347 questions
Thread Starter
Drifting
Joined: May 2001
Posts: 1,630
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From: Brandywine, Chester and Ridley Valleys Pennsylvania
347 questions
I'm looking at building a 347 for a project car (a Vette, of course). I like the idea of a 4:56 rear and an 8,000 rpm redline with Enderle/Hillborn injection on the street as something a little different from the more "grunting" whallop of the traditional 383 or what have you. Not that there's anything wrong with big displacement, I just want something that can be "wound-up". Streetability isn't an issue, so long as it won't need rebuilds every thousand miles.
My questions are, does the lofty powerband or the geometry of the rotating mass rule this baby out for "street" use? (My definition of "street" = the car will idle with your foot off of the gas for a couple of minutes without stalling or overheating, though it might come close) :D
What's involved in ensuring a long life for an engine like this one that'll probably get flogged hard Friday and Saturday nights? Besides the obvious things like ultra-frequent oil changes and whatnot. Forged rotating mass? Heavy duty valvetrain components? Structural reinforcement of the block or heads?
Any tips from someone with some SB Chevy experience of this type?
My questions are, does the lofty powerband or the geometry of the rotating mass rule this baby out for "street" use? (My definition of "street" = the car will idle with your foot off of the gas for a couple of minutes without stalling or overheating, though it might come close) :D
What's involved in ensuring a long life for an engine like this one that'll probably get flogged hard Friday and Saturday nights? Besides the obvious things like ultra-frequent oil changes and whatnot. Forged rotating mass? Heavy duty valvetrain components? Structural reinforcement of the block or heads?
Any tips from someone with some SB Chevy experience of this type?
Thread Starter
Drifting
Joined: May 2001
Posts: 1,630
Likes: 0
From: Brandywine, Chester and Ridley Valleys Pennsylvania
Re: 347 questions (Gordonm)
I believe it's a 305 crank with in a 400 block... I could be wrong. I guess it really doesn't have to be a 347, if there's another combo which can "wind-up", I'd consider. I remember seeing a 302 Chevy in a newer Z28 a couple of years ago (tribute to the '69 302 Transam Camaros), it was supergharged and made like 600 hp at 7000 rpm on pump gas. 302 ci is a little small IMHO, especially since I don't plan on forced induction and the car will still weigh a bit over 3000 lbs.
Can anything larger be expected to rev to 8-10k? Given identically strong components, would the bigger displacement engines be "limited" by the time it takes to combust the mixture in such a big cylinder (as compared to the smaller cylinder of the smaller displacement engine)?
Can anything larger be expected to rev to 8-10k? Given identically strong components, would the bigger displacement engines be "limited" by the time it takes to combust the mixture in such a big cylinder (as compared to the smaller cylinder of the smaller displacement engine)?
Instructor
Joined: Nov 2001
Posts: 116
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From: Houston Texas
Re: 347 questions (TrueBlue ChevyDude)
I am not sure what a 347 is, but I can tell you some things it is not. A 305 has the same stroke as a 350, but different bore size. The 305 and 350 cranks are not interchangable though because of different balancing. A 350 crank in a 400 = 377 (may be with .030 overbore, I can't remember.) This combo is known to rev because of a shorter stroke and larger bore than the 383. Of course 400 crank in 350 block bored .030 = 383. Ford guys make 347's by stroking 302's with a custom stroke crank. And I beleive you can get around 325 with a 302 crank (chev of course) in a 400 block. That one should really rev.
Team Owner
Joined: Oct 1999
Posts: 31,977
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From: Guinness Its whats for B'fast JAWGA
CI 3-4-5-9 Veteran
Re: 347 questions (thunderbolt47)
347 out of a 400 would have to be a 4.125" bore and a 3.25" 327 crank. I would go with a 377 using 350 crank.
Another idea I've been playing with is Crower makes 3.625" stroke crank and drop it in a Motown block at 4.185" bore for a 398. Great rod ratio and a big bore for breathing maybe with a blower or turbos.
Another idea I've been playing with is Crower makes 3.625" stroke crank and drop it in a Motown block at 4.185" bore for a 398. Great rod ratio and a big bore for breathing maybe with a blower or turbos.
Drifting
Joined: Jul 2001
Posts: 1,418
Likes: 1
Re: 347 questions (TrueBlue ChevyDude)
If you are willing to go to a big block a Merlin block with a 3.75 crank and a 4.500 bore will make a 475 that will spin up nicely.With big heads this motor in a Hydro with a 2 speed Lenco is shifted at 9200 rpm.I suspect any street car exhaust system would limit this capability though
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: 347 questions (mountainmotor)
As far as I know a 347 is a Ford engine :confused:. My buddy actually has a 347 stroker engine in his Mustang. A 347 is a 302 w/ 3.400" Stroke and 5.400" rods.
I'm not sure if there is any way to make a Chevy engine into a 347 though.
If you are out for a stroker engine why not go with a 383....or you could go with a de-stroker engine (377). If you went with a 377, you could rev that baby till the cows came home :)
I'm not sure if there is any way to make a Chevy engine into a 347 though.
If you are out for a stroker engine why not go with a 383....or you could go with a de-stroker engine (377). If you went with a 377, you could rev that baby till the cows came home :)
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Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: (scorp508)
Actually Scorp, I think you are correct. I'm pretty sure the LS1s are truely a 347 but are "labeled" a 350....much like some of the old Chevelles had a 402 (396, +.030") but were labeled a 396.
Much of this is because of the popularity of the Chevy engines. The 350 has become such a well-known Chevy engine, why would they want to label it a 347....or at least that was the reasoning behind the 396/402 deal. :)
Much of this is because of the popularity of the Chevy engines. The 350 has become such a well-known Chevy engine, why would they want to label it a 347....or at least that was the reasoning behind the 396/402 deal. :)
Melting Slicks
Joined: Apr 2000
Posts: 2,793
Likes: 46
From: Elizabeth City, NC
Re: (bence13_33)
I ran a 377 in a 55 Chevy drag car that I used to have. It would rev easliy up to 8500. It was a 400 with a 350 crank. Just be aware it takes alot of $$$$ to make a reliable high revving motor. But they are nice to hear none the less. This particular motor pushed the 55 to many a 9.9x timeslip.
Safety Car
Joined: Aug 2000
Posts: 3,909
Likes: 26
From: Clymer PA
Re: (LPDesRoche)
Lee:
What exactly did you have done to that 377? My buddy is building a 377 for his '89 S10 Pickup. He is building it to blow the doors off of my 'Vette once I get the 467 dropped in (specifics in my sig.). You really have me thinking that he is going to blow me off with ease. :(
What exactly did you have done to that 377? My buddy is building a 377 for his '89 S10 Pickup. He is building it to blow the doors off of my 'Vette once I get the 467 dropped in (specifics in my sig.). You really have me thinking that he is going to blow me off with ease. :(
Melting Slicks
Joined: Apr 2000
Posts: 2,793
Likes: 46
From: Elizabeth City, NC
Re: (bence13_33)
Bence,
I hope your buddy knows what it takes to reliably spin a motor that high. I had an old set of the AFR 220cc heads with a competition port job, very unstreetable cam (solid roller), 13:1 CR, and a victor intake I believe(I had so many combo's in that car its hard to remember..LOL) He better pay extra attention to the weight of the valve train. Especially if this is to be a street motor, more than likely it will see more run time than a drag car.
I hope your buddy knows what it takes to reliably spin a motor that high. I had an old set of the AFR 220cc heads with a competition port job, very unstreetable cam (solid roller), 13:1 CR, and a victor intake I believe(I had so many combo's in that car its hard to remember..LOL) He better pay extra attention to the weight of the valve train. Especially if this is to be a street motor, more than likely it will see more run time than a drag car.
Safety Car
Joined: Aug 2000
Posts: 3,909
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From: Clymer PA
Re: (LPDesRoche)
Here is what he told me:
377 De-Stroked Engine
4340 Forged H-Beam Rods, Forged Pistons, Forged Crank
400 Small Block Heads, 1.94/1.60 Valves, Gasket Matched Port Job
Aluminum Full Roller Rocker Arms
10:1 Compression Ratio
296 Duration, 105 Lobe Seperation Flat Tappet Solid Lifter Cam
Weiand Stealth Intake
750cfm Carburetor
Turbo 350 Transmission
3.73 Rear Gears
Not Sure What Stall Converter
One of his buddies has a Coronet 440 Drag Car running 10.4s...he will be helping him with the build up. I'm sure he'll institute some old hot rodding tricks too. He said he's planning on revving it pretty high.
What do you think? I am building my engine to be pushing 525-550 horsepower. I'm worried that he's going to beat me (especially considering I'll weigh 600+ lbs more than he will, and I'll be driving a stick).
377 De-Stroked Engine
4340 Forged H-Beam Rods, Forged Pistons, Forged Crank
400 Small Block Heads, 1.94/1.60 Valves, Gasket Matched Port Job
Aluminum Full Roller Rocker Arms
10:1 Compression Ratio
296 Duration, 105 Lobe Seperation Flat Tappet Solid Lifter Cam
Weiand Stealth Intake
750cfm Carburetor
Turbo 350 Transmission
3.73 Rear Gears
Not Sure What Stall Converter
One of his buddies has a Coronet 440 Drag Car running 10.4s...he will be helping him with the build up. I'm sure he'll institute some old hot rodding tricks too. He said he's planning on revving it pretty high.
What do you think? I am building my engine to be pushing 525-550 horsepower. I'm worried that he's going to beat me (especially considering I'll weigh 600+ lbs more than he will, and I'll be driving a stick).
Melting Slicks
Joined: Apr 2000
Posts: 2,793
Likes: 46
From: Elizabeth City, NC
Re: (bence13_33)
Well it looks like the heads will be the slow point of that combo. Even with alot of porting, its just an out of date design. And with the CR that low he will be giving up alot of power. You definitaly have a shot. You should make lots more TQ than he will. That will help you alot. Like I said before the one I had was very much a race motor. Not a street/strip motor. You should be ok.
