Hi all, im building a 383 from a later vortec engine (880 block) and just popped in the cranks to check where I will need to clearance it. Having seens some video's on YouTube I was expecting a fair few places that would need attention. I put the I-beam rod on a piston and installed it and the only place that looks close (but not touching) is the rod bolt on the even numbered cylinders. Everything else has at least an 1/8 to 1/4 gap. Webs are good so I really dont see anywhere that needs doing other than light relief where the rod bolt gets close (a little less than 1/16th) Ive heard tales that the 880 blocks had shorter cylinders so the bottoms would be higher up so the rods dont get close to them at all. Anybody know if there is any truth to that or have I just got lucky?

Also its a fully balanced eagle kit with eagle bushed rods and ARP bolts.
Thanks all.


383 clearance with 880 block and eagle rods

 

Your situation seems more the result of the rods you are using, as opposed to anything about the block. Stock rods, or any with bolts & nuts instead of capscrews really, would cause ALOT more trouble.

 

I would say 0.050" clearance or more and you are good to go. I discovered the rotating assembly on my 383 will actually hit the cam. However I was advancing and retarding the cam and gently rotating until I found it to contact. I was more than 90° advanced or retarded before the contact ever happened. Hopefully my single roller chain holds up.

 

What cam are you using? In my build I am worried about this as well.

Sorry to the OP,I don't mean to hijack your thread, but I think it's critical to 383 stroker builds using a 880 block that we educate ourselves regarding this particular clearance.

 

Block casting doesn't matter AT ALL to the cam clearance. It's the same dimension (cam-crank centerline distance) in ALL stock SBCs.

Strictly a matter of the rods and the cam itself, and of course the cam timing.

 

with all due respect, no ****

 

No appology needed, its all usefull info for everyone. Im using the comp cams xfi cam as i'm determined to use my crossfire injection setup. Obviously I have bored TBI's, bigger injectors and the renegade manifold but if all else fails i'll go aftermarket ecu to run it. Its the comp cams 12-364-4 extreme xfi.

 

Precisely. Wrong question to ask. "If I need to add 2 + 2, should I buy a TI or a HP calculator?" The answer is, NO; you need to learn to do it in your head. Just isn't relevant. Just like, rod/cam clearance, while FOR SURE "critical to 383 stroker builds using a 880 block" or ANY other block, isn't something that "that we educate ourselves regarding this particular clearance" as if the 880 block is different in this regard. It is a property of cams and their installation, and rods; NOT blocks.

 

I that vein, (FWIW), I've been looking at over the counter aftermarket 383 shortblocks and in the couple of inquiries I've made regarding cam/rod interference , all of have come back with the caveat that a small base circle cam will be needed. While there are probably others, the SCAT Pro Series and Ultra Lite rods are the only ones I know of that are advertised a stroker clearanced. That should exclude the need for the small base circle. At least for most cams and cam timing anyway. I can't say about the block clearancing on that though as the cam interference was what I was investigating.

 

I'm just curious and not to hijack your thread, but if you are building a 383, why are you using a flat tappet cam and it is pretty wimpy? Are you going to use the stock ECM? What heads? If you rotating assembly is close, take care of it now and avoid issues don the road, it just makes sense. Thanks

 

Yes, bit of a wimpy cam but I am hoping to use the standard (but chipped) ecu. The reason for the flat tappet setup is that I bought the cam before I found the block, I know its the wrong way round of doing things but thats where I am. The setup I have should yeald 10.9:1cr which im happy with. A few other factors are to be considered but i'm happy with it so far.

 

This :
and this:
will not work.

A static compression ratio of 10.9:1 and that cam with 252/266 advertised duration will result in a dynamic compression ratio of 9.4:1. THAT kind of dynamic compression means nothing less than high octane racing fuel.
I suggest you reexamine your compression ratio target and /or cam choice before putting all of this together.

 

My build is going to be around 9:1 dynamic and actually higher when the Rhoads lifters are bled down at lower RPM. With the Rhoads lifters bled down it will be closer to 9.5 DCR. But using the 0411 and coil per cylinder. Also not expecting to be able to run full timing on pump gas. Going to be using E85.

I have backed Vortec heads down all the way to 24° of timing and not noticed a huge difference in power from 32° on a 8.4:1 DCR iron head setup. It was not until the cooler, slower burning E85 was the fuel of choice tha bumping the timing made a rather drastic difference in torque across most of the RPM range.

 

Fair enough. I would ask the OP if he is going to do the same.

 

OK, thanks. Was just wondering what you were really trying to build. 10.9 is getting high, I'm at 10.6-10.7ish and can still run 91 pump gas with no issue. I do use 93/94 at the track when the laptop comes out. I think you will have issues. Still run mid 12s, so I'm happy. Trying to get mine down to 12.4 or better, this is with a bone stock 82 chassis interior and all the trimmings. My cam is fairly large and my TC is going to be changed out for this winter to a 9.5" 3,600, need to drop my 60' another tenth, also going to mod the trans for first gear. I think I can do the lower times then. Jan/Feb is the best air here in AZ for racing.

 

Thanks all for your valued input. Good News.... Upon cleaning up and reshaping the combustion chambers, felpro compressed gasket thickness and the pistons leaving a 0.020" gap to deck at the top of the stroke the recalculated compresion ratio is 10.03 to 1 giving a DCR of 8.95. As he will only run on Shell V-Power 98 ron he should run like a champ.

Ive completed putting the bottom end together and will get the rest together by the end of the week. That might be it for a month or so as i'm getting the 87 700r4 ive got rebuilt to handle the torque first.

Thanks again.

 

The other poster's experiences with a sophisticated tuning approach notwithstanding (Fast355 is quite advanced if any of our other exchanges have relevance), the new lower SCR and DCR lend themselves to a less volatile specification. With a DCR approaching 9:1, I would still choose not to proceed however that's with the Canadian 94 octane fuel that's available. If your octane ratings are calculated the same as they are across the pond, then the added resistance to detonation with the 98 would be the make or break difference to me.
Out of curiosity, what's the thickness of your FelPro head gasket? Will you be close to the typical 40 thou target for head to piston clearance? Keeping the quench in or around that mark will give further assistance in keeping spark knock at bay.
My experiences have shown me that ignition timing has a greater impact on output than does the compression ratio. I've wasted a lot of time (and possibly one engine) chasing that last half point of CR while at the same time, having to neuter the timing to keep everything from rattling to pieces.
That said, having the optimum timing curve and the highest CR will yield the best results.

Finished doing just that. I assembled a great list of replacement parts for the added strength and durability and had my transmission guy put it all together, Probably the best shifting automatic I've ever owned and should the specs prove out, something equivalent to GearStars Level IV offering.