more... ×

Recommended Posts

hey guys just after some opinions on some upgrades which im trying to work out for my 351 cleveland. My rear main seal has gone so thought since motors coming out may aswell upgrade the engine currently is very mildly worked and hoping to get a bit more out of it. Bottom end is basically standard but im just thinking of doing top end with some 2v edelbrock performer rpm alloy cylinder heads 61629 and a comp cams magnum 294S. Intake manifold abd carbs im thinking of going and redline tunnel ram to suit the 2v heads and a couple 465 holleys on top. Ignition im running a full msd set up with 6al 2 box and behind the motor is a toploader and for diff 9 inch with 4:11. Only other thing im thinking is fuel setup to replace to standard pump with a robbmc pn1020 mechanical pump holley reg and fuel cell in the boot and changing fuel line up to 1/2 inch. Still research and thought id ask for some opinions if im on the right track or anyone has a similar setup to give us a hand to work it out. Any help would be greatly appreciated.

 

Share this post


Link to post
Share on other sites

OK you need to start with a (realistic) target HP and intended use.

You need to pick a camshaft and build the engine around it. Your cam size, duration, lobe sep, etc will determine what comp you should run, which is where you start from with your machining, piston choice, manifold, etc.

Seems like you have a basic plan, can't see anything wrong with that list except the tunnel ram and twins. It been proven time and again that this is a step backward from a decent single 4-barrel and air gap. There's an episode of Engine Masters where they back-to-back a single vs dual/tunnel ram and the single was superior in every way.

The only reason why you'd use the duals is to have some jewellery sticking out the bonnet.

Regarding the rest, the devil is in the detail. The Edelbrock heads will need a bit of work to match what's available from CHI or AFD. They're pretty much designed to be a sensible upgrade from stock 2Vs. They may however fulfil what you need unmodified if your target HP is within their flow capability.

If your bottom end is actually stock, the pistons will be way down the hole, killing any advantage that the alloy heads would give to the compression capability they give.

I know you only want to do a top end upgrade, but if you want to do it all properly, zero deck the block, use minimal dish pistons and don't go near lumpy-tops. You could run 11.5 compression with those heads if you use the right cam. Aim for a dynamic compression in the high-8s to see what chamber size and/or piston to use. There are free online calculators to help you with this.

You'll need a steel flywheel and a good harmonic balancer if spinning it over 6000. The bottom end will take 6500 if it's balanced reasonably. I've seen a well-prepped 351 sit on 7500 in a race boat with stock crank and rods.

Sent from my CPH1607 using Tapatalk

Share this post


Link to post
Share on other sites

Thats my engine specs that i have done about 5000km since the rebuild. I got dynoed at 343hp at the wheels so if i can gain an extra 100hp and say my realistic hp say im aiming for 450hp at the wheels.

Im able to say much about pistons and bottom end as i havnt pulled the engine out yet to check what pistons i do have to work out comp with heads but your saying to work around the cam im happy with my choice of the being a solid flat tappet magnum 294S comp cam but the description states i need a 10:1 compression so i should work that off piston and heads?

I was looking at the chi 3v heads but they are very pricey and the afd site says there all sold out which was the reason why i was looking at edelbrock. 

haha yeah i watched the episode of engine masters when they get the 50hp extra out of the tunnel ram but all i was going that way for a bit of jewellery out the bonnet as i like the style but if i can pull more power out of a high rise manifold and 4 barrel may do that

Share this post


Link to post
Share on other sites

You are approaching the practical limit of the 2V heads at that power level, though bolting on a set of alloys alone won't make another 100hp. I must say 343 at the wheels is already a pretty stout street motor.

450 at the wheels is getting serious indeed, as that's in the mid-500s at the crank. To make that, a stock stroke 351 would have to spin pretty hard and have a forged bottom end to cope with it.

A motor that makes the power you're after would give little change from 15K if you had to buy the whole package, and would likely be a stroker as it's easier, cheaper horsepower.

You can bolt on horsepower up to a point, but the whole thing has to cope with the extra stress too.

On a side note: I have learnt from bitter experience, don't trust other people's workmanship, unless there's proof of it being done professionally. Otherwise, your engine might make the numbers, but not for very long.

Sent from my CPH1607 using Tapatalk

Share this post


Link to post
Share on other sites

yeah may start looking at a stroker kit or maybe a forged rotating assembly for a 351 was trying to keep cost down buy just doing top end but by the sounds of it may not work in my favour and 100% i hear what your saying about the bitter experience thats why i thought id jump on here and ask for opinions so i can work out my options and try source and get it done myself so i know im getting a good job 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×