engine choices

[MJORDAN]

Since the motor is out and the charger is removed, looking into rebuilding the 302 or building a 351 for my 95gt DD/summertime car.

I know it'll be .030 over, gt40 heads, and gt40 intake for sure. All articles i've read people say go stroked or boosted. Dont really want that, just looking for a clean, fun driver.

Will the front accessories from the 302 work on the 351?

 

[Win]

how do you know it will be .30 over?? If it's ok just have it cleaned up and use it. If it isn't then bore it .30 and use the GT40 heads and do some home port and polish on the GT40 Intake.

 

[Paul]

If you're not doing big heads/intake then there's really no reason for a 351 swap.

Just do a 302/306, or maybe a 347 if you're going to buy a whole new rotating assembly.

 

[MJORDAN]

If i'm doing a whole motor why take the chance with a 60,000 mile bore job? It'll be new top to bottom.

I just eyeballed a 351 roller block that I had forgotten I had reason I was thinking swap.

The 302/306 would be better since I already have headers and such but the 351 is tempting.

 

[NXcoupe]

Yes, never use a stock bore that has more than a couple hundred miles on it. I have rebuilt engines for a living, and never have I pulled a stock engine apart and run a dial bore gauge through it and said, wow, that's still perfect! Never. The factory didn't used to use a torque plate on their engines when honing. A torque plate simulates the distortion that the block experiences when a cylinder head is torqued down onto it. Pre distorting it will allow you to hone it round. then when the torque plate is removed, they cylinder is now distorted but will be round again when the head is torqued onto it. I have my own aluminum torque plates for the engines I rebuild and build for customers.
I will give you guys some tips, that most have to pay for, use it or ignore it as you please. Have your block align honed first, then have it decked, that square's the decks with the centerline of the crank so all the cylinders have equal compression as long as the combustion chambers are equal. Then have it bored and then torque plate honed to within .0005 of your target. This is what most general automotive machine shops go to, race engines are much closer tolerances than that.
If you are going all motor, then go with the largest cubes, I recommend the Probe 347 street fighter series, their 5.315 rod length keeps the pin out of the oil ring groove. Those are the pistons and rod length I used in my 600 rwhp vert that is in the builds section.
Hope this helps.

 

[LAFENATU]

Yes, never use a stock bore that has more than a couple hundred miles on it. I have rebuilt engines for a living, and never have I pulled a stock engine apart and run a dial bore gauge through it and said, wow, that's still perfect! Never.

You've never just used larger rings if the motor still looks in really good shape?

 

[NXcoupe]

haha, NO! But I am doing this for others, and not just trying to get ring seal in something. You also have to look at taper in the cylinder, even a slight amount can cause the rings to move in and out of the piston ringland. This movement in and out causes additional wear to the rings, causing premature failure. So no, I don't do that kind of stuff. It is a short term cure and will rob the engine of power. What people do in their garages is up to them. I only look at optimal performance. As I said in my previous post, take the info or leave the info, I was just throwing out some tech knowledge for the board to use. other than that, I keep most of my build techiniques to myself.
One more thing that is general knowledge, if you take a used bore that 'looks' good, it in fact is tapered and not circular anymore, the rings will only seal in the places that they touch on start up, then as they wear, or 'break in' they will seall around the circumference of the cylinder bore, cool right? wrong, as the rings wear and seal, they are no longer round, so when they wear abnormally to seal to a no longer perfectly round cylinder wall, the ring stops moving in the piston and the ring will stay in one spot. This will also cause the rings to wear. MOst people don't realize that rings will move in a circular direction around a piston as the piston moves up and down in the cylinder. AFter wear patterns get so bad in a higher milage engine, then the rings stop to move and carbon builds up around them, also causing further problems. It's how an engine wears out.
I'm done with engine building 101. HOpe this helps.

 

[sbr420a]

good info for sure.

 

[Mean98GT]

that nx guy knows his sh!t. id do what he says.

 

[LAFENATU]

Absolutely good info.

I have seen a few motors with larger rings and they have run strong for a long time..that's why I was wondering if that is a viable action.

Good info homey.

 

[NXcoupe]

No problem man. And I'm not saying they won't run decent, I'm saying if they make say 300 hp rebuilt just slapped together, they could make 320 to 350 rebuilt with everything perfect. I was made a believer on torque plate honing with my r/s car. Ok, one more example and then my class is dismissed, lol. I run r/s, we have to run a stock cam, flat top pistons, no portwork, tfs or edelbrock heads, edlebrock performer or TFS street heat, 70mm tb and 80 mm m/a, also allowed 1.7 rockers. So anyway, most guys with those mods make what, 250 or so? Maybe 280? mine made 280 and I got lots of props from my buds. Anyway, I did two things, one I will tell you, I had my block torque plate honed and used the studs I was using for the engine for the torque plate process, instead of just using the bolts the plate came with. I put the car on the dyno, now mind you there was one other thing I figured out and tried, but basically this is a rebuilt 306, it made 315 on the dyno. rwhp. two small details that netted 35 hp. It is making a little more than that now all motor. And on the spray, ooooohhhh, it's pretty. That graph goes nearly straight up!