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Is this guy crazy?

jimmy'sjimmy

jimmy'sjimmy

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i am looking to buy a 383 stroker kit for a TBI 350. i looked on ebay and found this company called mad dog and the rep gave me a kit and all but the numbers sound kinda crazy. first of all the cam he offered at first was for .485 lift and 244 duration and this is for a TBI. then he also suggested 10.5/1 compression so im not sure if i can trust this company. I told him i didnt want to go that high so he offered a cam w/ .447 and 222 duration and pistons with 9.5/1. the kit balanced and shipped for $1400. anyone have any suggestions before i make a big mistake?
 
Your not building a camaro, your building a truck engine, shorter compression ratio, and not such a tall cam, you'll be OK
 
Companies will do that for some reason...try to unload on you some outragoulsy high performance parts. I had a sales rep at Blue Racer Cams (back before Crane Cams bought them) try to sell me a 302* advertised duration camshaft for a dually tow rig one time. I told him he was crazy, and opted for a cam with 265* of advertised duration.

The second option (9.5:1 comp/222* cam) the guy gave you is doable with TBI. Ask who the manufacture of the camshaft is and the part number? You need to make sure you buy a cam, which is compatible with a computer. Crane Cams and Comp Cams both make a camshaft, which is specificly manufactured to be computer compatible .

The 9.5:1 compression, with an aftermarket computer compatible camshaft, may need a little custom chip tuning, in order to work properly. A slightly lower 9:1 compression would be easier to run on a computer controled engine.
 
depends on what the parts are.

Personally I say, NEVER buy a prebalanced rotating assembly. Is the crank internal balance? I don't care for prebalanced assemblies because does that come with a flexplate? Balancer? those need to be balanced with an external balance motor(or neutral balanced with an internal motor). That and who knows to what standards those guys are doing it. I say piece it together. WHy do you need rods? My 383 has stock GM rods out of my 89 350 TBI with ARP bolts in them. Would work just fine for whatever power a TBI engine can create(unless youa re throwing nitrous at it). I say, cast(but internal balanced) crank, stock rods, hyperuetic pistons, decent balancer, and a good flywheel, all balanced by a local race shop. That is exactly what my engine is except I was stupid and got an external balanced crank. Screwed myself becase I'd like to have a manual and I'd have to have my entire rotating assembly rebalanced to make that work out now.
 
I just built my 383. Don't buy a kit....no offense but i take it you don't build engines everyday....it's extremly expensive and you have to know how to do it. It's not something you just wake up and do one morning. If you want a good solid engin look at buying a short or long block off of e-bay....do some checking up with the seller....least expensive is not always the way to go. Or check around town and find a good engine builder/machine shop and talk to those guys....they can get you squared away with the right parts combo. Pay someone the 400 dollars to put it together...your not building a 800hp monster you just need about 300hp and 300ftlbs torque at low rpms. As for the right cam, buy a kit from summit pn: CCA-K12-235-2 that's a comp cams complete 4x4 kit....works great in my engine...put out 400hp @5650 and 450 torque at 3500rpms on the dyno. That's way overkill for what we do...and sometimes all that power get's real scary on the trail. As for crank and rods, you should beable to pick up a scat 9000 series crank for about 230 and scat forged i beams for about 200. Kicker is they need to be balanced another 250. KB pistons will run you about 230 and again need to be balanced. anything under 10:1Cp is ok for iron heads...you need aliuminum to get to 10.5 10.8:1 on pump gas. I run 9.6:1 for saftey....i don't like detonation.
I have about 2300 in my engine after all the machine work was done and about 3k after i put all the other parts on it (drives, oil pumps, intake, carb, valve covers, and such).
Hope this helps. If you would like to get in more dept about the subject e-mail me at [email protected]
mike
 
Would compression really have an effect on a TBI system? The only thing that really screws up a TBI motor are things that change the vacuum signal to the MAP sensor. Which would mean anything in the intake, exhaust, cylinder heads, displacement and cam shafts. Personally, I think the 222 degree at .050 would be a horrible choice for a TBI motor in a truck. Sounds like some old performance grind that has been around for 30+ years. Take advantage of the newest cam grinds, esp the ones intended for computer controlled vehicles.
 
Would compression really have an effect on a TBI system?
Click to expand...

I have heard that high compression can mess with knock sensors. I doubt that 9.5:1 would cause a problem, but 10:1 could with lower grade gas. Plus there could be a problem with timing advance curve with higher compressions.

Personally, I think the 222 degree at .050 would be a horrible choice for a TBI motor in a truck.
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This is why I said he should get the manufacture and part number for the cam they are talking about. There are older cams, with (single duration/narrow lobe seperation) specs for carbureted vehicles, and there are newer cams (split duration/wider lobe seperation) specificly designed for computer controled vehicles, which have a similar number at @.05 lift. Since he did not expand on the camshaft spcifications, it is hard to tell. Crane has a Computer Controled cam with about 218/222 at @.050 lift. Comp Cams has a similar one, which is about 218/224 @.050
 
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222 @ .5 and .447 is not that far off from a stock grind....Look at the specs of a stock cam.....
 
I would never buy a cam out of a box unless it was bone stock. If they didn't ask you everything and what size is your underwear before custom designing a kit, then you will not get what you want.

Talk to a real engine builder with 25s years under his belt, such as a racer that builds for the public. He can steer you right.

For a cam: Go to a cam grinding shop with all info about the engine such as rpm range, what you are doing with it, pistons, compression ratio of engine (which is NOT the compression ratio of the pistons), c.i., trans type, stall speed of TC (if applicable), heads and cc of the combustion chambers, bottom end power, etc. and the shop will custom grind you a cam. First time I did this ruined me on ever buying an out of the box cam.

As you can tell, I didn't cover every base. talk to people who know around your area as you'll be better off making friends with the local guru that you can call and who would subsequently know the history on what you are doing, not the 20 yr old down the road that has a hot rod, he's still learning even though he may be an excellent mechanic.
 
Or, get a GM crate motor. Its like opening the best present you never got as a kid (whos not still a kid). The torque motors come with a warranty too.:D
 
Read all the fine print in that mad dog ad. IIRC I was looking at some of there stuff and basically, once you bought it, they were done with it. I can't remember if it was engines or transmissions, or both.
 
FLAT TAPPET HYDRAULIC CAMSHAFT
INTAKE LIFT-.382" * EXHAUST LIFT.402" *
INTAKE DURATION @.050-165.9 * EXHAUST DURATION @.050-174.8
LOBE CENTER SEPERATION -111.9
CAMSHAFT MECHANICAL SPECS:
INTAKE VALVE OPENS @ -30.2 BTDC * INTAKE VALVE CLOSES @ 16.1ATDC * INTAKE LOBE CENTERLINE - 111.8
EXHAUST VALVE OPENS @ 18.1BBDC * EXHAUST VALVE CLOSES @ -23.3 ATDC * EXHAUST LOBE CENTERLINE - 111.8


So if I am readying that correctly, the 222 @ .050 has almost 50 degrees more duration at .050 than the stock cam. And thats just on the exhaust lobe. And I'd bet it has a different lobe separation angle which would really screw with the vacuum signal.
 
ryan22re said:
FLAT TAPPET HYDRAULIC CAMSHAFT
INTAKE LIFT-.382" * EXHAUST LIFT.402" *
INTAKE DURATION @.050-165.9 * EXHAUST DURATION @.050-174.8
LOBE CENTER SEPERATION -111.9
CAMSHAFT MECHANICAL SPECS:
INTAKE VALVE OPENS @ -30.2 BTDC * INTAKE VALVE CLOSES @ 16.1ATDC * INTAKE LOBE CENTERLINE - 111.8
EXHAUST VALVE OPENS @ 18.1BBDC * EXHAUST VALVE CLOSES @ -23.3 ATDC * EXHAUST LOBE CENTERLINE - 111.8


So if I am readying that correctly, the 222 @ .050 has almost 50 degrees more duration at .050 than the stock cam. And thats just on the exhaust lobe. And I'd bet it has a different lobe separation angle which would really screw with the vacuum signal.
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Too hot to grab with your hands.:haha:
 
the kit comes with a new balancer and flexplate. my biggest problem is i have a new job now and the truck is 2hrs away without an engine in it. i have the block sitting at my old shop w/ all the machine work done. all i need is the guts and one of the older mechanics is going to help me assemble it. its going to have to be on weekends though. it was supposed to be a project for the summer because i didnt expect to get a job right after i graduated, so i took the motor out and now i am caught with my pants down.
 
I have bought from Mad Dog in the past, but not a kit.. I got the S.S. swirl polished vavles from him, I did put those in the Camaro I built....
 
AlphaMale said:
222 @ .5 and .447 is not that far off from a stock grind....Look at the specs of a stock cam.....
Click to expand...
No offense intended, but I have to disagree on two points. # 1- 10.0 to 1 compression is way to much on pump gas iron heads, and # 2- stock cams for '80's/ early 90's duration at.050 is closer to 200 deg. not 220. Not gonna fight about it, but check your facts.
 
theperfectgarage said:
No offense intended, but I have to disagree on two points. # 1- 10.0 to 1 compression is way to much on pump gas iron heads, and # 2- stock cams for '80's/ early 90's duration at.050 is closer to 200 deg. not 220. Not gonna fight about it, but check your facts.
Click to expand...

I'll disagree again. 10:1 is doable on good premium fuel.

You area 110% correct on the camshaft thing though. Stock cams for not just the late 80s but up into the late 90s, you are looking at a max of like 200* @.050". To the untrained eye 220 sounds like its SO CLOSE. But to those who know a damn thing about camshafts, that is a WORLD of difference. And to those who know ANYTHING about TBI, 220 is mildly absurd.
 
10:1 is doable on pump gas. I wouldn't go more in a truck for off-road but some would. Personal preference. Again get a cam ground custom. It is not expensive. Crate motor best bet.

Just remember that pistons along do not set the compression. cc the heads, measure the thickness of the gasket, etc
 
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