Hi,
Just few days ago I received my 383 stocker kit for 92 hydraulic solid Sbc. The block is already prepared (bored and aligned). Today I decided to put the crank into the block just to see if everything is ok.
So I've put bearing, crank, cam, timing chain. Looks perfect. All parts where moving excellent.
Now I try to put the piston with rod on the first cylinder and the problem is that during 2nd crank rotation rod hits the cam !!!.
The block is for hydraulic solid, but since I haven't got the right cam I try with the one from LT1 , which previously bought for my TBI. The LT1 cam doesn't have big lift and therefore rod hits cam.
Please help. I don’t know what to do. What kind of cam I should buy ? Do you think it would happens as well on hydraulic solid cam ?. Stroke is 3,75, rods lenght 5,7. Kit was already balanced ???
Thanks for the feedback
Robert

 

Rod hit's the cam? How do yo know this? Are you looking at the block upside down with the oil pan off? Please elaborate.

If anything, the rod is hitting the bottom of the cylinder's bore... as 350's need to be machined (notched) for clearance to accept the 400's (3.75 inch) stroke....

 

I had to use a small base circle cam when I did my 383.

 

Sounds like you seen a SMALL base circle cam. clearancing your bod bolts will help also.

How bad is it hitting?

 

Hey if you've got a "hydraulic solid" cam, you probably have a fixed-roof convertible, all wheel drive rear wheel drive, inline V6, manual automatic trans, assisted manual steering, power manual brakes, and overhead cam w/ pushrods on your 4-door coupe.

PS: you need a small base circle cam to avoid interference w/ the rods, and some serious reading if this engine's going to have a chance to live past initial startup...

 

Ok. First thanks for your feedback
Just for clarification: Now I have still Camaro '89 TBI 305 manual trans In the car.
But the engine which I talk about is en 350 2 bolt block from 92 GMC. The block itself its one rear seal but unfortunately it's not roller (its solid).
Now I bought already balanced 383 stoker kit (crank, pistons, rods, flywell, etc) (the rods where already machined for clearance), so I thought that it allows me to put any type of cams to this block. Off course the crank it's 400 3,75 stroke.
I putted LT1 (cam) just to see if crank rotate together with cams the rods hit cam ! The Lt1 cam is the one I have at the moment
So As I know LT1 cam doesn't have huge lifts however its profile its more aggressive (cause it's roller) than stock flat tapped cam.
Now the question how do I know what kind of cam do I have to buy to avoid clearance problem ?
We do not have shops In Poland so I can't find easy way to check that ? How to measure which the most aggressive cam (still street able) I can put without buying it ?
If it should be small base circle cam where I have to buy or grind this one ?
Thanks
BTW I just put one first rod and I didn't machined the block for the clearance. I has to be done for all of the rods or any special numbers or it depends of the block castings ? Is it possible the block machinning it's not neeed to take bigger stroke

 

Sorry It's my mistake off course. The block is one piece seal but not roller version. And the cam should be flat tapped wright ?
You know if you think in a different language it could heppens

 

A small base circle cam is what you need, and you'll need to measure the rocker contact path after you get a head bolted onto it to determine the length of pushrod you'll need to go with it.

Most cam manufacturers have a small base circle option for exactly this problem.

 

??? Am I the only one confused

 

rollers came in '87 ..

what he needs is a small base circle mechanical (solid) roller cam.

 

I think he's refering to a Flat tappet lifter block.

The only thing I can suggest is if you can dig up a large flat tappet hi perf cam to try and mock up for clearance.
If the cam is a little larger than the one you plan on running, all the better. Surely someone else that is local to you has a old cam maybe with a wiped lobe that they can donate or lend to ya before you order your cam. You want a minimum of .030" clearance between the rod or rod bolt head) and the cam lobe at the closest point. I believe there are only 2 to 4 lobes that actually get close to the rods at any point.
I forget which ones they are.
Any of the popular cam grinders can grind a high performance flat tappet cam on a smaller base circle for ya.
Some, have these ready to ship in the popular grinds.
Should check pushrod , rocker arm geometry and adjust.

You can probabily grind the offending rods without upsetting the balance job significantly. You may need only minor grinding on ne or two rods to get the .030" clearance if they were all ready clearanced.
The camshaft must be degreed in to the motor to mean anything. Advancing or retarding the cam in the motor will change the clearance.

 

Sorry for the mistake. Off course F-Bird has a right saying that this is block for flat tapped lifters.
Thanks for the explanation regarding the rods. So If I understand well It's the best idea to have the similar cam or just slightly larger and check for the clearance.
It doesn't mean that if I would buy any small base circle cam it will fit my application right ?
What is the main difference between small base circle cam and normal flat tapped cam ? The lobs are smaller ? So the valves will open less then normally. I need to use bigger rockers 1.7 ?
Do you have any recommendation where I have to grind (buy) the cam for me ?
Appreciate for any help
Siwir

 

Hey I ran into the same problem as you, it was a stupid mistake that I made and I am embarrassed to tell you the problem! I bought a marine cam!. Marine engines turn the opposite direction and that is why your rod hits the cam. I found this out the hard way!! Just look up the cam number and verify this, and if it is a marine cam just send it back and get a new one. Good luck with your build.

 

A small base circle cam is just that the cams "base circle" is smaller. The cam will have the same valve action and specs as a standard base circle cam. The lifter will sit slightly lower in the lifter bore. May need a longer pushrod.

There is no way to absolutely guarantee that any small base circle cam will fit your motor once its clearanced for a certain off the shelf cam with a specific grind, unless the cams are identical other than the base circle.. But a larger grind cam with the same LSA installed on the same intake C/l could be used to mock up and clearance the motor. Then the smaller grind will surely fit.

A roller has a completely different shape to the lobe than a flat tappet cam. A flat tappet cam may clear with room to spare and a roller may hit. Usually its right in the middle of the lobe lift, right where a roller cam is fatter.

Any of the popular cam Co's can produce a small base circle cam for ya. in any grind you want.
Crane Comp Isky all good.

 

No offense,but after some of the questions you've asked,I would really recommend you seek a proffessional to assemble your engine.I'm not picking on you,but you lack some crucial knowledge necessary for this engine to live any time at all.Trust me,it may cost now,but it will make your engine live a long,happy life,as opposed to a short,violent one.

 

hey i had the same problem. i used a custom grind cam and when i got done building the motor (short block) i turned it over and i hit on 2 lobes. All i need to do was take alittle off so we ground down m rod where it was hitting. I closed my eyes when the engine shop did that. $1200 eagle rotating assembly. but alls good nothing unbalance only had to take off very little. If you don't have the cam go with the small base circle cam. thats what my engine builder told me after we found the problem. oh well fixed it the same and i've put about 2000 miles on the motor with no problems. that includes a 1200 mile ride from Ms. to Ct. hopethis helps some