[john31s]

I recently got a copy of Rocky Rotella's How to Rebuild Pontiac V8s. I saw in the back of the book there is a section of engine combos, in particular a combo for a stock 350 4-barrel with small value heads. It says it’s good for 340 to 355 hp using a the stock crank, #16 cylinder heads, stock 4 barrel intake w/ quadrajet, and a Tomahawk flat-tappet cam. It also calls for some work to be done on the bottom end including forged pistons, ARP studs, forged connecting rods. I would like to run this combo but don’t want to open up the bottom end. What I really want to know what could the stock bottom end stand up to power wise, my car only has 38,000 miles and change from new.

[MNBob]

This is an interesting question for me because I am in the same situation, only with a 400. I want more power – maybe a cam and heads but no bottom end changes with the low miles.
I am not an engine expert, but I always thought if you stay below 5000 rpm, you are pretty safe.

[72blackbird]

You can always swap on ported heads and a hotter cam and get more power out of a stock short block, provided you're got good compression and the rings aren't too worn. There are plenty of warmed-up 350P's and 400's out there running just fine and making twice as much power as they did before. But we all know you can only push stock cast rods and rod bolts so hard and so long before something breaks- it's your engine, and only you have your self to blame if you do toss a rod because you revved it too hard or too long. There are no guarantees with a stock bottom end.

[ponyakr]

use a good rev limiter--like the msd soft touch. i wouldn't leave home without it! they helped keep all my 455's alive--i set em on 5500 rpm., but shifted at 5000. raced lots of cast rod 455's--never lost 1!

[Mr Twister]

In the H O racing book there was a chapter that had the answer you are looking for and a chart. If I can find mine, Ill post the info unless someone else chimes in first. Seems like the magic number for 3.75 stroke engines was 6100 (guessing here). I don't feel that cast 541000 rods are a automatic black mark for performance, but they have limits. If you stay below their limit they are OK. If rebuilding then forged rods are always better.

[WARPed]

I believe you can have 1 hp per cubic inch NA reliably if your bottom end is in good shape - but there is always that chance as mention above for failure. Years ago I ran 400's w/ cast rods to 6500 regularly with out a problem.

[PunchT37]

I would worry about the cast piston before the cast rod. Rpm`s and detonation will be the killer. Stock 350? 400 HP and below 5600 rpm wouldn`t bother me. Keep a good tune on it. We used to turn one to 7200. It lasted a while. Course, we finally broke the ring lands out of 3 pistons.

350`s are one of the tougher Pontiac engines as they have thicker blocks, the same rods as most, and lighter pistons than a 400 with the same stroke. Same could be said about the 326. But, the 350 had the later valve angle heads vs. the 326.

[Ben M.]

Originally Posted by PunchT37

Stock 350? 400 HP and below 5600 rpm wouldn`t bother me. Keep a good tune on it.

I agree. If the rings are in good shape you can hop the engine up without too much trouble, just keep the RPMs down. Of course if the rings are in bad shape pumping the power will expose the problem pretty quickly...

[Brent Flynn]

Originally Posted by john31s

I recently got a copy of Rocky Rotella's How to Rebuild Pontiac V8s. I saw in the back of the book there is a section of engine combos, in particular a combo for a stock 350 4-barrel with small value heads. It says it’s good for 340 to 355 hp using a the stock crank, #16 cylinder heads, stock 4 barrel intake w/ quadrajet, and a Tomahawk flat-tappet cam. It also calls for some work to be done on the bottom end including forged pistons, ARP studs, forged connecting rods. I would like to run this combo but don’t want to open up the bottom end. What I really want to know what could the stock bottom end stand up to power wise, my car only has 38,000 miles and change from new.

The thing i would worry about, most, is the rings... Swap a new set of heads on it, and the thing might start smoking/using oil... It would be worth tearing down, recondition rods/rod bolts.... balance, hone, and reassemble. Would pistons be flat tops? or beveled? Either way , that engine would be good to 5500, assuming no detonation... I have a .060 350, balanced, rod bolts, with Keith Black Hyper pistons in it... ran it to 5500, with .480/280* crane, #11 heads, cast intake, qjet...ran 13.90s in '83Malibu wagon, and 3.73 gear. Probably had true 8.5 to 1 compression. I still have it, has about 45,000 miles on it... Its for sale, complete... Intake to pan. i see you are in NJ...

[U47]

Originally Posted by john31s

I recently got a copy of Rocky Rotella's How to Rebuild Pontiac V8s. I saw in the back of the book there is a section of engine combos, in particular a combo for a stock 350 4-barrel with small value heads. It says it’s good for 340 to 355 hp using a the stock crank, #16 cylinder heads, stock 4 barrel intake w/ quadrajet, and a Tomahawk flat-tappet cam. It also calls for some work to be done on the bottom end including forged pistons, ARP studs, forged connecting rods. I would like to run this combo but don’t want to open up the bottom end. What I really want to know what could the stock bottom end stand up to power wise, my car only has 38,000 miles and change from new.

If you have the run of the mill 350 2bbl engine ( 68-69 ) then your engine is equipped from the factory with Moraine 100 bearings instead of the 350 H-0 Moraine 400 bearings. The 400's are a must before you spin anything with more horsepower. Start there first, then proceed.