Jimbo 89

I just bumped the "cam for L98" thread for those in doubt.
this might apply only to the 89's, not sure on that!!!

JAKE

I've been awaiting an explanation on the relationship between the alleged 10 degree cam timing retard and the 4500 RPM power drop too.

Years ago, when I owned a 86 TPI Vette, I did some research on it's power bottle-neck, which I'll share once the above has been cleared up.

Jake

DaNewmanator

So far I have not been able to confirm this but I am not doubting its true... I am running a Performance Cam in my Built L98 so I'm not concerned.

Just a thought, but if the cam timing was holding the L98 to 4500, why not just advance the CAM timing and run the TPI intake all day long at 6500 RPM??? Seem like the best bang for your buck

It's well documented that there is no comparison in Torque/Horsepower between the LT1 and TPI and actually the Horsepower gains are almost Identical to the mini ram. From what research I have done is that the TPI runners are known for there great low end torque and are what limit the L98 from making power at higher RPM's

JAKE

I just saw this remark and am wondering if you would elaborate "The hole is not important . . ."

Jake

DaNewmanator

Hey Jake, I believe he was referring to the tolerances in cutting the distributor hole. I took the comment as " it doesn't have to be exact as there is a little bit of wiggle room".

cv67

Its the runner length that limits the rpm...the fact it was designed for a 305 doesnt help. On the GM retarding the cam thing Id have to see some proof of that I find it hard to believe. Most cams you install 10deg retarded it wont even run.

redrose

advancing the cam will improve breathing, just EXACTLY what the tPi does NOT want as it's 'airflow challenged' from birth...'limited' air means going to hit 'the wall' at lower engine speed.

btw, what is the 'intake CL' noted on the cam timing card from your 'perf cam'...lemme guess, 106* ATDC (maybe a degree either way)...degree your oem cam and, lemme guess again, oem it was 116* int CL

rodj

Jake ,
the dist is fully supported and aligned by the block , not the intake which only serves as a hold down point.
If you make the hole in the intake slightly OS you can mock it up and weld the spacer in the correct location/angle rather than trying to guess where to position spacer

856SPEED

Glad I went w/the mini.....

cv67

So when you install an aftermarket cam how come it still hits the same TPI wall.

856SPEED

; WELL SAID BECAUSE THAT IS ONE OF THE STRANGEST POSTS I HAVE SEEN! SORRY....that struck me funny....cam degree??????

I always thought the wall at 4500 RPM is related to the L98 intake of course........LONNNNG RUNNERS!!!!!!!

should have just "re-degreed" my stock cam and ran that bitxx up to 6500 RPM with no choking.......would have saved myself a lot of headaches and cash

cv67

Especially with a non adjustable timing set.

redrose

actually i prefer to broach my own keyway in the 'correct'
location after prelim degree read...most 'adjustable' sets only have +4/0/ -4 and rarely can get 'right on'

tpi 421 vette

The runner length is just too long to support any high rpm hp. And as mentioned, it was designed for a 305.

And there is a forum member on here that had a converted LT1 intake that the dist hole wasn't deep enough, and it just barely was deep enough to drive the oil pump. Well on the dyno, it lost oil pressure and took out the engine because the distributor didn't have enough grip on the oil pump drive rod. And there was alot of other problems he ran ito to make a LT1 intake work on a first gen SBC.

I would go with a miniram, bolts right on, and everything is engineered out of the box to work. And the miniram has much bigger intake plenum and runners. If you look at the two side by side, there are alot of big differences.

pologreen1

After reading tpi 421 vette post, and you go cheap with a cobbled LT1 intake, you should know you were warned how easy the miniram is. Sure some have it, some have shops, and tools to make stuff work right, not that you don't but...

DaNewmanator

Hey Rodj,

I see you have a skinny distributor mocked up in your pic. Did you end up running that setup on your corvette? If so, what did you do to convert the HEI style wiring over for these connections?

Thanks,

Mike

JAKE

QUOTE=856SPEED;1572966811]; WELL SAID BECAUSE THAT IS ONE OF THE STRANGEST POSTS I HAVE SEEN! QUOTE]

STRANGE is putting it mildly!

One link says the LT1 intake has to have a distributor hole precisely drilled, yet another post says it doesn't matter and references "wiggle room".

Then we have the 10 degree cam retard assertion, where, on another thread, a stock cam is being compared to an aftermarket cam, each having different LSAs. The conclusion being drawn is that the stock cam is 10 degrees retarded. WOW! LOL

Maybe it's just a test. LOL

Jake

rodj

Somebody elses nice pics.I used same dist on my HSR.
Mike at www.eficonnection.com ( amounst others) does a adapter harness ($15) to connect from the big HEI harness connector to the small F-Body type dist so no cut / splice needed and your wiring stays stock.


You also need the 2 wire coil pigtail ($10) to connect your remote mount coil
See
http://www.eficonnection.com/eficonn..._pigtails.aspx

twin540

94-97 lt1 accel regulator exc. corvette
I don't know if it well work on you're aplication. Are the end adapters screwed on? You might need a remote regualator..

rodj

Aeromotive make several stock replacement LT1 regs like #13107. You can remove the return fitting made for stock hard lines and use a -6AN fitting for braided lines
If the end of the rail is already threaded you can just screw a # 13301 straight into the rail
( use heavy EFI 20- 65psi spring )
Pic shows a connection to other rail for balance; bypass return is at bottom