I have a 390 with a comp cams 292 .560 lift and 10.5 compression. broke it in last weekend and ran great, started it today and started runnin rough, found #1 intake push rod bent. i have been told its the cam timing, or the pushrod length, or i need hardened rods. the thing that gets me is it was only 1 pushrod, any help is appreciated...

 

What rocker assembly are you running? The pushrod length should have been checked when putting it together but who knows you may have gotten 1 that was different. I would start there first, as that's the easiest check.

 

I am using the stock none adjustable with factory length rods

 

That's a lot of cam for the stock rocker shafts. They have a tendency to bend easily if not installed carefully.
FE's That Bend Push-rods, A Dirty little Secret .: Articles
Here's a good article.

You may want to get some end stands to support the ends of the shafts that hang out in space for this much cam. I have them on mine with the stock shafts and comp xe274h cam. Like $120 from Precision Oil Pumps, which in my book is cheap insurance.

 

I learned something new today; thanks very much Sleepy. I haven't opened my engine up yet (this is my first FE powered vehicle). The 2105 manifold and 1406 carb are on their way so I was thinking about a new cam (and headers) but I had no idea these engines used a non-adjustable valvetrain. Glad I found out before I pulled the valve covers and had a 'WTH?' moment.

 

The hydraulic flat tappet cams have non adj. valve trains. The hydraulic lifter and correct length of push rods set the lash. On engines equipped with a mechanical cam and solid lifters, the valve train is the adj. version. Your truck will be the non adj. hyd. flat tappet. Glad to help.

Oh and you'll definitely want to use headers on the rebuild. The factory logs are pretty restrictive. A mild RV type cam and it'll be pretty stout with some improvement in mpgs.

 

When tightening the rockers arms, snug all bolts finger tight and then front to rear i/2 turn each and then do it again until bottomed out. Final torque is 40 ft. lbs.

 

Since the vast majority of this trucks usage will be to pull around a 16' travel trailer the mileage was a big concern. I'd like to see a little more torque but she's not going to the drag strip (well, maybe once ) and it would be a pretty unusual situation that had me spinning over 4,000 RPM.

Any experience with the Rhoads variable duration lifters in an FE? I've used them on over-cammed Pontiac engines in days gone by in order to keep them semi-streetable.

The cam I'm looking at for this truck (360 incher) is a Howards
Part Number: HRS-252461-12 Advertised Duration 292/302, Lift .519/.546


Not planning a full rebuild since the engine only has 78k on it from new and it runs GREAT. But I know it can run better so I figured that I would do a top-end rebuild - clean up the heads, upgrade cam/manifolds/carb, electronic ignition. Although I do have a little oil drip from the rear main seal and that would be easier to fix with the engine out and apart .....

 

You could also just upgrade to the stock adjustable rocker assemblies.

 

That's too much cam for the ol 360. There's no way(without decking the block) to get the compression up high enough to make use of it. I know you may not want to hear it but for the price of all the top end parts, you could easily swap in a 390 crank and rods. That would net you more power per $$ than anything you can do to the 360. If you're set on keeping it a 360 then I would look at something like Comp cams XE256H, Lunati voodoo 250/256 or a similar profile. The more duration you throw at a 360 the more a dog it's going to be down low.

No experience with Rhoads. You don't have to do anything fancy with the valvetrain if you are running a mild hyd flat tappet cam, just use the lifters and springs it comes with and break it in properly. Or as tater_51 said, if you want you can swap to the factory adj. rockers, but they aren't necessary.

Happy Easter everyone! He died and was raised so we could have life eternal. God bless!

 

I'd sure rather hear it now instead of after I bought the parts There are a few things that seem to be unique to the FE - most of my engine experience is with Pontiac and an occasional Chevy - so I'm glad to get advice from the folks that have 'been there and done that'. This is also the first time I've gone into a vehicle with efficiency, rather than brute power, as a guideline for parts selection. If I was going to the extent of really rebuilding then I'd seriously have to consider the 445 kit just because, I mean, why wouldn't I?

My plan right now is to just extract the best bang for the buck out of the stock 360 so getting more air in and out more efficiently is the focus. I would have gone with stock FE 4 BBL parts except the Performer manifold and carb were available at reasonable prices. I wasn't going to part with $300 each for those items but at $314 for both items delivered - used but very clean - I just had to do it.........

I'm interested in learning more about the adjustable valve train option; any good starting point you can suggest for info on that? I'll dig around a bit on the engine forum to see what I can find there but if you know of links to any good articles about the swap, I'd appreciate it.

 

Since you mention it, mpgs will actually be equal or a little better with the 390. The 360 has no quench, the pistons sit .104" in the hole...that's a long way. Makes for about 7.6:1 static CR. It's very inefficient.

I understand you want the best you can get from your current setup though. That's a fair deal on the intake/carb and should be just fine for your intended use. It's nice not to have to lift that factory hernia maker intake for sure! I started the same way on mine. Perf. RPM intake, 1405 carb, headers, MSD, and some C8AE-H heads with CJ size valves and a little port and polish all went on the 360 one by one as I could afford it. It was surprisingly pretty quick, still terrible on gas, but really not bad performance. Then when I had the dough, all I had to do was bore and stroke, swap cams and lifters, slap on the 750 Holley, and perform the oiling mods + new ARP hardware everywhere and now here I am with the 445.

You don't need the adjustable rockers for any cam that you can make use of with the 360. Adjustable rockers are used on hyd. flat tappet engines to either complement an Aggressive cam upgrade, make use of a slightly higher lift ratio (1.76 vs 1.73) or to compensate for bad valvetrain geometry. The OP may have use of them in his setup though.

Either way I think it would be money better spent elsewhere than on something you don't really need to begin with. If you read and follow that tech article on setting pre-load and checking clearances you wont have any problems with the non-adj. rocker arms. I don't.

 

Decisions, decisions, that's what makes each build unique. Good luck with your project, sounds like your on the right track, the guys on this website know their stuff, they sure helped me. i just finished a 416 build and went with the small Crane 343901, looking for good low end. I decided on the adjustable rockers for convenience of set-up. I bought all new shafts, arms, push rods, etc. but there are used sets out there for cheap (e-bay, craigslist) all depends on what you want to spend. Good luck and keep us posted.

 

Thanks guys, I'm curious about the change to adjustable valve train mostly from an academic standpoint right now; just trying to learn all I can about what makes the FE unique or different. And I figure that since I'm never going to build a high RPM engine out of it, most of what I'm doing now can be retained if I wind up going bigger. Same headers and manifold and, unless I go serious big, the 600 CFM carb will get the job done. I'm a shopper and an opportunist so if a smoking hot deal on a 390 shows up along the way, I've got no problem jumping on the deal.

I'm also learning restraint, though....I left the $300 complete, running, 460 on CL for someone else to buy.

 

I'm pretty sure Comp Cams recommended using adjustable rockers (or at least aftermarket rockers and pushrods) with all of their non-stock level camshafts.

The stock pushrods are easy to bend in the first place..... also with you adding a different intake, did you verify that non of the pushrods are rubbing or binding in the intake?


best of luck,
Drew