Have You Tried a 302 Based 363 (Dart Block)?

[skullandbones]

I am looking ahead as I have about 1400 miles on my 302. But looking to my next engine combination can't hurt as that time will be here before I know it. I've always liked the CID around the 360 range but with the 302 it is limited to the 347 for all practical purposes. However, the Dart blocks change that scenario. I have been checking out the 363 (302 based). My plan is to basically swap out the two short bocks when the time comes. I like what I have except the limited CID. What I'm planning is a Dart SNF (3 of the mains have spayed 4 bolt pattern) with an Eagle rolling assembly. This combo is supposed to be good up to 750 hp and safely operate in the 7000 rpm range. I'm looking at a 6500 rpm red line and plus 400 hp. So that would be well within the parameters of the setup. My main goal is to do a short block exchange with no component alterations. If you didn't know it, you would think it was still a 302. The only upgrades would be a little more radical cam than the .5 lift and 220/220 duration (I think it is equivalent to a E cam) and the valve springs to support that setup.

I'm a little surprised not to have seen much about this engine configuration. So If anyone has had direct experience or friends who have such setups with details about how they worked. Curious to see how the 363 would perform vs a 347.

Thank you in advance,

WEK.

[Blue MK3]

I have a 347 stroker (based on a 302) in my car that generates, according to the dyno test data printout, 445 hp and 433 # of torque. Rev limiter chip is 6000, but the dyno test went to 6500. That gives you what you want, and with gobs of low end torque. Why go to the added expense of the Dart block? BTW, I'm a street driver; no track stuff.

[edwardb]

Couple of comments. I think you mean DART SHP block, not SNF. A little over a year ago when I was deciding on the engine build for my Mk4, pretty much decided to do a DART block, and also after visiting in person decided on Fordstrokers in Chicago for the short block build. Had a chance to talk to Jim for an extended time, compared blocks side by side, etc. I decided 347 was enough for me, but the larger bore of a 363 build is certainly a viable option for the DART SHP block. The 363 is the same stroke and rod ratio as a 347, and those have been proven now to be reliable. Just make sure to have the right pistons made for this application. Jim only uses SCAT cranks and rods, and doesn't have much good to say about Eagle. But I'm sure there are builders out there who say the opposite. DART says the SHP is good for up to 700 HP. Probably to protect the marketing space of their higher end blocks. But Jim says they'll go north of 1000 without a problem. Needless to say, plenty strong for our application. Assuming you're using hydraulic lifters, I think you're going to want the redline around 6,200 - 6,300. Good chance of valve float in the 6,500 - 7,000 range you suggested. 347 or 363, they need to breath to make power. The heads from your 302 will fit the 363 block, but will limit the power. Will still be strong, but not what it could be. I went with AFR 185's and a QF 750 carb on an Air-Gap intake. Jim spec'd a custom cam for me, balancing power with streetability. He thinks I'll be in the 450 -475 HP range with the parts I'm using. The engine is running and I've completed a few go-kart runs. It runs great and I can tell it's going to be very strong. A DART based 363 with the right parts should be near 500 with the right parts.

This is a pretty interesting article with lots of info: http://www.hotrod.com/techarticles/hrdp_1204_the_363_the_hottest_ford_stroker/

[skullandbones]

Hi Edwardb,

I was trying to type SBF and the n is next to the f. I have been reading about your build but didn't notice the engine details until yesterday. That's going to be a very nice ride. I think I am not quite settled on the other components but I will get more info as I go along and the date gets closer. I do want the SCAT crank and H rods but not sure on the pistons. I'm thinking a Comp cam may be the right way to go. They will do a custom grind for your particular setup. The AFR 205 heads look good too. That would be a screaming engine. I still think with the correct springs, cam, and pistons that 6500 red line is realistic. I've seen the Spec racers in the heat of battle and you see them at 6300 on an off all day long.

Blue MkIII: I've read so many good things about the Dart, it's hard to not consider it. There is supposed to be improved oiling and cooling jackets. The cylinder skirts are longer to stabilize the pistons on the longer stroke. The cylinder walls are thicker so the added bore is safe. I like the idea of having a system that is rated high and I can work well under that rating and still work at my limit (400+ hp and 6500 rpms). I guess you could say the Dart won't have to work as hard to achieve those numbers I mentioned.

WEK.

[edwardb]

I do want the SCAT crank and H rods but not sure on the pistons. I'm thinking a Comp cam may be the right way to go. They will do a custom grind for your particular setup. The AFR 205 heads look good too. That would be a screaming engine. I still think with the correct springs, cam, and pistons that 6500 red line is realistic.

Blue MkIII: I've read so many good things about the Dart, it's hard to not consider it. There is supposed to be improved oiling and cooling jackets. The cylinder skirts are longer to stabilize the pistons on the longer stroke. The cylinder walls are thicker so the added bore is safe. I like the idea of having a system that is rated high and I can work well under that rating and still work at my limit (400+ hp and 6500 rpms). I guess you could say the Dart won't have to work as hard to achieve those numbers I mentioned.

WEK.

My builder used Wisco forged aluminum pistons on my build. They are specifically made for a stroker application with the proper skirt and oil ring setup since they do come out of the bore at the bottom more than normal. Mahle I think makes a similar piston. There are others I'm sure. My cam is also from COMP Cam. It's a custom billet piece. Specs are: Intake Duration @.050": 224, Exhaust Duration @ .050": 232, Intake installed at Centerline: 106, Lobe Separation Angle: 110, Intake Lobe Lift: .348, Exhaust Lobe Lift: .354, Gross intake valve lift: .556, Gross exhaust valve lift: .566. It's was spec'd for my head and induction setup, plus to hit a balance between power but still decent street manners. It has a bit of a lope at idle, but not too extreme. Happy to idle at 750-800. So far seems really good. The redline will be limited by the hydraulic lifters. They just can't go higher than a certain point without starting to float. Doesn't matter what springs, pistons, etc. That's OK, actually, because these engines tend to be torquers, and don't need high RPM for the highest power. Jim (my builder) said that with solid lifters and forged internals 8,000 or more was possible. But that's really not practical for a street application. For the record, in doing a short block Ford 302 engine build, and now the DART short block engine build, I only noticed two very small differences. The DART block uses 1/2 inch head bolts (studs recommended) vs. 7/16 inch bolts, and there was a small interference with the Energy motor mounts. There's a small web on the DART block mounts that isn't on the stock block. It's a known issue, and just requires a couple of notches in the motor mounts. Everything else in my experience fit interchangeably.

To those who doubt the quality of the DART block, just need to compare the two side by side. It's a pretty strong case to upgrade. My builder had the two bare blocks on stands side-by-side in his office, and we went over them is some detail. I was an easy mark. Obviously, I was convinced. The DART weighs 40-50 lbs more. Some see that as a negative (which it could be I guess in some situations) but I look at it as steel adding strength. The 4-bolt billet mains are impressive. My builder said the added strength of the DART block adds at least 30-40 HP because the block doesn't "flex" like a stock block. Interesting. In the end, it's a $1000 - $1500 upcharge to an engine build (approx) and isn't for everyone. At reasonable power levels, the stock block does great. The DART adds a measure of safety that may not be an issue at our "normal" power levels. But I'm not expecting to break it under any conditions, it has more upgrade possibility should I ever choose to go that way, and I'm also of the opinion it adds to the resale value. Even though I don't plan to test that out any time soon.

[Carlos C]

WEK:

Years ago, people thought that the maximum that could be safely extracted out of a 302 was 331ci. Then came the 347. At first, this engine was an oil-burner, due to the very short piston skirt and the longer stroke. After years of R&D, that has been remedied. Although Dart is one of the best (and most expensive) in the field, I am concerned about extracting that many more cubic inches out of that block. I understand that this engine would be a direct and easy drop-in, but have you considered building a 351 block? You can safely go up to 427ci with it, and save yourself a lot of money if you buy an used block, like I did. Mine makes over 600 hp at the wheels all day, and yes, it's all Eagle hardware inside.

If you decide to stick with the Dart engine, do yourself a favor, and make sure that the durability and reliability are there. Good luck with your engine project.

Carlos

[skullandbones]

Edwardb: thanks for your insight on this subject. I didn't know the Dart weighed 50 lbs more but should have deduced that from the extra "meat" they have for boring and the web for strength. You have to get that strength from something. But if I was going to add 40 to 50 lbs that is where I would put it to reduce the rear bias a little more. The adjustment on the mounts is just a minor thing. We do stuff like that on almost all aspects of the build otherwise they would say, "hows your assembly going?".

Come to think about it: I believe the Spec racers do use a flat tappet cam on that TFS top end kit. I'm sure someone will correct me if I'm wrong on that. I just remember seeing videos of them reving in the middle 6000 range on a pretty consistent basis. I don't think I could give up my roller cam. I'd have to really think hard on that one.

Hey Carlos,

You are absolutely right! I've been looking at the 351 based block and it is strong and the geometry is there to do some amazingly high CIDs. I was even looking at a crate 351 which was pretty nice. However, at this point (could change my mind), I would like to do a swap out and keep everything I have the same for other components. I was more concerned with the deck height of 9.5 as compared with the 302 of 8.2 and the width of the engine more than anything. I got my headers perfect and all the other clearances including the hood where I had to do a turn down tube to make the 75mm throttle body clear the hood because of the Holley manifold.

Thanks,

WEK.

[edwardb]

Come to think about it: I believe the Spec racers do use a flat tappet cam on that TFS top end kit. I'm sure someone will correct me if I'm wrong on that. I just remember seeing videos of them reving in the middle 6000 range on a pretty consistent basis. I don't think I could give up my roller cam. I'd have to really think hard on that one. WEK.

The RPM upper limit is not about flat tappet vs. roller. It's about hydraulic vs. solid lifters. Flat tappets can be hydraulic too, and in fact were the norm in engine construction for decades. With the right springs, solid lifters can run at much higher RPM's than hydraulic lifters. The downside is they require regular maintenance to adjust the valve lash. Think Volkswagen Beetle. (I know because I had several back in the day.) Really no reason to run solids in our engines.

[skullandbones]

Never too old to learn, as they say. I did mean solid tappets not just flat but we never used hydraulics anyway so I got in the habit of misnaming them (back in the early hot rod days). I have come to the conclusion that 200 to 300 rpms is not worth it! I saw a set of high performance Lunati rollers for $850. Along with other valve train upgrades that would start approaching the cost of a fancy new racing block. I also talked with a fellow from Schneider Cams who stated that their OEM style rollers will support 6500 rpms (add states that too) and all other valve train components being good. Valve float due to the rollers would not be an issue. Still it's a lot of effort to get just a little improvement. I've always intended to improve the valve train when I change engines or short block so that is the next most important consideration (cam, lifters, springs, heads). But the Dart block is still looking good! WEK.