Looking at doing another 302 block based 347 to start off this year. Cracked the #2 main in the previous block, which was found after "other" damage had occurred. Looking at a couple of main stud girdles to use, and looking for any input or experience others may have with them. I've looked at both the "street" and "race" versions, and am wondering what the differences in HP levels are in which they can be used. My previous 347 was running high 6 and low 7 ET's depending on weather conditions, with a 3.89 gear set. Nothing real radical, but respectable for what it was. Had no idea it had enough grunt to crack one of the mains! But, I've been told that I was pushing the edge with a factory block. I already have a 351 to build, and will be doing so when I decide what I'm going to do on the front end situation. In the meantime, the little 347 will be going in. Would like to at least get a full season out of it lol. The price between the 2 main girdles is negligible, but the race version has to have the main caps machined, which isn't a problem...just need to know if it's overkill for what I'm needing, or a requirement. Thanks!
There has been alot discussion lately on what real effects the main girdle has on any engine, and personally I'm not convinced that it would have done any good in your situation where you broke the main cap. So, what does a main girdle to..............well....it ties the mains together from front to rear, but what about counteracting the rotational force of the crank........or whip.............virtually nothing. It only sits on top of the 2 bolt mains and really doesn't add any strength like a 4 bolt main does by holding the mains with more bolts...............that is the reason I put 4 bolt main caps on both of my 351w early blocks. Whatever girdle you decide to by, make sure it is perfectly flat (machine ground) and that you machine the tops of the mains so you have a perfect mating surface..........this is not like a 4 bolt main setup where you have an air gap on the splayed mains................if you don't you will end up changing the line bore by up to .002" when you torque them down. When I was having my 351w refreshened the machinest called me and told me that he was getting ready to line hone the block with the main stud girdle on..............and everytime he would torque the mains he would get a different reading in the main bore...........0005 one time, .0008 the next and even got .001 one time...........and this was with studs not bolts, and the studs had been in the motor for awhile so there should not have been that kind of stretch. The only real way to build an effective stud girdle is to tie it to the block, not just the mains. When I was building my Ford Flathead and trying for 300+HP at the crank............the only way to keep it alive at over 5000rpm was to put billet main caps on all 3 mains, yes, only 3 main caps, and then put the girdle over the mains (machined of course), then tie that to the pan rail. For you guys not familar with a Ford Flathead, the block weighs as much as a 460 block, and the Mercury Crank which is steel is about 65lbs after grinding/polishing/knife edgeing. The only issue is that you have to build a new pan to go over the girdle, but that is the price you pay.............IMHO
I'd use a steel version like Probe/CHP and it would have to mate flush with the caps in order to work properly....so grinding the caps is mandatory. Might also look into thicker or billet caps (try Pro-Gram Engineering) that can be fitted to your block. Once all that is done the main limiting factor will be the strength of the block bulkheads. What 302 block are you using? Link to Pro-Gram...... http://www.pro-gram.com/catalog.jsp
86 roller block...I'd like to step up to a Man O War block...but not until I see how the economy is going to do lol. Can get one for roughly $2600 within driving distance to pick up, fully machined...which is what I'd like to do, just not right now
Kind of what I was afraid of...would a non-roller block be any better? I've got a couple of those siting around I could use if it makes a difference.
Depends on the year model. Older the better. Mexican block would be ideal but hard to find at a reasonable price.
I think both I have are 72 vintage...not positive though. May be worth a shot. Honestly just looking to get something to drop my stroker kit into until I either decide on the front end, or the Man O War block. Right now, leaning towards just getting the block and dropping my stuff in later in the season. Season starts on April 14 here, and I'd like to have something in place to just go out and make some rounds.
Just a side note about different Ford 302 and 351 blocks. Because of the added material in the main bearing area the "Hecho en Mexico" 302 block and the 71 though 74 351w blocks can actually accept non-splayed 4 bolts on the center 3 mains. The 351 blocks weigh about 10lbs more than the 75 and up blocks. Here is a picture of one of my 351 blocks with 4 bolt mains.
I have seen a couple go for around $700 bare, but that was couple of years ago. One interesting note is that some of these blocks made their way into US cars/vans/light trucks in the 70/80's. A couple of things to look for, the obvious is the MF and "Hecho en Mexico" in the valley, usually the blocks will have a casting number of D1ZM which would be 71 or could be D1XM which again would be 71 and there is a MF near the distributor hole. If you are in a wrecking yard look for some early pickups and Econoline vans with V8's. I believe the years would be 70 through early 80's. May be worth a shot next time you go to a wrecking yard......IMHO http://www.oldwestracing.com/index.html?http://www.oldwestracing.com/articles/mexican.htm
Hmmm...now you've got me wondering. One of the engines I have is out of an early 70's Econoline Van...I'm guessing the odds are not in my favor of having something decent though lol..
Ding, Ding, Ding...I think we have a winner lol. Sounds like what I'm going to do. Should at least get me to the track with some respectable numbers for a while
