10mpg

Mt Camaro has a blown motor, completely fubar, threw a rod out of the sump..

I have located a 305 from a 3rd gen, TBI

Mine is an IROC Z-28 TPI

This 'new' engine has roller rockers, and something called a 350 ramjet cam in it..?

Apparently the original cam can come with it..

My question is:

Will my standard TPI work with a TBI engine and this cam+ roller rockers? I like the TPI system it looks cool and has proved very reliable and great on fuel so I'd like to keep it..

Any thoughts?

sofakingdom

iTrader: (1)

The "RamJet" is a replacement engine from GM, with its own unique FI system. It has a real gentle cam that won't "make alot of power" but is quite friendly as far as compatibility.

I'd use that one rather than the TBI one. Not a real huge difference or anything; but ANY cam is better than the one TBI motors got.

I'd also STRONGLY suggest using your TPI heads. TBI heads have this enormous lump in the intake port that is highly restrictive, limiting the power potential to even less than TPI will allow. You will be thoroughly underwhelmed if you use them. Probably cost you 30 HP or so off of what your TPI motor made.

Atilla the Fun

The specs are a bit mild for the RamJet cam, but it makes off-idle torque like few others. and lower-range torque was the whole entire point of the TPI having such long runners. It makes a good match. Also agreed on using the TPI heads rather than the TBI heads.

10mpg

Thankyou, i suspected something like that.... I can't afford to loose any power from the original,

Is the compression ratio the same as my TPI?

Gordiggz

As long as the deck height is stock on the new block and you use the TPI heads and stock style gaskets, you should yield an identical compression ratio.

10mpg

If my TPI cam is ok would it be better to use that that the Ramcharger one?

Gordiggz

I'm not a cam expert, but it's 100000x easier to swap a cam with the motor out, so it'd be a safe bet to use the TPI cam.

Only concern then would be that the new motor has roller lifters. Alot of the TBI motors have holes already drilled in the lifter valley for the dog bones. Will need to tap the holes. If you search for some more info on roller lifters there's a ton of info.

Not sure what would happen if you just used regular lifters on the tpi cam.

10mpg

Sounds like a plan!

The only issue is, the seller told me this engine had a roller cam, which to my mind would make it a TPI not a TBI?

Chevy V8's are thin on the ground over here and even for a 305 quite expensive so i want to get the right one!

Gordiggz

Ramjet 350 cam specs:

Camshaft: Hydraulic roller tappet
Lift: .460" intake, .481" exhaust
Duration: 196° intake, 205° exhaust @.050" tappet lift

Centerline: 104° ATDC intake, 109° BTDC exhaust

Found this on another site for 87 305tpi/automatic:

Model
Tach
GM P/N
Lift
Duration
Lobe
Yelw
Red
In.
Ex.
In.
Ex.
Sep
In.
Ex.
1986-87
305 AT (LB9)
4500
5000
10088155
.350
.384
179
194
109.0
108
-112

Again I'm no expert, but if you weren't planning on tuning the ECM to accept the new cam, I'd stick with the TPI's original. It very well might work with the Rjet cam and TPI setup though. I just wouldn't chance it. Looks like that ramjet cam is definately a roller so the TPI cam should swap right in.

Gordiggz

Also found some guys talking about using it (RJ350 cam) on a TBI motor with good results:
https://www.thirdgen.org/forums/tech...ons-305-a.html

Maybe do a little more digging and see ifanybody runs it with TPI