Hi guys. This is my first post and I want to say hi to everybody and thanks in advance. I'm a novice engine builder but am smart enough to do lots of homework and ask for help from more knowledgeable people than me. I'm looking for some advice on building a pump gas Hydraulic roller 327. I have researched a lot of the 60's era builds but they were all 11:1 compression motors with solid cams (30 30 cams). I'm looking to get about 425 HP and even more important as much torque and mid range power that I can get out of this mighty mouse on pump gas (9.5:1 compression). This will be a 80% street vehicle (and yes before anyone says it, I know that I could get more power out of a 350 or 383 but everybody have those and i want something different. I have built a 350 but have always been interested in the mighty mouse 327's ...plus a 327, would be more correct to the truck it's going in) Here's what I have. I have a 1966 Chevy short-wide PU. It has a 12 bolt with 3.73 gears with a 700R4. I'm going to have about a 2000-2500 stall. I have a 68 327 block with forged crank that unfortunately will have to go to .060 over to be cleaned up. The block is at the machine shop as we talk getting bored, aligned honed, decked to .010, and balanced. I thought about going with a 6" rod but have decided to stay with 5.7's. To get my compression ratio right (about 9.5:1), I'll be using forged flat top pistons (probably Speed Pro brand) with Moly rings, machine shop owner is going to recondition some forged i beam connecting rods (he builds a lot of circle track cars and some customers replace them after one use but he guarantees that they are good). I will be using ARP rod and main bolts. Machine shop owner recommended following cam XE294 HR from Comp cams. it's duration at .050 is 242 (intake) and 248 (exhaust) with 110 degree lobe separation and valve lift of .54 (intake) and .562 (exhaust). Is it too radical? I have always used hydraulic flat tappet cams but was told that a roller could take more duration. This will mainly be a street truck (no AC but possibly could have some day) so I don't want to accidentally put to much cam in it like a lot of people do. Does this cam look OK to you guys? As far as the heads, I'm looking at the Dart SHP, Aluminum, Assembled, 72cc Chamber, 200cc Intake Runner Cylinder Heads. They have 2.02 intake and 1.6 exhaust valves. (I don't know if I should go with a smaller intake runner size 185 cc or larger ones like the 200 cc or 215 cc. Can someone explain this too me? These heads are assembled but I will match springs to cam. I plan on using an Edelbrock Performer RPM Air Gap intake (1500 to 6500 rpm). I have two carburetors to choose from. I have a Holley 4150 750 Double Pumper or a 600 cfm Edelbrock. I'm thinking the Holley 750 might be best. Anyways, guys any and all advice would be appreciated. Thanks
1) keep in mind, what usually sinks the beginnner, is the desire to be different from everyone else. Everyone else does what works, b/c it works, and a 388cid (.06 over) will make the power you want, where you want it. Pulling it from fewer cubes means running a higher RPM (and radical gears, tho that 3.06 first gear and 3.73 rear will help with launch, but the RPM drop between gear shifts will hurt), and learning how to get it from a lower RPM requires...dyno experimenting. Its what even the guys who know what's going on, spend their money on.there is nothing wrong with following the herd, learning that, and moving up. but it still takes time and money...those who have gone before you, tend not to want to give up their hard learned lessons for free, ya know?2) that 1968 crank can be offset stroke to 340cid with pre 1968connecting rods, that would be oldschool if you change your mind on a stroker. it'd be different b/c no one's doing those anymore.3) longer connecting rods will help the piston dwell at TDC, which allows the combustion to build before the piston goes down. since you've decided not to, consider where combustion will occur--a large chamber head will allow most of the expansion to occur in the head's combustion chamber, pushing mostly on the head. doesn't sound like its the way to go, does it? better to have a small chamber head, and deep piston pockets--that's where the shorter connecting rod helps--so combustion mostly happens inside the piston dish, and pushes mostly on the piston instead.4)filling those chambers ,and emptying them out, is where you will get some power. focus on a tuned exhaust, and a tuned intake runner. that's how a 302 ford pulled a lightweight mustang to 1/4 mile times not seen since the 428 cobra jet.5)smaller intake runners will hurt the flow at high RPM, generally speaking. Higher RPMs make a small displacement engine churn out more power. unfortunately life is a series of decisions 3) high compression works with long duration cams, as they bleed off compression. But they are also hi RPM cams, and frankly, that was the 283/327's benefit, its ability to rev high.
Just because you can't do it...doesn't mean its impossible
OK, I've changed my build up some. Let me know what you guys think of this combination and please offer ant suggestions you might have. I am now going with a hydraulic flat tappet instead of roller (couldn't justify hp gain to cost). I chose the Comp Cams XE 274 (230 intake and 236 exhaust @.050). I'm going to put some Brodix IK 180 aluminum cylinder heads (70 cc and 180 intake runners)with some mild porting and polishing. I'm also going to use a gasket matched Brodix HP 1 intake manifold with a Holley DP 750 on top. I was told that I'm probably gonna need to put smaller jets in. I'm using Speed Pro forged Aluminum flat-tops (+5.4 cc) pistons and had my block decked to .010. If my figures are right using a .041 head gasket, this will give me about a 9:5:1 compression ratio. I'm hoping that this combination will get me about 425 hp and about 400 ft lbs of torque. The block and rotating assembly is at the machine shop getting balanced and final hone. It won't be long before I can start building this mighty mouse. I'm so excited I can't hardly stand it. I love hearing a motor come to life!!!
Help, I've got another question. Did 68 large journal blocks use small journal main bolts? Machinist told me that ARP 123 5001 were wrong and that I need ARP 134 5002 (which is for small journal). I know they changed blocks up in 68 and that they changed from small to large journals (well actually medium if u count 400 sbc) from 67 to 68. They also changed blocks again in 69 with 350 and last yr for 327. Are all 68 blocks this way or could this have been left over main bolts they put in my motor? I just thought it was strange. Has anyone heard of this?