L-98 engine block ?
Thread Starter
Racer
Joined: Jul 2002
Posts: 447
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From: Malta Europe
L-98 engine block ?
As some of you read my other post !! I am thinking of buying a stroker kit for my 88 vette !! I want big gains so I am thinking of doing the 427ci stroker kit from summit !! but I have a few questions that I like to ask becouse I am lost on this one :confused: summit says that you need spechial cam shaft on this kit so I send them an E-mail and they said that you need this =cam requrements of .870" base circle and 109 degree intake centerline !!!1)what does that mean ?? :confused: this cam shaft is $429.95 from summit and you need to bore the block to 4.125" to make this kit works !!! so I have a question of both !! 2)Can the L-98 can be bored to 4.125" ?? 3) or I need to use a different block for this set up ?? 4)Can the stock computer can handle all of these changes with a custom chip ?? and please 5)explain the cam shaft part becouse I wished that I could use the ZZ9X cam on this one !!! please explain to me becouse I am lost :confused: Thank you in advance !!
marlon
marlon
Team Owner
Joined: Aug 2000
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From: San Pedro CA
Re: L-98 engine block ? (marlon88)
ok... I am going out here... I have been doing some study on the geometry of engine timing...
if I understand all of it correctly, the numbers are all referencing timing of the valve opening and closing.
I think the base circle is what happens when you add up all the different center lines.
if you pick up a cam, and look down it, the center of each lobe is X* apart, that X is is the gap... it works in with lift and duration and has everything to do with valve overlap.
now.. I don't know if what they are saying correct for your build... I have not gotten to that point yet.
if I understand all of it correctly, the numbers are all referencing timing of the valve opening and closing.
I think the base circle is what happens when you add up all the different center lines.
if you pick up a cam, and look down it, the center of each lobe is X* apart, that X is is the gap... it works in with lift and duration and has everything to do with valve overlap.
now.. I don't know if what they are saying correct for your build... I have not gotten to that point yet.
Team Owner
Joined: Sep 2001
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From: Athens AL
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Re: L-98 engine block ? (marlon88)
I dont think the L98 block can handle that, youd need a 400 block.
Yes a custom chip will make the car make its best power, however, with a cam that will be as big as that one seems to be, you may have a crappy idle and this car wouldnt be suited for daily driving.
Yes a custom chip will make the car make its best power, however, with a cam that will be as big as that one seems to be, you may have a crappy idle and this car wouldnt be suited for daily driving.
Le Mans Master
Joined: Mar 2002
Posts: 5,889
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From: Castro Valley Calif.
St. Jude Donor '03 thru '26
Re: L-98 engine block ? (vader86)
I'm with Vader. A safe rule of thumb is if you want to go 400c.i. or over, you need to use a 400 block, although there are a few exceptions.
In reading your post, I'd recommend you do a search on the forum for the specific cubic inches you want to build, then research the components thoroughly as you can. It's a real bummer when you combine stuff that doesn't fit or isn't designed for your total package and therefore doesn't produce. If there's some reason you want to build around that particular cam, then search that cam and locate successful components for it.
Get some advice from the forum like you're doing in this post. There are some incredibile minds here :yesnod: and they all want to see you succeed.
Good luck to you!
In reading your post, I'd recommend you do a search on the forum for the specific cubic inches you want to build, then research the components thoroughly as you can. It's a real bummer when you combine stuff that doesn't fit or isn't designed for your total package and therefore doesn't produce. If there's some reason you want to build around that particular cam, then search that cam and locate successful components for it.
Get some advice from the forum like you're doing in this post. There are some incredibile minds here :yesnod: and they all want to see you succeed.
Good luck to you!
Drifting
Joined: Feb 2000
Posts: 1,994
Likes: 0
From: Charleston, WV
Re: L-98 engine block ? (Caboboy)
Well first off a 350 block can't be bored an eith safely and that's what it would require. You must use a 400 block to do that.
Second..... the base circle needs to be smaller because the stroke of this engine is longer than the stock 400 and the rods will hit the cam.
The base circle is the bottom of the lobe or the round part. this has to be smaller to give the rods clearance so they don't hit the cam. As the base circle gets smaller the lobe can also be made smaller hence MORE clearance. The other numbers that you mentioned refer to cam timing or how many degrees before or after top dead center a valve event occurs. Then you have overlap which is the amount of time BOTH valves are open at the same time. There's more but I think this will get you going . :seeya
Second..... the base circle needs to be smaller because the stroke of this engine is longer than the stock 400 and the rods will hit the cam.
The base circle is the bottom of the lobe or the round part. this has to be smaller to give the rods clearance so they don't hit the cam. As the base circle gets smaller the lobe can also be made smaller hence MORE clearance. The other numbers that you mentioned refer to cam timing or how many degrees before or after top dead center a valve event occurs. Then you have overlap which is the amount of time BOTH valves are open at the same time. There's more but I think this will get you going . :seeya
Thread Starter
Racer
Joined: Jul 2002
Posts: 447
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From: Malta Europe
Re: L-98 engine block ? (vettmech)
Well seems like a 383 0r 396 in the near future for me ,becouse seems way of my budget to change the block !! so I like to use my original block !! so I think 396 will be good for me !!! I guess it will make power of my vette what you think ?? which you like most 383 or 396 ?? wich one will squesse more hp out from the L98 ?? :chevy
Le Mans Master
Joined: Jan 2002
Posts: 5,320
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From: Kyle TX (Because Mojo Made me fill it in)
Re: L-98 engine block ? (Nathan Plemons)
Wouldnt going 396 be pushing the limits of the 350 L98 block? Thats making it awfully thin. (from what I have been reading)
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From: Athens AL
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Re: L-98 engine block ? (marlon88)
well the 383 stuff is cheap simply because of competition and demand, 396 shouldnt cost much different for parts, but ill bet the machine work will be higher
What intake are you gonna put on this thing? MR?
What intake are you gonna put on this thing? MR?
Melting Slicks
Joined: Jun 2000
Posts: 3,215
Likes: 6
From: Tampa Florida
Re: L-98 engine block ? (VetteNoob)
A normal 355, 383, and 396 all have the same bore 4.030. This is biggest factor between reliability when it comes to bore or stroke. Stroke is simply installing a longer 'arm' in the block.
Reason you probably need the 'special' cam is the base circle is smaller than a normal small block chevy's due to large stroke (rods more further and will contact the camshaft unless you clearance the rods/bolts or install a reduced base circle camshaft. Any major cam companies carry this...Summit certainly doesn't make them. Also, base circle is the heel of the cam...where there is no lobe (and hence lift)/the part of the cam lobe that is circular. Not explained very well.
I would recommend buying an engine building book like John Lingenfeltors (On Modifying Small Block Chevy Engines at a book store near you:) Seriously, I have it and it is written quite well, with much info-course any book is good.
:)
Reason you probably need the 'special' cam is the base circle is smaller than a normal small block chevy's due to large stroke (rods more further and will contact the camshaft unless you clearance the rods/bolts or install a reduced base circle camshaft. Any major cam companies carry this...Summit certainly doesn't make them. Also, base circle is the heel of the cam...where there is no lobe (and hence lift)/the part of the cam lobe that is circular. Not explained very well.
I would recommend buying an engine building book like John Lingenfeltors (On Modifying Small Block Chevy Engines at a book store near you:) Seriously, I have it and it is written quite well, with much info-course any book is good.
:)