Just how bad is the come 304 manifold

Post by **delcowizzid** » Thu Mar 12, 2026 9:49 am

Well here it is i back to back tested the come twin throttle with a single plane edlebrock victor jr 4 barrel manifold on a 304. Was tuning the come on a 304 and made stupid low power and had atrocious fuel distribution issues. Swapped out the manifold and viola huge power gains hahaha purple is the come

20260312_184050.jpg

Post by **Gareth** » Thu Mar 12, 2026 8:23 pm

Thats a huge improvement!!!

What makes you say that it had fuel distribution issues with the COME?

onslaught · Post by **onslaught** » Thu Mar 12, 2026 10:07 pm

I dont suppose you had EGT/O2 per cylinder during your tests? What did the plugs look like after each pull?

Years ago a friend of mine modified the COME lid to reduce volume towards the rear and it fixed a lot of the problems but its a bit of screwing around and testing for what is already a very expensive manifold.

No one makes an OTS front entry manifold for the HV8 apart from COME (Redline used to/still make a tunnel ram for EFI heads but would need a fabricated lid/TB added etc) so its either spend a fortune or spend a fortune fixing the COME so for my project it's either spend a fortune or try not to look at the ugly elbow on a single plane I already have.

Post by **delcowizzid** » Thu Mar 12, 2026 11:51 pm

Gareth the plugs progressively got darker from front to back .had to add so much fuel to get the front in tune that the rear would start missfiring and the front were still real lean .

Post by **Gareth** » Thu Mar 12, 2026 11:56 pm

FAAARRRKKKK

MPC001 · Post by **MPC001** » Fri Mar 13, 2026 2:00 am

Amazing difference

Post by **vlad01** » Fri Mar 13, 2026 8:05 am

I can confirm they are shit. Gareth, don't know if you recall, it was actually on your dyno with HQ's car. It was down 75 Nm across the entire range except at the very peak hp and idle remaining about the same compared to the factory bananas. So basically, it turned a big toque mound into a flat plateau.

Post by **delcowizzid** » Fri Mar 13, 2026 8:09 am

Here's the plugs from the come vs the victer junior haha

20260204_091300.jpg

20260312_131323.jpg

Deuce · Post by **Deuce** » Fri Mar 13, 2026 8:10 am

delcowizzid wrote: Thu Mar 12, 2026 9:49 am Well here it is i back to back tested the come twin throttle with a single plane edlebrock victor jr 4 barrel manifold on a 304. Was tuning the come on a 304 and made stupid low power and had atrocious fuel distribution issues. Swapped out the manifold and viola huge power gains hahaha purple is the come
20260312_184050.jpg

Is this the:
10.2 comp, kelford 170-d, 304"?

I've seen a picture of the plugs, variation is wild.
Far more extreme than my combo front to rear... (I sent him pics to compare)

Maybe the manifold just prefers more motor under it

Deuce · Post by **Deuce** » Fri Mar 13, 2026 8:12 am

delcowizzid wrote: Fri Mar 13, 2026 8:09 am Here's the plugs from the come vs the victer junior haha
20260204_091300.jpg
20260312_131323.jpg

Ahh yes, top picture is the same one he sent me.

Glad to hear it's going better for him now.
Great work delcowiz

Just how bad is the come 304 manifold

Just how bad is the come 304 manifold

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Re: Just how bad is the come 304 manifold

Re: Just how bad is the come 304 manifold

Re: Just how bad is the come 304 manifold

Re: Just how bad is the come 304 manifold

Re: Just how bad is the come 304 manifold

Re: Just how bad is the come 304 manifold

Re: Just how bad is the come 304 manifold

Re: Just how bad is the come 304 manifold