Hey guys... I just got my block back from the machine shop, and I have the parts to give me two options when I build my shortblock. I'm not sure which way I want to go at this point... whichever one I DON'T build, will be done at a later date. Some info: The block is a "509" factory block, with Milodon splayed caps. The cam is a Lunati solid roller (268/270 @.050, .632/.632) The heads are CNC'd Brodix Track 1's that flow 302cfm on the intakes. The bearings are coated. If it goes in the '55, it will have a ported Weiand tunnel ram with two 550 Holleys (that's what's on the 406 in there right now). It will also be backed by a 3500 converter in a th350. If it goes in the Chevy II, it will get the ported Edelbrock Super Victor with a 825 Race Demon. This will be backed with a 4000 converter in a reverse manual th400 with a brake. Option 1: 406... Eagle forged rotating ***embly, the crank is .010/.010, 6" H beam rods, and SRP pistons. 11.6:1 compression. This same exact combo in my Chevy II with a junk short block built by "Speed-o-motive" that had 60% leakdown on all 8 cylinders went 10.70's before it spun the 3 center mains that were barely held in place with the ******** chinese main caps they put on it. Option 2: 377... GM 1182X crankshaft, std/std. **** 6" 4340 cap screw rods, coated Mahle pistons. 11:1 compression. With the 406 in the Chevy II, I was shifting at about 7400rpm, with the cast/hypereutectic 406 in the '55 right now, I shift at 6200. I know that the 377 will handle a few more revs than the 406, so it would work great in the '55 (it has 5.13's in it!), but the Chevy II has the ch***is dialed in to work better with a serious motor. I know that the 406 will make more torque than the 377, but too much torque makes it hard to get out of the hole! Let me know what you guys would do... Thanks! Steve
Depends what YOU want to do. Do you want to get the Chevy II back on the road or do you want to make the 55 fly? I would probably leave the 55 alone and probably put the 406 in the Chevy II. You have a good ch***is under it and the torque of the 406 will be more fun than spinning a 377. Plus you have a little more compression... Yeah, I'd do that.
Well, Mike, IF I put the new motor into the '55, the 406 that's in the '55 right now will go in the Chevy II. It's just a motor I built back in high school shop cl***, (seriously ported 487X heads, 10:1, comp 292 Magnum, and roller rockers w/Ti retainers) but I ran it in the Chevy II for a season (after I puked the "good" motor) with a 750 Holley on a Victor Jr, and while I never took it to the track, my **** told me that it was damn near as quick as the "good" motor, which SHOULD have made almost twice the power... Plus, then the '55 might be good for more than 1/8 mile!
Go with the cubes.....unless you plan on running the Chevy II again. -Lee Atomic Radio www.atomicpinup.com
Had this same dilema with a friends car in need of a motor. It boiled down to the 406 has more durability and a broader torque range. We played with gear ratios to get the car where we wanted it. 377's are becoming common with turbo guys who need it to rev into boost. Naturally aspirated the 406 is the way to go.
377=rpm. Tunnel Ram likes 4,000+ I built 377 for a guy and it is like driving a 302 chevy, but with more ***. With your cam specs Id go with the 377.
Is there any reason as to why the compression is only 11:1? Either engine would greatly benefit from much higher compression with the cam suggested. Also, do not underestimate the carb either combination will want. We ran a Davinci tweaked dominator on a 406 in a chevy II that really screamed.
I have to ditto on the 377. The last one I did I added a sn93 paxton and custom made-by-me 1000 cfm fi to the 10.5 comp srp pistons, crower 6" rods and a custom 3.50 stroke crank. Protopline heads, scorpion 1.65 rollers. I ran a small hyd cam cause I was a fraidy cat and this was for my daily driver pickemup truck. Only 4 pounds o boost, but was built to handle 15.............FUN? oh yes, practical...nope... Man did it sing.. Would I do it again hell yes only this time I would grow a pair....
These are regularly driven street cars, so pump gas is a necessity. Plus, 2 valve relief flat tops + 64cc chambers = 11.x:1
Speed-O-Motive uses only Milodon caps. Having installed Chinese made caps for other machine shops, whatever cost savings made in the initial purchase are eaten up by extra machining time to make them fit. It is highly unlikely any new block would have 60% leak-down. The factory 400 blocks are a thin wall casting. A torque plate is installed before honing and it is not unusual to move the cylinder walls .0015-.002. you can tell if a torque plate has been used because without it you'll find shiny vertical bars running in line with the head bolts. Even a 2500 lbs. car will have to make at least 400hp at the rear wheels to run 10.70's so it seems strange the engine would make 475-500hp at the flywheel with 60% leak-down. In any case, why bother with this 35 year old junk when Dart has new SHP block available for $1,450? ***uming both the 377 and 406 have same bore there is no benefit in breathing or v.e. due to bore difference so your question can be narrowed down to choice of stroke. We know the longer 3.750" stroke 406 will provide more low end torque but at the expense of increased piston speed and friction at high rpm while the 3.50" stroke 377 give up low end torque but less friction at rpm. So the decision is based on how you plan to use the engine.
I'm gonna go ahead and call ******** right NOW. You want me to send these piece of **** chinese caps back to you, or will this video work??? http://inkandsteel.com/HAMB/PICT1409.MOV If you REALLY want to go there, I'll spill the beans about EVERYTHING that was SUPPOSED to be done to this motor that wasn't, Everything that was done INCORRECTLY, and how much after the promised delivery date it actually showed up. You might just want to admit that you used Chinese caps. Have a nice day! Steve Filpansick (look it up in your records to find out about the abortion you sent me)
Wow Steve, look who showed up to play! Business must really be slow over at ****-o-motive. I wouldn't advise telling everyone about everything that was wrong with the engine. You don't have that kind of time and you would probably tire after the first hour of typing.
Sounds like the ****o dude has stirred the hornets nest a bit here. I have never been a fan of the spacer bearing engines after rebuilding some of them. I just don't agree with clamping a main bearing inside of another main bearing with the soft surface on the face of the first bearing.It seems that the bearings move around a bit and start to etch on each other. Build the big cubes with the 400 size mains. Can't beat the cubes as we have built the 421 version of this engine and it hauls some serious ***>>>>.
An old hot rod adage says "There is no subs***ute for cubic inches." That said, for me the difference comes down to curb weight. The Chevy II is several hundred lbs lighter than the 55 so a high revver 377 would be best. The 55 could use the torque of the 406 to move it off the line.
Compression ratio is not the end-all in determining whether pump gas can be used in a motor or not. Based upon the duration numbers of the cam specified, I would guess that the motor will bleed cylinder pressure at low speed. You can call your cam manufacturer and have him use his simulator software to determine what the cranking pressure will be. Anything under 220psi will run on pump gas. A good example is 2 motors that my father and brother built. Both 540 Chevys, big roller cams, and aluminum heads. Dad's was 10:1 and brother's was 13.5:1 ratio. The high compression motor was a beast; it ended up pushing a 5000lb truck 10.0s in the quarter with 150 shot of nitrous. It was driven on the street with pump gas all the time. Dad's was a dog until you got the revs over 5000 then it would come alive.
how does a professional machine shop destroy a small block chevy when millions of backwaters stuff "rebuilt" threefiddys in thier joe dirt camaros and drive them into a guard rail.
377. I had a 377 in a 2900 pound car with 456 gears and it ran 10.78 on the motor with 10.5 slicks. It was a 2 bolt block fit with 4 bolt caps. A gm steel crank. You use to be able to get 1 peace main bearing that did not use spacers. It was a full roller motor with some very ported dart heads. O ya 14.5 compression.That thing lasted for years I ended up running nos though it for about a year. It blew up by falt. I liked that motor so much when I blew it up I berried it in my back yard next to my dog. Scott
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