3.8V6 to 5.0 TBI Swap

[Mayronus]

HELLO !
MY car :
1984 Cutlass Suprime coupe brougham 3.8v6 231
I bought L03 V8 305 (5.0 TBI) 1989 with th700mods (I know,I know but to buy 350 in Poland is almost impossible, and

to transport one of those from USA to Poland i need to sell my kidney to afford it 😉 )
Modification done:
ported&polish heads,roller rocket arms 1.6 (Crane Cams), valve springs (Crane Cams), roller chain&gears
(Crane Cams),
camshaft: 1991 Chevrolet Corvette L98. it should have aroUND 240HP
I'd like to do carb conversion and as far as i know i will need performance intake manifold non EGR+ neck (Weiand?),

+/- 600 cmf carb street/strip No Emission (Holley?,Rochester Q-jet ?)carb,performance fuel pump+LINES

Any sugestions what intake/carb brand/model???
Please add everthing i will aditional need in tbi to carb conversion.

What lowering spring should I use to get at least 2" Eibach,Hotchkis,Edelbrock, any other ? I couldyn't fainde

belltech in Summit catalog 🙁


LS1 front/rear brake conversion what I will need? ls1 front calipers/brakets/rotors anything else?
What modyfications I must do to the spindle/hub? Can I instal lsi rear disc brakes to my 3.8 v6 Transaxe ?
Please, can you add some pictures.

THANK yOU

 

[85 Cutlass Brougham]

Well, I would use a Quadrajet and an HEI ignition as they may be available elsewhere in Europe. There should be an American car community in Great Brittan or Germany as they have American bases, and some of the soldiers probably brought cars over. There also may be clubs, etc in these countries that cater to American cars and someone may have parts. For an intake manifold, an Edelbrock Performer is pretty much the universal intake for mild Small Chevys, but a Wieand 8004 or Holley Contender would also be possibilities. if you run the Quadrajet, a factory intake will also work as long as it is from a Quadrajet equipped engine. The thing to remember is that this is a pretty universal engine. Chevy and GMC trucks and vans will also have them.

 

[Yoda]

Late 80's and early 90's L98 Corvette 350's made around 240 horses. Give or take a few depending on the year.

A stock G-body era 305 made around 150 HP. Many made less than that. HO 305's were quite naturally a little higher (170 or so) but still well under 200 HP. The highest output 305's went into the late 80's and early 90's IROC Camaros and were overrated at 215 Horse. They actually made around 205. They were also TPI engines and had a bit of a power advantage over carbureted engines.

Your estimate of 240 HP seems a bit on the hopeful side.

Please do not fall into the trap of looking for a bigger cam. The L98 is as big as you should go with the little 305. No bigger. With limited cubic inches at your disposal you don't want to sacrifice any more low RPM torque than you absolutely have to. That is unless you plan to use the car primarily at the strip and run deep rear end gearing like 4.10:1 or lower. In that case, knock yourself out. With the L98 cam and only 300 inches you should be looking at a smaller carb. 650 CFM or less.

If you really want 240 or more HP out of your 305 you need to toss the ported and polished stock heads and get some Trick Flow heads. They make a complete head with a small chamber suitable for a 300 inch build. To my knowledge they are the only aftermarket company to make serious pro grade 305 heads. Everyone else disregards the little mouse and concentrates on 350+ and 400+ small blocks. Heads for those blocks will require some serious machining to get a small enough chamber to work with 300 inches. Trick Flow make heads comparable to AFR in quality and power with the added benefit of a little more torque at the cost of some peak power. Perfect for a 305 G-Body. They are also significantly cheaper than AFR heads. Still pricey though at around $1000 but I don't think you will be able to make 250 HP with a 305 any other way without camming the thing right out of streetability.

Forgot to mention you manifold query. Edelbrock Performer or Performer RPM. Try to avoid the hype and stay away from the Air Gap model. Most small block Chevy 305s run best with a performer or Performer RPM depending on cam and heads. With your stock ported heads go with the Performer. If you splurge for the Trick Flows bump up to the RPM. The Air Gap will make more peak power but you will experience more drivability issues as the carb never really warms up properly and you'll have idle mixture troubles that seem to come and go for no apparent reason.

 

[Mayronus]

I was thinking abut this serup to my 5.0 v8 :
intake Weiand stelth summit : WND-8151 or X-celerator wnd-7546
Carb Holley double pumper 600cmf or Edelbrock performer 600cmf
What fuel pump shoul I use?

 

[Yoda]

Don't use the single plane.
Use the dual plane.

You don't have enough motor to require an aftermarket high volume fuel pump. The stock pump will be fine.

 

[85 Cutlass Brougham]

Don't use a double pumper carb! On that engine all it will do is use more gas without giving more performance. You want a Holley 1850 600cfm vacuum secondary if using a Holley, or better yet, get an Edelbrock 600. Your best choice would be a Rocheseter Quadrajet off a 305 powered something though. It's a 305. Also, 305 heads, ported or not, will not have much air flow. So, the engine will be limited to low RPM torque more than horsepower. That is why you want a dual plane intake (Edelbrock Performer or Wieand 8004 would be the best choices) and a vacuum secondary or air valve secondary style carb. Also, a stock mechanical fuel pump will serve your needs just fine. Besides, you really can't spin a stock 305 bottom end too high anyways before all the guts fly out of it, so this is the best plan for that engine. Trust us. We live with these engines every day and know what we are talking about! I run a Performer and a Quadrajet on my 350 with a HEI ignition, and my engine is making 350+ hp and 400+ ft/lbs of torque (what that is in the Metric system, I dunno as I don't know the conversion to Newton-Meters or PS).

For heads, I think the L35 Vortec heads off a 1996-99 light duty truck 350 would be your best choice. Cheap to buy, and I think they clear the 305's bore, but do some research first as I have never done anything to a 305. I always use a 350 or 400 instead. They may have been sold in Europe too. I know the 350 is used in Australia by Holden, and GM sells cars and trucks in Europe under Vauxhall, Isuzu and Opel. The Vauxhall Monaro, for example, is the same as the Holden Monaro and Pontiac GTO, and uses the new Gen III LSX series of engines, so maybe some vehicles with the older Gen I engines went there too.

 

[Yoda]

The truth is, in the larger picture, that very little work has gone into developing parts and power strategies specifically aimed at the 305. The restrictive heads, small bore and comparatively long stroke make it difficult to hop up.

As 85 CB just mentioned the 2 bolt mains limit the stress and RPM that can be imposed upon it. Your selection of parts makes one wonder if you aren't trying to turn it into a screamer. If that is so, you have an uphill battle in front of you and are likely to blow the thing up.

Stick to mild parts and aim for slow RPM torque.

If you are rebuilding the thing from the ground up you may want to investigate the possibility of stroking it and truly concentrating on torque. GM says the 305 block(s) have a maximum stroke potential of 3.75". The challenge would be finding pistons of that bore with a pin location suitable for the larger crank. I would imaging the new GM HT383 crank would likely drop right in depending on the rear seal. At 3.8" and therfore only .025" longer throw than a standard 400 crank I imagine pan rail clearance would not be difficult to achieve. You'd also want to get a different cam, though, with a smaller base circle diameter which would also require new pushrods and lifters. A big undertaking but if you are starting from scratch already and can't find a 350 it might be worth looking into. I don't have a calculator handy but I guess that would put you somewhere in the vicinity of 330 inches. With a 206/210 @.050 duration cam with a 110 LSA, the Trick Flow heads, (a thicker gasket, say .051 to .065") Performer RPM/Quadrajet combo and a decent ignition system you could make 275 HP and close to 350 lb/ft of torque. Again, the real challenge of that kind of buildup would be finding pistons and determining how to adjust the chamber size to achieve a reasonable compression ratio. It would be one helluva torqey 305 block, that's for sure. I also imagine your engine would be quite unique especially in your area.

If you are just bolting parts on stick with the mild route.

 

[Mayronus]

The best engine intake + carb should be : Weiand Action + (Summit WND-8004) or (Summit edl-2104)
Carb: Edel-1406 600cmf ? Stock fuel pump or go with electric one ? Fuel line ? Do I need to buy any bracket
like Trans kiskdown cable HLY-20-95 ? Fuel filter, When I remove ECM I need some thing For lockup : TCI 376600
That Will Do? What distributor I will need Full mechanical one ? Should I buy rev limiter to ?
Anything else i will need in MY swap From 3.8v6 to 5.0 tbi/carb ??
Sorry to be a paine but when I place the order on summit I dont wont to miss anything.



Ls1 brakes conversion A-Z
I've made some resarch and found That :
Front :
Cutlas Brackets :
http://cgi.ebay.com/ebaymotors/GRAND-NA ... 243608790&
+ new ls1 calipers,rotors,pads form rockauto
What brake lines should I use? Ls1 or from Cutlass ?

I need to remove Cutlass rotor from cutlass hub??? than Modify Spindle to fet properly New bracket ???

Rear:
Is this Proper way for Cutlass 84 7.5"/8.5" transaxe ?
http://www.thirdgen.org/ls1reardisc

Do I need to change Brake booster and master cylinder ???

Should I add anything else ???

Thank You !!

 

[85 Cutlass Brougham]

Stay away from the electric fuel pump. You just don't need it and it is expensive, and adds too much complexity. You will need a bracket for the kickdown linkage to the bell crank of the carb, unless you use the Quadrajet from 1976-1980 as it has the right geometry, and works with a stock carburated 305 throttle bracket. For a fuel line, you can make one out of tubing and some SAE (English) fittings. You can order one too, but making it is cheaper unless you do it wrong, which can be varying degrees of bad. Just don't put it anywhere near the positive post of the alternator or you will find out what that means. Also, watch out for wear areas where wires or lines could rub on metal and make a hole in the insulation or tubing.
You don't need a rev limiter unless you are going to drive it way outside the power band. You are probably safe to 6,000 RPMs and the automatic trans will upshift at full throttle way before that. Even if you are shifting manually it is likely you won't go too high as it would be pointless. I would recommend spending a little extra and getting MSD's HEI distributor for $150. I plan on buying one for my car when I am a little farther along. It is not made in China, but in the US so the parts are probably better than, say, Proform's parts.

If you go to the Engine forum, I wrote a complete list of everything needed for a 3.8 to 350 swap, and it is a sticky at the top of the page.

 

[Badlatitude]

Is there a reason you want to swap in a 305 over the 3.8 v6? IMHO the 3.8 is a great lil motor and well to be honest if you are going to jump thru hoops to get a chevy small block to poland WHY would you use a v8 motor that most guys rip out to swamp in a 350 the 305 is kind of like the b*st*rd step child of the small block family and not all small block parts fit them like with the 327s 350s and chevy 400s ect