Need advice, swirl port 350

[Beatdown Z]

My buddy needs help deciding what to do with his 89 GMC Jimmy. The truck has a pretty crappy drivetrain setup. It has a swirl port headed 350, 750 Holley with mechanical secondaries, 214/224 cam(think it's an Elgin grind), Edelbrock Performer intake, stock manifolds, stock converter, TH400, 2.73 gears, and 35" thornbirds.

His main complaints are not enough vacuum for power brakes and no lowend torque.

He's wanting to swap in a new cam(201/207 or single pattern 207) or swap the stock TBI 350 cam back in. Anyone have experience with swirl-ports and what works best?

The stock manifolds will stay, because he is planning on a front mount turbo kit in the future. And because of that, he thinks his gearing is fine(mind you, he's still running ten bolts).

 

[bucket]

GEARING! GEARING! GEARING! GEARING!!!!!!! Ditch those gears, they absolutely SUCK for ANY truck, let alone one running 35 inch tires! Needs to be somewhere in the 3.73-4.56 range. Then after changing the gearing, swapping on a vacuum secondary carb will really help out too.

 

[89Suburban]

 

[Jims86]

yup...3.73 minimum. That cam does not seem too big...was it installed straight up? maybe take it for a dyno tune. Swirl ports work really good with carbs.
If he is going to turbo it, the best thing is to swap the TBI cam and injection back in, and get an Edelbrock TBI performer manifold, and have the barrels machined to 2" to use a 454 throttle body base.
TBI 350 and 400 is a great drivetrain, until someone who doesn't know what they are doing starts working on them.

 

[350runner]

Did he rebuild the motor with the cam swap? Or just slapped in a cam? Compression sounds low. I've coot a similar cam in my swirl ported 350 with flat tops about 9.5 comp and have 22in vac in park 15-16 in gear.

 

[Jims86]

Did he rebuild the motor with the cam swap? Or just slapped in a cam? Compression sounds low. I've coot a similar cam in my swirl ported 350 with flat tops about 9.5 comp and have 22in vac in park 15-16 in gear.

Yup...bottom end may need a freshen up...or valve job

 

[Beatdown Z]

Yup...bottom end may need a freshen up...or valve job

Yeaaa, about that... The truck overheated, hydrolcked, and bent two rods last summer. So, he bought two used pistons and rods and slapped them in. It does smoke on start up sometimes so it could use a valve job/guides.

Didn't degree the cam, so it's wherever it landed, lol.

Maybe I should convince him to let me throw my wideband in it so i can at least verify the A/F ratio is in check.

He has a lot of other projects going on, so he's not wanting to dump too much money in it. But that is actually why I'm trying to help him figure out if he can keep running his current cam to save some time and money.

 

[Beatdown Z]

Anyone know a good size turbo for a swirl port 350? Only looking to run about 10psi and looking for near instant spool. I was thinking along the lines of a 66/65.

 

[Beatdown Z]

This is what happened to his gears last weekend.

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He was getting ready to ebay another set of 2.73's! Luckily I had 3.73's on the shelf. So we'll see how he likes the truck with the new gears in a day or two.

 

[Beatdown Z]

Welp, he says with the 3.73's it feels like it did with the 2.73's and stock cam. He is going to swap the stock cam back in, for the extra off-idle grunt and vacuum for his power brakes.

Now I need to work on convincing him to replace that Gov-Bomb diff it has in it.