Build My Motor

[RXTbone]

Please build the motor for my '66 A-code fastback. It'll be a summer street car/daily driver.

Here's what I have to start: 351W low mileage block, stock internals (truck engine). GT40P heads. 4 speed top loader. 8.8/3.73 traction lock.

Money is an issue, so use it only if you have to. Use as many stock parts as you can... I'm looking for around 350 rwhp. Tell me the HP you think I'll get with your build and the 1/4 times.

Thanks for your time and any help you may provide!

 

[bnickel]

what year is the motor? if it as f4te casting then you have a roller block 351 which is awesome, i would almost trade my built 351 for it. anyway if it is a roller block you're in luck, any 5.0 mustang roller cam will bolt right in. to get 350 RWHP i would look at a b303 or bigger motorsport cam maybe even an x303 shouldn't be too lopey in a 351, other than that a good intake like a weiand stealth and a set of headers with a 750 carb and electronic ignition and that should be good to go. i'm going to assume this is a roller motor for now, since you did not say what year truck it came out of but you did say it was a truck and low mileage so i'm going to assume 94 or newer which would make it a roler block. if not let us know and we can post mor combo's but we need more specifics

 

[RXTbone]

The block casting number is D9AE...

Thanks for the help!

 

[BrownPSU78]

DIY port and polish might help.
--Brown

 

[XXBULLETSXX]

Ah well hell I'm not missing out on this one.
Who wants to stop by my house and pull my heads and do a valve job. I will supply Tools, warm enviroment, Beer (to a point) maybe even some lunch and dinner; you supply parts and labor.
If I have any takers email me asap before someone else beats you to it!

 

[RXTbone]

My main concern is what I can, or shouldn't use from the stock engine. I think the engine is from a '79 truck...

Thanks!

 

['69Stang]

I would sell the GT40p heads and get a set of good aluminum ones. AFR 185’s are the way to go. If they are too pricey look for a used set of the top brands like Twisted Wedge or Edelbrocks, even an old set of the iron Windsor Sr’s. The GT-40ps will not support the airflow needed for the power levels you are looking for. Since you are on a budget you can forget about the roller cams because they are expensive when you start adding in the roller lifters ($250+). A good alternative would be a solid flat tappet cam with duration numbers in the mid to upper 230’s, lift around .580 on a 110 LSA. Make sure to get your compression around 10.5:1 to make power. A good ignition (electronic) and an MSD6AL would help, too.

 

[RXTbone]

I'm going to sound like the noob I am...

I've heard very good things about GT40P's, including a number of articles that claim they have better flow than the Cobra heads. I understand the higher priced aftermarket performance heads will ultimately flow better, but will the GT40P's flow enough to get the numbers I want? With the addition of a cam, intake and exhaust, I figured I could easily reach 350-375HP. Am I wrong?

Which brings me back to the stock parts - can I use the stock crank, etc.?

Thanks for the input!

 

[shelbe67]

yes I think that you can reach your goal in hp but you will be limited from the heads bnickle has the best combo I think central coast mustang I think offers that combo for a 302 and I think that it makes or so they claim 350hp so you should make more easily with a 351

 

[bnickel]

if the casting number is a D9 then yes it is a 79 model, but i think the A denotes it as a passenger car block, but i could be wrong on that one. at any rate a cam with about .525 up to about .550 lift or so should with about 230*-240* duration @ .050 should get you where you want to be. the p heads should be ok for the power level you're looking at, but probably no more than that, but that's ok, any more and you would need a much more aggressive short block assembly antway. i would recommend at least port matching the intake side of the heads, and a little bowl blending for better airflow, but those are pretty easy to do, even with just a dremel tool, although a die grinder would be much quicker.

 

['69Stang]

I'm going to sound like the noob I am...

I've heard very good things about GT40P's, including a number of articles that claim they have better flow than the Cobra heads. I understand the higher priced aftermarket performance heads will ultimately flow better, but will the GT40P's flow enough to get the numbers I want? With the addition of a cam, intake and exhaust, I figured I could easily reach 350-375HP. Am I wrong?

Which brings me back to the stock parts - can I use the stock crank, etc.?

Thanks for the input!

The GT-40 or GT-40p heads are very good heads, even under-rated heads for a 302. But they simply don’t have the port volume to support an engine in the 347+ CID range that is looking to make good power up to around 6000-6200 RPM’s. These heads will choke off a 351-357 CID Windsor and cause them to be very torquey and responsive up to a peak in the 5200-5400 RPM range where they will run out of breathe. If you want a very responsive low to mid RPM 351 Windsor the GT-40p heads would be fine, but they are not a performance head by any stretch of the imagination for an engine that size. Remember, the GT-40/p’s are actually a copy of the original 351 Windsor heads. That’s right they are actually 351 Windsor heads, which was the hot swap for a 302 in the 1970’s. We know that the stock 351 Windsor heads were not world beaters for the 351 Windsors. Therefore, sell the GT-40p’s to someone that has a 302 and get a set of heads that have at least 185cc runners, all the way up to 205cc’s if you are daring – like the AFR 205’s, Victor Jr.s, or Windsor Sr.’s. Hell, my 351 Cleveland has reduced/stuffed intake ports that still measure approximately 225cc’s (stock is ~240cc’s).

Again, the AFR 185’s are probably a great compromise for a 351W street motor. But there are other very good alternatives that might be cheaper. Define your goals from a cost and performance stand point and then your options become clearer. Good luck.