Calling all L98 cam & rebuild experts

[livinez]

Well the 80K mile engine is torn down and in great shape(thank you!) The previous owner must have used a block sealer to stop freeze plug leak because it started again when I flushed the coolant system. That and a quite rusty flywheel area.
No ridge in cylinders and very little babbit deposit in pan. Will rering and bearing anyway. And hand lap valves in. (not recut seats.)
Anyway my question for you who know is; should I change cam for something slightly more aggressive?
Along with a slightly higher stall speed torque converter. (500 RPM+ more than stock.
Won't be buying spendy intake systems, but will be going with better flowing mufflers and gutting catalytic. Maybe headers.
Would know what I'd do with a carb motor but this is my first venture into TPI and dont know what the stock cam profile #s are.
And understand that the L98 is best left a low end grunt motor from reading past posts. At least for a guy who doesnt need this car to be a fuel burning rocket ship!
Once again this vette novice is leaning on your expertise.
Thanks, TC

 

[8388]

If you have no plans to up grade the intake, runner and plenum. I would limit the cam duration to about 208/210 @ .50. But to be quite honest, the stock L98 intake set up is barely enough for a 305ci. So in order to get the most out of the package you really should consider upgrading. The trick to keeping the stock ecm happy is to maintain the engine vacuum about where it is currently.

 

[Edmond]

TC,

IMO, I think it'd be a waste of time to rebuild that motor just to bring things to stock specifications. Just the time you spend won't be worth it.

The intake on the TPI Vette's is the intake originally designed for the 305, so it's woefully inadequate to say the least.

Getting headers without doing some head work would be a waste of money. The TPI is really choked by the intake and heads, IMO.

But pick your combination out carefully before you buy anything. A bad combination will not only cost you money in terms of parts, but time in terms of labor.

 

[iron cross]

For a really nice cam up grade, use the GM 151 hydraulic cam. It`s actually for a 327/350 used in the mid 60`s. A new set of valve springs from the same years and you will notice a significant improvement.

 

[Mad-Mic]

mind as well pull it and fix the freeze plugs. while your at it get it honed out and a bearing/forged piston set and freshen the low end up. you could up your compression ratio from 9.5:1 to 10.5:10 - 11:1. you can get a LTR setup to run impressive #'s. if you have an 87 and up you got aluminum heads. they aren't that bad in flow compared to the 85-86 iron heads. one of the first things i did to mine was open up the exhaust. i'm adding a set of TPiS Long Tubed headers on my 87 in a few weeks.

if you got the extra cash get a big mouth base from accel or edlebrock. AS&M or SLP runners and port the plenum,base and runners. a nice high lift cam, some roller rockers then add an AFPR and dial that baby in

it's still Pulling, Sucking, Pushing, Blowing. not much difference in carburation and EFI/TPI systems. in earlier C4's you can someone what push the parameters with mods with out going with a custom chip but you'll eventually get to a point that you'll need one. i would say mid 12's would be the cut off for stock chip. rest of it's tuning just like carburation for the most part. get a shop manual and start having some fun

 

[livinez]

Thanks all

Just got a email from Gordon at witch hunter and I guess my injectors are pretty much junk. He says the money to clean them is better spent on other ones...,sigh
Mad-Mic,
Got manual
The engine is pulled.
Cylinders are great and will ball hone a new x-hatch and rering it. Heads look great too. Will clean them and check both block and head surfaces for warpage.
New bearings "free mods", new MAF relays, gutted cat, new mufflers, slam this 2 bolt puppy back together and go back to driving and smiling!
Not going to spend the bucks to copy what I have in a 69 4-bolt in another car.
At least not with this vette.Will just enjoy driving it and when the time comes send it to a new home and get a C3 to put my other motor in or a better equiped C4 to build.
Maybe next vette will be the Big Dog.
Maybe I should return to the working world 1st !
Thanks again, TC
By the way, I see a ported manifold for these motors on Ebay. Bids at $76

 

[Mad-Mic]

hook me up with the link

sounds like a good setup you got going! it should run low 13's high 12's very easily on that setup you are doing. i'd make 1 suggestion. get a set of 1.5 roller rockers to compliment the setup

your basically doing what i'm doing but i'm going just a few inches farther with mine but not much.

what other car(s) do you have?

 

[tntcorvette]

your '85 has a loose converter from the factory...as a matter of fact it is the loosest of the entire C4 line...should stall about 2200 rpms or so depending on the cam.

I still run the stock converter with my choke your chicken 3.07 gears and I can flash to ~2500 rpms.

 

[tntcorvette]

can you do me a BIG FAVOR???

Please weight your crankshaft and connecting rods and post their weights.

Thanks alot!

 

[livinez]

good info TNT

When it hits the road again I'll see if mine behaves so. The tranny was recently rebuilt but don't think converter was changed. Everything else is bright shiny new and converter has surface rust. But then again EVERYTHING in the flywheel area was rusty due to leaking freeze plug.
Mad Mic I found that ported base by searching for "corvette intakes" Bidding is done tonight. I quit bidding when I was out bidded at $250. Just don't want to spend the money for the rest of intake parts on this car.
Other rigs;
69 Datsun 2000 roadster
82 Cutlass with built chevy 355
31' motorhome with warmed over 440
Dead row now includes 89 Mazda MPV 4WD former parts runner/ski wagon. Which I replaced with a 88 chev 1/2 ton today.
Had a much larger "fleet"? but sold them all as I was getting either bored with them or sick of dealing with/looking at them.
Still got a S10 back there somewhere and oldest son is driving Toyota shortbed all cuted up but stock.
355 is headed for a new home as the 16 year old gets the cutlass but not all those horses!!
:crazy
Maybe I will stick it in the Dat roadster as Me and other male members of family have schemed and bench raced.
Change manifold and will have 400HP in short wheelbase 2000lb car!
We like that idea. Maybe let the teen do high school nite at the drags this summer...,hmmmm.
But first must get vette back on road as styling grocery getter!
Should be by end of next week.

 

[rrubel]

TNT, Mike Antonick says that the crankshaft is 51.85 lbs and the conn rods are 0.855 lbs each... This is for a stock '85.
[RICHR]

 

[tntcorvette]

thanks for the info!

is this pretty much the standard weight for a 3.480 (or what ever the length is) iron 350 crank that is internally balanced?

And if my math is correct .855 lbs equal 388.17 grams (454 grams in a pound).

Is 51.85lbs pretty light for a 3.480" iron crankshaft?

Anyonw know what the later L98 & LT1/LT4 cars crankshaft and rods weight?

Just curious here.