351W 4V

[Mach1 Driver 560]

I've got a 2V which only has 9.5:1 compression. I've seen different numbers but believe the 4V to have 10.7:1. Is that correct? I assume the pistons, intake and carb change- anything else? Do you have any trouble running 91 octane? Thanks.

[1969_Mach1 333]

Yes, the 4 barrel 351W motors for 1969 had flat top pistons and the 1969 and 1970 cylinder heads had smaller combustion chambers than the 1971 and newer, 60cc vs. 64cc respectively.  Giving the 1969 and 1970 4 barrel 351W a 10.7:1 static compression ratio.

My 69 351W is a factory 4 barrel with 10.7:1 CR.  The static CR has been calculated several times and it is in fact 10.7:1.  I haven't heard any pinging running 91 octane fuel.  As a precaution I do now mix Torco Accelerator with 91 octane pump gas at a ratio to obtain 94-95 octane.  Plus, the motor seems to run better and I can advance the timing and speed up the advance curve from stock settings.

Keep in mind, camshafts play a big role in determining the dynamic compression ratio.  Stock cams will increase the dynamic CR vs. aggressive cams that will reduce the dynamic CR.  Also, keep the motor running cool, mine runs at about 175-180 deg. F and make certain the A/F mixture is not too lean.  You know, you want to see a little color on the plugs and not have them white like on new cars.

Is your motor stock, have you changed the camshaft or anything else?

[Mach1 Driver 560]

6 hours ago, 1969_Mach1 said:

Is your motor stock, have you changed the camshaft or anything else?

Mine is a completely stock 2V that I will probably stroke. I remember when they made the switch to unleaded and lowered the octane. I would occasionally go to a station that sold what they called avgas at the time- it was 105. I'd get a few blocks away and the idle would smooth out and she would purr like a kitten.

Since your CR is fairly steep for today's pump gas, I was curious how it behaved. I was planning something around 10.1:1. I figure that if I get stuck some place where I can only get 89 it will still run ok. I have a Sunoco very close that sells 90 with no ethanol. Thanks

[1969_Mach1 333]

I don't drive my Mach 1 much so I don't mind mixing Torco Accelerator with the fuel.  I never intended on driving the car much as I was building it.  The motor behaves just fine with this mixture.  Before using the Torco Accelerator I did use straight 91 octane pump gas.  It ran fine, but seems to have more power with the Torco Accelerator mixed in.

If you plan on driving the car a lot I would definitely consider a slightly lower static CR so you don't have to worry so much about fuel or additives. 

[barnett468 418]

Exactly what are you trying to accomplish?

[Mach1 Driver 560]

1 hour ago, barnett468 said:

Exactly what are you trying to accomplish?

We've been over this before and I appreciate your interest. After reading that the 4V had 10.7:1 compression and wasn't merely the addition of a four barrel, I was curious how those engines fared with today's gas. It will be some time before I actually get to the engine part of the restoration, and I'm considering how far I want to take it. Do I want to bolt some go-fast parts onto a basically stock but refurbished short block, or bore it for more cubic inches? The stock block may be enough for me.

For crude estimating purposes and given a 351W 2V short block, how much extra HP might one expect from : AFR 205 cc heads, Edelbrock 5081 intake with a Sniper (strictly for convenience), FPA 4 tube step headers, and here is the big variable- a mild cam (not lopey). I have read others estimate 40 HP for the heads, 20 HP for the intake/carb, 20 HP for the headers and wild numbers for the cam ranging from 25-100 HP. I'm guessing 20 for the cam. Would a total increase of 100 HP be an unreasonable estimate? I know all the stuff to make it breathe better doesn't do much good without a big cam, but I don't want to constantly hear and feel all the racket.

 

 

[barnett468 418]

you need to determine how much additional power you want first before people can make useful suggestions. you also need to tell them your gear ratio, trans type, tire size. elevation where the car will be driven most of the time, and whether you want a lite to lite speedster or a freeway flier etc.

as far as wanting a fairly smooth idle goes, in general, the wider the cams lsa, the smoother an engine will idle. from what little you posted so far, i would say to start with a cam that has at least 112 lsa instead of 110.

boring the block to make more power is pointless because it wont give you much but the more you bore it, the more load it will put on the cooling system because the cylinder walls will be thinner. most blacks are hard to cool at .040" over and most are junk at .060 because they simply can't be cooled.

increasing compression does little to increase hp. you mat get around 3% more hp thru the entire rpm range for each additional point of compression if all else remains the same.

in general, the bigger the cam, the less bottom end the engine will have, so to regain some low end performance, numerically higher gears need to be installed which makes the engine rn at higher rpm all the time.

most mild to moderate 351 street engines run 10.0 compression at the most, with around 9.5 being the least.

you can run around 1/2 to almost 1.0 point higher compression with aluminum heads than you can with iron heads and have the same level of detonation potential.

stepped headers do not always make the most power, and for a mild build, hedman elites are by far the best bang for the buck and an excellent choice.

afr 205 heads are way to big for a nearly stock 351, and a complete waste of  on one.  you would be far better off with nothing bigger than 185's.

these heads would be fine for a mild build with a non roller cam, and the pair costs less than just one afr head.

https://www.summitracing.com/parts/edl-5023/overview/make/ford

 

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[Vicfreg 771]

I did a 393 stroker with Edelbrock Performer RPM Intake, heads and cam.  Nice combo. Their crate engine makes around 400 HP, so they have lots of data on that if you want to use that as a comparison.

One thing to watch out for is that the deck height of the 1969 and 1970 blocks is slightly less than the later 351 W blocks. (9.48" vs 9.5")

The stroker kits have what is called a "stack height", mine was right at 9.48". However, previous owner(s) at some point had shaved the block down at the head surface, so I needed to mill my pistons slightly.   Another option is to use thicker head gaskets (I don't recommend this).  Check the stack height and actual deck height  before making final decisions on your build.

Due to the lift height of my cam,  I also used the smaller valve edlebrock heads to avoid valve train interference. 

 

[Mach1 Driver 560]

21 hours ago, Vicfreg said:

I did a 393 stroker with Edelbrock Performer RPM Intake, heads and cam.  Nice combo. Their crate engine makes around 400 HP, so they have lots of data on that if you want to use that as a comparison.

One thing to watch out for is that the deck height of the 1969 and 1970 blocks is slightly less than the later 351 W blocks. (9.48" vs 9.5")

The stroker kits have what is called a "stack height", mine was right at 9.48". However, previous owner(s) at some point had shaved the block down at the head surface, so I needed to mill my pistons slightly.   Another option is to use thicker head gaskets (I don't recommend this).  Check the stack height and actual deck height  before making final decisions on your build.

Due to the lift height of my cam,  I also used the smaller valve edlebrock heads to avoid valve train interference. 

 

Thanks I called them up. They said it has a very lopey cam, and since I don't want that they suggested 2182, which has an LSA of 112 like Barnett suggested. That will drop 30-40HP. The intake with this package is 7581 which is a dual plane. Since I'm going with a Sniper, a single plane 5081 is probably more appropriate, but I'll have to ask. Its also .65" shorter. Can you run the big stock blue bucket air cleaner, or does it hit the hood? 

[1969_Mach1 333]

If you are building a stroker motor using a 1969 or 1970 351W block you need to keep in mind the deck height on 1969 and 1970 351W blocks are 0.023" shorter than 1971 and newer 351W blocks.  9.480" vs. 9.503" respectively.  Therefore piston selection with the correct compression height is critical.  Otherwise, the pistons will be above the deck and the static CR will be too high.  There are few off-the-shelf standard pistons available for the 1969 and 1970 blocks.  Do your homework and math before selecting parts.