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post #1 of 3 (permalink) Old 06-12-06, 11:19 PM Thread Starter
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Q's about a 400 with Clev. 4V heads

A few years back my dad got the idea on his own (somehow) to do a 400 (.030 overbore) with Cleveland 4V heads, which I think you guys have seen before probably (this combo I mean). It really only takes the Weiand spacers for putting a Cleveland intake onto a 400 to do this, except the ports have to be opened up A LOT to get them to 4V size. So essentially I'll refer to it as a 400C 4V.

The machinist left a lot of blanks as to some of the details in this engine, it went through a set of rings in 5000 miles so I got to go through it myself not too long ago and see all the parts that were in it. It has a .505 lift Comp Cams (275DEH part number IIRC, which I think is the adv. duration? 275?), it has these cheap cast pistons :( :
and closed chamber 4V heads with stock 4V intake and Holley 750 carb.

Supposedly the engine had somewhere in the mid 10s compression, but it's very fuzzy now and the machinist never gave us a definite number as he was supposed to go back and check his notes and never did I guess. Anyway, I was hoping first of all that someone could tell me if this sounds right based on the configuration of the pistons, head, etc. (I don't know an exact cc spec on the piston dish, but it's not a lot). I'm curious because even running 87 octane with lots of timing this engine never detonates, maybe because it's running a bit rich right now.

I also wonder how much power this bottom end will stand, it's basically a stock 400 bottom end with the cheap pistons. Also how much RPM should it stand? The engine is in a 77 F-150 and despite all the weight of the big longbed truck, it runs neck and neck with an 88 GT Mustang. I figure it's around 300 HP at the wheels maybe? I think it should be making a lot more but not since it still has stock exhaust manifolds, 2.25" exhaust, and stock intake and air cleaner assembly. With all that and some tuning, I think 400 crank HP should be pretty easy and maybe 350 WHP. What do you think?

Sorry for still more questions but this is one of the few places I know to ask and I figure I should put all my questions together.

I would like to put headers on this engine, but it's an odd combination. The headers need to fit the truck frame and engine placement with a 400 block, but have the big tubes and flange for the 4V heads. I haven't found any headers specifically for this combination. I think 1.75" tubes would be about right for the intended use of this engine, and I can find headers for a 400 in a truck, I assume I could just cut the flange off these and mate a 4V flange up to them?

Also, doesn't this kind of combo deserve at least 2.5" dual exhaust? And I want to get a crossover pipe on it also, I'm sure that will help a bit and give it a great sound along with the Flowmasters that are already on it.

That's it for now, thanks,
John Lewis

Last edited by John L.; 06-12-06 at 11:20 PM. Reason: Typo
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post #2 of 3 (permalink) Old 06-15-06, 07:12 AM
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Re: Q's about a 400 with Clev. 4V heads

Hello John.
These are all good questions. The CR of stock 400 pistons with open chamber 2V heads is about 8.5. I doubt using stock pistons with closed chamber heads will give 10.5:1 CR?
I believe you could rev such a motor to about 5000rpm max.
With decent headers, a non-restrictive air cleaner you should be able to do better. You can also pick up single plane inlet manifolds designed for 400s from California Speed Supplies in Brisbane, and do away with the spacers-although how useful these are for 4V heads I don't know.
Headers for 400 in F-series trucks can be obtained from the US and a number are manufactured with this in mind.
One site you must try John is:
The 335 series engine forum
This is a forum designed for F-series trucks and is US based. As you may be aware the 400 and 351M were put into millions of F-series trucks in the US. There are people on the forum who have forgotten more about 400 motors than i'll ever know.
I have a 400 in an XD Fairmont: 30 thou oversize, roller rockers, Badger flat top hyper pistons, 2V open chamber heads with 4V valves approx. CR 10.5-11.0:1, FMX with big block bellhousing, pacemaker headers(4 into 1), 3000 high stall converter, 9" rear 3.89:1.
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post #3 of 3 (permalink) Old 06-15-06, 09:06 PM Thread Starter
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Re: Q's about a 400 with Clev. 4V heads

Thanks, that's some good information there. I pretty much want to stick with 4V stuff, as with the extra displacement the massive ports are a little more sane on the street than they would be on a 351 or *gasp* 302. Plus they're just cool...! I can use any 351C intake, so that's no problem, Weiand still makes them and perhaps some others. The problem with headers is most that I find are for the 2V heads and the whole flange will fit into the 4V exhaust port!! I may be able to chop a large tube 400 header and weld it to a 4V flange however.

I also believe the compression ratio is lower than I previously thought.

Yes, tons of 351Ms and 400s around here, this one isn't quite so anemic anymore though.

I will check out that site, thanks for the info.

John Lewis
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