I was hoping to get some advice on a 400 build.

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

My truck is a 78 2wd F250 with the 351M, C6, 3.73 rear, and 235 85 R16 tires. I currently have the stock 2 barrel and manifolds. I plan on towing a travel trailer that is ~4000lbs loaded on the highway. I live in the pacific NW so being able to maintain speed on hills is a concern. I want to stay with 87 octane, so I would like to keep the CR under 9 to 1. <o></o>

<o></o>

I am looking at an engine from Portland Engine Rebuilders – anyone dealt with them before? Anyway, they sell a 400 that has been balanced with a new flex plate and new harmonic balancer. It is line bored and torque plate honed. They only have access to stock 7.9 compression ratio pistons, but can shave the block and head for higher. They install new bronze valve guides, pushrods, rocker arms and valves. The seats are three way carbide cut. They use a crowler 15965 cam (specs, 1200-5200 RPM Range, 258/264 Adv. Duration, 477/486 Gross Lift) with crowler 6803 springs, and a 9 key way true roller chain.<o></o>

<o></o>

Does anyone have any experience with this cam? <o></o>

What kind of power can I expect with this engine?<o></o>

How much of an increase is there going with the edelbrock 3771 with 4v EGR adapter and 1406 carb?<o></o>

How much of an increase is there going with headers?<o></o>

<o></o>

Just trying to build the best engine for my application and I don’t want to have to worry about pinging under load.<o></o>

<o></o>

Thanks<o></o>

 

Frist, talk to TMI, he sponsors this forum. He has more info on a build like this than most. Check out his website for more info.

Many on this board will recommend the Comp Cams 255DEH cam for 351M or the 265DEH cam for the 400. Check you specs agains these cams. Cam timing should be set strait up, not 4* retarded like factory, with a 9 keyway timing set you should be able to do this.

Check your local requirements for emissions. A 28 year old truck may not have to have an EGR system. If the truck was origially built without it, don't put it on. Edelbrock #2171 would be the same intake w/o EGR.

Thermostat cooper-Robertshaw 333-192

Headers Headman#89260 are one choice. Followed by 2 1/4 inch dual exhaust.

get your plan together and discuss with this forum. THey are a great source of information.

 

1978Crew,
Thanks for your advice. I did talk with Tim and would love to use his pistons if I were going with aussi heads, but I am worried about towing with 9.3-9.5 CR, stock open chamber heads, and 87 octane. If anyone is runnings these on 87 and towing I would like to hear about your setup. I may just get the zero deck height pistons and have Tim dish them more to get the CR I want instead of decking the block --seems like less work.

The crowler cam seems comparable to the DEH255. Is the DEH265 perfered on a 400 with higher compression or even on one that is stock?

The only emissions my truck came with was EGR and from what I have read it would be advisable to keep it. I know I could recurve the distributer to run without it, but am unsure if that would keep me from passing a smog sniff test. I think the extra cost for recurving a distributer is about the same as the difference between the EGR and non-EGR manifold plus 4V EGR adapter. If my emissions will not be affected I may give the recurve a try.

I am hoping to get as much feedback as possible so that I can choose that best build without wasting money on uneeded items. That is why I was trying to find out how much torque and HP that engine would produce at maybe 8:1, 8:5, and 9:1 and then with the 4v and headers. Since it is just a stock 400 with straight up timing and aftermarket cam, I guess I need to know what that adds so I can modify the published numbers for the 400 with those CRs. I think I found one post showing that headers added ~40 lbs of torque, but if I don't need that I would rather not add the cost. I know I can add the intake and headers later, so I am not as worried about that stuff, but I want to get the compression right so I don't need to go back in or live with something that is not right.

I guess the hard part right now is that I am unsure how much power I need to tow with. If anyone has a similar setup and tows please let me know your thoughts.

Thanks,
Jeff

 

If you are towing on the highway, part of the problem is the RPM range of the torque curve, not the peak torque. I would go with the higher compression piston and a bigger cam, and headers. You will still have plenty of torque to get you going, but when the tranny downshifts, it won't push the RPMs up past torque range. The secret is to make it breathe. A 3771 intake with an Edelbrock #1406 carb and headers with a little work on the exhaust port will keep the motor breathing to nearly 4000 RPM.

With 78.4cc heads and pistons with 13cc dish pistons, you will get about 9.34:1 CR, but the 265DEH cam will reduce the Dynamic CR to 7.82:1. You will have a flat torque curve between 425 ft-lbs and 440 ft-lbs from 2000 to 4000 RPM. This should run on 87 Octane under most conditions, but if you dish the pistons a little more and drop the CR to about 9.1:1, you should never have any problem.

Keep the EGR, unless you plan to replace the distributor.

 

Thanks Danlee,

I think I will go with Tim's pistons and set them up for 9:1, probably a better idea than shaving alot off the deck. Do you think the line bore, torque plate hone, and full balance is necissary? I could see line boring if it was really off, and I know that torque plate boring, honing, and balancing are recommended for high performance engines, but does the engine I'm building really need it. If the engine would last substatially longer than it may be worth it, but I don't really see this engine seeing over 4,000 RPM often.

Thanks again for your help.

 

'xcuse for interrupting, but what effect has the EGR on the distributor curve?
Never heard of that, and i'm planning on removing it also, as by my understanding it just cost's power.
I have some parts already, like the 2771 edel, holley carb, new cam, and a full MSD ignition.
thanks.

 

Balancing is almost automatic when you do a rebuild like this as is boring and honing. What is being line bored? Is it the crankshaft or the camshaft? Will your machinist install oil restrictors in the cam bearing feeds?

These things are not just for high performance, but for longevity.

 

In 1971 the 400 motor was introduced in the big Ford cars and Wagons to replace the 390. It had 9.0:1 CR and no EGR. The Distributor Advance Curve was set for that motor. In 1972, the CR on the 400 dropped significantly and EGR was installed. The Distributor Advance Curve was accelerated, since the addition of exhaust gas into the air-fuel mixture slowed the burn rate. All this was done to reduce the NOx emmisions.

When you remove the EGR, the Distributor Advance Curve must be readjusted to 1971 specs to allow for the faster burn rate of the air-fuel mixture. If you don't do this then significant detonation can occur, since the spark will be too early in some RPM range.

Many aftermarket distributors have adjustable advance curves. The Ford Duraspark distributor can be modified to 1971 specs with some spring changes. One of our sponsors at Performance Distributor can supply a HEI type distributor with the proper advance curve.