wcook174

so I have the car running, it runs alright I bought a 5.7 out of a 92 or 91 truck with 130,000 miles, and swapped in a 214 224 @.50 444 int 446 ex lift camshaft and new lifters, timing chain and gaskets, everything else is bone stock it did have a 305 before also the cam has a range from 1600-5200 rpm I know 5 grand is probably a little much for a stock bottom end truck 350

My issue is it will only rev to 4,000 ish before it sputters and will not rev any higher. it is a manual t5 and these cars I read do not have rev limiters, I tested that myself with the old 305 and hit 6500 rpm I've tried advancing and retarding the timing for not much of a change. I do not have a timing let yet but will buy one if I need
Any suggestions on what the issue is? could it be not enough fuel pressure or something else?

Schurkey

Verify fuel pressure under heavy load. You'll want to be on the high-side of spec; perhaps even above spec since the engine is modified.

Connect a scan tool, make sure that all the sensors are reporting reasonable info. Make sure the knock sensor isn't showing excess activity.

Are the valve springs tired?

Are you getting full throttle? Lots of times the gas pedal bends, the pedal hits the floor before the throttle plates are fully open.

Did you use the 350 fuel injectors or the 305 injectors?

Did you degree the cam? What is the cranking compression?

If you don't have a timing light, you likely have no idea what the base or total timing is. Does the timing advance work?

The swirl-port heads are not known for high-rpm performance.

wcook174

Thanks for the help this is great info and I'll get to verifying all of the different things
I'm also new to this forum thing sorry if it's formatted weirdly

Schurkey

That'll make a big difference, if you used the wrong injectors.

Again, that could explain a lot. Harder to diagnose and correct, though.

Electronic--shared between ECM and the ignition module. If either one is defective, or the wire harness connecting them, you could have no spark advance. Poor power, poor fuel economy, increased emissions, and poor driveability.

If you want to keep the TBI intake manifold, your only practical choice is the TBI heads from Summit. I don't know of any other aftermarket aluminum heads that have the correct angles on the intake manifold bolts.

https://www.summitracing.com/parts/sum-162108

DynoDave43

iTrader: (11)

Well, there ARE TBI intakes set up for the Vortec bolt pattern. But they are so damned expensive you could probably buy cheap heads in a more common pattern, get a used intake and adapter, and go that route.

I'm not a fan of offshore heads, so I'm going with Vortecs, and using a used 4bbl. Vortec bolt pattern intake with an adapter for the TBI, if I keep the TBI.

I'd start by checking those injectors, and seeing what you have. The first post in this thread has a little table of injector paint marks (assuming the user provided good info). The info is probably here on this forum too, but a search turned this up first. http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers

Here's an example of what those paint marks look like, from an old thread here on TGO.



So you are probably focusing on these two.

5235279 - White / Green - 54pph - 5.0L / 305 Cars/Trucks

5235206 - Orange / Black - 61pph - 5.7L / 350 Cars/Trucks

If you have white and green stripes, you need some new injectors.

Schurkey

The Genuine GM Vortec heads-to-TBI-throttle body manifold was always outrageously expensive...but Pandemic Pricing is now officially insane.
https://www.summitracing.com/parts/nal-12496821

The heads I listed are made in the USA by Trick Flow, but branded as "Summit". Summit owns Trick Flow.

Using a non-TBI intake manifold will require substantial fabrication to get the throttle/cruise control/TV cable bracket to fit, retain the EGR, and retain various accessory braces.

I used a GM "ZZ4" intake manifold on my K1500 with (different, older) Trick Flow heads. It was a mess getting everything to bolt up properly, particularly the EGR which required two entirely different adapters, one of which is not available commercially--I had to make it--and the A/C brace is still not connected to anything on the manifold.

aliceempire

iTrader: (14)

I think I'd rather spend the money on the fitting manifold than all the dinking around to make a retrofitted manifold work. Sure it's expensive compared to carbed manifolds but still beats hsr, sr, miniram prices by a wide margin, and we pay for those all the time. But it's all opinion I guess.

DynoDave43

iTrader: (11)

I know. It's madness. I overpaid for a used one with the conventional head pattern years ago, when I thought I'd be running some World Products heads. But what I paid for it is nothing by today's standards. I guess with the value of stuff right now, I should sell that manifold (and a lot of other parts I've accumulated and won't need).

Nice! Those look like good heads.

The real problem here is that I CAN'T READ, or didn't do it carefully in this case anyway. I thought the OP had said he was contemplating a CHEAP set of heads, and that more often than not means chinese. And I'm not a fan. But to each his own. My apologizes for confusing the matter.

I'm not aware of what I would consider to be a "good" answer to this problem. The TBI intakes are not known (stock or aftermarket) for their great flow. And even the Eddy TBI is slightly taller than stock...something my hood line just doesn't need.

Using a carb intake with an adapter creates it's own issues. You need an adapter (cost, and thickness that aggravates the hood clearance issues, plus double gaskets for more leak potential). It also can create linkage issues as you mentioned, but I think that's mostly if the throttle body ends up mounted higher, no? And yes, keeping EGR in some form takes more work.

Hmmm...is that the 12496820 intake? That's the one I was hoping to run! I liked it for it's A) Vortec head intake bolt pattern, B) very low height...just slightly less than an Eddy Performer, and C) you can retain EGR using a Vortec-like feed setup.

I was not aware of the missing compressor brace bolt location, although with the EGR provision changing the front of the intake around, I guess that makes sense.

But again, I'm not aware of a drop-in solution that meets all these needs.

Sorry to take the conversation slightly off topic OP.

Schurkey

No. This has the older, six-bolts-per-head bolt pattern, not the four-bolts-per-head Vortec pattern.
https://www.summitracing.com/parts/nal-10185063

It's almost exactly the same height as the TBI manifold, but the adapter plate raises the throttle body a little bit.

EGR is similar to stock, but uses a different EGR gasket that isn't compatible with the TBI EGR valve. And the whole valve has to be moved rearward to clear the IAC motor on the throttle body.

DynoDave43

iTrader: (11)

I gotcha.

This is the one I have. With some fiddling, I hope to make it work.

https://www.summitracing.com/parts/nal-12496820

dmccain

iTrader: (2)

These fitment/clearance issues is why I ran 083 heads and a stock intake bored out. Kept it simple. Seems to pull pretty good RPMS too .