390 Aluminum intake?

[wyngnut55]

After putting about 2000 miles on 390 F100 after a frame off resto, I determined the poor old engine is tired. I didn't want to spend money and rebuild until I determined where the engine was in its lifespan. I have the engine out at the machine shop getting bored .040 over and having the heads done with new hardend valve seats. Decided I'm going to get rid of this HEAVY cast 2 barrel intake and put a Edelbrock 4 barrel carb with aluminum intake. Also a cam & dish pistons.
I was told at the engine machine shop that they have seen some problems with aluminum intake manifolds. It seems they move around a little to freely when you lay it on the engine. Getting it to seat & seal right can be a problem. They have seen many sucking oil from the valley into the intake.
Has anyone else seen this? Is it better to fine a old cast iron 4 barrel intake? This friggen engine must weigh 700 lbs!
Also, has anyone seen the problem with hammered valve seats in older engines running unleaded gas?
Thanks

[DuckRyder]

IME it is more of a gasket issue than an intake issue. The old blue Fel Pro Perma Torque were notorious on the FE Forums for blowing out. Feel Pro has changed the gaskets. If you cam find Victor they are good too.

I don’t know if your heads are already in process or how bad they are, but make sure you know what you are in for, because aftermarket aluminum heads are relatively cheap. In fact I’m pretty sure you can get an entire Edelbrock top end kit for what’s a very reasonable price once you start adding up individual parts.

For a lot more detail, give us a lot more detail

[wyngnut55]

Original symtoms... Leaking rear main and low oil pressure at idle (approx 4 psi) Tore the engine completly down. Rear main bearings are worn through to brass and center thrust bearing is worn through on side. Not sure why? Heads look good, engine looks like it has been done before, already .030 over. Was quoted $800 for heads and about the same to clean, bore block & polish cranck. Was quoted $1200 for heads at another shop. Getting manifold, 4 barrel carb, cam,timing chain,lifters,valve springs,pistons & all gaskets through Summit racing.

[Ranchero50]

Original symtoms... Leaking rear main and low oil pressure at idle (approx 4 psi) Tore the engine completly down. Rear main bearings are worn through to brass and center thrust bearing is worn through on side. Not sure why? Heads look good, engine looks like it has been done before, already .030 over. Was quoted $800 for heads and about the same to clean, bore block & polish cranck. Was quoted $1200 for heads at another shop. Getting manifold, 4 barrel carb, cam,timing chain,lifters,valve springs,pistons & all gaskets through Summit racing.

Wear on one side from the throw out bearing pressure on a manual tranny. Good reason not to hold the clutch in. I've never had valve seats go bad from newer fuels. To me we just don't put the miles on these trucks to necetate that work and you gain so much with aluminum heads that it's not viable to rebuild the old ones unless you want to stay original for originals sake. I'd also figure out your timing and try to get car style pistons versus low comp truck pistons. Again, we just don't load these trucks down with weight and use them like trucks enough to justify the detuning for load. Run the timing more advanced for the same reasons. Better economy and performance at running weight.

[DuckRyder]

I agree with Jamie.

Set of E-heads complete is like 1500.00 and will have big valves and so forth. Time you spend 800.00 plus springs and retainers for the factory heads you aren’t that far...

Plus with AL heads you gain resistance to detonation, can run forged flat top SpeedPros without concern... voice of experience here...

Whole Edelbrock top end kit is like 2400.00 and makes over 400HP on a “car” short block, the cam wouldn’t be my first choice but it is hard to argue with that if it fits your goals.

[wyngnut55]

I haven't had any work done or bought any parts yet. Needs to do the bore before I order pistons. Just took the block & heads in Friday afternoon. I have a C6 auto trans. The cam, Lifters, valve springs, timing chain all come in a kit $450. Not wanting to get a ton of money in this thing, Looking right now, I may have about $3500 total in the engine doing what I described. I do use it as a truck sometimes, also tow a mini excavator occasionally. Price of aluminum heads looks closer to $2000

[DuckRyder]

Cool,

What cam kit yo looking at?

[wyngnut55]

K33-234-4 Comp Xtreme energy cam and lifter kit, Summit. Thinking I may go with the automotive pistons. 90% of time I drive this thing empty. Doubt I will ever get more than 4 or 5,000 miles a year on this thing. Thanks for the input, never done performance rebuild before, just long block stock swaps.

[DuckRyder]

That should make good power, watch the quench and compression. Has a early intake close angle (54) so stay conservative on the compression... should make a nice efficient engine with excellent manners.

[wyngnut55]

Cool! Any advise on a piston kit at Summit? Machine shop is expecting .040 over bore.

[DuckRyder]

Do you know what the cc of the heads are (or the casting number) and does the matching shop anticipate having to shave the block or heads?

L2291F-40 IF the heads are above 72cc and they don’t anticipate shaving either the block or heads, probably H304P-40 if any of this is not the case.

Let me run some DCR numbers Monday of Tuesday to get a better idea.

[wyngnut55]

Don't have any numbers but can find out tomorrow. Don't want to do anything radical. Pistons are in MKP601M-300 rebuild kit I was planning on ordering, Think the automotive pistons is a good suggestion. Would like to get complete rebuild kit with that type pistons.

[DuckRyder]

Yep that’s truck pistons...

Hang on...

[DuckRyder]

Hmm...

It looks like summit at least doesn’t offer the kit with car pistons, which is weird, maybe call them?

[DuckRyder]

Here is why you don’t want a “truck” piston. It is actually a car piston for a longer stroke (410 mercury) and the compression height will put it well down in the hole at TDC. With a modern composite head gasket it will put your compression ratio at less than 8:1 probably.

I actually have all three of the pistons we are discussing and shot some comparison photos to illustrate. I will try to find the post and or pictures and show them here... gimme a while.