I am a little uncertain as to what to do for my shortblock this season. Last year I did a 388 which came apart in less than 100 miles. The rotating assembly was:
-Eagle 1pc 3.75" cast steel crank, external balance
-Eagle 5.7" SIR 5140 steel I-Beam rods
-Speed-Pro 4.060" Power Forged Pistons, flat-tops

My block is .060" over, pourous and needs to replaced. I have had several people tell me that I should switch to an older casting block (which would mean switching to a 1pc RMS) if I want to re-use my .060" pistons. I was planning on getting a different block, new crank (sell the old one) and redoing the 388. While I am pushing the limits on how much I can spend this year, I am starting to think that maybe I should build a 400 based motor this time around. The jist of my setup is
-AFR 195cc heads
-RPM Air-Gap intake
-Speed Demon 750 DP
-Crane 1.6 Gold rockers
-Hooker 1.75" Super Comps
-Th350
-3500 converter
-3.73 gears
-26"x10.5" ET Streets (may switch to 28's)
-Last year I had a Comp XE274 flat tappet hydraulic cam which was 230*/236*@.050", .523"/.523" lift and had a 110LSA. I found a guy that had Comp grind him a custom billet solid roller for his 383 w/ 10.5:1, AFR 195s and a dual-plane intake. He installed and degreed it but switched to a hydrualic roller setup before it was run. Specs are 236*/242*@.050", .614"/.629" lift (less the .016"/.018" lash) and is ground on a 108LSA. I got a good deal and bought the cam, lifters, and Comp 954 springs. The springs have 237 lbs on the seat and 537 open. The cam card is at the bottom of the post.

The car is used mostly for racing but is also driven on the street some (including the 8 mile drive out of town to the track). I like to think of it as strip/street. I am not sure if it is worth spending a bunch of extra money for 'a little bit more shortblock' or if I should rebuild what I have and build something bigger and stronger later on. Like everyone, I'd like to build the best setup right away but I think I'll have to settle for the best on my budget for this season. What are you guys' thoughts?

Trevor

 

The camshaft and cylinder heads would be on the small side in a 400, stick with the 388 since you already have the bottom end for it anyway.

Do you have any idea why your 388 let go before 100 miles? Might be worth looking into so you don't repeat any mistakes :shrug:.

 

That cam is very close to my crower special grind I have in my 383. It should run strong.Putting it all in a 400 would make even better power but if you are on a low budget right now and plan on doing something else later I'd agree with unknown_host and keep it in the 388

 

Hey Trevor, I have a 400 block if you are interested.

 

Can I ask what failed to cause to come apart so early???? I need to ask cause I have a friend that just got an eagle crank, and sir rods for his engine (although he is thinking about upgrading some stuff). So I am just curious what the problem was.

Thanks
Jason

 

The 383 that a local shop put together for me last year could have its life span measured in minutes. I took apart the motor after 100 miles and found (among other things):
1. They used the wrong rod bearings (and later admitted it) which cut into the radius on my crank
2. A cam bearing was scuffed on install
3. The rings were lined up on 4 pistons
4. The front main bearing fell out when I flicked it with my finger
5. Cylinder # 4 was porous and pitted badly. Several cylinders had significant amounts of rust in them.
6. The rings on cylinders #5 and #7 are rusty.
7. Only half of the rod bolts had assembly lube on them,
the other half had none

 

I don't think I'd blame the engine size ot the parts you used. I built a 383 2 seasons ago, still running strong. I would try to find another block, can the crank be saved? If it turned blue by the journals, I wouldn't use it at all. Try Atlanta crankshaft company, they tend to have very good prices. The eagle cranks looks pretty good to me. I bought one last year for 144.00 from them. Bolt stretch is important on the sir rods. Good luck on your rebuild.

 

Thanks for the reply

I think its time for you to find a new engine builder. It hard trust someone with stuff like that. I have assembled my own stuff so I guess I would have no one to blame but myself if something happens, but then again I guess I would know better to try run something that isn't right. Well thanks for letting me know, I was worried that is was a part failure problem rather than assembly. Good luck with your next one.

Later
Jason

 

I am not blaming the 383 size; I am simply considering a 406 build just because a 400 based motor is a platform to make a little more power than a 383. The only size issue I may have had was going .060" on a new style block. I have been told by many that I need to use an older casting block if the pistons are .060". The crank is useble (with some TLC) but is for a 1pc RMS.

I will definately never use that machine shop again. I figured that I should be learning on stock junk rather than my 'good' motor (even though it still used pretty cheap parts.

 

Every guy that I know that's running a HOT 400 block does have a hard time cooling them down at the track. My 383 cools to 140 degrees in 4 minutes after a run. We run Pro + Super Pro. By the time we get fuel in it and a little jucie in the batt. it's time to get back in line. I don't believe a stock Chevy 400 crank is the quality that the eagle is. I also don't think that the extra .126 is worth the extra heat. But that's just my 02. Alot of 4x4 pickup trucks had the 4 bolt main one piece seal block. I have 3 and still looking.

 

Decided to put together a 406...

A few guys have told me that the car would likely go faster if I picked a cam with a little less lift (closer to .550") but the same or a few degrees more duration. The heads flow pretty much the same at .500" and 600" but the way I see it, if the peak is higher, the valve will be at .500 or more for a longer period of time. I am somewhat unsure as to how the extra lift hurts performance???

 

How fast was your car with the comp cam XE274? I punched the combo into my engine analizer program and then put it into the drag race analizer and came up with 12.0@110 assuming a 3550 race weight. Also assuming I had the exhaust flow close.That was also using the AFR190's because I didnt have the 195 option.I then mocked up a 406 with your new cam and did the same thing and came up with 11.66@113.77 with the RPM manifold and using a victor jr it came down to 11.42@116.

 

I never made it to the track with the xe274.

Not 100% sure what the race weight will be with all of the changes since the last weigh in, but I am thinking ~3700lbs. Also, I am at about 1750' above see level.