I'm swapping a 350 into my 89 iroc which currently has a tpi 305 in it. I'm trying to do it cheaply as possible using parts I already have. I'll be using a 91 4 bolt truck 350 I have laying around. It currently has the stock cam and crappy tbi swirl ports. My plans are to pull the heads and cam and drill and tap the bosses for the spider tray. I'm planning on using an used roller cam out of an LT1 and reusing the roller lifters and hardware out of the 305 (unless there is a better budget friendly alternative you guys can recommend, I don't have the cam yet). I'm also planning on using the 305 tpi heads assuming they are better than the swirl ports currently on it. I will probably replace the valve seals while the heads are off. Can I get away with reusing the springs or should I just pick up a new set? If so what kind of springs should I use keeping with my low budget theme? Also what head gaskets do you guys recommend to keep the compression pump gas friendly? I'd like to reuse the stock valves that are in the heads unless that will cause problems.. What other odds and end will I need for my swap? I will be using a new knock sensor for a 350 tpi. I have a good set of injectors laying around from my 86 corvette, should I use them instead of the 305 injectors? Would the prom from my 86 vette work or will I need one from an f-body? Could I use the 305 prom and have it run reasonably well? While it's apart I will also replace the timing set with a double roller set. What am I forgetting? Any suggestions to make it run better? I will also be replacing all gaskets. Suggestions please!

 

If the truck 350 has a flat tappet cam in it now, get a budget summit flat tappet cam+lifter set for it Summit K1102 or K1103 will work very well. If the rear gears are low 2.73 ish use the K1102. will work fine with stock springs etc.
Bolt the 305 TPI heads and induction on the 350 and go. Any tuning issues will be minimual. It will run just fine.

 

it's flat tappet at the moment but has all the bosses for a roller cam, I already have all the nessicary hardware for a roller cam and I can get a used LT1 cam for under $40.. I figured that would be the way to go.. would it really be better to use a flat tappet when I can do a roller cam cheaper? I was also leaning toward the roller swap so if in the future I want to go bigger the holes will already be tapped and I won't have to do it while the engines in the car.. though I suppose I could just tap them now anyway even if I use a flat tappet cam for now.. Edit: I just looked at the cams you recommened and noticed they are slightly more aggressive than the LT1 cam.. What were the factory L98 cam specs for comparison?

 

You're going to get a bunch of metal filing in the motor when you try to drill for the spider. The K1102 cam will make as much or more power as the factory LT-1 cam will in your 350. It's a toss up. Are the tops of the lifter bosses completely machined ready for the roller lifter dog bones?

I would degree in and install the K1102 cam in a probabile "straight up" orientation with the same .050" intake valve closing point ABDC as the LT-1 cam goes in and call it good. You'll never know the difference.
If you want to get fancy, add 1.6 rockers to the intakes.
.447" in .442" ex net valve lift with the K1102 cam.

Does your 350 have a dished piston? If so use a thin steel shim head gasket
felpro 1094. Spend a bit of time home porting the 305 TPI heads and you'll be a motoring real good.

(If it was my motor Ii would degree in the Summit K1102 Cam so that the intake valve closes at 32 to 34deg ABDC @.050" lifter rise.)

 

I think your plan is a good one. As was mentioned above, make sure that the tops of the lifter bores are machined flat and ready to receive your dogbones. If not, it's a flat tappet cam like the K1102 in your future.

You'll also need to make sure the front of the block is drilled and tapped for the cam retaining plate (swap over from your 305 as well). There are 2 different bolt pattern retaining plates- narrow and wide. So if your block is drilled and tapped but you can't get the bolts to line up with your old 305 retaining plate you'll need to get a different/later model retaining plate. I don't know when the change-over year was between narrow and wide bolt pattern retaining plates. And, of course, you'll need a roller cam timing chain set to go with your factory-style roller cam.

The truck 350 almost certainly has dished pistons in it. With 305 heads on top you'll be in the mid 9s for compression, give or take. I would steer clear of thin steel shim head gaskets in this case as you don't know how flat the new 350 block and old 305 heads are. Get a cheap set of GMPP .028" compressed thickness composite head gaskets for only $32/pair at Scoggin Dickey and you won't have to worry if things aren't completely flat.

At some point, you're going to want to address the tuning issue. Agreed, a MAF TPI system like you've got is much more forgiving of changes in the engine's basic breathing, but you've got more than just 45 extra cubes to feed- you've also got a MUCH different cam in there than stock. Your original 1989 305/auto engine almost certainly has the "peanut cam" in it (do a search here for "peanut cam" and do some reading). It's a teeny tiny little sucker with very short duration and low lift. The LT1 roller or K1102, while not "large" cams by any stretch of the imagination, will be real fire-breathers compared to your original peanut cam. The combination of the extra cubes and bigger cam will make your factory tuning a fair bit off. Yes, it'll probably still run pretty good with the MAF to keep tabs on things, but tuning will probably pay good dividends when you can afford it.

 

AFAIK the only differences is that the holes arn't tapped but I have yet to start pulling the engine down since its in storage at my shops warehouse so I don't know for sure.. as far as the metal filings I was planning on masking tape on all the lifter bores and drain back holes I can and using rags to cover the rest and using a shop vac while drilling to keep filings to a minimum.. once I get it apart I'll decide I suppose.. it's just ironic that the flat tappet cam is the more expensive option for once!
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Thanks for the responces guys keep em coming!! Does anyone know if the prom from my L98 vette would work in the maro?

 

Sell your used hyd roller lifters and buy this Split 1.6/1.5 set of heavy duty rockers
http://www.competitionproducts.com/p...sp?number=6748
Elgin #6748 self aligning

Or split up a 1.6 ratio set with a friend. use 8 1.6 rockers on the intakes only
http://www.competitionproducts.com/p...sp?number=6738
Your cost is $40 each+shipping.

Elgin cam+lifter kit #E923M
http://www.competitionproducts.com/p...p?number=E923M

Or if you prefer with new springs and seals +cam and lifters
Elgin E923K
http://www.competitionproducts.com/p...p?number=E923K

You can easily prep your heads for 1.6:1 rockers by lengthening the push rod hole in the head using a 5/16" rat tail file in an electric drill. Lengthen the hole in the head towards the rocker stud a bit (about .030"). The hole is not that critical cause the rocker arm is self aligning but the push rod runs closer to the rocker stud with 1.6 ratio rockers.

 

thanks for the replys.. which cam would the 1.6's on the intakes benefit? Also should I swap in my L98 injectors or reuse the LB9 injectors?

 

Also today I got a used cam out of a 95 vette lt1 for free..the specs I found online are @.050" 205int 207exh .447"int .459"exh 117lsa... is that correct? Still not sure which way I'm going on the cam until I pull the intake off the 350 sometime this week but I'll take anything for free..

 

Yep, that sounds about right for specs to me. Mid 200s duration, mid 400s lift and a real wide LSA.

 

so it should work alright for my goals? The price was right.. hopefully the lifter bores are machined and all I have to do is some drilling and tapping.. if not a budget flat tappet cam it is.. I will also be disassembling the rotating assembly and giving the block a bath w/ a steam jenny and giving it a new rattle can paint job.. and throw a new set of rod and main bearings in it if everything looks good, hopefully I can just give the journals a lil polish.. it ran fine and had good oil pressure when it I pulled it so I'm keepin my fingers crossed.. hopefully we arn't too busy this week at work so I can make some progress..