Author Topic: Good intake manifold for towing engine?  (Read 954 times)

Offline Stewart G Griffin

  • Site Supporters
  • Senior Member
  • ******
  • Posts: 3069
Good intake manifold for towing engine?
« on: January 31, 2018, 10:05:20 AM »
Proposed engine is either the basic crate 350 OR the L31 crate 350---which has 9.4 compression, roller lifters and 64cc vortec heads.   i know a 383 or big block would be better, but i want to keep it low-budget for now.

It will be in either a 2WD 3/4 suburban or 2WD 1-ton crewcab, so i'm assuming the highest gear i can get is 3.21.  And it's likely it could be as low as 4.10 or even 4.56.

Trailer will be an open 16' car trailer.  Total weight of trailer (with car) is between 5000-6000lbs.

Desired speed is at least 65.   Most likely 65-75.   i'm thinking cruise rpm should be around 2200-2500.  Terrain is not seriously mountainous, but not totally flat either......

Exhaust manifolds will be stock and rest of exhaust will be basically stock.

Assuming that we're staying with a quadrajet (for now), would the Edlebrock performer RPM (high-rise) be a good intake manifold choice for this towing engine?   Remember that we have plenty of vertical room under hood.

Offline Stewart G Griffin

  • Site Supporters
  • Senior Member
  • ******
  • Posts: 3069
Re: Good intake manifold for towing engine?
« Reply #1 on: January 31, 2018, 05:14:36 PM »
P.S.
Transmission will be either TH-350 or TH-400.  i will get overdrive eventually.

Offline VileZambonie

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 17317
Re: Good intake manifold for towing engine?
« Reply #2 on: January 31, 2018, 05:29:29 PM »
A dual plane intake but let me ask you, why not build it right the first time? If you want overdrive, don't do it later, do it when you're putting the powerplant together. Buy a parts truck with an LS setup
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

Offline Irish_Alley

  • Tim
  • Global Moderator
  • Senior Member
  • *****
  • Posts: 13067
  • Family is not an important thing. It's everything.
Re: Good intake manifold for towing engine?
« Reply #3 on: January 31, 2018, 08:53:24 PM »
a 1 ton should come with 4.10 or 4.56 besides that i would do like vile said and find a parts truck for 1k or so and have OD and most if not all you want. the gearing that comes in the 1 ton will be good for that terrain
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline 68post

  • Newbie
  • Posts: 7
  • Newbie
Re: Good intake manifold for towing engine?
« Reply #4 on: February 03, 2018, 10:28:22 PM »
I wouldn't change from the stock intake if I was sticking with stock exhaust manifolds. That said, the Performer EPS is tuned to hit torque peak @ 3,500 rpm on a 350ci.

You'd gain quite a bit more torque by just switching to long tube headers than changing an intake.
« Last Edit: February 04, 2018, 12:30:43 AM by 68post »

Offline 75gmck25

  • Frequent Member
  • **
  • Posts: 356
  • 1975 GMC K25 Camper Special, 350/TH350/NP203
Re: Good intake manifold for towing engine?
« Reply #5 on: February 04, 2018, 09:30:28 PM »
When buying new, you want better than the basic crate 350 or the 350/290 hp (same low compression engine).    Its exactly the same as a mid 70's smogger 350, with inefficient heads, low compression, low lift flat tappet cam, and two piece rear seal. 

If you move up to the L31 engine you get Vortec heads, roller cam (191/196 @ .050) and a 1 piece rear main seal.  However, you do lose the ability to use a mechanical fuel pump.  If you buy that L31 crate you will have the option of later tweaking the heads to allow more lift, and then add a higher performance roller cam that will give you much more horsepower.

Look for the engine masters episode on youtube where they took the basic crate 350 and dyno'd it at about 240 horsepower.  Then they bolted on Vortec heads and a mid range flat tappet cam and brought it up to about 350 horsepower. 

Blueprint engines also has a crate 350 with Vortec heads and higher performance roller cam (220/224 @ .050) that makes 373 HP, and its priced at $2,599.  Its more than the L31 crate, but it would give you quite a bit more horsepower right from the start.

Bruce