Engine build opinions?

Ok Guys, I'm pulling the engine out of my 77 ski this winter. So far I have a set of GT-40 heads at a friends machine shop getting decked and a valve job and new springs all according to the cam card from the new cam from cam research. I have a set of Hi-Tek manifolds on their way. I am ordering the Edelbrock performer intake and plan on a DUI distributor with Livewires. Also some engine dress up goodies, fel-pro gaskets, SS intake bolts. I have a Acme 540 already on the boat. All this started with the plan to repair an oil leak.

I know they aren't GT-40P heads, but I got them cheap to start with and CR allreday ground my cam. The engine only has 480 hrs on it and with just me, it already topped out at 49. I am worried that with these mods I might have to re-prop it since I can already get 5000 rpms with the Acme 540.

What am I missing?

Yes on the rpm. Got the cam specs handy?

The 540 should do you fine. You'll spin it higher but that's where you'll be making power.

Don't forget a new double roller timing set. If you're going all out, no harm in adding roller rockers. 1.7's may be the way to go if your cam specs are conservative. Make sure you order a shim kit to get your lifter preload set properly... Depending on how much you decked the heads, you may need new pushrods- but I'm guessing you knew that!

That .460 grind is conservative... That engine would like the .490 that 1.7's would buy you. Rollers certainly aren't needed but are nice- and the only way to get the bigger ratio so far as I know. This did not strike me as a budget build, with the hiteks and all.

I wouldn't sweat the higher rpms. They're likely safer than loading the engine down with a bigger prop... Let it spin.

Yup, gotta measure pushrods length after the heads are on.

I guess it's maybe like asking someone who makes the best truck or what oil to use . For what it's worth here is a chart I found a few years back on heads. You will most likely have to zoom in to read.

That makes sense since the Ps were for passenger car and the GT-40s were on SVT engines.

I've got a call into my machine shop who spected the springs too make sure they are still the right ones for a 1.7 rocker.

I did order the air gap performer rpm last night.

You guys still think it's ok to spin a 35yr old 351W up to 5200? The book says 4600. Could it be because of the springs in the old head design?

I recently build a Harley that Makes it's peak power at 6500 now that had a readline of 5800 out of the box. But we built the bottom end to handle it.   Making twice as much power too I might add ;)

Cam bearings arent a high wear item. If compression was good, oil pressure was good, and everything looks clean when you break it down, I wouldnt think twice about bolting on the extra hp and spinning it to 5200 or so. No need to tear into the bottom end if its wearing just fine.

The 351w is a stout piece and the bottom end can handle the extra revs just fine. Ive read 6000rpm is no problem for a stock bottom end. The "max operating RPM" called out in manuals (usually 4400) has more to do with where the stock engine (with its low compression ratio and low flow parts) will perform best. Spinning it any higher would have made the boat go slower... but it would not have started breaking things.

Im not sure the Air Gap is the way to go (versus the regular RPM)... might be tough to keep that valley clean. Operating temps are also fairly low on our engines, so I wouldnt expect to see much gain with it. Hopefully the height is the same as the regular RPM? Thats one thing to keep in mind- it will be 1" taller than the regular Performer, so motorbox clearance may become an issue. Playing with the carb, arrestor and spacer may be required to fit everything.

Question for anyone who used the DUI Livewires, do you have to have them custom cut, or will the standard 351W models reach. It says (over the valve cover) next to the model number C9059.

Taylor wires are what i use also.
They are as good as any you'll find.

Ford Cobra 1.7 are Crane Energizer rockers
(stamped "Ford" on one side and "Energizer" on the other.
and they fit under the stock valve covers.
Buy a Ford rocker shim kit.

I'll bet your going to be surprized with hood clearance or lack of,
I was.

Waterdog wrote: Ford Cobra 1.7 are Crane Energizer rockers (stamped "Ford" on one side and "Energizer" on the other. and they fit under the stock valve covers. Buy a Ford rocker shim kit.

Andy is Summit the best place to purchase or have you found a better source.

Waterdog wrote:    Taylor wires are what i use also. They are as good as any you'll find. Ford Cobra 1.7 are Crane Energizer rockers (stamped "Ford" on one side and "Energizer" on the other. and they fit under the stock valve covers. Buy a Ford rocker shim kit. I'll bet your going to be surprized with hood clearance or lack of, I was.

As soon as it comes in I will start measuring and see what I have to work with.

Has anyone put an RPM under a late 70's engine box? If so how did you make it work?

I'm not worried about the rockers clearance, I bought taller valve covers already.

OK,I ordered the Crane Cams 44746-16 - Crane Energizer Pedestal Mount Roller Rocker Arms 1.7 with Ford shims from Summit.

http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=10147

They aren't real tall. They remind me of 351C covers as they kind of turn up. It will be close, but I think they will be fine.

I believe all of the 6582 FMS valve covers are considered "stock height"... though they may have a tad more clearance than some stock covers. The FMS 1.6's fit just fine under mine... but not all rockers are created equal! No problem fitting with the exhaust manifolds though.

TRBenj wrote: That .460 grind is conservative... That engine would like the .490 that 1.7's would buy you. Rollers certainly aren't needed but are nice- and the only way to get the bigger ratio so far as I know. This did not strike me as a budget build, with the hiteks and all. I wouldn't sweat the higher rpms. They're likely safer than loading the engine down with a bigger prop... Let it spin. Yup, gotta measure pushrods length after the heads are on.

I agree with Tim. I have been told by a professional engine builder that roller lifters are better for their reduced wear capability. Also, you can more aggressive with cam grinds. But wiht rollers, you can be a little less concerned about ZDDP content in your lubricating oil.

Jef,

I can send you a copy of my Desktop Dyno 2003. You can plug in all your numbers and install various parts and get a fair idea of what the engine performance will look like. Also, it allows you to swap various parts to get the performance you want without tying up alot of money buying parts and swapping pieces.

PM me with your email address and I can send you a .zip file of it.