lehr

I have an LT1 with a carb and a msd hei ignition. I want to use a comp cams XR270hr cam, the comp cams tech line guys says you can't use a standard small block cam in an LT1 block...I'm not buying it ???

93M6Formula

As long as it's a roller cam, it's fine...

lehr

Thanks that's what I thought...

leadfoot4

iTrader: (1)

When you say "MSD HEI ignition", do you mean a top-mounted distributor, at the rear of the engine? If so, yeah, you're OK. The main difference in the LT1 specific cams is the pin on the nose, to drive the Opti-spark.

lehr

Yes a top mount dist. Thank

BizZzatch350

iTrader: (33)

The reason why he said no is the bigger issue is the pilot hole for the later vented opti. A cam dowel can be adjusted, the pilot has to be machined to accommodate for the vented opti. LT1 Cam pilot holes are different than a Gen 1 SBC Cam. If you're not running an opti as is the case, you'll be fine. You could get away with it on an unvented car provided you ran an LT1 timing set. But that's the reason why he said no it won't work. Some one sold me a cam once and put it in a LT1 box, so it had the right part number. Went to install it, getting ready to button the motor up, my vented opti would not go on. Live and learn.

WS Sick

I had the same happen to me, I took my stock cam and that cam to my machinist and he made a pilot hole for me for 20 bucks.

lehr

Great thanks guys !

Motorvation

There is one problem. The LT1 has the cam retainer plate to keep the cam from walking in the block, most Gen I blocks (non rollers) don't have that and the cam isn't machined for that. You will most likely have to ditch the cam plate and use a cam thrust button instead. I don't know the clearance from the face of the cam to the timing cover so they may not have a button for that either. You can't do with out one of these, you must have something in place to keep a roller cam from walking.

Look at the pics in these two links for comparison:

Gen I roller cam


Gen II roller cam

Catmaigne

iTrader: (6)

Sbc cam will also have a fuel pump lobe you won't be using. Dunno if that will create problems or not.

transbird95

iTrader: (4)

When i was running the lt4 hotcam itcame with a fuel pump lobe. It should be fine.

joelster

There is a different bolt pattern from an LT1 roller cam to a standard sbc cam for the timing gear. I'm not sure if a roller cam sbc uses the flat tappet gear pattern or if the roller cam sbc pattern is the same as the roller LT1. I have a camshaft installation tool for an sbc and it doesn't line up with the 3 bolt holes on an LT1 cam. Ask Ed, he's probably swapped a hundred cams.

WS Sick

If it is for a factory style SBC roller cam it will have the small bolt pattern and it will have the surface to mount against the cam retaining plate. When I used one I only had to have the opti pilot hole drilled and put in a longer dowel. If it is for the 85 earlier SBC blocks it will use the wider timing gear bolt pattern and not have the lip.
The pictures above show the difference.
Most of the TBI truck and pass car motors had a roller block with the older cam (hyd non-roller). The holes for the lifter retainer and the cam retainer are there just not tapped.
The Hott cam has a fuel pump lobe as did the GM 847 I used to have.

lehr

Ok who is Ed ?
Its my understanding that Chevy only made one small block hot cam, I have a friend that told me he put one in his Dads non Lt1 engine with a non Lt1 timing set so the bolt pattern must be the same.

WS Sick

Right if the cam is a factory style 87 up roller cam it can use a timing chain made for that. it just so happens the LT1 also uses that cam, but it's timing set also has to drive the distributor and the water pump.
Me myself am running an electric water pump and since my opti is the 95 up style I can run a timing set designed for a traditional SBC with a factory style (87 up) roller cam.

I know clear as mud right?

Get the timing set designed for what youre doing, if you have the factory water pump use the stock LT1 style for the appropriate year (either a 92-94 or a 95-97). If you have a 92-94 you are still limited since the cam gear of the timing set is splined for the driveshaft of the opti.

lehr

Thanks Sick, I got you now.