Rebuilding my ‘68 350. Aiming to up the torque some (why not) and increase the dependability. Any reliability tricks and updates to make? Running a Quadrajet on a TA stage 1 intake, TA alum heads, TA front cover, HEI, switching to a TA hyd roller cam setup from the TA hyd 284, TA headers, pistons and rods are stock replacements. 3200 stall with a 700-r4. Currently runs well, stays cool, oil sits 25-65 depending on heat and rpm. Just looking for any ideas while it’s apart. Prefer to do it the right way once even if it’s a little more work. Thanks!
I think my only real advice is to go with a nice set of custom pistons to sit at zero deck. The factory pistons will be way in the hole and that will give up a lot of torque due to lack of quench.
Like Sean said custom pistons. I bought these through TA. As for oil mods at least enlarge passages from pickup to pump and front cam bearing. TA double groove front bearing as well. I went for the extra money for the coated ones. My machinist also added a balance line from the galley at the back of the block to the front by oil pressure sender. He also enlarged oil feeds to main bearings. Should have motor back soon, would of been done already but I’m no longer in a rush since car was totaled.
@72gs4spd Do you have the TA number for the pistons? Are they higher compression? I was looking at the current options they have available. Definitely looking at the oil add ons and coated bearings this round, I should add it ran great*, spun #8 rod bearing earlier this week.
You probably over revved engine with that huge converter and crazy spread on first gear to second.Is that what was behind the engine when you spun bearings.? You will want to do oiling modifications to block and you will want more information to set block up for roller cam. A few guys here had issues and it did damage block . You will really want better rod bolts at least. Once assembled you will,need to check piston to valve clearance. And you really do want higher compression lightweight pistons for this combo. the sp3 intake would be a better choice here with the aluminum heads, the roller cam and that big torque converter. a ta performance backgrooved front cam bearing would be wise here also. Get the clean up porting done by ta. You will need to recurve distributer. Get 5/8 pickup tube/screen .
@alec296 You are correct there, got a deal on the converter/ trans combo I couldn’t pass up. Tuning the governor she cleared 6k a couple times. The impressive part was this was last fall and I drive the car a few times a week during the season. (Michigan, so no winters). What issues has there been with the roller cams? I haven’t had an issue with the current hydraulic, I was just looking into hydraulic roller for the durability with the lifters/cam.
When using a roller cam you need to secure it in the block at the front so it doesn’t push forward. There are several ways to do this and at first a few people didn’t get it right. I personally go against the popular belief on roller cams for these engines. I see a bunch of downsides and I prefer a flat tappet for all mild combos. 1. cost 2. There have been a lot of roller lifter failures 3. Yes roller cams can be more aggressive without compromising street ability, however most combos don’t need a giant cam anyway 4. Weight of the lifters is much higher 5. Valve spring pressures are way higher When really pushing the limits of the cam specs that’s when the roller cam shines. Less loss of low rpm torque while still maximizing high rpm potential. Those TA pistons are custom order so they aren’t listed. You can get them in any compression ratio you want just call them. Before ordering figure out the piston compression height you need to get zero deck and also what dish CC you need to hit your target compression ratio. The machine ship can help you measure the block to determine the dish and compression height needed.
They’re custom order from AutoTec through TA. I’ll look up the part number, but you’ll have to call and talk to Mike Sr to order as my machinist did. He knew what he wanted and yes there high compression.
The SBB 350 is a more compact engine than the BBB 455, so there is more potential for interference between the cam and connecting rods. I think a few guys had to clearance their rods a bit. My roller cam uses spring pressures that are nothing more than a high performance flat tappet cam uses, 370/145. My engine was originally built with the TA supplied Morel roller lifters. About 4 years ago, I swapped in the better Johnson roller lifters. My engine has been together for about 9 years now. Yes, it adds a lot of expense. It was initially about 1000.00 over a flat tappet build, but the Johnson lifters were almost twice as expensive as the Morels from TA (350.00/630.00). I also have roller rockers which are expensive all by themselves.
@LARRY70GS Thanks Larry, within reason I’m willing to spend the cost for a motor I can assemble and not tear into for 9+ years. Talking with TA it sounds like the cam I was looking at would be similar. Benefits of both worlds, lower spring pressures and higher durability of the full roller setups. I’ll check out the Johnson lifters.
That’s the differences I’ve been trying to weigh. The hydraulic roller isn’t a true roller so the valve pressures don’t get off the charts. For a mild build focused more on something like the power tour it may make more sense to stay with the flat tappet. Haven’t had any complaints with my current cam setup. (TA 284)
The cam you have is already broken in and happy I would keep it. In my opinion the biggest reason roller cams are so popular is because engine builders prefer them vs doing a flat tappet break in procedure which has a chance of failure.
More H.P. & torque does not = better dependability and reliability. Stuff wears faster and breaks, plus you're always dicking around with something... Doesn't get any better than stock for longevity.
Too late for that it’s being rebuild already. I can think of a dozen upgrades that improve reliability vs stock. I do agree within reason but the stock timing set is reason alone to tear it down.
That’s true but when I was in the planning stage for my build and sat down with my machinist I explained I wanted to retain reliability and stay on pump gas, but squeeze out as much as we can. He asked what I was looking for and I said 500 HP and I’m happy anymore above is a bonus. I will post all the was done when it’s finished on my thread when I have it.
It took awhile for engine builders to realize that the oil producers had reduced the zinc content and as a result there was a rash of break-in failures for flat tappet cams. If you run a flat tappet cam these days it's a smart practice to only use oils made for a flat tappet engine. Never-ever let modern car oil near it. Also apparently the zinc drops out over time so we can't take advantage of contemporary long oil change intervals. So between $10 a quart oil and 3000 mile oil changes it can add up. It takes a lot of that to add up to the cost of a roller cam setup, but in 100K miles it's just about paid for. And then there's the convenience of long oil change intervals as well. That's why I'm changing over. Jim
I do agree with that, although lighter bottom end and breathing better than factory should aid in dependability and in turn free up some power. It's the always dicking around that will limit it
So currently talking with my engine machinist, he agrees on the flat tappet vs roller points. For my goals, he agrees it is better to stay with the flat tappet. My current plan is Checking deck height '73 donor Crank cleaned up Molnar H Beam rods Custom pistons through TA, upping the CR to 10:1 (Was stock around 8.5) TA coated bearings Larger oil pickup and new oil pump TA Alum heads Reusing Cam, lifters, rockers, TA Stage 1 intake, headers, quadrajet. @Jim Blackwood As far as the oil comment, what is recommended to run? I have always run 10w-30 full synthetic with zinc additive.
