Thread: pumping a 6 cylinder

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a friend of mine wants to finish his boys pickup while hes in the army.it has a 250 ci and thats what the guy wants to build but we cant find any place to find any performance parts,anybody have info on this?

Check out Clifford Performance. You can also pick up a copy of the Chevrolet Inline Six-Cylinder Power Manual for about $20.00.

Personally, I'd swap the six for the relatively new 4.2L inline six in the new Trailblazers (275 HP) as these can now be reasonably purchased from your local salvage yard. Just make sure you buy the trans and the wiring harness/computer with it.

250s arent exactly sought-after motors. As such, theres not much of an aftermarket to them. But, as an inline 6 person myself, theres a few tricks. Bump up the timing a few degrees, port the head, along with the intake runners. Then uncork the exhaust, throw a decent carb on top, match with a coil and youll notice a profound difference. If your not happy with that, shave the head. I would be willing to bet your motor is running 8.6:1 tops. Chances are its leaning more towards 8:1.

along with that intake getting ported... you can buy a kit to pull the 1bbl off... if its running one... i dont know chevy 6s.. and you can bolt on a 2bbl

thanx guys,im much obliged

I'd lean towards a 292 out of a chevy bus or big truck. Same dimensions as the 250 but gobs of torque (like Fords 300 inline).

I just sold a clifford intake that would fit your 250. I was going to put it on my 194 inline 6 but decided not to. If you use this intake, I believe you have to use Clifford headers as well. OH yeah, in JC Whitney you can order a Offenhauser Intake for a single 4 bbl carb setup that will fit a 250, forget how much $. I think it was around $220 for the intake.

Good luck in building your engine...

Steve

i dunno if a 4bbl would be a good idea unless you put a wild cam in there.... but as i've been told... camming an inline 6 isn't a good idea... cause they tend to never idle right once you put a cam in it... probably best to leave it a 2bbl, roller rockers, maybe bore it out a lil, get some headers, they do make them... if you really want to get tricky, you could have your head milled and raise the compression just a little bit...

Has anyone used the new 4.2 with a manual trans? I'm looking at all options for my 36' Chevy. I was originally planning for a 292 I6 (w/4 Spd) but am told that there is length issues with the small engine bay.

Originally posted by Swifster
Check out Clifford Performance. You can also pick up a copy of the Chevrolet Inline Six-Cylinder Power Manual for about $20.00.

Personally, I'd swap the six for the relatively new 4.2L inline six in the new Trailblazers (275 HP) as these can now be reasonably purchased from your local salvage yard. Just make sure you buy the trans and the wiring harness/computer with it.

JCwhitney.com also sells a 2bbl adapter to work on a four bbl. If a new cam is needed, a very mild cam can be used. Very mild. Headers also make a difference, that and a decent exhaust system. The 250 can be overbored .030.
Back in the early '70's I remember stroker kits, flowed heads, pop up pistons. I remember a tri 40DCOE Weber set up.
Then, there was even a straight six following. The 240Z engine was a combination of the Chevy straight six, and the empty oiler from the Mitsubishi Zero fame. You could run that engine out of oil, and make it to somewhere to get it fixed.

Look up "Inliners International" online; they even have a forum for 250s, I think.