I am currently building a 70 Ranchero with a 351 Cleveland and have a 6-71 BDS blower to put on the motor.

I have had the heads redone but it still has the stock bottom end.
I was hoping to put the blower on the motor in the Ranchero and drive it with lower boost until I got a new motor put together. (Building another Cleveland) I was wondering how much boost is safe to run on a Stock Cleveland before I throw rods and melt pistons.
Any help is certainly welcome as I am not a Cleveland expert.

maybe 4 to 6 LB
thats heavily under driven of course , you really need to measure the current compression and work out the ratio then we can help more .

 

I was thinking around 6 lbs.That is what I ran in my 03 Harley truck safely.
The engine is a 2 barrel head 1970 model. I looked it up in the book and it said 9.5-1 compression. I am not certain this is true however.
I am going to get it running with a Holley and no blower to dial in every thing else first. Once I am happy with it I will toss on the 6-71 with about 30% underdrive just for shits and giggles.
I am also building a bullet proof 4 bolt main so later I can swap it over and smoke some bowties.
I had the heads done because one of the valves on the passenger side of the block stuck. I put it back together and another valve (same side) stuck.
I took it back to my machine shop and they reworked it. I put it back on and yet another valve stuck.
I am changing machine shops.

 

If your building another motor, wouldn't it be a good excuse to blow it up then have to drop the other one in?

 

I would just hate to blow up a perfectly good cleveland just for sh*ts and giggles

 

I've seen plenty semi stockers on 6lb's. You'd be safe there provided your timing and fuel is sorted.

 

boost on cast parts won't hurt a motor. When you spin those stock parts to 5-6k, the rpm's kill the motor.

 

my two bits , i run a 6/71 on a 2v cast cleveland that already had near 100.000klms on it and also toploader and 3.5 gears .

All i did was go over the ignition and make sure it was spot on ( stock bosch electronic ) , changed spark plugs for two ranges colder than factory spec , run the engine on pump 98 ron ( usually Shell ) , fatten up idle mixutres ( 2x 600vac ) and she's happy as a clam 6.5lbs boost and wont drive in a straight line . Static comp at 9.2 : 1 ,fuel pressure at 5.5psi idle , check plugs after punishment and blow by through tappet covers , all good so far .

No two engines are the same but a good cooling system and keeping the revs to no more than 5800rpm seems to agree with it

 

forgot to mention is 351 open chamber , seems to like 4.0degrees inital timing for easy hot and cold starts and plug gaps out to max recommended .

 

watch your oil at the crank, i cut bth my main and rods 20 thous. and run oil restrictions in the mains trw forged 30 over and smoothed the lifter galley opened the return port behind the distributor and added holes in the valley for oil return. just my 2 sense and i spin it @ 7000 for the last 18 years!!! no shit:hy: